New Mission Tackles Mystery of Martian Past
On a clear night, you might see Mars to the West - a reddish dot in the sky. Closing in now is a new spacecraft expected to land around 1 am next Monday. This Mars Science Laboratory was designed to delve into mysteries about water, life and climate change raised by the previous crafts to reach the 4th planet from the sun.
New Mission Tackles Mystery of Martian Past
If we found life on another planet, the discovery would go a long way toward answering the deepest open questions in biology: How did life originate, how widespread is life in the universe, and are there alternative recipes for life?
There’s no obvious sign of life on any of our neighbors in the solar system. But desolate, frozen Mars keeps calling scientists back. In the Martian landscape, geologists see dry riverbeds and floodplains that hint at a warmer past that just might have allowed life to originate.
All life on Earth appears to be related, using DNA and RNA molecules to pass down assembly instructions and other information. We share stretches of this genetic code with bacteria, yeast, and amoebas.
But if life originated independently on Mars, it might use a completely different way of storing and transmitting information. And so, if the Mars Science Laboratory lands safely next week, instruments will begin to analyze the soil, air, and rocks for life, past or present.
The warm period was early in the history of the solar system — it looks to have begun freezing up by 3 billion years ago. The Martian atmosphere today is too thin to hold in much heat, but perhaps greenhouse gases once blanketed the planet and were later lost.
Experts say the nice period happened early — around 4 billion years ago. By 3 billion years ago Mars was already starting to dry up. But that somewhat balmier time corresponds to when life was getting started on our planet. According to chemical analyses in ancient rocks, life had already taken hold here 3.8 billion years back — not too long after the planet cooled off enough to have a solid surface.
The Mars Science Laboratory will release a Mini-Cooper-sized rover called Curiosity into a crater where water might have once pooled. Andrew Knoll, a professor of Earth and planetary science at Harvard University, says he’s excited about some of the novel science the rover is equipped to do.
Some of its instruments will look for signs of methane and other organic compounds in the atmosphere. Others will seek them in the rocks and soil. Finding them wouldn’t necessarily mean that Mars once had living matter, but the Curiosity rover could turn up new clues in the search for life there.
Knoll and other biologists say one of the most exciting capabilities of the new rover is the ability to analyze carbon isotopes - a technique has been used to determine if carbon was once part of living matter here on Earth. Carbon comes in several isotopes – alternative forms that differ by atomic weight. For various reasons, living things on Earth do not take up carbon-13 as easily as carbon-12. So the remains of living matter contain relatively little carbon-13.
On Mars, the carbon isotopes can offer clues, though Knoll warns that there are ways to tilt the ratio of isotopes in the absence of life.
The fact that life started relatively early in Earth's history gives scientists hope that it might have sprung up elsewhere in the universe. Life has also been found in some seemingly hostile environments — in Antarctic ice, boiling hot springs, and buried a mile underground living on geothermal energy and minerals.
One of the big challenges is being able to recognize signs of past life and not overreact to false alarms. In 1996, NASA made the explosive announcement that a team of researchers had found signs of fossil bacteria in a meteorite that fell to Earth from Mars. Tiny forms looked to the NASA team like bacteria, and organic compounds called polycyclic hydrocarbons resembled similar compounds made in living things here.
Soon after the announcement, though, biologists quickly pointed out that the shapes NASA thought were bacteria and the compounds could be explained by processes that involved no life. And so it all hangs in doubt.
One of those skeptical voices was paleontologist John Grotzinger, then at MIT and now at Caltech. NASA apparently doesn’t hold a grudge against naysayers, since he’s now chief scientist on the coming mission.
There is little doubt, at least, that this rock, called ALH84001, and others like it did come from Mars. Tiny bubbles of trapped gas match the composition of samples studied by the Viking mission back in the 1970s.
The discovery that the rock and others originated on Mars opens up the possibility that life crossed the divide between the two planets. It’s slightly more likely that life would go from Mars to Earth, since Mars cooled off sooner and Earth is larger and therefore a bigger target.
Whatever Curiosity turns up, Mars does have a story to tell. The Mars Pathfinder mission in 1997 found evidence of massive past floods, during which water threw rocks and even boulders around the landing site. Still, scientists aren’t sure how much water flowed over Mars, how warm it got, or what kind of an atmosphere it had.
And nobody is quite sure what changed to make Mars into the dry, frozen wasteland it is today. “We don’t know what happened but we know it was something big,” said Grotzinger. “Even if life never evolved on Mars, we would want to know what happened.”
Contact Faye Flam at 215-854-4977, fflam@phillynews.com, or follow on Twitter @fayeflam. Read her blog at philly.com/evolution.
There are many keys in Mars waiting to be unlocked. A storehouse of information, many clues awaiting discovery, that could shed much light on Earth. The introduction of Curiosity is very exciting indeed - this is the first device to measure carbon isotopes? Although I am a novice (read "dumbell"), I find this very important. I also remember that 1996 announcement, and that, I believe, was made in good faith. As the saying goes "We don't know where we're going until we know where we've been." Is the history of Mars pertinent to us? I believe it is - as our nearest neighbor, we have much to gain in our exploration of the Red Planet - definitely looking forward to future developments. Great Piece!— fineprintJK1- In last month's issue, Scientific American had an interesting piece on the complex engineering in getting the land rover down safely on the Martian surface so it can roam around. After parachuting most of way, it will use an innovative system relying on cables for the last 50-100 meters (How does a parachute work in such a thin atmosphere, less than 1% of the density of earth's atmosphere?). I'll be following the results closely.— donleonard
- Life. Why is it that we are still so dumb as to go looking for ourselves, to classify 'life' so narrowly as to mean carbon- and methane-based? To me it smacks of Columbus' time when mankind thought the world was flat. If it's -300 degrees somewhere and something cruises past a camera, trust me, it's another form of 'life' we are too ignorant to consider. And our government would never tell us, just as certainly.— PhillySubsMac
- Great article, as always. Was there life on Mars? Is there still? If so, is it related to us, or an independent origin? By implication, is the origin of life on a suitable planet (as Mars once was) a rare event, or almost commonplace? I envy the coming generation who, if we can get our problems on this planet under control, can look forward to seeing these questions answered in their lifetimes.— PaulBraterman
- Origins - Mars, Venus and Creation with Dr. Danny Faulkner
http://www.youtube.com/watch?v=wja4QaUHl78
*
http://www.ctvn.org/programs-origins.asp— dab - Ann Coulter thinks we should populate Earth until "there's standing room only," then colonize outer space. Wouldn't it be OK to just turn out the lights, and leave evidence that we were once here?— jxxphilly
- One factor in favor of colonizing Mars is that it would no longer be compulsary to share a planet with Ann Coulter and her ilk.
— Didymus
In pursuit of her stories, writer Faye Flam has weathered storms in Greenland, gotten frost nip at the South Pole, and floated weightless aboard NASA’s zero-g plane. She has a degree in geophysics from the California Institute of Technology and started her writing career with the Economist. She later took on the particle physics and cosmology beat at Science Magazine before coming to the Inquirer in 1995. Her previous science column, “Carnal Knowledge,” ran from 2005 to 2008. Her new column and blog, Planet of the Apes, explores the topic of evolution and runs here and in the Inquirer’s health section each Monday. Email Faye at fflam@phillynews.com.
Reach Planet of the at fflam@phillynews.com.
