You can’t bring Mars to the lab, but you can bring a lab to Mars! In fact I still can’t quite believe that EDL scheme worked so well! But that’s what Curiosity really is, a scientific laboratory, and here’s a few details on the goals and philosophy behind it.
Many experts think that Mars was once a very different place than it is today. Both the earth and Mars had mostly taken shape by 4.5 billion years ago. Both had accreted out of the solar nebula swirling around our nascent sun. The sun was smaller and dimmer then, earth and Mars were probably covered in thick clouds belched up by the prodigious residual heat of planetary formation. It likely took tens of millions of years before a stable, solid surface congealed on either world. But cool they did, and eventually both planets begin collecting liquid water on their respective surfaces.
That’s when paleobiologists believe the first simple replicating organisms developed on earth – it had to happen pretty quick. The earliest marine sediments we have found on earth, dating to about 3.8 BYA, already show geochemical signatures consistent with widespread colonies of chemosynthetic bacteria. If the conditions on Mars were the same, it’s reasonable to infer that there might have been life in the oceans of that planet, too. But there were big changes in the air for Mars.
Planetary scientists believe the molten iron core of Mars cooled many times faster than earth’s, which makes sense; Mars is a much smaller planet, which means a greater amount of surface area to volume and less insulation between the hot core and the cooling surface, so it would radiate internal heat much faster into the infinite cold sink of space than a larger planet. Once that core began setting like cement, the Martian oceans were doomed. The great internal dynamo deep inside seized up. Mars lost its protective magnetic field, and nothing stood between the harsh solar wind and the Martian atmosphere.
Models suggest that the atmosphere would be stripped away quickly, in a few hundred million years at the most. As the ambient pressure dropped and the sun beat down, the oceans would first evaporate and then sublimate. Water vapor rose high into the Martian sky where it was broken down into constituent oxygen and hydrogen by unfiltered UV. The lighter hydrogen quickly escaped, the reactive oxygen left behind combined with any elements at hand. Carbon became CO2, iron and other minerals in the drying valleys oxidized. In as little as a billion years after its birth as a warm, wet world, Mars was transformed into the bone dry, frozen rusty planet we see today.
But how wet and warm was Mars? How long did that youthful blush last? Did Martian life gain a brief foothold only to be cruelly snuffed out? Or, if so, did some hardy organisms survive the eons, perhaps below the surface where the last remnants of precious water remain? Those are some of the questions this mission will shed light on.
Curiosity is a one ton, self-propelled all-terrain vehicle bristling with scientific instruments powered by a heart of dying plutonium. Curiosity is not specifically designed to find life, it is designed to find the conditions and ingrediants for life. Its eyes can see in wavelengths invisible to our own, its ears can pick out subtle whispers in the midst of a screaming sand storm; it can virtually sniff Martian air and taste Martian soil. The rover even comes equipped with drills for boring into solid rock and magnifying glasses to peer deeply into the liberated material. And it is landing in one of the best places possible to do this: Gale Crater.
Gale is a one-hundred mile wide scar punched deep into low laying Martian bedrock more than 3 billion years ago by a spacerock about as large as the dino killer that hit us at the end of the Cretaceous. In the crater’s center is a big pile of what looks like sedimentary debris, three miles high and so vast it can be seen from telescopes in earth orbit. If there were sizable oceans on Mars this region would have held one of the deepest. If there are sedimentary strata revealing clear signs of warm, salty water, the crater walls and central mountains will reveal it like pages in an ancient diary. If life persisted into the great drying, their final stand may be preserved here. And if there are even now organisms eking out a living, or in freeze dried stasis waiting for summer rains that will never come, this would be an ideal place to find them.
But that technology comes at a cost, both in dollars and payload. Curiosity weighs about ten times as much as the heaviest rover ever sent to Mars. Therein lays tonight’s adventure: the method used to safely land Spirit and Opportunity, a combination of parachutes and big crash balloons that bounced over the Martian terrain like giant beach balls, will not work. Engineers had to come up with something revolutionary. What they came up with is gripping …
If Curiosity had crashed all over Gale Crater taxpayers would have been out
a billion two billion plus dollars and, thanks to shortsighted budget cuts, it could have set back exploration of Mars by decades. But oh baby,now that Curiosity succeeded, the EDL team will become legend, NASA will produce the most amazing pictures ever taken of any planet outside of the one we’re sitting on, and humanity may well stand on the precipice of the greatest discovery in history.