Watery Mars, again
Hauber et al, in a letter in this week's Nature, count the craters in glacial deposits in a caldera on the northestern flank of Hecates Tholus, a volcano on Mars, and come up with an age of between 5 million and 24 million years... They did this using image data from Mars Express' High Resolution Stereo Camera and from the Mars Orbiter Camera. The upshot: there were glaciers on Mars, in the mid-latitudes, relatively recently—in planetary science terms, 5-24 million years ago is as good as yesterday.
Sure, I know, watery Mars stories are almost a dime a dozen these days. Thought I'd point it out anyway because it really does suggest very strongly there's water ice there—and lots—still just below the surface. The letter points out that CO2 just isn't a likely culprit given the latitude, and given the appearance of the surface (significant sublimation of the ice below hasn't eaten away the surface features), there's no reason to think the ice isn't still present.
Ver' neat. Interesting both in terms of the possible explanation (the time of deposit is about the same as a time the obliquity of Mars' axis was higher, which might explain climate changes permitting water ice on the surface in mid-latitudes), and ramifications for exploration (water ice near the surface would be awfully useful, if we ever want to send anything to Mars that actually needs water to function... like, say, ourselves).
And though there's no mention of it, every single one of these stories always makes me wonder: if Mars' climate really is so close to ours (and that is pretty close, in planetary terms), and liquid water really might have been possible for extended periods at some point in the past, I still find myself thinking: we might still find evidence for life there, whether or not there's anything actually alive still present. Always been one of those who thinks the origin of life is a bit more likely than most seem to; it certainly seems to have taken off here pretty much as soon as the crust had cooled enough. Crossing my fingers.
Postscript: looking at it further, the Hauber et al correspondence actually suggests one of the least dramatic results: apparently there are also images suggesting that glaciation may also have been occurring on the surface at the base of Olympus Mons as little as 4 million years ago, and evidence even for a frozen water body approximately the size of the North Sea at as little as 3 million BP—the latter in a paper by Murray et al, same issue. The Murray et al thing is the real eye-opener, to me—not the least because they suggest such lakes might still, conceivably, exist (the fact that they might once have existed, and so recently, isn't, apparently, particularly new). And yes, they do mention the possibilities for finding evidence for primitive life in such formations.
Sure, I know, watery Mars stories are almost a dime a dozen these days. Thought I'd point it out anyway because it really does suggest very strongly there's water ice there—and lots—still just below the surface. The letter points out that CO2 just isn't a likely culprit given the latitude, and given the appearance of the surface (significant sublimation of the ice below hasn't eaten away the surface features), there's no reason to think the ice isn't still present.
Ver' neat. Interesting both in terms of the possible explanation (the time of deposit is about the same as a time the obliquity of Mars' axis was higher, which might explain climate changes permitting water ice on the surface in mid-latitudes), and ramifications for exploration (water ice near the surface would be awfully useful, if we ever want to send anything to Mars that actually needs water to function... like, say, ourselves).
And though there's no mention of it, every single one of these stories always makes me wonder: if Mars' climate really is so close to ours (and that is pretty close, in planetary terms), and liquid water really might have been possible for extended periods at some point in the past, I still find myself thinking: we might still find evidence for life there, whether or not there's anything actually alive still present. Always been one of those who thinks the origin of life is a bit more likely than most seem to; it certainly seems to have taken off here pretty much as soon as the crust had cooled enough. Crossing my fingers.
Postscript: looking at it further, the Hauber et al correspondence actually suggests one of the least dramatic results: apparently there are also images suggesting that glaciation may also have been occurring on the surface at the base of Olympus Mons as little as 4 million years ago, and evidence even for a frozen water body approximately the size of the North Sea at as little as 3 million BP—the latter in a paper by Murray et al, same issue. The Murray et al thing is the real eye-opener, to me—not the least because they suggest such lakes might still, conceivably, exist (the fact that they might once have existed, and so recently, isn't, apparently, particularly new). And yes, they do mention the possibilities for finding evidence for primitive life in such formations.
posted by AJM at 10:30 a.m. (Permanent Link)
