Pale Blue Dot - Carl Sagan [85]
Perhaps the chemical or fossil remains of early Martian life can still be found—subsurface, safely protected from the ultraviolet radiation and its oxidation products that today fry the surface. Perhaps in a rock face exposed by a landslide, or in the banks of an ancient river valley or dry lake bed, or in the polar, laminated terrain, key evidence for life on another planet is waiting.
Despite its absence on the surface of Mars, the planet’s two moons, Phobos and Deimos, seem to be rich in complex organic matter dating back to the early history of the Solar System. The Soviet Phobos 2 spacecraft found evidence of water vapor being outgassed from Phobos, as if it has an icy interior heated by radioactivity. The moons of Mars may have long ago been captured from somewhere in the outer Solar System; conceivably, they are among the nearest available examples of unaltered stuff from the earliest days of the Solar System. Phobos and Deimos are very small, each roughly 10 kilometers across; the gravity they exert is nearly negligible. So it’s comparatively easy to rendezvous with them, land on them, examine them, use them as a base of operations to study Mars, and then go home.
Mars calls, a storehouse of scientific information—important in its own right but also for the light it casts on the environment of our own planet. There are mysteries waiting to be resolved about the interior of Mars and its mode of origin, the nature of volcanos on a world without plate tectonics, the sculpting of landforms on a planet with sandstorms undreamt of on Earth, glaciers and polar landforms, the escape of planetary atmospheres, and the capture of moons—to mention a more or less random sampling of scientific puzzles. If Mars once had abundant liquid water and a clement climate, what went wrong? How did an Earthlike world become so parched, frigid, and comparatively airless? Is there something here we should know about our own planet?
We humans have been this way before. The ancient explorers would have understood the call of Mars. But mere scientific exploration does not require a human presence. We can always send smart robots. They are far cheaper, they don’t talk back, you can send them to much more dangerous locales, and, with some chance of mission failure always before us, no lives are put at risk.
“HAVE YOU SEEN ME?” the back of the milk carton read. “Mars Observer, 6’ × 4.5’ × 3’, 2500 kg. Last heard from on 8/21/93, 627,000 km from Mars.”
“M. O. call home” was the plaintive message on a banner hung outside the Jet Propulsion Laboratory’s Mission Operations Facility in late August 1993. The failure of the United States’ Mars Observer spacecraft just before it was to insert itself into orbit around Mars was a great disappointment. It was the first post-launch mission failure of an American lunar or planetary spacecraft in 26 years. Many scientists and engineers had devoted a decade of their professional lives to M. O. It was the first U.S. mission to Mars in 17 years—since Viking’s two orbiters and two landers in 1976. It was also the first real post—Cold War spacecraft: Russian scientists were on several of the investigator teams, and Mars Observer was to act as an essential radio relay link for landers from what was then scheduled to be the Russian Mars ’94 mission, as well as for a daring rover and balloon mission slated for Mars ’96.
The scientific instruments aboard Mars Observer would have mapped the geochemistry of the planet and prepared the way for future missions, guiding landing site decisions. It might have cast a new light on the massive climate change that seems to have occurred in early Martian history. It would have photographed some of the surface of Mars with detail better than two meters across. Of course, we do not know what wonders Mars Observer would have uncovered.