Just back from a brief trip to California. It wasn't a Mars related trip (asteroids, actually) but I did pick up, as many others have been reporting recently (for example Leonard David and David Chandler) that something is afoot at JPL; it sounds very likely that there is a fairly large announcement in the offing about the role of water in the formation of the hematite at the Meridiani Planum site.
When the haematite was first discovered by the TES spectrometer on Mars Global Surveyor, the TES team pointed out that the haematite might have been laid down in a maritime setting. Tim Parker of JPL has spent more than a decade mapping features that he interprets as shorelines around the northern lowlands of Mars, and one of these shorelines, the so-called "meridiani shore", encompassed the heamatite site. If the meridiani shoreline was in fact a shore, the argument ran, then the hematite site would be on an ancient sea-bed – a plausible enough place to find this sort of hematite.
Since then, more attention has focused on the posibility that the haematite might have been made through a hydrothermal interaction between groundwater and some sort of volcanic rock. This would still be pretty interesting, but arguably rather less so than the discovery of something created on an ancient sea-bed. An outline of the different possibilities, and of ways that they can be distinguished, can be found in an abstract by Ray Arvidson and some colleagues here. (Arvidson, a professor at Washington University, is one of the people who has been working on the rovers for the longest; he was a champion of the hematite site at site selection meetings.) If there's a big announcement coming, it presumably has something to do with distinguishing between these possibilities.
If the data points to a big body of water, the next question (at least my next question) is whether it was ice covered or open to the atmosphere. For Mars to have had blue-water lakes, seas and even oceans, rather than ice-covered seas, would imply a vastly different climate in its early history. It's very hard to see how Mars could have been warm enough for open water without the benefit of significant amounts of methane in its atmosphere. Planetary atmosphere experts have told me that the only way they can imagine getting an adequate amount of methane into the atmosphere is by having methane-producing bacteria pump it out. So open water on early Mars might be seen as a suggestive indicator of life on early Mars. (Note that this argument goes in the opposite direction to the more general argument that water makes life a possibility because life needs water; here the argument would be that life makes open water a possibility, because open water requires a greenhouse of the sort only life can provide.) An ice-covered ocean would not need quite so much warmth, and might be plausible if Mars merely had a much thicker carbon-dioxide atmosphere back then. It strikes me that it's possible the layered bedrock Opportunity has been studying might offer ways of distinguishing between ice and open water at the surface.
Let's hope the rumours are true and we'll be hearing more soon.
Meanwhile, there's an opinion piece of mine on the "Bush Vision" in the latest issue of Prospect magazine, available on the web here (this link will probably rot sometime in April). A few jokes and subtleties probably dropped out during the editing process -- but that's what you should expect if you write more words than the magazine has paper and ink. The gist of the piece is that the Bush plan is more significant than many have argued -- in part because it makes the human spaceflight programme easier to cancel, in the long run.
NB, haematite is also known as hematite
UPDATE: The press conference has now been announced for 14:00 EST on Tuesday March 2nd, at NASA HQ
I attended last September's Division of planetary sciences meeting in California -- and there was one unprepossessing little poster there with an announcement that could be sheer dynamite where Mars exploration is concerned.
Michael J. Mumma of Goddard, an expert in detecting trace gases in planetary atmospheres, claimed that he has used two different ground-based IR telescopes to find very strong evidence of traces of methane in Mars' atmosphere, in amounts which must be biogenic -- and, moreover, it seems to be concentrated over one of the two near-equatorial regions found by Odyssey to be puzzlingly rich in near-surface wter. His spectra were shown on the poster, and by God there's no doubt at all about the absorption line -- it stands out like a sore thumb, and if it isn't CH4 it must be something else in exactly the right place. He also said that he's seen what may be a second CH4 absorption line, but at the time of the poster he was still trying to rule out other gases as its cause. He has just told me by E-mail that his findings seem to pan out, and he has submitted a paper on the subject to "Icarus".
Posted by: Bruce Moomaw | March 02, 2004 at 07:42 AM
You're right that is a bombshell if true. There had been an earlier tentative identification of methane from another team and I had been waiting to see it confirmed but hadn't heard anything since then:
High-Resolution Spectroscopy of Mars: Recent Results and Implications for Atmospheric Evolution.
The Fifth International Conference on Mars, July 19-24, 1999, Pasadena, California, abstract no. 6016
http://adsabs.harvard.edu/cgi-bin/bib_query?1999ficm.conf.6016K
Posted by: Robert Clark | March 02, 2004 at 12:34 PM
If there's methane that can be detected from the earth then surely it will show up in the Mars Express Planetary Fourier Spectrometer data.
Posted by: Oliver Morton | March 02, 2004 at 04:17 PM
Much of the puzzlement over "early wet Mars" is due to the "faint young Sun" - but what if it wasn't faint? Julianna Sackmann and Arnold Boothroyd have shown that an early heavy Sun is feasible and not ruled out by current known solar interior conditions...
http://www.cita.utoronto.ca/%7Eboothroy/sun5.html
http://xxx.lanl.gov/abs/astro-ph/0210128
...in which case the Sun was brighter and also the cooling effect of cosmic-rays lower as well...
http://au.arxiv.org/abs/astro-ph/0306477
...Hence the problem is not as severe as previously imagined. Maybe.
Adam
Posted by: Adam | March 02, 2004 at 10:59 PM
the earth there are the caverns
....
is not possible that:
Mars are the caverns with the water
lakes,rivers
and finally " LIFE " ?
TAKE A LOOK: http://www.nexusitalia.com/cronachemarziane.html
ME
Posted by: ME | March 29, 2004 at 11:24 AM