It Came Out of the Sky
|David Grinspoon, Principal Investigator for NASA’s Exobiology Research Program and author "Venus Revealed" and "Lonely Planets"|
"Lonely Planets: The Natural Philosophy of Alien Life," by David Grinspoon, is a humorous and balanced look at the history and science of astrobiology. Awarded the 2004 PEN Literary Award for Nonfiction, this book was described by Frank Drake as "Superb… Anyone, even a professional scientist, who wishes to become familiar with contemporary astrobiology should read this book. It’s a prime place to become more than casually acquainted with one of the hottest, most interesting fields of science."
In this excerpt from the new Forward to the paperback edition, Grinspoon discusses the exciting discoveries unveiled by the twin rovers on Mars.
On a tranquil late afternoon in early January 2004, the sky split open and an alien ship dropped out. In a tired, rusty desert land where nothing more than a dust devil had stirred for a hundred million years, the monotony was shattered and a thundering, glowing ball of light rushed toward the ground. Suddenly, at about 200 feet, the visitor inflated like an angry puffer fish, growing to many times its original size, and then, seconds later, landed with a mighty "Whump!", bouncing as high as a four story building. After 28 more bounces – each one raising a fearsome cloud of dust which slowly drifted off- it came to rest on a desolate, sandy plain scattered with worn and broken rocks.
Nineteen days later, on the other side of the world, a twin vessel made a similarly strange, bouncing entrance, rolling to a stop in a small crater sunk into a vast flat wasteland of salt-crusted rocks sprinkled with metallic, berry-like spheres. Each visitor quickly began to transform itself, deflating its landing cocoon to reveal a small hibernating creature within. Extending wheeled legs, mechanical eyes and other peculiar sensory limbs, each slowly crawled off its now defunct landing pod. The Martian arrival had begun.
|Opportunity’s size dominates crater. Within thirty feet was bedrock. Click image for larger view.|
Back on Earth, just two months later, in late March ’04, hundreds of scientists pursuing alien life congregated in a hastily constructed NASA facility in Northern California – a colossal white tent with semi-translucent siding, illuminated by rows of massive searchlights. Armed government guards checked ID of all who wished to enter. At first glance it resembled some top secret X-Files type government installation, but a peek inside dispelled that impression.
Instead of emotionless space-suited functionaries intent on inscrutable experiments, the giant hall was filled with a motley assortment of nerds (myself among them) and student nerds-in-training. Fashions ranged from suits and ties to sandals and shorts. Information-packed posters hung in long rows, displaying the latest scientific results on "astrobiology" – the study of extraterrestrial life. A platoon of head-setted journalists, chasing us around with microphones and cameras, completed the scene. Altogether we comprised the Third Astrobiology Science Conference, held at NASA’s sprawling Ames Research Center, spread along the southwestern shore of San Francisco Bay – a tentful of carbon-based, water-loving, marginally intelligent organisms gathered on the thin skin of planet Earth, to prognosticate about the possibilities of life beyond.
We had a lot to talk about. NASA’s two Mars Exploration Rovers had made their spectacular bouncing landings only two months prior, and had already made fantastic discoveries which had recharged and refreshed the perennial debates about life on Mars.
|Burns Cliff Cloud Cover. Click image for larger view.|
Image Credit: NASA/JPL
The most eagerly awaited moment of the weeklong conference came when Steve Squyres, Principal Scientist for the Mars Rovers, gave us an update on the activities of his two little Martian robot geologist puppies, Spirit and Opportunity. There was an air of celebration at this session, as a community that has known recent and repeated failure enjoyed a great success. This cockamamie bouncing-on-airbags landing scheme had worked once before with the Sojourner rover in 1997, but we all had a lot more riding on this attempt than just the equipment.
During the weeks prior to the landings there had been a palpable nervousness, fueled by the fact that we still aren’t sure what went wrong with our last attempt to land on Mars in 2000, and tempered somewhat by the thought that this time we were sending two identical, carefully tested rovers and at least one of them ought to work.
This time they both did. Each survived the bouncy landing without a hitch, and at the time of the Astrobiology Conference each was inching across one of the thousand unexplored deserts of Mars, scratching and poking among the ruddy dirt and ancient rocks, shaking loose buried secrets, snapping pictures all the while.
|Steve Squyres, sporting signature attire of jeans over cowboy boots |
Squyres – rail thin, angular, and as always sporting jeans over cowboy boots – was looking very bright-eyed for someone who’d been living on Martian time for the last three months. As far as I can tell, he hasn’t changed a bit since we first crossed paths in the summer of 1978 as students at Cornell. I ran into him in the hallway before his talk and, though at that moment he was the coolest person in the solar system, he didn’t act with one ounce of self-importance. He recounted the latest rover findings and the fun he was having, as if he were just an old colleague at a meeting telling me about his latest pet project. Which he was, but His pets were on Mars, and they were on the move.
Steve took the stage, to thunderous applause, meant for the triumphant little robots as well as for their driver. He began with a spirited recap of the rovers’ initial forays on Mars and a preview of their possible futures. Then he got right to the good stuff – the possible stuff of life on Mars. What had we found? When I think about it I still get so excited I can hardly talk – or type.
All my life, and my professional career, I’ve been enthralled with the possibility that, through planetary exploration, we can learn something definite about whether we have living company in the universe beyond Earth. Well, the universe had just dropped us a big hint. We found rocks on Mars which were formed of sulfate salts. The only way we know of to make that kind of rock is through the evaporation of salty seas from a place that must have been soaking wet for significant periods of time.
|Rover computer rendering on the edge of a depression; banner image shows rock called Wopmay at Opportunity site|
Why are we so hyped-up about finding sea-formed rocks on Mars? Well, as far as we know at present, life needs water. On Earth, where there is water there is life. Over the last few decades circumstantial evidence had been building for large quantities of surface water in the Martian past. Orbital photographs revealed shapes strongly suggestive of watery rivers and lakes. Yet, there has always been the nagging possibility that we were searching so hard for signs of the familiar that we were misinterpreting the photos and maps, mistaking the action of lava, wind, ice or some other unknown carver for the work of our beloved water.
But the rocks don’t lie. Now, at last, we’ve sampled the ground itself, and the evidence is no longer circumstantial. We’ve found the smoking gun (which in this case is a dripping super-soaker) of past habitability. We now know there was other wet ground, beyond the Earth in our Solar System. Right next door. Buckets of rain once ran like salty tears over the face of our little red brother Mars.
This discovery proves that Mars is indeed an important place for astrobiology exploration – a place where many kinds of Earth life could once have survived- so why not Martians? The idea that we might really find fossils of bygone creatures on the red planet can no longer be regarded as far-fetched.
|Shadow cast by Spirit over Gusev tire tracks. |
Image Credit: NASA/JPL
Among other things, this will be a major shot in the arm for our desires and plans for future missions, providing the encouragement (and most likely the funding) we need to keep going, to send new machines there that can look for fossils or chemical traces of past life. Soon we will want to return Martian samples to Earth. With the right Mars rocks in our own laboratories we will be able to more definitively test the idea that life once graced our red planetary neighbor.
The raised prospect of new missions to -and from- Mars heightened the exigency of our ethical discussions, topics which just a year ago seemed more academic. How much should we care about – and spend to guard against – the possibility that we might contaminate Mars with microbes from Earth, or even the slight but disquieting chance that we could bring something back from Mars that might enjoy snacking upon our own biosphere?
Does the news that Mars once had the conditions for life increase the threat of contamination? Perhaps not. With regards to modern life, the news from the surface is not encouraging. Many of us believe that whatever biology once graced this rusty world disappeared long ago, along with the sputtering geology and the evaporating seas. The Mars rovers are wandering places where almost nothing has happened in uncountable eons.
|Columbia Hills, 2.5 km from Gusev landing site|
Image Credit: NASA
Seen up close, these landscapes verify our belief that the surface of Mars is incredibly ancient. There is nothing in the new photos to suggest any recent action, beyond the frequent bursts of dusty winds. Most of the geological activity is long gone, leaving a surface freeze dried, ossified and sculpted in places into bizarre forms not seen on Earth, because you couldn’t find a place on our planet that has been left to the wind alone for a billion years. The rovers haven’t found much that changes our views of present day circumstances on Mars. Their biggest discoveries are about conditions in the deep past, including the enticing possibility of ancient life.
As of this writing both rovers are still crawling over new Martian vistas and calling home daily with their latest dispatches. They have both remained remarkably healthy in the killing Martian cold, but will they survive the coming winter? Spirit has developed a bum wheel, and Opportunity is tempting fate with daring exploits in a scary-looking crater. They may roam for another year, or die in the coming weeks, but either way they have, by any measure, far surpassed our expectations.
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