Time to Head for Mars?
Are we alone?
That has been one of the fundamental questions about the universe since humankind first realized that we live on only one planet in its vastness. And of course, the first places to look for the answer are the nearest planets that have any prospects for supporting life at all, since that's a requisite condition for finding intelligent life. Hence the long fascination with Mars.
The latest robot emissary sent to resolve the old issue descended to the surface of the red planet on Sunday evening (US time). The descent was first violent, as it crashed into the thin, dry Martian atmosphere at a velocity sufficient to escape the planet's gravity, and then gentle, with parachutes and rockets. It was a new spacecraft design, with a mission derived from two previous Martian mission failures.
One was the Mars Polar Lander, with which contact was mysteriously lost just before it was to enter the Martian atmosphere in 1999 on its way to the south Martian pole. Its companion explorer was the Mars Climate Orbiter, which was supposed to brush the top of the Martian atmosphere to slow it down into an orbit around the planet, whence it was to relay data from the lander back to earth while also monitoring the planet from a polar perspective at a constant sun angle. Instead, it flew into the atmosphere at a steep angle, destroying the spacecraft almost instantly from the rapid deceleration and heating for which it was not designed. Ignominiously, this was a result of confusion between metric and English units between NASA and its contractor.
The new spacecraft was designated Phoenix, as a symbol of its arising from those failures. Like another Greek myth, it is a hybrid of two spacecraft -- a lander from a mission canceled after the MPL/MCO failures, and backup versions of many of the same instruments carried by MPL before its loss. It is now set to carry out their intended mission and -- for the first time -- explore the polar regions of the planet close up. However, while MPL was aimed at the southern hemisphere, Phoenix has landed on the plains of the Martian arctic regions, in the far north. But both polar regions are now known to have large quantities of water in the form of ice, so either will serve the purpose of the present mission, which is to determine if in the past there was water in liquid form, long thought to be required for life to develop and thrive.
Interestingly, it was the first "soft landing" on Mars in over three decades. The last time that NASA used retrorockets to perform final landing maneuvers on Mars was also the first -- in the Viking program in 1976. The Mars Pathfinder and later rovers came hurtling down in a bouncing ball that gradually took away the energy of the fall, but such a scheme wouldn't necessarily scale up well for a craft the size of Phoenix, which was anyway designed before the technique was proven. And landing gently is good practice for when we eventually send humans, who won't take well to the bone-crushing and vertigo-inducing accelerations of a long superball ride absent major steps toward body modification.
The lander will carry a robotic arm with an ice pick, to chip away samples of the frozen soil. It also has a portable oven and laboratory to examine them for evidence of not just ice, but perhaps microbes, or at least organic chemicals which would be precursors for life, if that life is anything like we understand it on earth. It will have about three months to do so, before the Martian boreal winter sets in and the craft gets buried under ice, mostly dry ice, as the atmosphere itself (mostly carbon dioxide) freezes and solidifies around it. At this point the vehicle will be dead because its solar panels will be covered and unable to produce electricity, and it has only a twenty-four hour battery, which will drain over the winter to the point that it will be unable to "wake up" if and when the ice melts or sublimates. For those three months, unlike the popular Mars rovers, it will perform its experiments in a single location, lacking the ability to transport itself elsewhere. So, as is always the case, a failure to detect such signs won't be indicative of their absence. It may have just been unlucky in landing spots. Mars is smaller than earth, but it is a very big planet nonetheless, and it's all land and no sea. If life signs are scarce, the search for them may remain elusive, even with hundreds of probes. After all, how likely would it be to find a dinosaur fossil if the search was based on simply throwing a dart at a map, even of western Colorado?
This mission, like all Mars missions, is not just to answer pure science questions. It is also ostensibly a precursor to eventual human trips to Mars. The discovery that water is available in large quantities at the poles was encouraging to those who plan to "live off the land" there. But perhaps those who hope to one day be Martians themselves should also hope that Phoenix doesn't find signs of life, at least current life. If it does, it's not at all inconceivable that the planet would be put under quarantine from humanity so that we don't contaminate it with our own life forms (this is a concern even for the robotic envoys, such as Phoenix, to the point that they are scrupulously sterilized prior to launch). Beyond that, for reasons having nothing to do with Mars, some say that we should hope that we are alone because to learn otherwise might be a bad omen for the human race.
In any event, given the current budgetary, schedule and technical difficulties of NASA's new manned spacecraft programs, Ares and Orion, and the uncertainty of the political support for them in the next administration, such a mission seems very far off right now. The Phoenix landed on the forty-seventh anniversary of JFK's speech to Congress in which he declared a national goal of sending a man to the moon in that decade. George W. Bush made a similar announcement a little over four years ago, in which Mars was designated a destination for human explorers, but only in passing as part of (in reference to returning to the moon) "...and beyond." So congratulations to JPL, but unless Phoenix finds Marvin, with plans for interplanetary conquest, including earth-shattering kabooms, don't expect its successful landing to result in any new presidential speeches on human spaceflight initiatives.