Before there was life as we know it, there were molecules. And after many seemingly unlikely steps these molecules underwent a magnificent transition: they became complex systems with the capability to reproduce, pass along information and drive chemical reactions. But the host of steps leading up to this transition has remained one of science’s beloved mysteries.
New research suggests that the building blocks of life — prebiotic molecules — may form in the atmospheres of planets, where the dust provides a safe platform to form on and various reactions with the surrounding plasma provide enough energy necessary to create life.
“If the formation of life is like a jigsaw puzzle — a very big and complicated jigsaw puzzle — I like to imagine prebiotic molecules as some of the individual puzzle pieces,” said St. Andrews professor Dr. Craig Stark. “Putting the pieces together you form more complicated biological structures making a clearer, more recognizable picture. And when all the pieces are in place the resulting picture is life.”
We currently think prebiotic molecules form on the tiny ice grains in interstellar space. While this may seem to contradict the readily accepted belief that life in space is impossible, the surface of the grain actually provides a nice hospitable environment for life to form as it protects molecules from harmful space radiation.
“Molecules are formed on the dust surface from the adsorption of atoms and molecules from the surrounding gas,” Stark told Universe Today. “If the appropriate ingredients to make a particular molecular compound are available, and the conditions are right, you’re in business.”
By “conditions,” Stark is hinting at the second ingredient necessary: energy. The simple molecules that populate the galaxy are relatively stable; without an incredible amount of energy they won’t form new bonds. It has been thought that life could form in lightning strikes and volcanic eruptions for this very reason.
So Stark and his colleagues turned their eyes to the atmospheres of exoplanets, where dust is immersed in a plasma full of positive ions and negative electrons. Here the electrostatic interactions of dust particles with plasma may provide the high energy necessary to form prebiotic compounds.
In a plasma the dust grain will soak up the free electrons quickly, becoming negatively charged. This is because electrons are lighter, and therefore quicker, than positive ions. Once the dust grain is negatively charged it will attract a flux of positive ions, which will accelerate toward the dust particle and collide with more energy than they would in a neutral environment.
In order to test this, the authors studied an example atmosphere, which allowed them to examine the various processes that may turn the ionized gas into a plasma as well as determine if the plasma would lead to energetic enough reactions.
“As a proof of principle we looked at the sequence of chemical reactions that lead to the formation of the simplest amino acid glycine,” Stark said. Amino acids are great examples of prebiotic molecules because they are required for the formation of proteins, peptides and enzymes.
Their models showed that “the plasma ions can indeed be accelerated to sufficient energies that exceed the activation energies for the formation of formaldehyde, ammonia, hydrogen cyanide and ultimately the amino acid glycine,” Stark told Universe Today. “This may not have been possible if the plasma was absent.”
The authors demonstrated that with modest plasma temperatures, there is enough energy to form the prebiotic molecule glycine. Higher temperatures may also enable more complex reactions and therefore more intricate prebiotic molecules.
Stark and his colleagues demonstrated a viable pathway to the formation of a prebiotic molecule, and therefore life, in seemingly common conditions. While the origin of life may remain one of science’s beloved mysteries, we continue to gain a better understanding, one puzzle piece at a time.
The paper has been accepted for publication in the journal Astrobiology and is available for download here.
The theory of Lithopanspermia states that life can be shared between planets within a planetary system. Credit: NASA
With the recent discovery that Europa has geysers, and therefore definitive proof of a liquid ocean, there’s a lot of talk about the possibility of life in the outer solar system.
According to a new study, there is a high probably that life spread from Earth to other planets and moons during the period of the late heavy bombardment — an era about 4.1 billion to 3.8 billion years ago — when untold numbers of asteroids and comets pummeled the Earth. Rock fragments from the Earth would have been ejected after a large meteoroid impact, and may have carried the basic ingredients for life to other solar system bodies.
These findings, from Pennsylvania State University, strongly support lithopanspermia: the idea that basic life forms can be distributed throughout the solar system via rock fragments cast forth by meteoroid impacts.
Strong evidence for lithopanspermia is found within the rocks themselves. Of the over 53,000 meteorites found on Earth, 105 have been identified as Martian in origin. In other words an impact on Mars ejected rock fragments that then hit the Earth.
The researchers simulated a large number of rock fragments ejected from the Earth and Mars with random velocities. They then tracked each rock fragment in n-body simulations — models of how objects gravitationally interact with one another over time — in order to determine how the rock fragments move among the planets.
“We ran the simulations for 10 million years after the ejection, and then counted up how many rocks hit each planet,” said doctoral student Rachel Worth, lead author on the study.
Their simulations mainly showed a large number of rock fragments falling into the Sun or exiting the solar system entirely, but a small fraction hit planets. These estimations allowed them to calculate the likelihood that a rock fragment might hit a planet or a moon. They then projected this probability to 3.5 billion years, instead of 10 million years.
In general the number of impacts decreased with the distance away from the planet of origin. Over the course of 3.5 billion years, tens of thousands of rock fragments from the Earth and Mars could have been transferred to Jupiter and several thousand rock fragments could have reached Saturn.
“Fragments from the Earth can reach the moons of Jupiter and Saturn, and thus could potentially carry life there,” Worth told Universe Today.
The researchers looked at Jupiter’s Galilean satellites: Io, Europa, Ganymede and Callisto and Saturn’s largest moons: Titan and Enceladus. Over the course of 3.5 billion years, each of these moons received between one and 10 meteoroid impacts from the Earth and Mars.
It’s statistically possible that life was carried from the Earth or Mars to one of the moons of Jupiter or Saturn. During the period of late bombardment the solar system was much warmer and the now icy moons of Saturn and Jupiter didn’t have those protective shells to prevent meteorites from reaching their liquid interiors. Even if they did have a thin layer of ice, there’s a large chance that a meteorite would fall though, depositing life in the ocean beneath.
In the case of Europa, six rock fragments from the Earth would have hit it over the last 3.5 billion years.
It has previously been thought that finding life in Europa’s oceans would be proof of an independent origin of life. “But our results suggest we can’t assume that,” Worth said. “We would need to test any life found and try to figure out whether it descended from Earth life, or is something really new.”
The paper has been accepted for publication in the journal Astrobiology and is available for download here.
NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER, FL – NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) space probe thundered to space today (Nov. 18) following a flawless blastoff from Cape Canaveral Air Force Station’s Space Launch Complex 41 at 1:28 p.m. EST atop a powerful Atlas V rocket.
“Hey Guys we’re going to Mars!” gushed Bruce Jakosky, MAVEN’s Principal Investigator at a post launch briefing for reporters.
“Now I am a Martian,” beamed Jakosky gleefully, as well as is everyone else who has worked on MAVEN since the project was conceived some ten years ago, he noted.
Today’s countdown was absolutely perfect culminating in a spectacular and on time lift off that rumbled across the Florida Space Coast to the delight of cheering crowds assembled for the historic launch aimed at discovering the history of water and habitability stretching back over billions of years on Mars.
“I take great pride in the entire team,” said Jakosky.
“Everyone was absolutely committed to making this work.”
MAVEN launches atop Atlas V booster on Nov. 18, 2013 from NASA’s Kennedy Space Center, Florida. Credit: Mike Killian/mikekillianphotography.com
The $671 Million MAVEN spacecraft separated from the Atlas Centaur upper stage some 52 minutes after liftoff, unfurled its wing like solar panels to produce life giving power and thus began a 10 month interplanetary voyage to the Red Planet.
“We’re currently about 14,000 miles away from Earth and heading out to the Red Planet right now,” said MAVEN Project Manager David Mitchell of NASA’s Goddard Space Flight Center at the briefing, after the 5,400-pound spacecraft had been soaring through space for barely two and a half hours.
“The first trajectory correction maneuver (TCM) is set for Dec. 3,” added Mitchell. There are a minimum of four TCM’s to ensure that the majestic probe remains precisely on course for Mars.
“Safe travels MAVEN!” said Mitchell. “We’re with you all the way.”
NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center. Credit: Ken Kremer/kenkremer.com
It will take the spacecraft 10 months to reach the Red Planet, with arrival scheduled for Sept. 22, 2014.
Jakosky noted that while the launch is a big milestone, it’s just the beginning.
MAVEN’s purpose is to accomplish world class science after arriving at Mars and completing a check-out period before it can finally begin collecting science data.
MAVEN will answer key questions about the evolution of Mars, its geology and the potential for the evolution of life.
“MAVEN is an astrobiology mission,” says Jakosky.
Mars was once wet billions of years ago, but no longer. Now it’s a cold arid world, not exactly hospitable to life.
“We want to determine what were the drivers of that change?” said Jakosky. “What is the history of Martian habitability, climate change and the potential for life?”
MAVEN will study Mars upper atmosphere to explore how the Red Planet may have lost its atmosphere over billions of years. It will measure current rates of atmospheric loss to determine how and when Mars lost its atmosphere and water.
The MAVEN probe carries nine sensors in three instrument suites.
The Particles and Fields Package, provided by the University of California at Berkeley with support from CU/LASP and NASA’s Goddard Space Flight Center in Greenbelt, Md., contains six instruments to characterize the solar wind and the ionosphere of Mars. The Remote Sensing Package, built by CU/LASP, will determine global characteristics of the upper atmosphere and ionosphere. The Neutral Gas and Ion Mass Spectrometer, built by Goddard, will measure the composition of Mars’ upper atmosphere.
“We need to know everything we can before we can send people to Mars,” said Dr. Jim Green, NASA’s Director of Planetary Science at NASA HQ in Washington, DC.
“MAVEN is a key step along the way. And the team did it under budget!” Green elaborated. “It is so exciting!”
Dr. Jim Green (5th from left), NASA’s Director of Planetary Science, poses with MAVEN spacecraft model and space journalists and photographers covering the Nov. 18 MAVEN launch at the Kennedy Space Center – including Ken Kremer (left) from Universe Today/RocketSTEM Media Foundation. Credit: Alan Walters/awaltersohoto.com
Over the course of its one-Earth-year primary mission, MAVEN will observe all of Mars’ latitudes at altitudes ranging from 93 miles to more than 3,800 miles.
MAVEN will execute five deep dip maneuvers during the first year, descending to an altitude of 78 miles. This marks the lower boundary of the planet’s upper atmosphere.
Stay tuned here for continuing MAVEN and MOM news and Ken’s MAVEN launch reports from on site at the Kennedy Space Center press site.
Learn more about MAVEN, MOM, Mars rovers, Orion and more at Ken’s upcoming presentations
Nov 18-21: “MAVEN Mars Launch and Curiosity Explores Mars, Orion and NASA’s Future”, Kennedy Space Center Quality Inn, Titusville, FL, 8 PM
Dec 11: “Curiosity, MAVEN and the Search for Life on Mars”, “LADEE & Antares ISS Launches from Virginia”, Rittenhouse Astronomical Society, Franklin Institute, Phila, PA, 8 PM
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.
Our Universe is big, and it’s been around for a long time. So why don’t we see any evidence of aliens? If they are out there, why haven’t they contacted us, and how do we contact them? What methods might they use to try and contact us?
Where do we look for signs of alien civilizations?
The search for extraterrestrial intelligence, otherwise known as SETI, are the methods that scientists have proposed to discover evidence of aliens in the Universe.
Perhaps the most famous method is listening for their signals. Here on Earth, we have exploited the radio spectrum to send signals through the air. We even use it to communicate with spacecraft in the Solar System.
So, since it works so well for us, it makes sense that aliens might use radio waves to communicate from star to star. If there’s an alien civilization out there beaming a signal directly at the Sun, our largest radio telescopes should be able to pick up their signal.
The problem is that the galaxy is huge, with hundreds of billions of stars. Any one of which could be the world where the aliens live. Furthermore, we don’t know which frequency the aliens might use to communicate with us.
Even though the search for ET has been going for many years, we’ve only explored a fraction of the millions of available stars and frequencies on the radio spectrum.
So far, no definitive signal has been discovered.
Gieren et al. used the 8.2-m Very Large Telescope (Yepun) to image M33, and deduce the distance to that galaxy (image credit: ESO).Another possibility is that aliens are using lasers to communicate with us. An alien could target an incredibly powerful laser at our star, and it would be detectable with our large optical telescopes. There have been a few dedicated searches for laser communication, and scientists have proposed we could search for these alien signals at the same time we’re searching for extrasolar planets.
Again, so far nothing has turned up.
View from inside the Borexino neutrino detector. Image Credit: Borexino CollaborationIt’s possible that aliens use a more exotic method of communication, like neutrinos.
Neutrinos are generated in high energy collisions, and can pass right through planets with ease. They would be incredibly difficult to detect with our current technology, but maybe advances in the future will make that a possible communication method.
But maybe Instead of searching for signals, we could look for their artifacts.
If the energy of transmitting signals across the vast reaches of space is too much, it might make more sense for aliens to construct self-replicating probes and let them journey from star to star.
These probes could leave behind an obvious alien-made structure which we could discover once we become a true spacefaring species.
We could also detect aliens by their impact on their home planets. With a large enough space telescope, we should be able to study the atmosphere of planets orbiting nearby stars. An industrialized civilization would probably be polluting its atmosphere with various gases — just like we have — which would be detectable.
Finally, we could search for evidence of aliens through their structures.
If a civilization starts building megastructures which block off a large portion of their star’s light, we should be able to detect evidence through our search for extrasolar planets.
A Star Trek-inspired space station.A gigantic space station would give off a much different light signature than a nice spherical planet as it passes in front of its star.
There have been a few attempts to reach out to other worlds directly, transmitting signals out into space. It’s unlikely that these signals will actually reach any other civilization, and some scientists are concerned about the wisdom of this kind of communication.
Do we really want to alert potentially hostile aliens to our location in the Milky Way?
It’s exciting to think that there are other alien civilizations around us in the Milky Way, and with a little more work, we could discover their location and maybe even communicate with them.
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
No answers today, only a question. But it’s one of the most interesting and meaningful questions we can possibly ask.
Where does life come from?
How did we get from no life on Earth, to the rich abundance we see today?
Charles Darwin first published our modern theories of evolution – that all life on Earth is related; adapting and changing over time. Look at any two creatures on Earth and you can trace them back to a common ancestor. Humans and chimpanzees share a common ancestor from at least 7 million years ago.
Trace back far enough, and you’re related to the first mammal who lived 220 million years ago. In fact, you and bacteria can trace a family member who lived billions of years ago. Keep going back, and you reach the oldest evidence of life on Earth, about 3.9 billion years ago.
But that’s as far as evolution can take us.
The Earth has been around for 4.5 billion years, and those early years were completely hostile to life. The early atmosphere was toxic, and a constant asteroid bombardment churned the landscape into a worldwide ocean of molten rock.
As soon as the environment settled down to be relatively habitable, life appeared. Just half a billion years beyond the formation of the Earth.
So how did life make the jump from raw chemicals to the evolutionary process we see today? The term for this mystery is abiogenesis and scientists are working on several theories to explain it.
One of the first clues is amino acids, the building blocks of life. In 1953, Stanley Miller and Harold Urey demonstrated that amino acids could form naturally in the environment of the early Earth. They replicated the atmosphere and chemicals present, and then used electric sparks to simulate lightning strikes.
Amazingly, they found a variety of amino acids in the resulting primordial soup.
Other scientists replicated the experiment, even changing the atmospheric conditions to match other models of the early Earth. Instead of water, methane, ammonia and hydrogen, they wondered what would happen if the atmosphere contained hydrogen sulfide and sulfur dioxide from volcanic eruptions. Environments around volcanic vents at the bottom of the ocean might have been the perfect places to get life started, introducing heavier metals like iron and zinc. Perhaps ultraviolet rays from the younger, more volatile Sun, or abundant radiation from natural uranium deposits played a role in pushing life forward into an evolutionary process.
Artists concept of shredded asteroid around white dwarf (NASA/JPL-Caltech)What if life didn’t start on Earth at all? What if the building blocks came from space, drifting through the cosmos for millions of years. Astronomers have discovered amino acids in comets, and even alcohol floating in distant clouds of gas and dust
Maybe it wasn’t the organic chemicals that came first, but the process of self organization. There are examples of inorganic chemicals and metals that can organize themselves under the right conditions. The process of metabolism came first, and then organic chemicals adopted this process.
Thermophilic (heat-loving) bacteria may be among the last living creatures on Earth, the study suggests. Credit: Mark Amend / NOAA Photo LibraryIt’s even possible that life formed multiple times on Earth in different eras. Although all life as we know it is related, there could be a shadow ecosystem of microbial life forms in our soil or oceans which is completely alien to us.
So how did life get here? We just don’t know.
Maybe we’ll discover life on other worlds and that will give us a clue, or maybe scientists will create an experiment that finally replicates the jump from non-life to life.
The idea that there is life on other worlds is humbling and exciting, and finding life on another world would change everything. This has been a driving force for scientists for decades. We find life wherever we find water on Earth, in pools of boiling water, inside glaciers, even in nuclear reactors.
Because of this, our best candidate for life is probably Mars.
The planet is hostile to life now, but evidence is mounting that it was once a warm and habitable world, with rivers, lakes and oceans. Mars could have vast reserves of subsurface water, where life could thrive even now.
If we did discover life there, it’s possible that it’s completely unrelated to Earth life. This would demonstrate that life can originate on almost any world, with the right conditions.
It’s also possible that life on Mars is related to Earth, and our two planets share a common ancestor billions of years in the past.
This is a theory called panspermia.
It suggests that life on Earth and Mars are connected. That life has been traveling from Mars to Earth and vice-versa for billions of years. “How is this possible?” you might ask.
Meteorites.
Mars Meteorite. Credit: NASAWe know that both Earth and Mars have been hammered by countless asteroids in their history long. Some of these impacts are so powerful, rock debris is ejected into escape orbits. This blasted rock could orbit the Sun for eons and then re-enter the atmosphere of another planet.
We know this is true, because we have meteorites on Earth which originated on Mars. Tiny gaps in the rock contained gases which match the atmosphere of Mars. You would think that an asteroid strike would sterilize life in the rocks, but amazingly, bacterial life can survive this process.
Microbial life can even withstand the harsh temperature, radiation and vacuum of space for thousands – possibly millions of years – riding inside their rocky spacecraft.
Some bacteria could even survive when their “space rock” enters the atmosphere of another world.
So a natural space exploration program has been in place for billions of years, with asteroid strikes hurling life-filled rocks into space, which then smash into other worlds.
Life on Mars has been elusive so far, but there are missions in the works which will have the scientific instruments on board to hunt for life on the Red Planet.
Artist illustration of a Europa probe. Image credit: NASA/JPLIf we do find it, will we discover that it’s actually related to us? If we find life under the ice on Europa, or in the cloud tops of Venus, will we discover the same thing?
It gets even stranger.
The Solar System is leaving a trail of debris behind as it orbits around the Milky Way, which could be colliding with other star systems. Which means, it’s possible that life around other stars is related to us too.
So maybe there’s no life on Mars, or if there is, maybe it originated on its own, or maybe it’s all related, as a result of trading life back and forth across giant spans of time and space.
Whatever the case, the search sure is going to be exciting.
An artist's conception of how common exoplanets are throughout the Milky Way Galaxy. Image Credit: Wikipedia
A new study suggests that the number of habitable exoplanets within the Milky Way alone may reach 60 billion.
Previous research performed by a team at Harvard University suggested that there is one Earth-sized planet in the habitable zone of each red dwarf star. But researchers at the University of Chicago and Northwestern University have now extended the habitable zone and doubled this estimate.
The research team, lead by Dr. Jun Yang considered one more variable in their calculations: cloud cover. Most exoplanets are tidally locked to their host stars – one hemisphere continually faces the star, while one continuously faces away. These tidally locked planets have a permanent dayside and a permanent nightside.
One would expect the temperature gradient between the two to be very high, as the dayside is continuously receiving stellar flux, while the nightside is always in darkness. Computer simulations that take into account cloud cover show that this is not the case.
The dayside is covered by clouds, which lead to a “stabilizing cloud feedback” on climate. It has a higher cloud albedo (more light is reflected off the clouds) and a lower greenhouse effect. The presence of clouds actually causes the dayside to be much cooler than expected.
“Tidally locked planets have low enough surface temperatures to be habitable,” explains Jang in his recently published paper. Cloud cover is so effective it even extends the habitable zone to twice the stellar flux. Planets twice as close to their host star are still cool enough to be habitable.
But these new statistics do not apply to just a few stars. Red dwarfs “represent about ¾ of the stars in the galaxy, so it applies to a huge number of planets,” Dr. Abbot, co-author on the paper, told Universe Today. It doubles the number of planets previously thought habitable throughout the entire galaxy.
Not only is the habitable zone around red dwarfs much larger, red dwarfs also live for much longer periods of time. In fact, the Universe is not old enough for any of these long-living stars to have died yet. This gives life the amount of time necessary to form. After all, it took human beings 4.5 billions years to appear on Earth.
Another study we reported on earlier also revised and extrapolated the habitable zone around red dwarf stars.
Future observations will verify this model by measuring the cloud temperatures. On the dayside, we will only be able to see the high cool clouds. A planet resembling this model will therefore look very cold on the dayside. In fact, “a planet that does show the cloud feedback will look hotter on the nightside than the dayside,” explains Abbot.
This effect will be testable with the James Webb Space Telescope. All in all, the Milky Way is likely to be teeming with life.
There are as many as four-hundred billion stars in our galaxy: the Milky Way. And there are more than one-hundred-and-seventy billion galaxies in the observable Universe. Most of those stars have planets, and many of those planets have got to contain useful minerals and fall within their star’s habitable zone where liquid water is present.
The conditions for life are probably everywhere.
But where are all the aliens?
And think about this.
The Universe has been around for 13.8 billion years. Human beings originated 200,000 years ago, so we’ve only been around for 0.01% of the age of the Universe. An intelligent species could arise on any one of those countless worlds, and broadcast their existence to the entire galaxy.
Once a species developed interstellar travel, they could completely colonize our galaxy within a few tens of millions of years; just a heartbeat in the age of the Universe.
So where are they?
As far as we know, Earth is the only place in the Universe where life has arisen, let alone developed an intelligent civilization.
This baffling contradiction is known as the Fermi Paradox, first described in 1950 by the physicist Enrico Fermi.
Scientists have been trying to resolve this mystery for decades, listening for radio signals from other worlds. We’ve only sampled a fraction of the radio spectrum, and so far, we haven’t detected anything that could be a signal from an intelligent species.
How can we explain this?
Maybe we really are the only planet in the entire Universe to develop life. Maybe we’re the first civilization to reach this level of advancement in the entire galaxy. But with so many worlds out there, that really seems unlikely.
Artist impression of an asteroid impact on early Earth (credit: NASA)Maybe civilizations destroy themselves when they reach a certain point. Nuclear weapons, global warming, killer epidemics, and overpopulation could all end humanity. Asteroids could strike the planet and wipe us out. But would this happen to every single civilization? one-hundred-percent of them? Even if ninety-nine-percent of civilizations destroy themselves, we’d still have a couple that made it through and fully colonized the galaxy.
Maybe they’re just too far away, and our signals can’t reach each other. But then, self-replicating probes could traverse those distances and leave a local artifact in every single star system.
Maybe we can’t understand their signals or recognize their artifacts. Maybe, but if aliens constructed a series of artifacts on Earth, I think we’d notice them. The aliens would have experience creating obvious structures.
Maybe they’re just too alien and we just can’t understand them. Maybe we’re too insignificant, and they don’t think we’re even worth talking to. We don’t need to talk to them to know they exist. If they flew through our Solar System, ignoring us, we’d still know they’re around.
Maybe they’re not talking to us on purpose, and we’re really in some kind of galactic zoo. Or aliens have a Prime Directive, and they’re not allowed to talk to us. Again, all the aliens? Not a single one has gotten through and snuck us some evidence? Milky Way. Image credit: NASA
There are many other potential solutions to the Fermi Paradox, but I personally find them all insufficient. The Universe is big, and old, and if extraterrestrial life is anything like us, it wants to multiply and spread out.
Perhaps the most unsettling thought is that something happens to 100% of intelligent civilizations that prevents them from exploring and settling the galaxy. Maybe something good, like the discovery of a transportation system to another Universe. Or maybe something bad, like a destructive technology that has destroyed every single civilization before us.
How do you feel about the Fermi Paradox? How do you resolve the contradictions? Whatever the solution, it’s really fun to think about.
