A Big Deal: Organic Molecules Found on Mars

by David Weintraub

MarsIn 1976, both Viking 1 and Viking 2 touched down on the surface of Mars. Both landed on vast, flat plains, chosen because they were ideal locations for landing safely. Perhaps the most important Viking experiment for assessing whether life could exist on Mars was the gas chromatograph and mass spectrometer (GCMS) instrument, built by a team led by Klaus Biermann of MIT. Ultimately, Biermann and his GCMS team reported a definitive answer: “No organic compounds were found at either of the two landing sites.” None, nada, zilch.

This scientific discovery had enormous importance for our understanding Mars. Summing up what we learned from the Viking missions in 1992, and in particular what we learned from the absence of any organics in the sampled Martian soil, a team of Viking scientists wrote, “The Viking findings established that there is no life at the two landing sites.” Furthermore, because these two sites were thought to be extremely representative of all of Mars, they concluded that this result “virtually guarantees that the Martian surface is lifeless everywhere.” 

If Mars is sterile, then SpaceX and NASA and Blue Origin and Mars One can all move forward with their efforts to land colonists on Mars in the near future. They needn’t wrestle with any ethical issues about contaminating Mars.

Fast forward a generation. In a paper published in Science last week, Jennifer Eigenbrode and her team, working with data collected by the Mars Science Laboratory (i.e., the Curiosity rover), report that they discovered organic molecules in Martian soil. The importance of this discovery for the possible existence of life on Mars is hard to overstate. The discovery of organics on Mars is a BIG deal.

Let’s be careful in discussing organic molecules. An organic molecule must contain at least one carbon atom and that carbon atom must be chemically bonded to a hydrogen atom. All life on Earth is built on a backbone (literally) of organic molecules (DNA). And life on Earth can produce organic molecules (for example, the methane that is produced in the stomachs of cows). But abiological processes can also make organic molecules. In fact, the universe is full of such molecules known as PAHs (polycyclic aromatic hydrocarbons), which are found in interstellar clouds and the atmospheres of red giant stars and which have absolutely nothing to do with life.

Repeat: the presence of organic molecules on Mars does not mean life has been found on Mars. The absence of organic molecules in the Martian soil, as discovered in the Viking experiments, however, almost certainly means “no life here.” 

Were the Viking scientists wrong? Yes, in part. Their conclusion that the plains of Mars are representative of every locale on Mars was an overreach. When assessing whether the environment on Mars might be hospitable to life, local matters. That conclusion shouldn’t surprise anyone. After all, we find significant differences on Earth between the amount and kinds of life in the Mojave Desert and the Amazon River basin. Why? Water.

The vast, flat plains of Mars are free of organics, but they are unlike Gale Crater. Gale Crater was once a lake, full of water and dissolved minerals. We know now that certain locations on Mars that were warm and wet for extended periods of time in the ancient past have preserved a record of the organic molecules that formed in those environments.

Could life have played a role in creating these molecules?  Maybe, but we don’t know, yet. We do know, however, where to keep looking. We do know where to send the next several generations of robots. We do know that we should build robotic explorers that can drill deep into the soil and explore caves in places similar to Gale Crater.

Abigail Allwood, working at NASA’s Jet Propulsion Laboratory, is building a detector called PIXL that will be sent to Mars on a rover mission that is scheduled for launch in 2020. PIXL will be able to make smart decisions, based on the chemistry of a rock, as to whether that rock sample might contain ancient, fossilized microbes. A later mission might retrieve Allwood’s PIXL specimens and bring them back to Earth for more sophisticated laboratory studies. With instruments like PIXL, we have a good chance of definitively answering the question, “Does Mars or did Mars ever have life?”

What does the presence of organic molecules in the Martian regolith mean, as discovered by Curiosity? Those molecules could mean that life is or once was present on Mars. Finding those molecules just raised the stakes in the search for life on Mars. The jury is still out, but the betting odds just changed.

Given all we currently know about Mars, should we be sending astronauts to Mars in the next decade? Do we have the right to contaminate Mars if is already home to native Martian microbes? These are important questions that are more relevant than ever. 

David A. Weintraub is professor of astronomy at Vanderbilt University. He is the author of Life on Mars: What to Know Before We GoReligions and Extraterrestrial Life: How Will We Deal with It?How Old Is the Universe?, and Is Pluto a Planet?: A Historical Journey through the Solar System. He lives in Nashville.

The search for deep life on Earth… and what it means for Mars

Onstott_Deep LifeThe living inhabitants of the soil and seas are well known to biologists. We have long studied their food chains, charted their migration, and speculated about their evolutionary origins. But a mile down an unused tunnel in the Beatrix mine in South Africa, Tullis C. Onstott, Professor of Geosciences at Princeton and author of Deep Life, is on a quest for mysterious bacteria and microbes that require neither oxygen nor sun to survive. When they open up an old valve, water full of microbes and even little worms flows—a discovery with stunning implications. The New York Times has chronicled Onstott’s research in a feature that asks, was there ever life on Mars? And could it still exist far below the surface? That organisms are nourished by our own earth’s core, thriving in darkness encased in hard rock provides major insights:

The same conditions almost certainly exist on Mars. Drill a hole there, drop these organisms in, and they might happily multiply, fueled by chemical reactions in the rocks and drips of water.

“As long as you can get below the ice, no problems,” Dr. Onstott said. “They just need a little bit of water.”

But if life that arose on the surface of Mars billions of years ago indeed migrated underground, how long could it have survived, and more to the point, how can it be found? Kenneth Chang writes:

If life is deep underground, robotic spacecraft would not find them easily. NASA’s InSight spacecraft, scheduled to launch in 2018, will carry an instrument that can burrow 16 feet into the ground, but it is essentially just a thermometer to measure the flow of heat to the surface. NASA’s next rover, launching in 2020, is largely a clone of Curiosity with different experiments. It will drill rock samples to be returned to Earth by a later mission, but those samples will be from rocks at the surface.

In the meantime, what can we learn deep in Earth’s mines? What do we know now about the energy required to sustain life underground? As Chang notes, if Beatrix is a guide, methane could be the answer:

As NASA’s Curiosity rover drove across Gale Crater a couple of years ago, it too detected a burp of methane that lasted a couple of months. But it has not detected any burps since.

Perhaps an underground population of methanogens and methanotrophs is creating, then destroying methane quickly, accounting for its sudden appearance and disappearance from the atmosphere. If Beatrix is a guide, the methane could be providing the energy for many other microbes.

Conventional wisdom is that Martian life, if it exists, would be limited to microbes. But that too is a guess. In the South African mine, the researchers also discovered a species of tiny worms eating the bacteria.
“It’s like Moby Dick in Lake Ontario,” Dr. Onstott said. “It was a big surprise to find something that big in a tiny fracture of a rock. The fact it would be down there in such a confined space slithering around is pretty amazing.”

A full account of Dr. Onstott’s work appears in the New York Times feature, Visions of Life on Mars in Earth’s Depths.

Read more about Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond here.

This day in history — Voyager 1 launched by NASA

Credit: Princeton University Press (for more images of other unmanned flights, please visit http://www.pinterest.com/princetonupress/world-space-week-iphone-backgrounds/)

Credit: Princeton University Press (for more images of other unmanned flights, please visit http://www.pinterest.com/princetonupress/world-space-week-iphone-backgrounds/)

The summer of 1977 was an exciting time for space exploration. Scientists prepped twin long-distance spacecrafts for a mission to explore the far reaches of the Solar System. Voyager 2 launched earlier in the summer, but Voyager 1 departed planet Earth on September 5 (coincidentally, the same date that the space shuttle Discovery would later return to Earth in 1984). The Voyager crafts took vastly different routes, but together they helped NASA flesh out a “family portrait of four giant planets, their ring systems and magnetic fields, plus forty-eight of their moons,” according to Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration by Chris Impey and Holly Henry. Here are some other quick facts about the Voyager mission gleaned from the book which is a fascinating history of unmanned space exploration:

1.) Each Voyager spacecraft weighs about 800 kilograms, about the same as a Smart Car weighs, but much less than a Mini Cooper (surprising how much they weigh — check it out.)

2.) They have traveled more than 10 billion miles–more than a trip to Pluto and back–since they launched in 1977 and they are still going. You can track their location and see their mileage ticking away at this neat site from the Jet Propulsion Laboratory of NASA.

3.) Attached to the body of each spacecraft is a gold-plate, copper phonograph record that contains musical selections, images, and audio greetings in many world languages. What is on this record? According to Smithsonian Magazine, this time capsule disc contains over 150 recordings including Chuck Berry’s “Johnny B. Goode”, whale songs, and a greeting from Nick Saga, Carl Sagan’s son in which he says, “Hello from the children of planet Earth.”

4.) The Voyager craft get great mileage — 80,000 miles per gallon — in part because they also use Radioisotopic Themoelectric Generators as a continuous source of power.

5.) The Voyager spacecrafts have about 160,000 Twitter followers and spend their time congratulating other Space missions. They actually have a good sense of humor as evidenced by this tweet:

6.) While the Voyager technology was cutting edge for the 1970s, it is quite obsolete now. The video camera attached to each Voyager craft was designed by RCA in the 1950s and the information they transmit travels at a rate 25,000 times slower than “basic broadband” internet service. In spite of this, Voyager supplied iconic images like this one of Neptune:

This image and others are available on the NASA Web site: http://voyager.jpl.nasa.gov/gallery/neptune.html

This image and others are available on the NASA Web site: http://voyager.jpl.nasa.gov/gallery/neptune.html

7.) Voyager 1 made lots of important discoveries about Jupiter including two new moons (Thebe and Metis) and a faint ring system. The Voyager spacecraft also observed  eruptions on Io, another Jupiter moon, which marked the first time volcanic activity was observed anywhere but Earth.

8.) Voyager 1 was the first man-made object to leave the solar system and it continues to travel out into the universe, sending bits of information back to scientists on Earth. NASA expects it will go silent sometime in the 2020s.

 


Read more about unmanned space exploration and missions like Voyager:

bookjacket

Dreams of Other Worlds:
The Amazing Story of Unmanned Space Exploration
Chris Impey & Holly Henry

Dreams of Other Worlds

In the sprint to identify planets beyond our Solar System, scientists scan the skies for habitable worlds similar to Earth with the goal of finding life beyond ours.  With each new confirmation of smaller and more Earth-sized planets, and a possible 400 billion exoplanets in the Milky Way alone, the odds are high that habitable worlds abound. Several of the missions discussed in Dreams of Other Worlds by Chris Impey and Holly Henry have been instrumental in this research, including the beloved Hubble Space Telescope.

Impey_Dreams_F13The book details the methods scientists use to detecting extrasolar planets, the wild variety of planets found so far, and the teams and researchers making the discoveries, including Planethunters.org, the online survey of Kepler data that citizen scientists are currently scouring for evidence of these worlds. The chapter on the Viking mission comments on how, in searching for life on Mars, James Lovelock and Lynn Margulis determined that volatile gases such as oxygen or ozone are replenished by living organisms in Earth’s biosphere and will be important biomarkers of life on exoplanets.  The chapter on the Spitzer mission details the ways complex organisms on Earth developed eyes designed to best use the light of our own star, the Sun, as well as how life forms elsewhere might be adjusted to existence on a planet orbiting a red dwarf star, the most common star type in the Milky Way. While the Hipparcos mission inadvertently identified exoplanets orbiting other stars, its successor mission, Gaia, is poised to detect thousands more.

Beyond artist depictions of exoplanets in orbit of distant stars, the book considers the artwork of Chesley Bonestell whose imaginative paintings of planetary landscapes inspired his and future generations to consider the variable landscapes within our Solar System and beyond.  And, of course, the gold-plated phonograph records attached to the ongoing Voyager spacecraft were intended for civilizations potentially inhabiting an exoplanet in our galactic neighborhood.

The book’s conclusion looks to the upcoming James Webb Space Telescope that will turn its infrared seeking lenses to the search of far-flung worlds.  What we find, the authors remind us, is bound to completely rewrite our understanding of life and where it can exist, as well as our place in the unimaginably vast universe that surrounds us.

 

Read a sample chapter from Dreams of Other Worlds: http://press.princeton.edu/chapters/i10067.pdf

“I found the first ballistic capture orbit to the moon with a painting,” Ed Belbruno

Ed Belbruno’s life and discoveries are the subject of a new documentary titled Painting the Way to the Moon by Jacob Akira Okada. Belbruno, a trained mathematician, discovered new ways to navigate the universe by taking advantage of gravitational pulls of various celestial bodies. Because of his work, space missions now use less fuel to traverse the stars and planets. And millions of Angry Birds Space fans should also thank Belbruno because his research is what determines the birds’ trajectories around space bodies and through gravitational pulls to eventual pig annihilation.

In the documentary, Belbruno, a brilliant painter in addition to mathematician and space scientist, credits his discovery to a Van Gogh-style painting he made of possible travel routes through space for his inspiration. Enjoy the complete trailer below:

Curious about Belbruno’s research? Please check out these Princeton University Press titles. Fly Me to the Moon is intended for general audiences, while Capture Dynamics and Chaotic Motions in Celestial Mechanics is a specialized textbook.

 

bookjacket

Fly Me to the Moon
An Insider’s Guide to the New Science of Space Travel
Edward Belbruno
With a foreword by Neil deGrasse Tyson

 

bookjacket

Capture Dynamics and Chaotic Motions in Celestial Mechanics
With Applications to the Construction of Low Energy Transfers
Edward Belbruno