No, it's not a surprise, though some of the news reports have made it seem that way. We've actually known for decades that Mars has huge deposits of regular, plain old water ice -- a very exciting thing, since water is the staff of life as we know it. And unlike other ice-covered or ice-filled bodies, like comets, or the moons of Jupiter and Saturn, which are always very, very, very cold, on Mars the temperatures do sometimes climb above the freezing point. So liquid water is possible there, at least a bit below the surface in certain places -- and, though this is controversial, possibly even on the surface sometimes.
The air on Mars is so thin that it's practically a vacuum, though, so any exposed water, or even any exposed ice, turns to vapor very quickly. But pictures from as far back as the Viking mission in the 1970s even showed occasional frost on the ground in the early morning, just after sunrise. The presence of ice near the surface, and some water vapor in the atmosphere, is why Mars is such an exciting place for astrobiologists -- or for anybody who is interested in the possibility of life elsewhere. Especially since we know that in the very early days of Mars, around 4 billion years ago, water actually flowed across the surface and may have formed lakes or even an ocean. That's what makes Mars the most Earth-like place we know of besides, you know, Earth.
So, as I was saying, the fact that the new Phoenix lander on Mars has proved the existence of ice just beneath the surface, which was announced at a press conference yesterday, is not really a surprise. That's what Phoenix was mostly designed for, in fact -- to study the ice, by melting bits of it in tiny ovens, to see what chemicals it contains, and whether the kinds of molecules needed by living creatures are present there.
So, what was just announced -- little bits of ice just below the surface, which were revealed by Phoenix's trench-digging tool, and which had vaporized within a few days -- is not at all surprising, but it is very important. It means that the hoped for ice is present at the place where Phoenix touched down, close to the northern polar region of Mars, and that it's very close to the surface and easy to reach.
That's pretty much what Phoenix chief scientist Peter Smith of the University of Arizona and the rest of the science team had hoped, and even expected. But hoping and expecting is a very different thing from actually proving it on the ground.
So this means there's every chance that, despite some mechanical and software glitches, the mission will be able to do what it set out to do, and could end up providing better evidence than ever before that Mars may be a habitable place.
But, contrary to other reports you may have read, one thing Phoenix will not do is prove whether there are any living organisms there now, or ever were in the past. That's because even though it has equipment to carry out the most detailed chemical tests ever done on Mars, as well as the highest-resolution microscopy, it does not have anything that could detect signs of life itself. And that's a darn shame.
The Viking mission, 32 years ago, was the only Mars mission that ever carried life-detection equipment, and it's results were controversial. The scientist in charge of one of the three life detection experiments on that mission is absolutely convinced that it did find life. Other members of the science team thought not. There's a very simple followup experiment that could prove it one way or the other, but in all these years, with four successful landers (and a few failures) on the planet since then, nobody has bothered to send that followup test.
What, the question of whether Earth is or isn't the only place in the universe with life isn't important enough to be worth checking?
Well, if Phoenix finds signs suggesting that the conditions for life are present, maybe that will spur NASA, or ESA, or JAXA, or somebody to go and look. Let's hope so.
The Phoenix mission, by the way, is the first mission ever sent to another planet whose control center, instead of being at a NASA center (or a Russian government space center) is actually on a college campus. It's located at the University of Arizona in Tucson. That's a wonderful new trend, and hopefully will offer some lucky students there a chance to watch, and maybe even participate in, a cutting edge planetary exploration mission. I'll be talking to them soon, and will report on how the presence of a Mars Mission Control on campus is affecting the students there.
(Photo credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University)
From your article: "little bits of ice just below the surface, which were revealed by Phoenix's trench-digging tool, and which had vaporized within a few days"
Is "water" ice the only substance that might vaporize under the vacuum type Mars atmosphere? In the absence of chemical identification, might not "dry" ice or frozen carbon dioxide also be the culprit?
Posted by: Dick Chanda | February 15, 2009 at 06:28 PM