Over the past few years, the field of astrobiology has made great strides. With missions such as Kepler making exoplanet discoveries commonplace, the question no longer is “Are other planets out there?” but “When will we find a true twin of Earth?”
A new book, “Five Billion Years of Solitude,” takes the reader from the earliest efforts of astrobiology, along with information on how life took hold on Earth, to how we can use that information to help understand how life may flourish on other worlds – all while giving us a glimpse inside the minds of some of the field’s most notable scientists.
To say that author Lee Billings tackles only the subject of astrobiology in “Five Years of Solitude” would be selling this book extremely short. While the main focus of the book is life on Earth and the possibility of life elsewhere, readers will find “Five Years of Solitude” incredibly engaging. Combining conversations with such legends like Frank Drake and Sara Seager with in-depth discussions of numerous science topics related to the search for life, Billings has created a book that is not only entertaining, but educational as well.
For those who aren’t well-versed in the details of astrobiology, the casual, “conversational” approach Billings takes to presenting scientific concepts makes for easily digestible reading. While the scientific concepts explained in the book are laid out in good detail, Billings doesn’t present them in an overly dry, or boring manner. Weaving scientific knowledge with interviews from heavy hitters in the world of astrobiology is one of the book’s strongest selling points. The book is both a primer on astrobiology, and a collection of knowlegde from some of the greatest minds in the field.
In the many conversations Billings has with people such as Geoff Marcy, Frank Drake, Sara Seager, and many others, one can get a “feel” for the sometimes insurmountable obstacles scientists face in trying to get their projects approved and funded. Readers will finish “Five Billion Years of Solitude” with a deep appreciation for the miracle of life on Earth, and the hard work and dedication researchers invest in understanding life on Earth, and the possibility of life elsewhere.
Additionally, Billings provides a gold mine of additional materials that readers can dive into if they want to immerse themselves much deeper into the field of astrobiology. If you are interested in the field of Astrobiology, and understanding how life developed on Earth (and possibly elsewhere), you’ll find “Five Billion Years of Solitude” a very engaging book.
Early on, Mars had giant active volcanoes, which would have released significant methane. Because of methane’s high greenhouse potential, even a thin atmosphere might have supported liquid water. Credit: NASA
Using a phone to search for signs of life? Yeah, we can get behind that. One group of researchers has a system that they’ve been testing out in analog environments with the aim of (eventually, one day, they hope) it being applied, say, to other planets — such as Mars.
Here’s how it works:
“Initially the human astrobiologist takes images of his/her surroundings using a mobile phone camera. These images are sent via Bluetooth to a laptop, which processes the images to detect novel colors and textures, and communicates back to the astrobiologist the degree of similarity to previous images stored in the database,” read a press release on the technology.
View of Mars’ surface near the north pole from the Phoenix lander. Credit: NASA/JPL-Calech/University of Arizona
The aim is to eventually have robots, if necessary, do the same thing on Mars or in other locations. Field tests have been done in Martian analog environments, with intriguing results.
“In our most recent tests at a former coal mine in West Virginia, the similarity-matching by the computer agreed with the judgement of our human geologists 91% of the time,” stated Patrick McGuire, who works in Freie Universität’s planetary sciences and remote sensing department in Germany.
“The novelty detection also worked well, although there were some issues in differentiating between features that are similar in color but different in texture, like yellow lichen and sulfur-stained coalbeds. However, for a first test of the technique, it looks very promising.”
You can check out more details in this paper on Arxiv, a site that publishes articles before they are peer-reviewed. The information has also been accepted for publication in the International Journal of Astrobiology.
Are Earthlings really Martians ? Did life arise on Mars first and then journey on meteors to our planet and populate Earth billions of years ago? Earth and Mars are compared in size as they look today.
Are Earthlings really Martians ?
Did life arise on Mars first and then journey on rocks to our planet and populate Earth billions of years ago? Earth and Mars are compared in size as they look today. NASA’s upcoming MAVEN Mars orbiter is aimed at answering key questions related to the habitability of Mars, its ancient atmosphere and where did all the water go. Story updated[/caption]
That’s the controversial theory proposed today (Aug. 29) by respected American chemist Professor Steven Benner during a presentation at the annual Goldschmidt Conference of geochemists being held in Florence, Italy. It’s based on new evidence uncovered by his research team and is sure to spark heated debate on the origin of life question.
Benner said the new scientific evidence “supports the long-debated theory that life on Earth may have started on Mars,” in a statement. Universe Today contacted Benner for further details and enlightenment.
“We have chemistry that (at least at the level of hypothesis) makes RNA prebiotically,” Benner told Universe Today. “AND IF you think that life began with RNA, THEN you place life’s origins on Mars.” Benner said he has experimental data as well.
First- How did ancient Mars life, if it ever even existed, reach Earth?
On rocks violently flung up from the Red Planet’s surface during mammoth collisions with asteroids or comets that then traveled millions of miles (kilometers) across interplanetary space to Earth – melting, heating and exploding violently before the remnants crashed into the solid or liquid surface.
An asteroid impacts ancient Mars and send rocks hurtling to space – some reach Earth. Did they transport Mars life to Earth? Or minerals that could catalyze the origin of life on Earth?
“The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock,” says Benner, of The Westheimer Institute of Science and Technology in Florida. That theory is generally known as panspermia.
To date, about 120 Martian meteorites have been discovered on Earth.
And Benner explained that one needs to distinguish between habitability and the origin of life.
“The distinction is being made between habitability (where can life live) and origins (where might life have originated).”
NASA’s new Curiosity Mars rover was expressly dispatched to search for environmental conditions favorable to life and has already discovered a habitable zone on the Red Planet’s surface rocks barely half a year after touchdown inside Gale Crater.
Furthermore, NASA’s next Mars orbiter- named MAVEN – launches later this year and seeks to determine when Mars lost its atmosphere and water- key questions in the Origin of Life debate.
Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182) and discovered a habitable zone, shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169). The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo
Of course the proposed chemistry leading to life is exceedingly complex and life has never been created from non-life in the lab.
The key new points here are that Benner believes the origin of life involves “deserts” and oxidized forms of the elements Boron (B) and Molybdenum (Mo), namely “borate and molybdate,” Benner told me.
“Life originated some 4 billion years ago ± 0.5 billon,” Benner stated.
He says that there are two paradoxes which make it difficult for scientists to understand how life could have started on Earth – involving organic tars and water.
Life as we know it is based on organic molecules, the chemistry of carbon and its compounds.
But just discovering the presence of organic compounds is not the equivalent of finding life. Nor is it sufficient for the creation of life.
And simply mixing organic compounds aimlessly in the lab and heating them leads to globs of useless tars, as every organic chemist and lab student knows.
Benner dubs that the ‘tar paradox’.
Although Curiosity has not yet discovered organic molecules on Mars, she is now speeding towards a towering 3 mile (5 km) high Martian mountain known as Mount Sharp.
Curiosity Spies Mount Sharp – her primary destination
Curiosity will ascend mysterious Mount Sharp and investigate the sedimentary layers searching for clues to the history and habitability of the Red Planet over billions of years. This mosaic was assembled from over 3 dozen Mastcam camera images taken on Sol 352 (Aug 2, 2013. Credit: NASA/JPL-Caltech/MSSS/ Marco Di Lorenzo/Ken Kremer-kenkremer.com
Upon arrival sometime next spring or summer, scientists will target the state of the art robot to investigate the lower sedimentary layers of Mount Sharp in search of clues to habitability and preserved organics that could shed light on the origin of life question and the presence of borates and molybdates.
It’s clear that many different catalysts were required for the origin of life. How much and their identity is a big part of Benner’s research focus.
“Certain elements seem able to control the propensity of organic materials to turn into tar, particularly boron and molybdenum, so we believe that minerals containing both were fundamental to life first starting,” says Benner in a statement. “Analysis of a Martian meteorite recently showed that there was boron on Mars; we now believe that the oxidized form of molybdenum was there too.”
The second paradox relates to water. He says that there was too much water covering the early Earth’s surface, thereby causing a struggle for life to survive. Not exactly the conventional wisdom.
“Not only would this have prevented sufficient concentrations of boron forming – it’s currently only found in very dry places like Death Valley – but water is corrosive to RNA, which scientists believe was the first genetic molecule to appear. Although there was water on Mars, it covered much smaller areas than on early Earth.”
Parts of ancient Mars were covered by oceans, lakes and streams of liquid water in this artists concept, unlike the arid and bone dry Martian surface of today. Subsurface water ice is what remains of Martian water.
I asked Benner to add some context on the beneficial effects of deserts and oxidized boron and molybdenum.
“We have chemistry that (at least at the level of hypothesis) makes RNA prebiotically,” Benner explained to Universe Today.
“We require mineral species like borate (to capture organic species before they devolve to tar), molybdate (to arrange that material to give ribose), and deserts (to dry things out, to avoid the water problem).”
“Various geologists will not let us have these [borates and molybdates] on early Earth, but they will let us have them on Mars.”
“So IF you believe what the geologists are telling you about the structure of early Earth, AND you think that you need our chemistry to get RNA, AND IF you think that life began with RNA, THEN you place life’s origins on Mars,” Benner elaborated.
“The assembly of RNA building blocks is thermodynamically disfavored in water. We want a desert to get rid of the water intermittently.”
I asked Benner whether his lab has run experiments in support of his hypothesis and how much borate and molybdate are required.
“Yes, we have run many lab experiments. The borate is stoichiometric [meaning roughly equivalent to organics on a molar basis]; The molybdate is catalytic,” Benner responded.
“And borate has now been found in meteorites from Mars, that was reported about three months ago.
At his talk, Benner outlined some of the chemical reactions involved.
Although some scientists have invoked water, minerals and organics brought to ancient Earth by comets as a potential pathway to the origin of life, Benner thinks differently about the role of comets.
“Not comets, because comets do not have deserts, borate and molybdate,” Benner told Universe Today.
MAVEN is NASA’s next Mars orbiter and seeks to determine when Mars lost its atmosphere and water- key questions in the Origin of Life debate. MAVEN is slated to blastoff for Mars on Nov. 18, 2013. It is shown here with solar panels deployed as part of environmental testing procedures at Lockheed Martin Space Systems in Waterton, Colorado, before shipment to Florida in early August. Credit: Lockheed Martin
Benner has developed a logic tree outlining his proposal that life on Earth may have started on Mars.
“It explains how you get to the conclusion that life originated on Mars. As you can see from the tree, you can escape that conclusion by diverging from the logic path.”
Finally, Benner is not one who blindly accepts controversial proposals himself.
He was an early skeptic of the claims concerning arsenic based life announced a few years back at a NASA sponsored press conference, and also of the claims of Mars life discovered in the famous Mars meteorite known as ALH 84001.
“I am afraid that what we thought were fossils in ALH 84001 are not.”
The debate on whether Earthlings are really Martians will continue as science research progresses and until definitive proof is discovered and accepted by a consensus of the science community of Earthlings – whatever our origin.
On Nov. 18, NASA will launch its next mission to Mars – the MAVEN orbiter. Its aimed at studying the upper Martian atmosphere for the first time.
“MAVENS’s goal is determining the composition of the ancient Martian atmosphere and when it was lost, where did all the water go and how and when was it lost,” said Bruce Jakosky to Universe Today at a MAVEN conference at the University of Colorado- Boulder. Jakosky, of CU-Boulder, is the MAVEN Principal Investigator.
MAVEN will shed light on the habitability of Mars billions of years ago and provide insight on the origin of life questions and chemistry raised by Benner and others.
…………….
Learn more about Mars, the Origin of Life, LADEE, Cygnus, Antares, MAVEN, Orion, Mars rovers and more at Ken’s upcoming presentations
Sep 5/6/16/17: “LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
Oct 9: “LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM
Sketch of the ‘AstroGardening’ robot within its Mars garden Credit: Vanessa Harden.
Editor’s note: This guest post is written by Louisa Preston, an Astrobiologist and Planetary Geologist. She is a TED Fellow, and Postdoctoral Research Associate at The Open University, UK.
In the last century humanity has taken gigantic leaps forward in the robotic exploration of the cosmos — not least in the search for habitable worlds and environments that could house life outside of the Earth. The next logical step is for humanity itself to leave the confines of our planet, and take on long-term human exploration of the Solar System. Mars in particular is a key target for future human planetary adventures even though on the face of it, it seems so hostile to human life. In fact Mars actually has the most clement environment of any planet in the Solar System outside of Earth and is known to have all of the resources necessary in some accessible form, to sustain life on the surface. So how might we survive on Mars? The crucial things for humans on Mars are the availability of oxygen, shelter, food and water, and not just endless consumables delivered to the planet from Earth. For humans to live long-term on Mars, they will need a self-sustaining habitat to be able to thrive in for generations.
In short, they’ll need a garden. And maybe a robot, too.
Any garden on Mars would need protection in the form of a greenhouse or geodesic dome that could keep the vegetables, fruits, grains and flowers sheltered from the extreme UV radiation that floods the Martian surface, whilst still allowing enough sunlight through to allow them to grow. This dome would also have to be strong enough to provide support and protection against potentially devastating Martian dust storms.
The crops would need to be kept warm, as outside the dome it will be on average a freezing -63 °C. Solar panels arranged outside the habitat and heating filaments underneath it could provide the desired warmth.
Liquid water is needed for irrigation of the plants and for future human consumption, but with water on Mars mainly frozen beneath the surface, we would need to mine the ice and melt it. The atmosphere on Mars is chiefly composed of CO2, which humans cannot use for any of our vital functions. However plants can! They can utilise this atmospheric CO2 to photosynthesise, which would actually create the oxygen we would need.
These are all important aspects of long-term human habitation of Mars that need to be tested and perfected before we arrive, but thankfully most of these can be investigated whilst safely here on the Earth in Mars analogue environments and specially designed spaces.
Our premise is that of a pioneer AstroGardening robot, designed and built by ourselves, to be sent to Mars to set up garden habitats in advance of the first human inhabitants. It will scatter ‘seed pills’ containing various seeds, clay and nutrients across the habitat and nurture the growing plants.
But before we actually go to Mars, we are working on an interactive ‘Mars Garden’ exhibit and AstroGardening Rover designed to educate and inspire.
Installation designer Vanessa Harden and I are building such a space; an interactive experience designed for museums and science centers to entertain and educate on the perils and benefits of gardening on Mars, the ways in which we need to design tools to do this, the plants that would best grow in Mars soil and the methods we might use to obtain liquid water.
Visitors to this Mars concept habitat will get to meet the AstroGardening robot himself and walk around a lush and tranquil Martian garden. They will also get to see the range of food stuffs that we can actually grow in the Martian soil such as asparagus, potatoes, sweet potatoes, radish, alfalfa, and mung bean.
Our aim for this exhibit is to communicate the science behind future human habitation of Mars, the effect we as humans can have on an environment, and the ethics and logistics of colonising other planets.
The exhibit has already been invited to tour around some of London’s most celebrated and beautiful venues such as observatories and planetariums, museums and art galleries, schools and universities, before heading across the ocean to the US and Canada.
But we need the public’s help to make this tour and exhibit a reality.
We have a Kickstarter page for this concept to raise the funds to begin building our vision. See our page and watch our video (below) to find out how you can help.
Clouds of cosmic dust in the region of Orion. Credit: ESO
The building blocks of life could have their beginnings in the tiny icy grains that make up the gas and dust found between the stars, and those icy grains could be the key to understanding how life can arise on planets. With help from students, researchers have discovered an important pair of prebiotic molecules in the icy particles in interstellar space. The chemicals, found in a giant cloud of gas about 25,000 light-years from Earth may be a precursor to a key component of DNA and another may have a role in the formation of an important amino acid.
“We found the ultimate prebiotic of prebiotic molecules,” said Anthony Remijan, of the National Radio Astronomy Observatory (NRAO).
Using the Green Bank Telescope (GBT) in West Virginia, researchers found a molecule called cyanomethanimine, which produces adenine, one of the four nucleobases that form the “rungs” in the ladder-like structure of DNA. The other molecule, called ethanamine, is thought to play a role in forming alanine, one of the twenty amino acids in the genetic code.
Previously, scientists thought such processes took place in the very tenuous gas between the stars. The new discoveries, however, suggest that the chemical formation sequences for these molecules occurred not in gas, but on the surfaces of ice grains in interstellar space.
“Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can ‘seed’ newly-formed planets with the chemical precursors for life,” said Remijan.
In each case, the newly-discovered interstellar molecules are intermediate stages in multi-step chemical processes leading to the final biological molecule. Details of the processes remain unclear, but the discoveries give new insight on where these processes occur.
“We need to do further experiments to better understand how these reactions work, but it could be that some of the first key steps toward biological chemicals occurred on tiny ice grains,” Remijan said.
The discoveries were made possible by new technology that speeds the process of identifying the “fingerprints” of cosmic chemicals. Each molecule has a specific set of rotational states that it can assume. When it changes from one state to another, a specific amount of energy is either emitted or absorbed, often as radio waves at specific frequencies that can be observed with the GBT.
New laboratory techniques have allowed astrochemists to measure the characteristic patterns of such radio frequencies for specific molecules. Armed with that information, they then can match that pattern with the data received by the telescope. Laboratories at the University of Virginia and the Harvard-Smithsonian Center for Astrophysics measured radio emission from cyanomethanimine and ethanamine, and the frequency patterns from those molecules then were matched to publicly-available data produced by a survey done with the GBT from 2008 to 2011.
A team of undergraduate students participating in a special summer research program for minority students at the University of Virginia (U.Va.) conducted some of the experiments leading to the discovery of cyanomethanimine.
“This is a pretty special discovery and proves that early-career students can do remarkable research,” said Books Pate, a U. Va professor who mentored the students.
The Moon photographed through the layers of the atmosphere from the ISS in December 2003 (NASA/JSC)
What lives at the edge of space? Other than high-flying jet aircraft pilots (and the occasional daredevil skydiver) you wouldn’t expect to find many living things over 10 kilometers up — yet this is exactly where one NASA researcher is hunting for evidence of life.
Earth’s stratosphere is not a place you’d typically think of when considering hospitable environments. High, dry, and cold, the stratosphere is the layer just above where most weather occurs, extending from about 10 km to 50 km (6 to 31 miles) above Earth’s surface. Temperatures in the lowest layers average -56 C (-68 F) with jet stream winds blowing at a steady 100 mph. Atmospheric density is less than 10% that found at sea level and oxygen is found in the form of ozone, which shields life on the surface from harmful UV radiation but leaves anything above 32 km openly exposed.
Sounds like a great place to look for life, right? Biologist David Smith of the University of Washington thinks so… he and his team have found “microbes from every major domain” traveling within upper-atmospheric winds.
Smith, principal investigator with Kennedy Space Center’s Microorganisms in the Stratosphere (MIST) project, is working to take a census of life tens of thousands of feet above the ground. Using high-altitude weather balloons and samples gathered from Mt. Bachelor Observatory in central Oregon, Smith aims to find out what kinds of microbes are found high in the atmosphere, how many there are and where they may have come from.
“Life surviving at high altitudes challenges our notion of the biosphere boundary.”
– David Smith, Biologist, University of Washington in Seattle
Although reports of microorganisms existing as high as 77 km have been around since the 1930s, Smith doubts the validity of some of the old data… the microbes could have been brought up by the research vehicles themselves.
“Almost no controls for sterilization are reported in the papers,” he said.
But while some researchers have suggested that the microbes could have come from outer space, Smith thinks they are terrestrial in origin. Most of the microbes discovered so far are bacterial spores — extremely hardy organisms that can form a protective shell around themselves and thus survive the low temperatures, dry conditions and high levels of radiation found in the stratosphere. Dust storms or hurricanes could presumably deliver the bacteria into the atmosphere where they form spores and are transported across the globe.
If they land in a suitable environment they have the ability to reanimate themselves, continuing to survive and multiply.
Although collecting these high-flying organisms is difficult, Smith is confident that this research will show how such basic life can travel long distances and survive even the harshest environments — not only on Earth but possibly on other worlds as well, such as the dessicated soil of Mars.
“We still have no idea where to draw the altitude boundary of the biosphere,” said Smith. This research will “address how long life can potentially remain in the stratosphere and what sorts of mutations it may inherit while aloft.”
Read more on Michael Schirber’s article for Astrobiology Magazine here, and watch David Smith’s seminar “The High Life: Airborne Microbes on the Edge of Space” held May 2012 at the University of Washington below:
Inset images – Top: layers of the atmosphere, via the Smithsonian/NMNH. Bottom: Scanning electron microscope image of atmospheric bacterial spores collected from Mt. Bachelor Observatory (NASA/KSC)
Artist concept of a Mars Sample Return mission. Credit: Wickman Spacecraft & Propulsion.
A Mars sample return mission has long been a dream and goal of many planetary scientists. Getting Martian soil samples back here on Earth would allow them to be studied in ways rovers and landers just can’t do. Of course, the big reason for getting samples of Mars back to Earth would be to really determine if there ever was – or is — life on Mars. But a sample return mission would be “hellishly difficult,” Steve Squyres of the MER mission once said.
But forget sending a lander, scooping up samples, putting them in a capsule and somehow rocketing them back to Earth. Human genome sequencer Craig Venter wants to send a DNA sequencing machine Mars, and beam back the DNA data to Earth. Not to be outdone, Jonathan Rothberg, founder the DNA sequencing company Ion Torrent, is working on getting his Personal Genome Machine to Mars and sending back the data.
In articles in the Los Angeles Times and MIT’s Technology Review this week the two biologists seem to be in a race, of sorts, to see who could send their DNA machines to Mars first. Venter was quoted as saying, “There will be life forms there,” Venter said, and wants to build a “biological teleporter.”
Rothberg is looking to be part of a NASA-funded project at Harvard and MIT called SET-G, or “the search for extraterrestrial genomes.”
An MIT researcher involved in the project, Christopher Carr, told Technology Review that his lab is working to shrink Ion Torrent’s machine from 30 kilograms down to just three kilograms so that it can fit on a NASA rover, and they are testing how well the device can withstand the heavy radiation it would encounter on the way to Mars.
With NASA’s current budget woes, a sample return mission likely couldn’t happen until around 2030. But another Mars rover mission may be slated for 2018, if all goes well, and a DNA sequencer could potentially be part of the mission, the two biologists said. And an in-situ DNA sequencer avoids the potential pitfalls of a sample return mission.
“People are worried about the Andromeda strain,” Venter said. “We can rebuild the Martians in a P-4 spacesuit lab instead of having them land in the ocean.”
Our galaxy has exoplanets, organic compounds, liquid water -- even a nebula shaped like a DNA helix -- but is there life? (Image credit: M. Morris/UCLA)
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Are we too hopeful in our hunt for extraterrestrial life? Regardless of exoplanet counts, super-Earths and Goldilocks zones, the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it. But even if life does exist somehow, somewhere besides Earth, would it really be all that alien?
In a recent paper titled “Bit by Bit: the Darwinian Basis for Life” Gerald Joyce, Professor of Molecular Biology and Biochemistry at the Scripps Research Institute in La Jolla, CA discusses the nature of life as we know it in regards to its fundamental chemical building blocks — DNA, RNA — and how its ability to pass on the memory of its construction separates true biology from mere chemistry.
The DNA structures that evolved here on Earth — the only place in the Universe we know for certain that life can thrive — have proven to be highly successful (obviously). So what’s to say that life elsewhere wouldn’t be based on the same basic building blocks? And if it is, is it really a “new” life form?
“Truly new ‘alternative life’ would be life of a different biology,” Joyce said. “It would not have the information in it that is part of the same heritage of our life form.”
To arise in the first place, according to Joyce, new life can take two possible routes. Either it begins as chemical connections that grow increasingly more complex until they begin to hold on to the memory of their specific “bit” structure, eventually “bit-flipping” — aka, mutating — into new structures that are either successful or unsuccessful, or it starts from a more “privileged” beginning as an offshoot of previous life, bringing bits into a totally new, immediately successful orientation.
With those two scenarios, anywhere besides Earth “there are no example of either of those conditions so far.”
That’s not saying that there’s no life elsewhere in the Universe… just that we have yet to identify any evidence of it. And without evidence, any discussion of its probability is still pure conjecture.
“In order to estimate probabilities, we need facts,” said Joyce. “The problem is, there is only one life form. And so it’s not possible to estimate probability of life elsewhere when you have only one example.”
Voyager included a golden record with images and sounds of Earthly life recorded on it... just in case. (NASA)
Even though exoplanets are being found on a nearly daily basis, and it’s only a matter of time before a rocky, Earthlike world with liquid water on its surface is confirmed orbiting another star, that’s no guarantee of the presence of alien life — despite what conclusions the headlines will surely jump to.
There could be a billion habitable planets in our galaxy. But what’s the relationship between habitable and inhabited?” Joyce asks. “We don’t know.”
Still, we will continue to search for life beyond our planet, be it truly alien in nature… or something slightly more familiar. Why?
“I think humans are lonely,” Joyce said. “I think humans are like Geppetto — we want to have a ‘real boy’ out there that we can point to, we want to find a Pinocchio living on some extrasolar planet… and then somehow we won’t be such a lonely life form.”
And who knows… if any aliens out there really are a lot like us, they may naturally be searching for evidence of our existence as well. If only to not be so lonely.
This artist's illustration gives an impression of how common planets are around the stars in the Milky Way. Credit: NASA, ESA, and M. Kornmesser (ESO)
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For many of us who grew up listening to Carl Sagan, watching robotic spacecraft travel to other worlds, and indulging in science fiction books and movies, it’s a given: one day we’ll find life somewhere else in the solar system or Universe. But are we being too optimistic? Two researchers say that our hopes and expectations of finding ET might be based more on optimism than scientific evidence, and the recent discoveries of exoplanets that might be similar to Earth are probably getting everyone’s hopes up too high.
Astrophysicist Edwin Turner from Princeton and researcher David Spiegel from the Institute for Advanced Study say the idea that life has or could arise in an another Earth-like environment has only a small amount of supporting evidence, most of it extrapolated from what is known about abiogenesis, or the emergence of life, on early Earth. Their research says the expectations of life cropping up on exoplanets are largely based on the assumption that it would or will happen if the same conditions as Earth exist elsewhere.
Using a Bayesian analysis — which weighs how much of a scientific conclusion stems from actual data and how much comes from the prior assumptions of the scientist — the duo concluded that current knowledge about life on other planets suggests Earth might be a cosmic aberration, where life took shape unusually fast and furious. If so, then the chances of the average terrestrial planet hosting life would be low.
“Fossil evidence suggests that life began very early in Earth’s history and that has led people to determine that life might be quite common in the universe because it happened so quickly here, but the knowledge about life on Earth simply doesn’t reveal much about the actual probability of life on other planets,” Turner said.
So, if a scientist starts out assuming that the chances of life existing on another planet is as large as on Earth, then their scientific results will be presented in a way that supports that likelihood, Turner said.
“Information about that probability comes largely from the assumptions scientists have going in, and some of the most optimistic conclusions have been based almost entirely on those assumptions,” he said.
Therefore, with all the exoplanets being found, and as our discoveries have become more and more enticingly Earth-like, these planets have our knowledge of life on Earth projected onto them, the researchers said.
How does an exoplanet researcher feel about this? Turner and Spiegel found a sympathetic soul in Joshua Winn from the Massachusetts Institute of Technology, who said that the two cast convincing doubt on a prominent basis for expecting extraterrestrial life.
“There is a commonly heard argument that life must be common or else it would not have arisen so quickly after the surface of the Earth cooled,” Winn said. “This argument seems persuasive on its face, but Spiegel and Turner have shown it doesn’t stand up to a rigorous statistical examination — with a sample of only one life-bearing planet, one cannot even get a ballpark estimate of the abundance of life in the universe.
It is true that science is about facts — not about what your gut feelings are. But there’s a strong argument that we need inspiration to do the best, most engaging science. Writer Andrew Zimmerman Jones blogged today at PBS about how many scientists were spurred to follow their careers by reading science fiction when they were young.
“The finest science fiction is inspired by the same thing that has inspired the greatest science discoveries throughout the ages: optimism for the future,” wrote Jones.
And perhaps that is what is mostly behind our hopes for finding ET: optimism for the future of the human race, that we really could one day travel to other worlds, and find new friends — “to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no one has gone before…”
Turner and Spiegel do say they are not making judgments, but just analyzing existing data that suggests the debate about the existence of life on other planets is framed largely by the prior assumptions of the participants.
“It could easily be that life came about on Earth one way, but came about on other planets in other ways, if it came about at all,” Turner said. “The best way to find out, of course, is to look. But I don’t think we’ll know by debating the process of how life came about on Earth.”
I for one welcome our alien dinosaur overlords…maybe.
Dinosaurs once roamed and ruled the Earth. Is it possible that similar humongous creatures may have evolved on another planet – a world that DIDN’T get smacked by an asteroid – and later they developed to have human-like, intelligent brains? A recent paper discussing why the biochemical signature of life on Earth is so consistent in orientation somehow segued into the possibility that advanced versions of T. Rex and other dinosaurs may be the life forms that live on other worlds. The conclusion? “We would be better off not meeting them,” said scientist Ronald Breslow, author of the paper.
The building blocks of terrestrial amino acids, sugars, and the genetic materials DNA and RNA have two possible orientations, left or right, which mirror each other in what is called chirality. On Earth, with the exception of a few bacteria, amino acids have the left-handed orientation. Most sugars have a right-handed orientation. How did that homochirality happen?
If meteorites carried specific types of amino acids to Earth about 4 billion years, that could have set the pattern the left-handed chirality in terrestial proteins.
“Of course,” Breslow said in a press release, “showing that it could have happened this way is not the same as showing that it did. An implication from this work is that elsewhere in the universe there could be life forms based on D-amino acids and L-sugars. Such life forms could well be advanced versions of dinosaurs, if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth.”
But not everyone was impressed with the notion of dinosaurs from space. “None of this has anything to do with dinosaurs,” wrote science author Brian Switek in the Smithsonian blog Dinosaur Tracking. “As much as I’m charmed by the idea of alien dinosaurs, Breslow’s conjecture makes my brain ache. Our planet’s fossil record has intricately detailed the fact that evolution is not a linear march of progress from one predestined waypoint to another. Dinosaurs were never destined to be. The history of life on earth has been greatly influenced by chance and contingency, and dinosaurs are a perfect example of this fact.”
