Posted on by Tim Reyes

By Boots or Bots? How Shall We Explore?

Over forty years separate the step made by an Apollo astronaut and the cleated wheel of the Curiosity Rover on Mars. (Photo Credits: NASA)

With robotic spacecraft, we have explored, discovered and expanded our understanding of the Solar System and the Universe at large. Our five senses have long since reached their limits and cannot reveal the presence of new objects or properties without the assistance of extraordinary sensors and optics. Data is returned and is transformed into a format that humans can interpret.

Humans remain confined to low-Earth orbit and forty-three years have passed since humans last escaped the bonds of Earth’s gravity. NASA’s budget is divided between human endeavors and robotic and each year there is a struggle to find balance between development of software and hardware to launch humans or carry robotic surrogates. Year after year, humans continue to advance robotic capabilities and artificial intelligence (A.I.), and with each passing year, it becomes less clear how we will fit ourselves into the future exploration of the Solar System and beyond.

On July 21, 1969, Neil Armstrong photographed Buzz Aldrin on the Moon. The Apollo 13 astronauts hold the record as having been the most distant humans from Earth - 249,205 miles. Since December 1972, 42 years, the furthest humans have traveled from Earth is 347 miles - to service the Hubble space telescope. The Mars Science Laboratory, Curiosity Rover resides at least 34 million miles and as far as 249 million from Earth, while the Voyager 1 probe is 12,141,887,500 miles from Earth. Having traveled billions of miles and peered through billions of light years of space, NASA robotic vehicles have rewritten astronomical textbooks.(Photo Credits: NASA)
On July 21, 1969, Neil Armstrong photographed Buzz Aldrin on the Moon. The Apollo 13 astronauts hold the record as having been the most distant humans from Earth – 249,205 miles. Since December 1972, 42 years, the furthest humans have traveled from Earth is 347 miles (equivalent to SF to LA) – to service the Hubble space telescope. The Mars Science Laboratory, Curiosity Rover resides at least 34 million miles and as far as 249 million from Earth, while the Voyager 1 probe is 12,141,887,500 miles from Earth. Having traveled billions of miles and peered into billions of light years of space, NASA robotic vehicles have rewritten astronomical textbooks.(Photo Credits: NASA)

Is it a race in which we are unwittingly partaking that places us against our inventions? And like the aftermath of the Kasparov versus Deep Blue chess match, are we destined to accept a segregation as necessary? Allow robotics, with or without A.I., to do what they do best – explore space and other worlds?

In May 1997, Garry Kasparov accepted a rematch with Deep Blue and lost. In the 17 years since the defeat, the supercomputing power has increased by a factor of 50,000 (FLOPS). Furthermore, Chess software has steadily improved. Advances in space robotics have not relied on sheer computing performance but rather from steady advances in reliability, memory storage, nanotechnology, material science, software and more. (Photo Credit: Reuters)
In May 1997, Garry Kasparov accepted a rematch with Deep Blue and lost. In the 17 years since the defeat, super-computing power has increased by a factor of 50,000 (FLOPS). Furthermore, Chess software has steadily improved. Advances in space robotics have not relied on sheer computing performance but rather from steady advances in reliability, memory storage, nanotechnology, material science, software and more. (Photo Credit: Reuters)

Should we continue to find new ways and better ways to plug ourselves into our surrogates and appreciate with greater detail what they sense and touch? Consider how naturally our children engross themselves in games and virtual reality and how difficult it is to separate them from the technology. Or is this just a prelude and are we all antecedents of future Captain Kirks and Jean Luc Picards?

The NASA 2015 budget passed on December 13, 2014, a part of the Continuing Resolution & Omnibus Bill (HR 83). Distribution of funds, percent of the total budget, percent change relative to the 2014 budget and relative to the White House proposed 2015 budget are shown. (Credit: T.Reyes)
The NASA 2015 budget passed on December 13, 2014, as part of the Continuing Resolution & Omnibus Bill (HR 83). Each  chart segment lists the allocated funds, the percent of the total budget, the percent change relative to NASA’s 2014 budget and percent change relative to the 2015 White House budget request. (Credit: T.Reyes)

Approximately 55% of the NASA budget is in the realm of human spaceflight (HSF). This includes specific funds for Orion and SLS and half measures of supporting segments of the NASA agency, such as Cross-Agency Support, Construction and Maintenance. In contrast, appropriations for robotic missions – project development, operations, R&D – represent 39% of the budget.

The appropriation of funds has always favored human spaceflight, primarily because HSF requires costlier, heavier and more complex systems to maintain humans in the hostile environment of space. And while NASA budgets are not nearly weighted 2-to-1 in favor of human spaceflight, few would contest that the return on investment (ROI) is over 2-to-1 in favor of robotic driven exploration of space. And many would scoff at this ratio and counter that 3-to-1 or 4-to-1 is closer to the advantage robots have over humans.

For NASA enthusiasts, NASA Administrator Charles Bolden and Texas representative Lamar Smith chairman of the Committee on Science, Space and Technology in the 113th Congress have raised CSPAN coverage to episodes of high drama. The lines of questioning and decision making define the line in the sand between Capital Hill and the White House's vision of NASA's future. (Credit: CSPAN,Getty Images)
For NASA enthusiasts, NASA Administrator Charles Bolden and Texas representative Lamar Smith, chairman of the Committee on Science, Space and Technology in the 113th Congress, have raised CSPAN coverage to moments of high drama. The lines of questioning and decision making define the line in the sand between Capital Hill and the White House’s vision of NASA’s future. (Credit: CSPAN,Getty Images)

Politics play a significantly bigger role in the choice of appropriations to HSF compared to robotic missions. The latter is distributed among smaller budget projects and operations and HSF has always involved large expensive programs lasting decades. The big programs attract the interest of public officials wanting to bring capital and jobs to their districts or states.

NASA appropriations are complicated further by a rift between the White House and Capitol Hill along party lines. The Democrat-controlled White House has favored robotics and the use of private enterprise to advance NASA while Republicans on the Hill have supported the big human spaceflight projects; further complications are due to political divisions over the issue of Climate Change. How the two parties treat NASA is the opposite to, at least, how the public perceives the party platforms – smaller government or more social programs, less spending and supporting private enterprise. This tug of war is clearly seen in the NASA budget pie chart.

The House reduced the White House request for NASA Space Technology by 15% while increasing the funds for Orion and SLS by 16%. Space Technology represents funds that NASA would use to develop the Asteroid Redirect Mission (ARM), which the Obama administration favors as a foundation for the first use of SLS as part of a human mission to an asteroid. In contrast, the House appropriated $100 million to the Europa mission concept. Due to the delays of Orion and SLS development and anemic funding of ARM, the first use of SLS could be to send a probe to Europa.

While HSF appropriations for Space Ops & Exploration (effectively HSF) increased ~6% – $300 million, NASA Science gained ~2% – $100 million over the 2014 appropriations; ultimately set by Capitol Hill legislators. The Planetary Society, which is the Science Mission Directorate’s (SMD) staunchest supporter, has expressed satisfaction that the Planetary Science budget has nearly reached their recommended $1.5 billion. However, the increase is delivered with the requirement that $100 million shall be used for Europa concept development and is also in contrast to cutbacks in other segments of the SMD budget.

Note also that NASA Education and Public Outreach (EPO) received a significant boost from Republican controlled Capital Hill. In addition to the specific funding – a 2% increase over 2014 and 34% over the White House request, there is $42 million given specifically to the Science Mission Directorate (SMD) for EPO. The Obama Adminstration has attempted to reduce NASA EPO in favor of a consolidated government approach to improve effectiveness and reduce government.

The drive to explore beyond Earth’s orbit and set foot on new worlds is not just a question of finances. In retrospect, it was not finances at all and our remaining shackles to Earth was a choice of vision. Today, politicians and administrators cannot proclaim ‘Let’s do it again! Let’s make a better Shuttle or a better Space Station.’ There is no choice but to go beyond Earth orbit, but where?

From the Soyuz capsule, Space Shuttle Endeavour during Expedition 27 is docked to the International Space Station 220 miles above the Earth. Before Apollo 11 landed on the Moon, plans were underway to develop the next generation spacecraft that would lower the cost of human spaceflight and make trips routine. Forty years have passed since the Saturn rocket last flew and four years since the last Shuttle. Supporters on Capital Hill appear resigned to accept a replacement for the Shuttle, while inhernently safer, will cost $600 million per launch excluding the cost of the payload. SLS is destined to server both humand spaceflight and robotic missions. (Photo Credit: NASA)
From a Soyuz capsule, Space Shuttle Endeavour, during Expedition 27, is docked to the ISS, 220 miles above the Earth. Before even Apollo 11 landed on the Moon, plans were underway for the next generation spacecraft that would lower the cost of human spaceflight and make trips routine. Forty years have passed since the last Saturn rocket launch and four years since the last Shuttle. Legislators on Capital Hill appear ready to accept a replacement for the Shuttle that, while inherently safer, will cost $600 million per launch excluding the cost of the payload. The Space Launch System (SLS) is destined to serve both human spaceflight and robotic missions. (Photo Credit: NASA)

While the International Space Station program, led by NASA, now maintains a continued human presence in outer space, more people ask the question, ‘why aren’t we there yet?’ Why haven’t we stepped upon Mars or the Moon again, or anything other than Earth or floating in the void of low-Earth orbit. The answer now resides in museums and in the habitat orbiting the Earth every 90 minutes.

The retired Space Shuttle program and the International Space Station represent the funds expended on human spaceflight over the last 40 years, which is equivalent to the funds and the time necessary to send humans to Mars. Some would argue that the funds and time expended could have meant multiple human missions to Mars and maybe even a permanent presence. But the American human spaceflight program chose a less costly path, one more achievable – staying close to home.

Mars, the forbidden planet? No. The Amazing planet? Yes. Forboding? Perhaps. Radiation exposure, electronic or mechanical mishaps and years of zero or low gravity are the perils that the first Mars explorations face. But humanity's vision of landing on Mars remain just illustrations from the 1950s and 60s. Robotics encapsulated in the Mars Exploration Rover and Curiosity Rover has taken a select few virtually within arms length of the Martian surface through the panoramic views used to navigate the rovers from millions of miles away. (Photo Credit: Franklin Dixon, June 12, 1964 (left), MGM (right))
Mars, the forbidden planet? No. The Amazing planet? Yes. Foreboding? Perhaps. Radiation exposure, electronic or mechanical mishaps and years of zero or low gravity are the perils that the first Mars explorers face. But humanity’s vision of landing on Mars remains just illustrations from the ’50s and ’60s. A select few – Mars Rover navigators – have experienced the surface of Mars in virtual reality. (Photo Credits: Franklin Dixon, June 12, 1964 (left), MGM (right))

Ultimately, the goal is Mars. Administrators at NASA and others have become comfortable with this proclamation. However, some would say that it is treated more as a resignation. Presidents have been defining the objectives of human spaceflight and then redefining them. The Moon, Lagrangian Points or asteroids as waypoints to eventually land humans on Mars. Partial plans and roadmaps have been constructed by NASA and now politicians have mandated a roadmap. And politicians forced continuation of development of a big rocket; one which needs a clear path to justify its cost to taxpayers. One does need a big rocket to get anywhere beyond low-Earth orbit. However, a cancellation of the Constellation program – to build the replacement for the Shuttle and a new human-rated spacecraft – has meant delays and even more cost overruns.

During the ten years that have transpired to replace the Space Shuttle, with at least five more years remaining, events beyond the control of NASA and the federal government have taken place. Private enterprise is developing several new approaches to lofting payloads to Earth orbit and beyond. More countries have taken on the challenge. Spearheading this activity, independent of NASA or Washington plans, has been Space Exploration Technologies Corporation (SpaceX).

The launch of a SpaceX Falcon 9 is scheduled for Tuesday, December 5, 2015 and will include the return to Earth of the 1st stage Falcon core. Previous attempts landed the core into the Atlantic while this latest attempt will use a barge to attempt a full recovery. The successful soft landing and reuse of Falcon cores will be a major milestone in the history of spaceflight. (Photo Credits: SpaceX)
The launch of a SpaceX Falcon 9 is scheduled for Tuesday, December 5, 2015 and will include the return to Earth of the 1st stage Falcon core. Previous attempts landed the core into the Atlantic while this latest attempt will use a barge to attempt a full recovery. The successful soft landing and reuse of Falcon cores will be a major milestone in the history of spaceflight. (Photo Credits: SpaceX)

SpaceX’s Falcon 9 and soon to be Falcon Heavy represent alternatives to what was originally envisioned in the Constellation program with Ares I and Ares V. Falcon Heavy will not have the capability of an Ares V but at roughly $100 million per flight versus $600 million per flight for what Ares V has become – the Space Launch System (SLS) – there are those that would argue that ‘time is up.’ NASA has taken too long and the cost of SLS is not justifiable now that private enterprise has developed something cheaper and done so faster. Is Falcon Nine and Heavy “better”, as in NASA administrator Dan Golden’s proclamation – ‘Faster, Better, Cheaper’? Is it better than SLS technology? Is it better simply because its cheaper for lifting each pound of payload? Is it better because it is arriving ready-to-use sooner than SLS?

Humans will always depend on robotic launch vehicles, capsules and habitats laden with technological wonders to make our spaceflight possible. However, once we step out beyond Earth orbit and onto other worlds, what shall we do? From Carl Sagan to Steve Squyres, NASA scientists have stated that a trained astronaut could do in just weeks what the Mars rovers have required years to accomplish. How long will this hold up and is it really true?

Man versus Machine? All missions whether robotic or human spaceflight benefit mankind but the question is raised: how will human boots fit into the exploration of the universe that robotics has made possible. (Photo Credits: NASA, Illustration - J.Schmidt)
Man versus Machine? All missions whether robotic or human spaceflight benefit mankind but the question is raised: how will human boots fit into the exploration of the universe that robotics has made possible. (Photo Credits: NASA, Illustration – J.Schmidt)

Since Chess Champion Garry Kasparov was defeated by IBM’s Deep Blue, there have been 8 two-year periods representing the doubling of transistors in integrated circuits. This is a factor of 256. Arguably, computers have grown 100 times more powerful in the 17 years. However, robotics is not just electronics. It is the confluence of several technologies that have steadily developed over the 40 years that Shuttle technology stood still and at least 20 years that Space Station designs were locked into technological choices. Advances in material science, nano-technology, electro-optics, and software development are equally important.

While human decision making has been capable of spinning its wheels and then making poor choices and logistical errors, the development of robotics altogether is a juggernaut. While appropriations for human spaceflight have always surpassed robotics, advances in robotics have been driven by government investments across numerous agencies and by private enterprise. The noted futurist and inventor Ray Kurzweil who predicts the arrival of the Singularity by around 2045 (his arrival date is not exact) has emphasized that the surpassing of human intellect by machines is inevitable due to the “The Law of Accelerating Returns”. Technological development is a juggernaut.

In the same year that NASA was founded, 1958, the term Singularity was first used by mathematician John von Neumann to describe the arrival of artificial intelligence that surpasses humans.

Unknowingly, this is the foot race that NASA has been in since its creation. The mechanisms and electronics that facilitated landing men on the surface of the Moon never stopped advancing. And in that time span, human decisions and plans for NASA never stopped vacillating or stop locking existing technology into designs; suffering delays and cost overruns before launching humans to space.

David Hardy's illustration of the Daedalus Project envisioned by the British Interplanetary Society: a spacecraft to travel to the nearest stars. Advances in artificial intelligence and robotics leads one to ask who shall reside inside such a future vessel - robotic surrogates or human beings. (Credit: D. Hardy)
David Hardy’s illustration of the Daedalus Project envisioned by the British Interplanetary Society – a spacecraft to travel to the nearest stars. Advances in artificial intelligence and robotics leads one to wonder who shall reside inside such vessels of the future – robotic surrogates or human beings or something in between. (Credit: D. Hardy)

So are we destined to arrive on Mars and roam its surface like retired geologists and biologists wandering in the desert with a poking stick or rock hammer? Have we wasted too much time and has the window passed in which human exploration can make discoveries that robotics cannot accomplish faster, better and cheaper? Will Mars just become an art colony where humans can experience new sunrises and setting moons? Or will we segregate ourselves from our robotic surrogates and appreciate our limited skills and go forth into the Universe? Or will we mind meld with robotics and master our own biology just moments after taking our first feeble steps beyond the Earth?

An excerpt of page 3 of NASA's FY15 Agency Mission Planning Model (AMPM). The figure emphasizes the list of planned projects and missions for human spaceflight (HEOMD) and the Science Mission Directorate (SMD) which represents robotic development and missions. The comparison shows the cost advantage of robotics over human spaceflight. The robotic missions will amount to hundreds of years of combined mission lifetime in comparison to the HEOMD missions that are still limited to months by individual astronauts in flight.(Credit: NASA)
An excerpt of page 3 of NASA’s FY15 Agency Mission Planning Model (AMPM[alt]); a 20 year plan. This figure emphasizes the list of planned projects and missions for human spaceflight (HEOMD), orange, and the Science Mission Directorate (SMD), green, representing robotic development and missions. The lopsided list is indicative of the cost advantage of robotics over human spaceflight. The robotic missions will amount to hundreds of years of combined mission lifetime in comparison to the HEOMD missions that are still limited to months by individual astronauts in flight.(Credit: NASA)
References:

The CROmnibus Is Here with Strong Funding for NASA & NSF (AAS)

NASA Gets Big Increase in FY2015 Omnibus, NOAA Satellites Do OK (SpacePolicyOnline.com)

Here’s How Planetary Science Will Spend Its $1.44 Billion in 2015 (Planetary Society)

Posted on by Paul Patton

Defining Life II: Metabolism and Evolution as clues to Extraterrestrial Life

The James Webb Space Telescope, scheduled for launch in 2018 may be the first to be capable of detecting biomarker gasses in the atmospheres of extrasolar planets. When an exoplanet passes between its star and Earth, an event called a transit, light that has passed through the planet’s atmosphere can be detected from a vantage point near Earth. When light passes through the exoplanet’s atmosphere, some wavelengths are absorbed and others transmitted. By analyzing the transmitted light spectrum, astronomers can learn the composition of the planet’s atmosphere. Astrobiologists hope to find biomarker gasses indicating the metabolic waste products of life. The oxygen in Earth’s atmosphere is a waste product of photosynthesis in plants and bacteria. The Webb telescope may be capable of conducting this test for planets larger than Earth (super-earths) transiting small stars. Space telescopes capable of conducting such research on a larger scale have been delayed by budget cuts. Credit: NASA

In the movie “Avatar”, we could tell at a glance that the alien moon Pandora was teeming with alien life. Here on Earth though, the most abundant life is not the plants and animals that we are familiar with. The most abundant life is simple and microscopic. There are 50 million bacterial organisms in a single gram of soil, and the world wide bacterial biomass exceeds that of all plants and animals. Microbes can grow in extreme environments of temperature, salinity, acidity, radiation, and pressure. The most likely form in which we will encounter life elsewhere in our solar system is microbial.

Astrobiologists need strategies for inferring the presence of alien microbial life or its fossilized remains. They need strategies for inferring the presence of alien life on the distant planets of other stars, which are too far away to explore with spacecraft in the foreseeable future. To do these things, they long for a definition of life, that would make it possible to reliably distinguish life from non-life.

Unfortunately, as we saw in the first installment of this series, despite enormous growth in our knowledge of living things, philosophers and scientists have been unable to produce such a definition. Astrobiologists get by as best they can with definitions that are partial, and that have exceptions. Their search is geared to the features of life on Earth, the only life we currently know.

In the first installment, we saw how the composition of terrestrial life influences the search for extraterrestrial life. Astrobiologists search for environments that once contained or currently contain liquid water, and that contain complex molecules based on carbon. Many scientists, however, view the essential features of life as having to do with its capacities instead of its composition.

In 1994, a NASA committee adopted a definition of life as a “self-sustaining chemical system capable of Darwinian evolution”, based on a suggestion by Carl Sagan. This definition contains two features, metabolism and evolution, that are typically mentioned in definitions of life.

Metabolism is the set of chemical processes by which living things actively use energy to maintain themselves, grow, and develop. According to the second law of thermodynamics, a system that doesn’t interact with its external environment will become more disorganized and uniform with time. Living things build and maintain their improbable, highly organized state because they harness sources of energy in their external environment to power their metabolism.

Plants and some bacteria use the energy of sunlight to manufacture larger organic molecules out of simpler subunits. These molecules store chemical energy that can later be extracted by other chemical reactions to power their metabolism. Animals and some bacteria consume plants or other animals as food. They break down complex organic molecules in their food into simpler ones, to extract their stored chemical energy. Some bacteria can use the energy contained in chemicals derived from non-living sources in the process of chemosynthesis.

In a 2014 article in Astrobiology, Lucas John Mix, a Harvard evolutionary biologist, referred to the metabolic definition of life as Haldane Life after the pioneering physiologist J. B. S. Haldane. The Haldane life definition has its problems. Tornadoes and vorticies like Jupiter’s Great Red Spot use environmental energy to sustain their orderly structure, but aren’t alive. Fire uses energy from its environment to sustain itself and grow, but isn’t alive either.

Despite its shortcomings, astrobiologists have used Haldane definition to devise experiments. The Viking Mars landers made the only attempt so far to directly test for extraterrestrial life, by detecting the supposed metabolic activities of Martian microbes. They assumed that Martian metabolism is chemically similar to its terrestrial counterpart.

One experiment sought to detect the metabolic breakdown of nutrients into simpler molecules to extract their energy. A second aimed to detect oxygen as a waste product of photosynthesis. A third tried to show the manufacture of complex organic molecules out of simpler subunits, which also occurs during photosynthesis. All three experiments seemed to give positive results, but many researchers believe that the detailed findings can be explained without biology, by chemical oxidizing agents in the soil.

Viking Lander
In 1976, two Viking spacecraft landed on Mars. The image is of a model of the Viking lander, along with astronomer and pioneering astrobiologist Carl Sagan. Each lander was equipped with life detection experiments designed to detect life based on its metabolic activities. These activities were assumed to be chemically similar to those of Earthly organisms. The three experiments included: 1) The labeled release experiment, in which radioactively labeled organic nutrients were added to Martian soil. If organisms were present, it was assumed that their metabolism would involve breaking down the nutrients for their energy content and releasing labeled carbon dioxide as a waste product. 2) The gas exchange experiment, in which Martian soil was provided with nutrients and light and monitored for the release of oxygen. On Earth, organisms that capture the energy of sunlight through the process of photosynthesis, like plants and some bacteria, release oxygen as a waste product. 3) The pyrolytic release experiment, in which Martian soil was placed in a chamber with radioactively labeled carbon dioxide. If there were organisms in the soil that photosynthesized like those on Earth, their metabolic processes would take up the gas and use the energy of sunlight to manufacture more complex organic molecules. Radioactive carbon would be given off when those more complex molecules were broken down by heating the sample. All three experiments produced what seemed like positive results. However, most scientists rejected this interpretation because the details of many of the results could be explained by supposing that there were chemical oxidizing agents in the soil instead of life, and because Viking failed to detect organic materials in Martian soil. This interpretation, especially for the labeled release experiment, remains controversial to this day and may need to be revisited based on recent findings.
Credits: NASA/Jet Propulsion Laboratory, Caltech

Some of the Viking results remain controversial to this day. At the time, many researchers felt that the failure to find organic materials in Martian soil ruled out a biological interpretation of the metabolic results. The more recent finding that Martian soil actually does contain organic molecules that might have been destroyed by perchlorates during the Viking analysis, and that liquid water was once abundant on the surface of Mars lend new plausibility to the claim that Viking may have actually succeeded in detecting life. By themselves, though, the Viking results didn’t prove that life exists on Mars nor rule it out.

The metabolic activities of life may also leave their mark on the composition of planetary atmospheres. In 2003, the European Mars Express spacecraft detected traces of methane in the Martian atmosphere. In December 2014, a team of NASA scientists reported that the Curiosity Mars rover had confirmed this finding by detected atmospheric methane from the Martian surface.

Most of the methane in Earth’s atmosphere is released by living organisms or their remains. Subterranean bacterial ecosystems that use chemosynthesis as a source of energy are common, and they produce methane as a metabolic waste product. Unfortunately, there are also non-biological geochemical processes that can produce methane. So, once more, Martian methane is frustratingly ambiguous as a sign of life.

Extrasolar planets orbiting other stars are far too distant to visit with spacecraft in the foreseeable future. Astrobiologists still hope to use the Haldane definition to search for life on them. With near future space telescopes, astronomers hope to learn the composition of the atmospheres of these planets by analyzing the spectrum of light wavelengths reflected or transmitted by their atmospheres. The James Webb Space Telescope scheduled for launch in 2018, will be the first to be useful in this project. Astrobiologists want to search for atmospheric biomarkers; gases that are metabolic waste products of living organisms.

Once more, this quest is guided by the only example of a life-bearing planet we currently have; Earth. About 21% of our home planet’s atmosphere is oxygen. This is surprising because oxygen is a highly reactive gas that tends to enter into chemical combinations with other substances. Free oxygen should quickly vanish from our air. It remains present because the loss is constantly being replaced by plants and bacteria that release it as a metabolic waste product of photosynthesis.

Traces of methane are present in Earth’s atmosphere because of chemosynthetic bacteria. Since methane and oxygen react with one another, neither would stay around for long unless living organisms were constantly replenishing the supply. Earth’s atmosphere also contains traces of other gases that are metabolic byproducts.

In general, living things use energy to maintain Earth’s atmosphere in a state far from the thermodynamic equilibrium it would reach without life. Astrobiologists would suspect any planet with an atmosphere in a similar state of harboring life. But, as for the other cases, it would be hard to completely rule out non-biological possibilities.

Besides metabolism, the NASA committee identified evolution as a fundamental ability of living things. For an evolutionary process to occur there must be a group of systems, where each one is capable of reliably reproducing itself. Despite the general reliability of reproduction, there must also be occasional random copying errors in the reproductive process so that the systems come to have differing traits. Finally, the systems must differ in their ability to survive and reproduce based on the benefits or liabilities of their distinctive traits in their environment. When this process is repeated over and over again down the generations, the traits of the systems will become better adapted to their environment. Very complex traits can sometimes evolve in a step-by-step fashion.

Mix named this the Darwin life definition, after the nineteenth century naturalist Charles Darwin, who formulated the theory of evolution. Like the Haldane definition, the Darwin life definition has important shortcomings. It has trouble including everything that we might think of as alive. Mules, for example, can’t reproduce, and so, by this definition, don’t count as being alive.

Despite such shortcomings, the Darwin life definition is critically important, both for scientists studying the origin of life and astrobiologists. The modern version of Darwin’s theory can explain how diverse and complex forms of life can evolve from some initial simple form. A theory of the origin of life is needed to explain how the initial simple form acquired the capacity to evolve in the first place.

The chemical systems or life forms found on other planets or moons in our solar system might be so simple that they are close to the boundary between life and non-life that the Darwin definition establishes. The definition might turn out to be vital to astrobiologists trying to decide whether a chemical system they have found really qualifies as a life form. Biologists still don’t know how life originated. If astrobiologists can find systems near the Darwin boundary, their findings may be pivotally important to understanding the origin of life.

Can astrobiologists use the Darwin definition to find and study extraterrestrial life? It’s unlikely that a visiting spacecraft could detect to process of evolution itself. But, it might be capable of detecting the molecular structures that living organisms need in order to take part in an evolutionary process. Philosopher Mark Bedau has proposed that a minimal system capable of undergoing evolution would need to have three things: 1) a chemical metabolic process, 2) a container, like a cell membrane, to establish the boundaries of the system, and 3) a chemical “program” capable of directing the metabolic activities.

Here on Earth, the chemical program is based on the genetic molecule DNA. Many origin-of-life theorists think that the genetic molecule of the earliest terrestrial life forms may have been the simpler molecule ribonucleic acid (RNA). The genetic program is important to an evolutionary process because it makes the reproductive copying process stable, with only occasional errors.

Both DNA and RNA are biopolymers; long chainlike molecules with many repeating subunits. The specific sequence of nucleotide base subunits in these molecules encodes the genetic information they carry. So that the molecule can encode all possible sequences of genetic information it must be possible for the subunits to occur in any order.

Steven Benner, a computational genomics researcher, believes that we may be able to develop spacecraft experiments to detect alien genetic biopolymers. He notes that DNA and RNA are very unusual biopolymers because changing the sequence in which their subunits occur doesn’t change their chemical properties. It is this unusual property that allows these molecules to be stable carriers of any possible genetic code sequence.

DNA and RNA are both polyelectrolytes; molecules with regularly repeating areas of negative electrical charge. Benner believes that this is what accounts for their remarkable stability. He thinks that any alien genetic biopolymer would also need to be a polyelectrolyte, and that chemical tests could be devised by which a spacecraft might detect such polyelectrolyte molecules. Finding the alien counterpart of DNA is a very exciting prospect, and another piece to the puzzle of identifying alien life.

Structure of DNA
Deoxyribonucleic acid (DNA) is the genetic material for all known life on Earth. DNA is a biopolymer consisting of a string of subunits. The subunits consist of nucleotide base pairs containing a purine (adenine A, or guanine G) and a pyrimidine (thymine T, or cytosine C). DNA can contain nucleotide base pairs in any order without its chemical properties changing. This property is rare in biopolymers, and makes it possible for DNA to encode genetic information in the sequence of its base pairs. This stability is due to the fact that each base pair contains phosphate groups (consisting of phosphorus and oxygen atoms) on the outside with a net negative charge. These repeated negative charges make DNA a polyelectrolyte. Computational genomics researcher Steven Benner has hypothesized that alien genetic material will also be a polyelectrolyte biopolymer, and that chemical tests could therefore be devised to detect alien genetic molecules.
Credit: Zephyris

In 1996 President Clinton, made a dramatic announcement of the possible discovery of life on Mars. Clinton’s speech was motivated by the findings of David McKay’s team with the Alan Hills meteorite. In fact, the McKay findings turned out to be just one piece to the larger puzzle of possible Martian life. Unless an alien someday ambles past our waiting cameras, the question of whether or not extraterrestrial life exists is unlikely to be settled by a single experiment or a sudden dramatic breakthrough. Philosophers and scientists don’t have a single, sure-fire definition of life. Astrobiologists consequently don’t have a single sure-fire test that will settle the issue. If simple forms of life do exist on Mars, or elsewhere in the solar system, it now seems likely that that fact will emerge gradually, based on many converging lines of evidence. We won’t really know what we’re looking for until we find it.

References and further reading:

P. S. Anderson (2011) Could Curiosity Determine if Viking Found Life on Mars?, Universe Today.

S. K. Atreya, P. R. Mahaffy, A-S. Wong, (2007), Methane and related trace species on Mars: Origin, loss, implications for life, and habitability, Planetary and Space Science, 55:358-369.

M. A. Bedau (2010), An Aristotelian account of minimal chemical life, Astrobiology, 10(10): 1011-1020.

S. A. Benner (2010), Defining life, Astrobiology, 10(10):1021-1030.

E. Machery (2012), Why I stopped worrying about the definition of life…and why you should as well, Synthese, 185:145-164.

G. M. Marion, C. H. Fritsen, H. Eicken, M. C. Payne, (2003) The search for life on Europa: Limiting environmental factors, potential habitats, and Earth analogs. Astrobiology 3(4):785-811.

L. J. Mix (2015), Defending definitions of life, Astrobiology, 15(1) posted on-line in advance of publication.

P. E. Patton (2014) Moons of Confusion: Why Finding Extraterrestrial Life may be Harder than we Thought, Universe Today.

T. Reyes (2014) NASA’s Curiosity Rover detects Methane, Organics on Mars, Universe Today.

S. Seeger, M. Schrenk, and W. Bains (2012), An astrophysical view of Earth-based biosignature gases. Astrobiology, 12(1): 61-82.

S. Tirard, M. Morange, and A. Lazcano, (2010), The definition of life: A brief history of an elusive scientific endeavor, Astrobiology, 10(10):1003-1009.

C. R. Webster, and numerous other members of the MSL Science team, (2014) Mars methane detection and variability at Gale crater, Science, Science express early content.

Did Viking Mars landers find life’s building blocks? Missing piece inspires new look at puzzle. Science Daily Featured Research Sept. 5, 2010

NASA rover finds active and ancient organic chemistry on Mars, Jet Propulsion laboratory, California Institute of Technology, News, Dec. 16, 2014.

Posted on by Paul Patton

Defining Life I: What are Astrobiologists Looking For?

In December, 2014 researchers in the Mars Science Laboratory Project announced that they had made the first definitive detection of organic materials on the surface of Mars. The sample was taken on May 19, 2013 from a rock that mission controllers named “Cumberland”. The Curiosity Mars rover drilled a hole 1.6 cm wide and 6.6 cm deep in the Martian rock. Powered rock from the hole was delivered to the rover’s Sample Analysis at Mars (SAM) instrument for analysis. The scientists drew their conclusions only after months of careful analysis. The identity and complexity of the organic substances remains uncertain, because they may have been altered by perchlorates that were also present in the rock, when the material was heated for analysis. The Viking Mars landers of 1976 had earlier failed to detect organic materials on Mars. Credits: NASA/Jet Propulsion Laboratory, Caltech

How can astrobiologists find extraterrestrial life? In everyday life, we usually don’t have any problem telling that a dog or a rosebush is a living thing and a rock isn’t. In the climatic scene of the movie ‘Europa Report’ we can tell at a glance that the multi-tentacled creature discovered swimming in the ocean of Jupiter’s moon Europa is alive, complicated, and quite possibly intelligent.

But unless something swims, walks, crawls, or slithers past the cameras of a watching spacecraft, astrobiologists face a much tougher job. They need to devise tests that will allow them to infer the presence of alien microbial life from spacecraft data. They need to be able to recognize fossil traces of past alien life. They need to be able to determine whether the atmospheres of distant planets circling other stars contain the tell-tale traces of unfamiliar forms of life. They need ways to infer the presence of life from knowledge of its properties. A definition of life would tell them what those properties are, and how to look for them. This is the first of a two part series exploring how our concept of life influences the search for extraterrestrial life.

What is it that sets living things apart? For centuries, philosophers and scientists have sought an answer. The philosopher Aristotle (384-322 BC) devoted a great deal of effort to dissecting animals and studying living things. He supposed that they had distinctive special capacities that set them apart from things that aren’t alive. Inspired by the mechanical inventions of his times, the Renaissance philosopher Rene Descartes (1596-1650) believed that living things were like clockwork machines, their special capacities deriving from the way their parts were organized.

In 1944, the physicist Erwin Schrödinger (1887-1961) wrote What is Life? In it, he proposed that the fundamental phenomena of life, including even how parents pass on their traits to their offspring, could be understood by studying the physics and chemistry of living things. Schrödinger’s book was an inspiration to the science of molecular biology.

Living organisms are made of large complicated molecules with backbones of linked carbon atoms. Molecular biologists were able to explain many of the functions of life in terms of these organic molecules and the chemical reactions they undergo when dissolved in liquid water. In 1955 James Watson and Francis Crick discovered the structure of deoxyribonucleic acid (DNA) and showed how it could be the storehouse of hereditary information passed from parent to offspring.

While all this research and theorizing has vastly increased our understanding of life, it hasn’t produced a satisfactory definition of life; a definition that would allow us to reliably distinguish things that are alive from things that aren’t. In 2012 the philosopher Edouard Mahery argued that coming up with a single definition of life was both impossible and pointless. Astrobiologists get by as best they can with definitions that are partial, and that have exceptions. Their search is conditioned by our knowledge of the specific features of life on Earth; the only life we currently know.

Here on Earth, living things are distinctive in their chemical composition. Besides carbon, the elements hydrogen, nitrogen, oxygen, phosphorus, and sulfur are particularly important to the large organic molecules that make up terrestrial life. Water is a necessary solvent. Since we don’t know for sure what else might be possible, the search for extraterrestrial life typically assumes its chemical composition will be similar to that of life on Earth.

Making use of that assumption, astrobiologists assign a high priority to the search for water on other celestial bodies. Spacecraft evidence has proven that Mars once had bodies of liquid water on its surface. Determining the history and extent of this water is a central goal of Mars exploration. Astrobiologists are excited by evidence of subsurface oceans of water on Jupiter’s moon Europa, Saturn’s moon Enceladus, and perhaps on other moons or dwarf planets. But while the presence of liquid water implies conditions appropriate for Earth-like life, it doesn’t prove that such life exists or has ever existed.

Europa
Jupiter’s icy moon Europa appears to host liquid water, an essential condition for life as we know it on Earth. Its surface is covered with a crust of water ice. The Voyager and Galileo spacecraft have provided evidence that under this icy crust, there is an ocean of saltwater, containing more liquid water than all the oceans of Earth. Europa’s interior is heated by gravitational tidal forces exerted by giant Jupiter. This heat energy may drive volcanism, hydrothermal vents, and the production of chemical energy sources that living things could make use of. Interaction between materials from Europa’s surface and the ocean environment beneath could make available carbon and other chemical elements essential for Earth-like life.
Credits: NASA/Jet Propulsion Laboratory, SETI Institute

Organic chemicals are necessary for Earth-like life, but, as for water, their presence doesn’t prove that life exists, because organic materials can also be formed by non-biological processes. In 1976, NASA’s two Viking landers were the first spacecraft to make fully successful landings on Mars. They carried an instrument; called the gas chromatograph-mass spectrometer, that tested the soil for organic molecules.

Even without life, scientists expected to find some organic materials in the Martian soil. Organic materials formed by non-biological processes are found in carbonaceous meteorites, and some of these meteorites should have fallen on Mars. They were surprised to find nothing at all. At the time, the failure to find organic molecules was considered a major blow to the possibility of life on Mars.

In 2008, NASA’s Phoenix lander discovered an explanation of why Viking didn’t detect organic molecules. If found that the Martian soil contains perchlorates. Containing oxygen and chlorine, perchlorates are oxidizing agents that can break down organic material. While perchlorates and organic molecules could coexist in Martian soil, scientists determined that heating the soil for the Viking analysis would have caused the perchlorates to destroy any organic material it contained. Martian soil might contain organic materials, after all.

At a news briefing in December 2014, NASA announced that an instrument carried on board the Curiosity Mars rover had succeeded in detected simple organic molecules on Mars for the first time. Researchers believe it is possible that the molecules detected may be breakdown products of more complex organic molecules that were broken down by perchlorates during the process of analysis.

electron micrograph of Mars meteorite
In 1996 a team of scientists lead by Dr. David McKay of NASA’s Johnson Space Center announced possible evidence of life on Mars. The evidence came from their studies of a Martian meteorite found in Antarctica, called Alan Hills 84001. The researchers found chemical and physical traces of possible life including carbonate globules that resemble terrestrial nanobacteria (electron micrograph shown) and polycyclic aromatic hydrocarbons. In terrestrial rock, the chemical traces would be considered breakdown products of bacterial life. The findings became the subject of controversy as non-biological explanations for the findings were found. Today, they are no longer regarded as definitive evidence of Martian life.
Credits: NASA Johnson Space Center

The chemical make-up of terrestrial life has also guided the search for traces of life in Martian meteorites. In 1996 a team of investigators lead by David McKay of the Johnson Space Center in Houston reported evidence that a Martian meteorite found at Alan Hills in Antarctica in 1984 contained chemical and physical evidence of past Martian life.

There have since been similar claims about other Martian meteorites. But, non-biological explanations for many of the findings have been proposed, and the whole subject has remained embroiled in controversy. Meteorites have not so far yielded the kind of evidence needed to prove the existence of extraterrestrial life beyond reasonable doubt.

Following Aristotle, most scientists prefer to define life in terms of its capacities rather than its composition. In the second installment, we will explore how our understanding of life’s capacities has influenced the search for extraterrestrial life.

References and further reading:

N. Atkinson (2009) Perchlorates and Water Make for Potential Habitable Environment on Mars, Universe Today.

S. A. Benner (2010), Defining life, Astrobiology, 10(10):1021-1030.

E. Machery (2012), Why I stopped worrying about the definition of life…and why you should as well, Synthese, 185:145-164.

L. J. Mix (2015), Defending definitions of life, Astrobiology, 15(1) posted on-line in advance of publication.

T. Reyes (2014) NASA’s Curiosity Rover detects Methane, Organics on Mars, Universe Today.

S. Tirard, M. Morange, and A. Lazcano, (2010), The definition of life: A brief history of an elusive scientific endeavor, Astrobiology, 10(10):1003-1009.

Did Viking Mars landers find life’s building blocks? Missing piece inspires new look at puzzle. Science Daily Featured Research Sept. 5, 2010

NASA rover finds active and ancient organic chemistry on Mars, Jet Propulsion laboratory, California Institute of Technology, News, Dec. 16, 2014.

Europa: Ingredients for Life?, National Aeronautics and Space Administration.

Posted on by Matt Williams

Student Team Wants to Terraform Mars Using Cyanobacteria

Living Mars. Credit: Kevin Gill
Artist concept of a 'Living' Mars. Credit: Kevin Gill

While scientists believe that at one time, billions of years ago, Mars had an atmosphere similar to Earth’s and was covered with flowing water, the reality today is quite different. In fact, the surface of Mars is so hostile that a vacation in Antarctica would seem pleasant by comparison.

In addition to the extreme cold, there is little atmosphere to speak of and virtually no oxygen. However, a team of students from Germany wants to change that. Their plan is to introduce cyanobacteria into the atmosphere which would convert the ample supplies of CO² into oxygen gas, thus paving the way for possible settlement someday.

The team, which is composed of students and volunteer scientists from the University of Applied Science and the Technical University in Darmstadt, Germany, call their project “Cyano Knights”. Basically, they plan to seed Mars’ atmosphere with cyanobacteria so it can convert Mars’ most abundant gas (CO2, which accounts for 96% of the Martian atmosphere) into something breathable by humans.

The Mars One University Competition poster. Credit: Mars One
Promotional image for the Mars One University Competition. Credit: Mars One

Along with teams from other universities and technical colleges taking part in the Mars One University Competition, the Cyano Knights hope that their project will be the one sent to the Red Planet in advance of the company’s proposed settlers.

This competition officially began this past summer, as part of the Mars One’s drive to enlist the support and participation of universities from all around the world. All those participating will have a chance to send their project aboard the company’s first unmanned lander, which will be sent to Mars in 2018.

Working out of the laboratory of Cell Culture Technology of the University of Applied Science, the Cyano Knights selected cyanobacteria because of its extreme ruggedness. Here on Earth, the bacteria lives in conditions that are hostile to other life forms, hence why they seemed like the perfect candidate.

As the team leader Robert P. Schröder, said to astrowatch.net: “Cyanobacteria do live in conditions on Earth where no life would be expected. You find them everywhere on our planet! It is the first step on Mars to test microorganisms.”

Cyanobacteria Spirulina. Credit: cyanoknights.bio
Cyanobacteria Spirulina. Credit: cyanoknights.bio

The other reason for sending cyanobacteria to Mars, in advance of humans, is the biological function they perform. As an organism that produces oxygen gas through photosynthesis to obtain nutrients, cyanobacteria are thought to have played a central role in the evolution of Earth’s atmosphere.

It is estimated that 2.7 billion years ago, they were pivotal in converting it from a toxic fume to the nitrogen and oxygen-rich one that we all know and love. This, in turn, led to the formation of the ozone layer which blocks out harmful UV rays and allowed for the proliferation of life.

According to their project description, the cyanobacteria, once introduced, will “deliver oxygen made of their photosynthesis, reducing carbon dioxide and produce an environment for living organisms like us. Furthermore, they can supply food and important vitamins for a healthy nutrition.”

Of course, the team is not sure how much of the bacteria will be needed to make a dent in Mars’ carbon-rich atmosphere, nor how much of the oxygen could be retained. But much like the other teams taking part in this competition, the goal here is to find out how terrestrial organisms will fare in the Martian environment.

Artist's concept of a Martian astronaut standing outside the Mars One habitat. Credit: Bryan Versteeg/Mars One
Artist’s concept of a Martian astronaut standing outside the Mars One habitat. Credit: Bryan Versteeg/Mars One

The Cyano Knights hope that one day, manned mission will be able to take advantage of the oxygen created by these bacteria by either combining it with nitrogen to create breathable air, or recuperating it for consumption over and over again.

Not only does their project call for the use of existing technology, it also takes advantage of studies being conducted by NASA and other space agencies. As it says on their team page: “On the international space station they do experiments with cyanobacteria too. So let us take it to the next level and investigate our toughest life form on Mars finding the best survival species for mankind! We are paving the way for future Mars missions, not only to have breathable air!”

Other concepts include germinating seeds on Mars to prove that it is possible to grow plants there, building a miniature greenhouse, measuring the impact of cosmic surface and solar radiation on the surface, and processing urine into water.

All of these projects are aimed at obtaining data that will contribute to our understanding of the Martian landscape and be vital to any human settlements or manned missions there in the future.

For more information on the teams taking part in the competition, and to vote for who you would like to win, visit the Mars One University Competition page. Voting submission will be accepted until Dec. 31, 2014 and the winning university payload will be announced on Jan. 5, 2015.

Further Reading: CyanoKnights, MarsOne University Competition

Posted on by Vanessa Janek

Gamma Ray Bursts Limit The Habitability of Certain Galaxies, Says Study

An artistic image of the explosion of a star leading to a gamma-ray burst. (Source: FUW/Tentaris/Maciej Fro?ow)

Gamma ray bursts (GRBs) are some of the brightest, most dramatic events in the Universe. These cosmic tempests are characterized by a spectacular explosion of photons with energies 1,000,000 times greater than the most energetic light our eyes can detect. Due to their explosive power, long-lasting GRBs are predicted to have catastrophic consequences for life on any nearby planet. But could this type of event occur in our own stellar neighborhood? In a new paper published in Physical Review Letters, two astrophysicists examine the probability of a deadly GRB occurring in galaxies like the Milky Way, potentially shedding light on the risk for organisms on Earth, both now and in our distant past and future.

There are two main kinds of GRBs: short, and long. Short GRBs last less than two seconds and are thought to result from the merger of two compact stars, such as neutron stars or black holes. Conversely, long GRBs last more than two seconds and seem to occur in conjunction with certain kinds of Type I supernovae, specifically those that result when a massive star throws off all of its hydrogen and helium during collapse.

Perhaps unsurprisingly, long GRBs are much more threatening to planetary systems than short GRBs. Since dangerous long GRBs appear to be relatively rare in large, metal-rich galaxies like our own, it has long been thought that planets in the Milky Way would be immune to their fallout. But take into account the inconceivably old age of the Universe, and “relatively rare” no longer seems to cut it.

In fact, according to the authors of the new paper, there is a 90% chance that a GRB powerful enough to destroy Earth’s ozone layer occurred in our stellar neighborhood some time in the last 5 billion years, and a 50% chance that such an event occurred within the last half billion years. These odds indicate a possible trigger for the second worst mass extinction in Earth’s history: the Ordovician Extinction. This great decimation occurred 440-450 million years ago and led to the death of more than 80% of all species.

Today, however, Earth appears to be relatively safe. Galaxies that produce GRBs at a far higher rate than our own, such as the Large Magellanic Cloud, are currently too far from Earth to be any cause for alarm. Additionally, our Solar System’s home address in the sleepy outskirts of the Milky Way places us far away from our own galaxy’s more active, star-forming regions, areas that would be more likely to produce GRBs. Interestingly, the fact that such quiet outer regions exist within spiral galaxies like our own is entirely due to the precise value of the cosmological constant – the factor that describes our Universe’s expansion rate – that we observe. If the Universe had expanded any faster, such galaxies would not exist; any slower, and spirals would be far more compact and thus, far more energetically active.

In a future paper, the authors promise to look into the role long GRBs may play in Fermi’s paradox, the open question of why advanced lifeforms appear to be so rare in our Universe. A preprint of their current work can be accessed on the ArXiv.

Posted on by Joshua Carroll

Spectroscopy: The Key to Humanity’s Future in Space

Credit: NASA/JPL/CalTECH/IPAC

Imagine, if you would, a potential future for humanity… Imagine massive space-elevators lifting groups of men, women, and children skyward off Earth’s surface. These passengers are then loaded onto shuttles and ferried to the Moon where interstellar starships are docked, waiting to rocket to the stars. These humans are about to begin the greatest journey humanity has ever embarked upon, as they will be the first interstellar colonists to leave our home Solar System in order to begin populating other worlds around alien stars.

There are many things we must tackle first before we can make this type of science-fiction scene a reality. Obviously much faster methods of travel are needed, as well as some sort of incredible material that can serve to anchor the aforementioned space elevators. These are all scientific and engineering questions that humanity will need to overcome in the face of such a journey into the cosmos.

But there is one particular important feature that we can begin to tackle today: where do we point these starships? Towards which system of exoplanets are we to send our brave colonists?

Of all of the amazing things we need to discover or invent to make this scene a reality, discovering which worlds to aim our ships at is something that is actually being worked on today.

Artistic view of a possible space elevator. Image Credit: NASA
Artistic view of a possible space elevator. Image Credit: NASA

It’s an exciting era in astronomy, as astronomers are currently discovering that many of the stars that we view in the night sky have their own planets in orbit around them. Many of them are massive worlds, all orbiting at varying distances from their parent star. It is no surprise that we are discovering a vast majority of these Jupiter-sized worlds first; larger worlds are much easier to detect than the smaller worlds would be. Imagine a bright spotlight pointing at you some 500 yards away (5 football fields). Your job is to detect something the size of a period on this page that is orbiting around it that emits no light of its own. As you can see, the task would be daunting. But nevertheless, our planet hunters have been utilizing methods that enable us to accurately find these tiny specks of gas and rock despite their rather large and luminous companion suns.

However, it is not the method of finding these planets that this article is about; but rather what we do to figure out which of these worlds are worthy of our limited resources and attention. We very well cannot point those starships in random directions and just hope that they happen across an earth-sized planet that has a nitrogen-oxygen rich atmosphere with drinkable water. We need to identify which planets appear to have these mentioned characteristics before we go launching ourselves into the vast universe.

How can we do this? How is it possible that we are able to say with any level of certainty what a planet’s atmosphere is composed of when this planet is so small and so very far away? Spectroscopy is the answer, and it just might be the key to our future in the cosmos.

Artistic impression of what Kepler-186f may look like. Image Credit: NASA Ames/SETI Institute/JPL-CalTech
Artistic impression of what Kepler-186f may look like. Image Credit: NASA Ames/SETI Institute/JPL-CalTech

Just so I may illustrate how remarkable our scientific methods are for this very field of research, I will first need to show you the distances we are talking about. Let’s take Kepler 186f. This is the first planet we have discovered that is very similar to Earth. It is around 1.1 times larger than Earth and orbits within the habitable zone of its star which is very similar to our own star.

Let’s do the math, to show you just how distant this planet is. Kepler 186f is around 490 lightyears from Earth.

Kepler 186f = 490 lightyears away

Light moves at 186,282 miles/ 1 second.

186,282 mi/s x 60s/1min x 60min/1hr x 24hrs/1day x 356days/1year = 5.87 x 1012 mi/yr

Kepler 186f: 490 Lyrs x 5.87 x 1012miles/ 1 Lyr = 2.88 x 1015 miles or 2.9 QUADRILLION MILES from Earth.

Just to put this distance into perspective, let’s suppose we utilize the fastest spacecraft we have to get there. The Voyager 1 spacecraft is moving at around 38,500 mi/hr. If we left on that craft today and headed towards this possible future Earth, it would take us roughly 8.5 MILLION YEARS to get there. That’s around 34 times longer than the time between when the first proto-humans began to appear on earth 250,000 years ago until today. So the entire history of human evolution from then till now replayed 34 times BEFORE you would arrive at this planet. Knowing these numbers, how is it even possible that we can know what this planet’s atmosphere, and others like it, are made of?

First, here’s a bit of chemistry in order for you to understand the field that is spectroscopy, and then how we apply it to the astronomical sciences. Different elements are composed of a differing number of protons, neutrons, and electrons. These varying numbers are what set the elements apart from one another on the periodic table. It is the electrons, however, that are of particular interest in the majority of what chemistry studies. These different electron configurations allow for what we call spectral signatures to exist among the elements. This means that since every single element has a specific electron configuration, the light that it both absorbs and emits acts as a sort of photon fingerprint; a unique identifier to that element.

A list of the elements with their corresponding visible light emission spectra. Image Credit: MIT Wavelength Tables, NIST Atomic Spectrum Database, umop.net
A list of the elements with their corresponding visible light emission spectra. Image Credit: MIT Wavelength Tables, NIST Atomic Spectrum Database, umop.net

 

The standard equation for determining the characteristics of light is:

c= v λ

c is the speed of light in a vacuum (3.00 x 108 m/s)

v  is the frequency of the light wave (in Hertz)

λ (lambda) represents the wavelength (in meters, but will usually be converted to nanometers) which will determine what color of light will be emitted from the element(s), or simply where the wavelength of light falls on the electromagnetic spectrum (infrared, visible, ultraviolet, etc.)

If you have either the frequency or the wavelength, you can determine the rest. You can even start with the energy of the light being detected by your instruments and then work backwards with the following equations:

The energy of a photon can be described mathematically as this:

Ephoton = h v
OR
Ephoton = h c / λ

What these mean is that the energy of a photon is the product of the frequency (v) of the light wave emitted multiplied by Planck’s Constant (h), which is 6.63 x 10-34 Joules x seconds. Or in the case of the second equation, the energy of the photon is equal to Planck’s Constant x the speed of light divided by the wavelength. This will give you the amount of energy that a specific wavelength of light contains. This equation is also known as the Planck-Einstein Relation. So, if you take a measurement and you are given a specific energy reading of the light coming from a distant star, you can then deduce what information you need about said light and determine which element(s) are either emitting or absorbing these wavelengths. It’s all mathematical detective work.

So, the electrons that orbit around the nucleus of atoms exist in what we call orbitals. Depending on the atom (and the electrons associated with it), there are many different orbitals. You have the “ground” orbital for the electron, which means that the electron(s) there are closest to the nucleus. They are “non-excited”. However, there are “higher” quantum orbitals that exist that the electron(s) can “jump” to when the atom is excited. Each orbital can have different quantum number values associated with it. The main value we will use is the Principle Quantum Number. This is denoted by the letter “n”, and has an assigned integer value of 1, 2, 3, etc. The higher the number, the further from the nucleus the electron resides, and the more energy is associated with it. This is best described with an example:

A hydrogen atom has 1 electron. That electron is whipping around its 1 proton nucleus in its ground state orbital. Suddenly, a burst of high energy light hits the hydrogen. This energy is transferred throughout the hydrogen atom, and the electron reacts. The electron will instantaneously “vanish” from the n1 orbital and then reappear on a higher quantum orbital (say n4). This means that as that light wave passed over this hydrogen atom, a specific wavelength was absorbed by the hydrogen (this is an important feature to remember for later).

Diagram of an electron dropping from a higher orbital to a lower one and emitting a photon. Image Credit: Wikicommons
Diagram of an electron dropping from a higher orbital to a lower one and emitting a photon. Image Credit: Wikimedia Commons

Eventually, the “excited” electron will drop from its higher quantum orbital (n4) back down to the n1 orbital. When this happens, a specific wavelength of light is emitted by the hydrogen atom. When the electron “drops”, it emits a photon of specific energy or wavelength (dependent upon many factors, including the state the electron was in prior to its “excitement”, the amount of levels the electron dropped, etc.) We can then measure this energy (or wavelength, or frequency,) to determine what element the photon is coming from (in this case, hydrogen). It is in this feature that each element has its own light signature. Each atom can absorb and emit specific wavelengths of light, and they are all tied together by the equations listed above.

So how does this all work? Well, in reality, there are many factors that go into this sort of astronomical study. I am simply describing the basic principle behind the work. I say this so that the many scientists that are doing this sort of work do not feel as though I have discredited their research and hard work; I promise you, it is painstakingly difficult and tedious and involves many more details that I am not mentioning here. That being said, the basic concept works like this:

We find a star that gives off the telltale signs that it has a planet orbiting around it. We do this with a few methods, but how it all first started was by detecting a “wobble” in the star’s apparent position. This “wobble” is caused by a planet orbiting around its parent star. You see, when a planet orbits a star (and when anything orbits anything else), the planet isn’t really orbiting the star, the planet AND the star are orbiting a common focal point. Usually with this type of orbital system, that common focal point is fairly close to the center of the star, and thus it’s safe to say that the planet orbits the star. However, this causes the star to move ever so slightly. We can measure this.

Once we determine that there are planets orbiting the star in question, we can study it more closely. When we do, we turn our instruments towards it and begin taking highly detailed measurements, and then we wait. What we are waiting for is a dimming of the star at a regular interval. What we are hoping for is this newly-found exoplanet to transit our selected star. When a planet transits a star, it moves in front of the star relative to us (this also means we are incredibly lucky, as not all planets will orbit “in front” of the star relative to our view). This will cause the star’s brightness to dip ever so slightly at a regular interval. Now we have identified a prime exoplanet candidate for study.

Diagram of how we can use aborbstion specral reading to determine the atmosphere of an exoplanet. Image Credit: A. Feild, STScl, NASA
Diagram of how we can use absorption spectral reading to determine the atmosphere of an exoplanet. Image Credit: A. Feild, STScl, NASA

We can now introduce the spectroscopic principles to this hunt. We can take all sorts of measurements of the light that is coming from this star. Its brightness, the energy it’s kicking out per second, and even what that star is made of (the emission spectrum I discussed earlier). Then what we do is wait for the planet to transit the start, and begin taking readings. What we are doing is reading the light passing THROUGH the exoplanet’s atmosphere, and then studying what we can call an Absorption Spectrum reading. As I mentioned earlier, specific elements will absorb specific wavelengths of light. What we get back is a spectral reading of the star’s light signature (the emission spectra of the star), but with missing wavelengths that show up as very tiny black lines where there used to be color. These are called Fraunhofer lines, named after the “father” of astrophysics Joseph Fraunhofer, who discovered these lines in the 19th century.

The dark lines represent the light frequencies that were absorbed by specific chemicals that this particular light passed through. Image Credit: Wikimedia Commons
The dark lines represent the light frequencies that were absorbed by specific chemicals that this particular light passed through. Image Credit: Wikimedia Commons

What we now have in our possession is a chemical fingerprint of what this exoplanet’s atmosphere is composed of. The star’s spectrum is splayed out before us, but the barcode of the planet’s atmospheric composition lay within the light. We can then take those wavelengths that are missing and compare them to the already established absorption/emission spectra of all of the known elements. In this way, we can begin to piece together what this planet has to offer us. If we get high readings of sulfur and hydrogen, we have probably just discovered a gas giant. However if we discover a good amount of nitrogen and oxygen, we may have found a world that has liquid water on its surface (provided that this planet resides within its host star’s “habitable” zone: a distance that is just far enough from the star to allow for liquid water). If we find a planet that has carbon dioxide in its atmosphere, we may just have discovered alien life (CO2 being a waste product of both cellular respiration and a lot of industrial processes, but it can also be a product of volcanism and other non-organic phenomena).

What this all means is that by being able to read the light from any given object, we can narrow our search for the next Earth. Regardless of distance, if we can obtain an accurate measurement of the light moving through an exoplanet’s atmosphere, we can tell what it is made of.

We have discovered some 2000 exoplanets thus far, and that number will only increase in the coming decades. With so many candidates, it will be a wonder if we do not find a planet that we humans can live on without the help of technology. Obviously our techniques will further be refined, and as new technologies, methods, and instruments become available, our ability to pinpoint planets that we can someday colonize will become increasingly more accurate.

With such telescopes like the James Webb Space Telescope launching soon, we will be able to image these exoplanets and get even better spectroscopic readings from them. This type of science is on the leading edge of humanity’s journey into the cosmos. Astrophysicists and astrochemists that work in this field are the necessary precursors to the brave men and women who will one day board those interstellar spacecraft and launch our civilization into the Universe to truly become an interstellar species.

Possible glimpse into our future... Image Credit: Battlestar Wiki Media
Possible glimpse into our future… Image Credit: Battlestar Wiki Media
Posted on by Paul Patton

Communicating Across the Cosmos 4: The Quest for a Rosetta Stone

The Rosetta stone, now displayed at the British Museum in London, was used by Jean-Francois Champollion to decipher Egyptian heiroglyphics, Credit: Hans Hillewaert, British Museum

On television and in the movies, it’s so easy. Aliens almost always speak English (at least in America they do). If it’s explained at all, we are typically told that they learned it by intercepting communications with our astronauts, or tapping into our television broadcasts. A universal translator device instantly abolishes communication difficulties. Hollywood aliens are, of course, human beings in costumes (these days augmented by computer graphics). They are equipped, as are we all, with a human brain, a human larynx, and human vocal cords; all singular products of the distinctive evolutionary history of our species.

Real extraterrestrials, if they exist, will be the product of a different evolutionary history, played out on another world.

They will know no human language, and be unfamiliar with the typical activities of human beings. Here on Earth no archeologist has ever deciphered an ancient script without knowing the language it corresponds to, even though such scripts deal with recognizable human activities. How could we ever devise a message that aliens could understand? Could we ever understand a message they sent to us? Communicating with alien minds may be one of the most daunting challenges the human intellect has ever faced.

In mid-November, the SETI Institute in Mountain View, California sponsored an academic conference on the problem interstellar communication ‘Communicating across the Cosmos’. The conference drew 17 speakers from a variety of disciplines, including linguistics, anthropology, archeology, mathematics, cognitive science, radio astronomy, and art. In this final installment, we will search for clues to a solution to the daunting problem of making ourselves understood to an extraterrestrial civilization.

Conference presenter and archeologist Paul Wason believes that the history of archeology provides an important lesson for how we might devise a message that can be deciphered by extraterrestrials. In the early 19th century the French archeologist Jean-Francois Champollion solved one of the great riddles of his field by deciphering Egyptian hieroglyphics. The critical clue was provided by an artifact discovered in 1799 in an Egyptian town that Europeans called Rosetta. It became known as the Rosetta stone.

The stone contained the same inscription in three different scripts. One of them was Egyptian hieroglyphics, and another was Greek, which Champollion knew how to read. Champollion used the Greek to decipher the hieroglyphics. Could we use the same strategy to create a cosmic Rosetta stone? Like Wason, Carl Sagan also grasped the importance of the Rosetta stone, and discussed it extensively in his 1980’s book and television series Cosmos. To create a cosmic Rosetta stone, we would need a language to stand in the role of Greek. It would need to be known both to us, and to the aliens. Could there possibly be such a thing?

Many mathematicians and physical scientists involved in SETI believe that mathematical and physical concepts could play the needed role. According to mathematician and conference speaker Carl DeVito, the natural numbers (0, 1, 2, 3 …) are useful to humans in dealing with the cyclical processes that are a everywhere in nature, and probably arise universally in the minds of intelligent beings. Astronomers have strong evidence that the laws of physics and chemistry worked out in laboratories here on Earth hold everywhere in the universe. That being the case, they hope that humans and aliens share a common understanding of basic concepts in these fields. If this is so, then such concepts might play the same role that Greek did for Champollion. SETI pioneers Carl Sagan and Frank Drake, along with their collaborators, employed a rudimentary version of this strategy when they constructed the message encoded on the phonographic record launched into space in 1977 aboard the Voyager 1 and 2 spacecraft. These spacecraft hurtled into interstellar space following the completion of their missions to explore the outer solar system.

An image encoded on the phonographic record carried aboard Voyager 1 and 2, intended to communicate how humans symbolize basic mathematical concepts. The left side depicts how humans, in western culture, represent the natural numbers using binary code and Arabic numerals. The vertical lines indicate binary ‘1’, and the horizontal lines binary ‘0’. On the right, additional numerals are given, and the use of scientific notation, and the operations of addition, multiplication, and division are depicted.
An image encoded on the phonographic record carried aboard Voyager 1 and 2, intended to communicate how humans symbolize basic mathematical concepts. The left side depicts how humans, in western culture, represent the natural numbers using binary code and Arabic numerals. The vertical lines indicate binary ‘1’, and the horizontal lines binary ‘0’. On the right, additional numerals are given, and the use of scientific notation, and the operations of addition, multiplication, and division are depicted. Credit: Frank Drake
An image encoded on the Voyager record intended to communicate standards of time, mass, and length to an extraterrestrial viewer, using basic concepts in physics encoded symbolically. In the upper right corner, each circle symbolizes a hydrogen atom. The diagram as a whole symbolizes a transition of the spin state of the electron. This transition involves the emission of a microwave radio wave of wavelength 21 centimeters, which is symbolized on the right side of the diagram. Radio emissions produced by this transition occurring in clouds of hydrogen gas in interstellar space are well known to radio astronomers. The wavelength is used as the standard of length (1 L). The time that this transition takes to occur is used as the unit of time (1t) and the mass of a hydrogen atom (1 M) is used as the standard of mass. Various units of measurement used by humans are then defined in terms of these standards. The units are then used throughout the pictorial portion of the message to indicate masses, lengths and times.
An image encoded on the Voyager record intended to communicate standards of time, mass, and length to an extraterrestrial viewer, using basic concepts in physics encoded symbolically. In the upper right corner, each circle symbolizes a hydrogen atom. The diagram as a whole symbolizes a transition of the spin state of the electron. This transition involves the emission of a microwave radio wave of wavelength 21 centimeters, which is symbolized on the right side of the diagram. Radio emissions produced by this transition occurring in clouds of hydrogen gas in interstellar space are well known to radio astronomers. The wavelength is used as the standard of length (1 L). The time that this transition takes to occur is used as the unit of time (1t) and the mass of a hydrogen atom (1 M) is used as the standard of mass. Various units of measurement used by humans are then defined in terms of these standards. The units are then used throughout the pictorial portion of the message to indicate masses, lengths and times. Credit: Frank Drake

Sagan, Drake, and their collaborators first used symbols in an attempt to communicate how humans represent the natural numbers using binary and base ten numerals. They used another set of symbols to depict some properties of the hydrogen atom, which they used to establish standards of distance and time. The distance and time standards were used repeatedly throughout the digital image portion of the message to specify the sizes and time scales depicted. The Voyager record included a greeting from then President Carter encoded as English text. Sagan, Drake, and their collaborators didn’t even attempt the monumental, and perhaps impossible, task of explaining President Carter’s text statement using their Rosetta stone.

Much like Wason and Sagan, computer scientist and conference presenter Kim Binsted, felt that the solution to interstellar communication lies in constructing a pidgin, a simplified version of a language developed to communicate between groups that share no language in common. She was doubtful though, that a cosmic Rosetta stone based on physics and math would let humans and aliens communicate about anything other than physics and math. It might never, for example, provide a way to convey the President’s good wishes. The hieroglyphics of the Rosetta stone were decipherable, in part, because they described the familiar human activities of an Egyptian pharaoh. Humans are clueless about what sorts of activities aliens typically engage in, and aliens are equally clueless about us. It’s hard to see how a Rosetta stone based on physics could bridge this sort of gap.

Philosophers Nicholas Rescher and Andre Kukla, neither of whom presented at the conference, have raised a more fundamental objection. They question whether extraterrestrials would use the same concepts to understand the physical and chemical world that we do. The concepts that modern western science uses to understand the physical world surely reflect the structure of that world. But they also reflect the history of our culture and the structure of our minds. Since aliens would differ from humans on both counts, it’s at least possible that their physical, and even their mathematical concepts might be different from ours. If that’s so, then physics can’t play the role that Greek did for Champollion. Every path forward is full of unknowns and difficulties, and Kim Binsted doubts a solution is possible.

There is a glimmering of hope for another kind of Rosetta stone based on another sort of “Greek”. Given the central role that visual images played in the Voyager message, it’s surprising that image based communication strategies didn’t receive greater emphasis at the conference. It’s true that here on Earth; animals have evolved a wide variety of non-visual ways to sense their surroundings. Some fishes can sense their environments by generating and detecting electric fields in the water. Many fish can use fields of water flow around their bodies to detect nearby objects. Bats, along with dolphins and whales, have evolved a sonar system, emitting sounds and analyzing their returning echoes. Scorpions can sense ground vibrations, elephants can hear sounds below the range of human hearing, and dogs have a remarkably acute sense of smell, to name just a few examples. Still, almost every Earthly animal has eyes of some sort.

Earthly evolution has invented vision several times, in different animal lineages. Vision is especially important for larger animals that live on land. This is because larger bodies can make larger eyes and larger eyes can give sharper vision and better light gathering abilities. Land environments are typically better lit than aquatic ones. Birds and mammals are the Earthly animals with the biggest and most sophisticated brains, and they also have the most acute vision.

Are alien environments likely to be well lit? Exoplanet hunters have focused their efforts on finding planets like the Earth, rocky terrestrial planets at the right distance from their star for temperatures to be in the range where water is a liquid. They have shown us that such worlds are fairly commonplace in the cosmos. The daytime surfaces of these exoplanets are likely to be flooded with visible light, just as is Earth. This light may be necessary for life on such a world, because most life on Earth depends on the energy of sunlight as trapped by green plants. For large, land dwelling animals in this kind of environment, vision provides more information, at a distance, than any other sense can. Since it evolved numerous times on Earth, it’s likely to do so elsewhere as well.

The eye of a squid is remarkably similar to our own. Squids are part of a group of animals called molluscs, which also includes slugs, snails, and shellfish. Molluscs are very distantly related to the vertebrates (animals with backbones, a group which includes humans). The most recent common ancestor of molluscs and vertebrates was a simple wormlike creature that lived more than 600 million years ago. The two groups have followed an independent course of evolution ever since. The fact that molluscs evolved complex brains and bodies along a different evolutionary path than vertebrates makes them a good model for understanding extraterrestrials. One group of molluscs, the cephalopods, a group which includes squids, octopuses, and cuttlefish, have evolved the largest and most complex brains of any invertebrate. Despite their separate evolutionary origin, the eyes of cephalopods are remarkably similar to vertebrate eyes, a phenomenon known as convergent evolution. Evolution solved similar problems in similar ways. These similarities suggest the possible usefulness of images in interstellar messages.
With a lens at the front and a sheet of light sensing cells at the back, the eye of a squid is remarkably similar to our own. Squids are part of a group of animals called molluscs, which also includes slugs, snails, and shellfish. Molluscs are very distantly related to the vertebrates (animals with backbones, a group which includes humans). The most recent common ancestor of molluscs and vertebrates was a simple worm-like creature that lived more than 600 million years ago. The two groups have followed an independent course of evolution ever since. The fact that molluscs evolved complex brains and bodies along a different evolutionary path than vertebrates makes them a good model for understanding some of the ways in which extraterrestrials, with an entirely separate evolutionary history, might be different from or similar to us. One group of molluscs, the cephalopods, a group which includes squids, octopuses, and cuttlefish, have evolved the largest and most complex brains of any invertebrates. Despite their separate evolutionary origin, the eyes of cephalopods are remarkably similar to vertebrate eyes, a phenomenon known as convergent evolution. Evolution solved similar problems in similar ways. Perhaps, even on another planet, evolution solves similar problems in similar ways. If aliens, like cephalopods, have some visual similarities to us, then visual images may be useful in interstellar messages. Credit: Carl Chun Die Cephaloden

The human visual system gathers information about a three dimensional world of objects and surfaces, partly by using motion cues. We have the ability to represent that world in two dimensions, using images. Kim Binsted worried that an alien visual system might not be capable of making sense of pictures made by humans. This worry was a potent one for the stick figures and line drawings that played such a prominent role in the pioneering interstellar messages of the 70’s. Those kinds of depictions use abstract visual conventions that an alien viewer might find impossible to figure out. Today, though, we needn’t worry about stick figures, because the information revolution gives us the ability to send high definition video. Still, we can’t be sure what an alien visual system would make of imagery encoded with the human visual system in mind.

Video imagery may provide a promising complement or alternative to the abstractions of physics and chemistry as the “Greek” for a cosmic Rosetta stone. If the aliens live on a planet like Earth, with liquid water on its surface, then we will share a mutual familiarity with water’s many manifestations. Just like us, aliens will have seen rain and snow, oceans, rivers, lakes, ponds, clouds, fog, and rainbows. If they have a sense of hearing, over a range of sound frequencies at least somewhat similar to ours, they will have heard waves crashing on beaches, rain hitting the ground, gurgling brooks, and the splash of a pebble dropped into a pond. When the senses work together to confirm one another, the certainty of perceptual recognition is even greater.

An audio-video movie depicting the mutually familiar phenomena of water could be just the bridge we need to cross the gulf of mutual incomprehension. This splashy, gurgling “Greek” could be the key to helping the aliens understand our audio-visual and still images, and ultimately, our symbols. As with the Voyager record, a simpler symbol system would first be needed to communicate to the aliens about how to view and listen to the presentation. That might be a big stumbling block. In the case of Voyager, a stylus head for playing the record was included on the spacecraft, which made it simpler to explain how to play it. A Rosetta stone that led the extraterrestrials to an understanding of our images could provide a means of communication extending well beyond the topics of physics, chemistry, and math. Several conference participants felt that imagery might help to convey things about human altruism, cooperation, morality, and aesthetic sensibilities.

The main message of the ‘Communicating across the Cosmos’ conference is a recognition of just how hard the problem of making ourselves understood to aliens will be. Kim Binsted ended her talk on a faint note of optimism. Even if all else fails, she supposed, there is something we can still communicate to the aliens. She showed a slide of her home doorbell. When it rings, she said, it conveys the message that someone is there, and where they are. It shows intent to communicate, and a benign willingness to reveal one’s presence. Even if it can’t be interpreted, an interstellar message conveys the information that a doorbell conveys. That message, the message that someone is there, would still be of monumental importance.

Even an interstellar message that can't be deciphered still tells us what a doorbell tells us: that someone is there.
Even an interstellar message that can’t be deciphered still tells us what a doorbell tells us: that someone is there. Credit: Jim Kuhn

Previous articles in this series:
Part 1: Shouting into the Darkness
Part 2: Petabytes from the Stars
Part 3: Bridging the Vast Gulf

References and Further Reading:

Communicating across the Cosmos: How can we make ourselves understood by other civilizations in the galaxy (2014), SETI Institute Conference Website.

F. Cain (2013) How Could We Find Aliens? The Search for Extraterrestrial Intelligence (SETI), Universe Today.

F. Cain (2013) Where Are All The Aliens? The Fermi Paradox, Universe Today.

A. Kukla (2010) Extraterrestrials: A Philosophical Perspective, Rowman and Littlefield Publishers Inc. Plymouth, UK.

M. F. Land and D-E. Nilsson (2002), Animal Eyes, Oxford University Press.

N. Rescher (1985) Extraterrestrial Science, in Extraterrestrials: Science and Alien Intelligence, Edited by E. Regis, Cambridge University Press, Cambridge, UK.

C. Sagan, F. D. Drake, A. Druyan, T. Ferris, J. Lomberg, L. S. Sagan, (1978) Murmurs of Earth: The Voyager Interstellar Record. Random House, New York.

C. Sagan (1980) Cosmos, Random House, New York.

J. J. Vitti (2013) Cephalopod cognition in an evolutionary context: Implications for ethology, Biosemiotics, 6:393-401.

Posted on by Tim Reyes

New Analysis Sets a Space & Time Zone for Complex Life

A new research paper reveals more details of the effect gamma ray bursts (GRB) have had on the development of complex life throughout the cosmos. Illustration depicts a beam from a GRB as might have been directed toward early life on Earth during the Cambrian or Ordovician periods, ~500 million years ago. (Illustration Credit: T. Reyes)

If too close to an environment harboring complex life, a gamma ray burst could spell doom for that life. But could GRBs be the reason we haven’t yet found evidence of other civilizations in the cosmos? To help answer the big question of “where is everybody?” physicists from Spain and Israel have narrowed the time period and the regions of space in which complex life could persist with a low risk of extinction by a GRB.

GRBs are some of the most cataclysmic events in the Universe. Astrophysicists are astounded by their intensity, some of which can outshine the whole Universe for brief moments. So far, they have remained incredible far-off events. But in a new paper, physicists have weighed how GRBs could limit where and when life could persist and evolve, potentially into intelligent life.

In their paper, “On the role of GRBs on life extinctions in the Universe”, published in the journal Science, Dr. Piran from Hebrew University and Dr. Jimenez from University of Barcelona consider first what is known about gamma ray bursts. The metallicity of stars and galaxies as a whole are directly related to the frequency of GRBs. Metallicity is the abundance of elements beyond hydrogen and helium in the content of stars or whole galaxies. More metals reduce the frequency of GRBs. Galaxies that have a low metal content are prone to a higher frequency of GRBs. The researchers, referencing their previous work, state that observational data has shown that GRBs are not generally related to a galaxy’s star formation rate; forming stars, including massive ones is not the most significant factor for increased frequency of GRBs.

As fate would have it, we live in a high metal content galaxy – the Milky Way. Piran and Jimenez show that the frequency of GRBs in the Milky Way is lower based on the latest data available. That is the good news. More significant is the placement of a solar system within the Milky Way or any galaxy.

The brightest gamma-ray burst ever seen in X-rays temporarily blinded Swift's X-ray Telescope on 21 June 2010. This image merges the X-rays (red to yellow) with the same view from Swift's Ultraviolet/Optical Telescope, which showed nothing extraordinary. Credit: NASA/Swift/Stefan Immler
The brightest gamma-ray burst ever seen in X-rays temporarily blinded Swift’s X-ray Telescope on 21 June 2010. This image merges the X-rays (red to yellow) with the same view from Swift’s Ultraviolet/Optical Telescope, which showed nothing extraordinary. Credit: NASA/Swift/Stefan Immler

The paper states that there is a 50% chance of a lethal GRB’s having occurred near Earth within the last 500 million years. If a stellar system is within 13,000 light years (4 kilo-parsecs) of the galactic center, the odds rise to 95%. Effectively, this makes the densest regions of all galaxies too prone to GRBs to permit complex life to persist.

The Earth lies at 8.3 kilo-parsecs (27,000 light years) from the galactic center and the astrophysicists’ work also concludes that the chances of a lethal GRB in a 500 million year span does not drop below 50% until beyond 10 kilo-parsecs (32,000 light years). So Earth’s odds have not been most favorable, but obviously adequate. Star systems further out from the center are safer places for life to progress and evolve. Only the outlying low star density regions of large galaxies keep life out of harm’s way of gamma ray bursts.

The paper continues by describing their assessment of the effect of GRBs throughout the Universe. They state that only approximately 10% of galaxies have environments conducive to life when GRB events are a concern. Based on previous work and new data, galaxies (their stars) had to reach a metallicity content of 30% of the Sun’s, and the galaxies needed to be at least 4 kilo-parsecs (13,000 light years) in diameter to lower the risk of lethal GRBs. Simple life could survive repeated GRBs. Evolving to higher life forms would be repeatedly set back by mass extinctions.

Piran’s and Jimenez’s work also reveals a relation to a cosmological constant. Further back in time, metallicity within stars was lower. Only after generations of star formation – billions of years – have heavier elements built up within galaxies. They conclude that complex life such as on Earth – from jelly fish to humans – could not have developed in the early Universe before Z > 0.5, a cosmological red-shift equal to ~5 billion years ago or longer ago. Analysis also shows that there is a 95% chance that Earth experienced a lethal GRB within the last 5 billion years.

The question of what effect a nearby GRB could have on life has been raised for decades. In 1974, Dr. Malvin Ruderman of Columbia University considered the consequences of a nearby supernova on the ozone layer of the Earth and on terrestrial life. His and subsequent work has determined that cosmic rays would lead to the depletion of the ozone layer, a doubling of the solar ultraviolet radiation reaching the surface, cooling of the Earth’s climate, and an increase in NOx and rainout that effects biological systems. Not a pretty picture. The loss of the ozone layer would lead to a domino effect of atmospheric changes and radiation exposure leading to the collapse of ecosystems. A GRB is considered the most likely cause of the mass extinction at the end of the Ordovician period, 450 million years ago; there remains considerable debate on the causes of this and several other mass extinction events in Earth’s history.

The paper focuses on what are deemed long GRBs – lGRBs – lasting several seconds in contrast to short GRBs which last only a second or less. Long GRBs are believed to be due to the collapse of massive stars such as seen in supernovas, while sGRBs are from the collision of neutron stars or black holes. There remains uncertainty as to the causes, but the longer GRBs release far greater amounts of energy and are most dangerous to ecosystems harboring complex life.

The paper narrows the time and space available for complex life to develop within our Universe. Over the age of the Universe, approximately 14 billion years, only the last 5 billion years have been conducive to the creation of complex life. Furthermore, only 10% of the galaxies within the last 5 billion years provided such environments. And within only larger galaxies, only the outlying areas provided the safe distances needed to evade lethal exposure to a gamma ray burst.

This work reveals how well our Solar System fits within the ideal conditions for permitting complex life to develop. We stand at a fairly good distance from the Milky Way’s galactic center. The age of our Solar System, at approximately 4.6 billion years, lies within the 5 billion year safe zone in time. However, for many other stellar systems, despite how many are now considered to exist throughout the Universe – 100s of billions in the Milky Way, trillions throughout the Universe – simple is probably a way of life due to GRBs. This work indicates that complex life, including intelligent life, is likely less common when just taking the effect of gamma ray bursts into consideration.

References:

On the role of GRBs on life extinction in the Universe, Tsvi Piran, Raul Jimenez, Science, Nov 2014, pre-print

Posted on by Paul Patton

Communicating Across the Cosmos, Part 3: Bridging the Vast Gulf

The cover of the phonograph record on the Voyager 1 and 2 spacecraft, which contains an interstellar message encoded on a phonographic record. The encoded instructions attempt to explain to extraterrestrials how to play the record. Credit: NASA JPL

If extraterrestrial civilizations exist, the nearest is probably at least hundreds or thousands of light years away. Still, the greatest gulf that we will have to bridge to communicate with extraterrestrials is not such distances, but the gulf between human and alien minds.

In mid-November, the SETI Institute in Mountain View, California sponsored an academic conference on interstellar communication, “Communicating across the Cosmos“. The conference drew 17 speakers from a variety of disciplines, including linguistics, anthropology, archeology, mathematics, cognitive science, radio astronomy, and art. In this installment we will explore some of the formidable difficulties that humans and extraterrestrials might face in constructing mutually comprehensible interstellar messages.

Optical PAyload for Lasercomm Science (OPALS) Flight System, the first laser communication from space. Credit: NASA/JPL-Caltech.
Optical PAyload for Lasercomm Science (OPALS) Flight System, the first laser communication from space. Credit: NASA/JPL-Caltech.

If we knew where they were, and we wanted to, the information revolution has given us the capability to send an extraterrestrial civilization a truly vast amount of information. According to SETI Institute radio astronomer Seth Shostak, with broadband microwave radio we could transmit the Library of Congress, or the contents of the World Wide Web in 3 days; with broadband optical (a laser beam for space transmission) we could transmit this same amount of information in 20 minutes. This transmission would, of course, take decades or centuries to cross the light years and reach its destination. These truly remarkable capabilities give us the ability to send almost any message we want to the extraterrestrials. But transmitting capabilities aren’t the hard part of the problem. If the aliens can’t interpret it, the entire content of the World Wide Web is just a mountain of gibberish.

Many conference participants felt that the problems involved in devising a message that could be understood by a non-human mind were extremely formidable, and quite possibly insurmountable.

Having its own separate origin, extraterrestrial life could be different from Earthly life all the way down to its biochemical foundations. The vast diversity of life on Earth gives us little reason to think that aliens will look like us. Given the different conditions of another planet, and the contingencies of a different history, evolution will have produced a different set of results. For interstellar messaging to be possible at all, these results must include an alien creature capable of language, culture, and tool-making. But if these abilities are founded on a different biology and different perceptual systems, they might differ from their human counterparts in ways that we would find hard to even imagine. Looking to our own possible future development, we can’t even be sure that extraterrestrials will be biological creatures. They might be intelligent machines.

According to cognitive scientist Dominique Lestel, who presented at the conference, understanding extraterrestrials poses an unprecedented set of problems. We face all of the problems that ethologists (scientists who study animal behavior) face when they study perception and signaling in other animal species. These are compounded with all of the problems that ethnologists face when they study other human cultures. Lestel worries that humans might not be smart enough to do it. He wasn’t alone in that opinion.

Explanation of the symbols on the cover of the Voyager record Credit: NASA JPL
Explanation of the symbols on the cover of the Voyager record. Credit: NASA JPL

Linguist and conference presenter Sheri-Wells Jensen said that humans have created more than 7,000 different spoken and signed languages. No one knows whether all human languages sprung from a single instance of the invention of language or whether several human groups invented language independently. Given the ease with which children learn a language, many linguists think that our brain has a specialized language “module” underlying the “universal” grammar of human languages. These special features of the human brain might pose a formidable barrier to learning the language of a creature with a different brain produced by a different evolutionary history. An alien language might make demands on our short term memory or other cognitive abilities that humans would find impossible to meet.

When human beings talk to one another, they rely on a system of mutually understood conventions. Often gestures and body language are essential to conveying meaning. Conference presenter Klara Anna Capova, a cultural anthropologist, noted that interstellar messaging poses unique problems because the conventions to be followed in the message can’t be mutually arranged. We must formulate them ourselves, without knowing anything about the recipients. The intended recipients are distant in both time and space. The finite speed of light ensures that query and response will be separated by decades or centuries. With so little to go on, the message will inevitably reflect our cultural biases and motives. In 1962, the Soviet Union transmitted a message towards the planet Venus. It was in Morse code, and consisted of the Cyrillic characters “Lenin”, “CCCP” (USSR), and “MIR” (the Russian word for “peace”). But the posited Venusians couldn’t possibly have known the conventions of Morse code, the Cyrillic alphabet, human names, countries, or possible relationships between them, no matter how intimately familiar these things would have seemed to the Soviets. Whether they are meant to build national prestige, sell a product, or cause humans to think deeply about their place in the universe, interstellar messages play to a human audience.

Given the long timescales involved in interstellar messaging, many conference participants noted the parallels with archeology. Archeologists have learned quite a lot about past human cultures by studying the artifacts and symbols they have left for us. Still, archeological methodologies have their limits. According to conference presenter and archeologist Paul Wason, these limits have much to teach us about interstellar messaging. Certain meanings are accessible to archeological analysis and others aren’t, because we lack the contextual knowledge needed to interpret them. Neolithic cave paintings speak to modern investigators about the skill and abilities of the painters. But, because we don’t have the needed contextual knowledge, they don’t tell us what the paintings meant to their creators.

To interpret symbols used in the past, we need to know the conventions that related the symbols to the things they symbolized. Linguistic symbols pose special problems. To understand them, we need to know two different sets of conventions. First, we need to know the conventions that relate the script to the words of the spoken language. Second, we need to know how the words of the spoken language relate to the things and situations it refers to. It is a sobering thought for would-be exolinguists that no one has ever succeeded in deciphering an ancient script without knowing the language it was written in.

What does all this tell us about our fledgling attempts to devise messages for aliens? The phonograph record carried on the Voyager 1 and 2 spacecraft includes a moving message from then President Carter, encoded as English text. It reads in part: “We hope someday, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination, and our good will in a vast and awesome universe.”

Human archeologists have never deciphered linear A, the writing system of the ancient Minoan civilization, due to its apparent lack of association with any known language. Unfortunately, since extraterrestrials likewise lack contextual knowledge of any human language, it is almost certain that they could never discern the meaning of President Carter’s text. The team that developed the Voyager message, which included astronomers and SETI pioneers Carl Sagan and Frank Drake, were well aware of the problem. Carter was, most likely, made aware. Interstellar messages play to a human audience.

An inscription written around the inner surface of a cup in Linear A, a script used by the Minoan civilization that has never been deciphered. Credit: Sir Arthur Evans, Scripta Minoa: The Written Documents of Minoan Crete
An inscription written around the inner surface of a cup in Linear A, a script used by the Minoan civilization that has never been deciphered. Credit: Sir Arthur Evans, Scripta Minoa: The Written Documents of Minoan Crete

Is it possible for us to do better? Some off-beat ideas were proposed. Both astronomer Seth Shostak and designer Marek Kultys thought we might consider sending the sequence of the human genome. This idea was quickly shot down by a comment from the audience. Why send them a key, they said, if the aliens don’t have a lock. The metaphor is apt. DNA can only do its job as a constituent part of a living cell. Reading and implementing the genetic code involves numerous highly specialized enzymes and other cellular parts. Even if alien biochemistry and cell structure are generally similar to their Earthly counterparts, there are many features of Earthly biochemistry that appear to be quirky products of the history of life on Earth. The probability that they would repeat themselves precisely on another world are, for all practical purposes, nil. Without the context of an Earthly cell, the sequence of the human genome would be meaningless gibberish.

In the twenty first century, our ability to transmit and process information has become astounding, but we still don’t know how information conveys meaning. Is there even a glimmering of a hope that we can reach beyond the limitations of our humanity to convey meaning to an alien mind? In the final installment of this report, we’ll consider some possibilities.

Previous articles in this series:
Part 1: Shouting into the Darkness
Part 2: Petabytes from the Stars

References and further reading:

Communicating across the Cosmos, How can we make ourselves understood by other civilizations in the galaxy?, SETI Institute

E. Howell (2014) How Do Aliens Think? We Need to Learn About Their Biology First, Analyst Argues. Universe Today.

J. Minor (2014) Will We Find Alien Life in 20 Years? You can bet on it. Universe Today.

C. Sagan, F. D. Drake, A. Druyan, T. Ferris, J. Lomberg, L. S. Sagan, (1978) Murmurs of Earth: The Voyager Interstellar Record. Random House, New York.

Posted on by Paul Patton

Communicating Across the Cosmos, Part 2: Petabytes from the Stars?

The Allen Telescope Array is the first radio telescope designed specifically for SETI Photo by Colby Gutierrez-Kraybill

Since it was founded in 1984, the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California, has been a principal American venue for scientific efforts to discover evidence of extraterrestrial civilizations. In mid-November, the institute sponsored a conference, “Communicating across the Cosmos”, on the problems of devising and understanding messages from other worlds. The conference drew 17 speakers from numerous disciplines, including linguistics, anthropology, archeology, mathematics, cognitive science, philosophy, radio astronomy, and art.

This is the second of four installments of a report on the conference. Today, we’ll look at the SETI Institute’s current efforts to find an extraterrestrial message, and some of their future plans. If they find something, just how much information can we expect to receive? How much can we send?

The idea of using radio to listen for messages from extraterrestrials is as old as radio itself. Radio pioneers Nikola Tesla and Guglielmo Marconi both listened for signals from the planet Mars early in the 20th century. The first to listen for messages from the stars was radio astronomer Frank Drake in 1960. Until recently though, SETI projects have been limited and sporadic. That began to change in 2007 when the SETI Institute’s Allen Telescope Array (ATA) started observations.

Consisting of 42 small dishes, the ATA is the first radio telescope in the world designed specifically for SETI. The SETI search is currently managed by Jon Richards, an engineer who is an expert on both the system’s hardware and software. He spoke at the conference about the project. The ATA is currently used for SETI research twelve hours out of each day, from 7 pm to 7 am. During the day, the site is operated by Stanford Research International to perform more conventional astronomical studies. When used for such observations, the dishes can function together as an interferometer, generating images of celestial radio sources. To minimize radio interference from human activities, the telescope is sited a six hour drive north of the SETI Institute at the remote Hat Creek Observatory in the Cascade Mountains of Northern California.

The ATA can detect signals over the range from 1 to 10 GHz. The researchers use several strategies to tell potential ETI signals apart from naturally occurring radio sources in space, and human-made terrestrial interference. Radio emissions from natural sources are smeared over a broad range of frequencies. Artificial signals designed for communication typically pack all of their energy into a very narrow frequency band. To detect such signals, the ATA can resolve frequency differences down to just 1 Hz.

When a radio source is moving with respect to the receiver, it appears to change in frequency. This phenomenon is called the Doppler effect. Because an alien planet and the Earth would be moving in relation to one another, a genuine ETI signal would exhibit the Doppler effect. A source of terrestrial interference that’s fixed to the Earth wouldn’t. If the beam of the telescope is shifted away from the target, a genuine alien signal emanating from a distant point in space would disappear, reappearing when the beam was shifted back. A signal due to local interference wouldn’t.

This illustration of the Doppler effect shows the change of wavelength caused by the motion of the source. Credit: ARM.
This illustration of the Doppler effect shows the change of wavelength caused by the motion of the source. Credit: ARM.

The ATA is designed to perform these tests automatically whenever it detects a potential candidate signal. To make sure, it repeats the second test five times. If a signal passes the tests, the operator is automatically sent an e-mail, and the candidate signal is entered into a database. Periodically, as a test, the telescope is programed to point in the direction of one of the two Voyager spacecraft. Because these spacecraft are hurtling through deep space beyond the orbit of Neptune, their signals mimic the properties expected from an alien transmission. So far, all the e-mails received have been generated by such tests, and by false alarms. The fateful e-mail announcing the successful detection of an extraterrestrial signal has not yet been sent.

Richards explained that the ATA’s most recent project has been to listen to more than one hundred Earth-like planets discovered by the Kepler space telescope between 2009 and 2012. Next year the ATA’s antenna feeds will get an upgrade that will increase their upper frequency limit to 15 GHz and greatly increase their sensitivity. Both ground-based and Kepler studies have identified numerous Earth-like planets at habitable distances from small dim red dwarf stars. A systematic search of these stars is planned next. If the SETI Institute can find the funding they hope eventually to expand the ATA to 350 dishes.

According to astronomer Jill Tartar, the retired director of the SETI Institute’s Center for SETI Research, the institute is hoping to become involved in a much larger international project; the Square Kilometer Array (SKA). When it begins operations in 2020, the SKA is planned to be the world’s largest radio telescope. It will consist of several thousand dishes and other receivers giving it a radio signal collecting area of one square kilometer. The advantage of having more collecting area is that the telescope is sensitive to fainter signals. If funding allows it to be built in the way currently planned, it will be capable of training multiple simultaneous beams at the sky, some of which Tartar said might be used to mount a continuously ongoing SETI search.

The planned Square Kilometer Array will be the world's largest radio telescope when it begins operations in 2018 Swinburne Astronomy Productions for SKA Project Development Office
The planned Square Kilometer Array will be the world’s largest radio telescope when it begins operations in 2018 Swinburne Astronomy Productions for SKA Project Development Office

Suppose we did find something. What sort of reply could we send? How much do we have the technological capability to send, if we wanted to? Back in 1974, in the first demonstration of the capacity for interstellar messaging, the Arecibo radio telescope transmitted a mere 210 bytes, and took 3 minutes to do it. The message consisted of a human stick figure and a few other crude symbols and diagrams. Because this primitive effort is still the most well-known example of interstellar radio messaging, prepare yourself for a stunning surprise. According to SETI Institute radio astronomer Seth Shostak, using broadband microwave radio, we could send them the Library of Congress (consisting of 17 million books) in 3 days, and the contents of the World Wide Web (as of 2008) in a comparable time.

Using the shorter optical wavelengths of a laser beam and optical broadband, we could send either one in 20 minutes. Since the extraterrestrials might tune in at any time, we would need to send the transmission over and over again many times. Although our transmissions could be sent in only days or minutes, they would, of course, still take decades or centuries to traverse the light years. This transmission capability presents a stunning opportunity. We can send anything. We can send everything. Could it really be that someday, beings from Tau Ceti will peruse your Facebook page?

So what can we expect from the aliens? Any message we might receive, Seth Shostak thought, would be of one of two possible sorts. A civilization already aware of our existence, he believed, would send us a huge message, rich in information content. This is because even if technological civilizations are fairly common in the galaxy the nearest one might be tens, hundreds, or thousands of light years away. Radio messages traveling at the speed of light will take that long to cross those distances, and decades or centuries will elapse between query and response. If we are contacted, Shostak really does think that we should send the aliens the entire content of the World Wide Web. Civilizations further away than 70 light years from Earth probably wouldn’t know that we exist, because radio signals from Earth haven’t reached them yet. Shostak didn’t think that civilizations would waste precious transmitting time and energy bombarding planets with petabytes of information if they didn’t already know that there was a technological civilization there. Worlds that weren’t known to harbor a civilization, Shostak speculated, might get put on a long list of potentially habitable planets to which the aliens might periodically send a brief “ping” hoping to get a response.

A petabyte of gibberish contains as much information as a petabyte of our world’s greatest art and literature (or tackiest YouTube videos). A petabyte of our world’s greatest art and literature is gibberish to a being who can’t understand it. We could send the aliens truly stunning amounts of information, but can we find some way to ensure that they will understand its meaning? Could we hope to understand an alien message sent to us, or would all those petabytes be for naught? In the next installment, we’ll learn that we face daunting problems.

Part 1: Shouting Into the Darkness

References and Further Readings:

Communicating Across the Cosmos: How can we make ourselves understood by other civilizations in the galaxy, SETI Institute.

N. Atkinson (2012), SETI: The Search Goes On, Universe Today.

S. J. Dick (1996), The Biological Universe: The Twentieth_Century Extraterrestrial Life Debate and the Limits of Science, Cambridge University Press, Cambridge, UK.

S. Hall (2014), Are We Ready for Contact?, Universe Today.

Allen Telescope Array, SETI Institute.