The highlight of the Mars Express session this morning, for me, was the very brief mention of methane in Vittorio Formisani's talk. But the single most astonishing fact was in Gerhard Neukum's. In its first three months in orbit, before the spacecraft has been fully commissioned, the High Resolution Camera has delivered more data to the earth than the Viking Orbiter cameras delivered in their entire operational lives. For almost two decades, that Viking archive was the state of the art for Mars geology; almost all the geology in Mapping Mars was done using that set of images, as well as a vast amount more that I never managed to fit in. I'd be surprised if there were a hundred people in the world who had looked at all that data; far fewer have really studied every frame. Those who have done so had to invest years of their careers in the undertaking. And HRSC sends back the same amount of data without breaking a sweat, providing first-look images at less than 10% of the planet. Wow.
On to the methane. Formisani spoke about it only bery briefly in an overview of PFS results, but he still managed to drop in a fairly big surprise. On average, PFS sees atmospheric methane at the 10.5 parts per billion level, +/- 0.5. But on different orbits it sees different levels. Sometimes it sees none. Sometimes it sees 30 parts per billion. Formisano argues that this means there are active sinks on the planet -- regions that somehow suck the methane out of the air. The obvious corollary is that if there are sinks on the surface, then the rate at which Mars has to add methane to its atmosphere in order to keep an average level of 10ppb will be higher than previous estimates, possibly quite a lot higher.
How these hypothetical sinks may be working their magic is not clear to me. It may be clear to Sushil Atreya, at the University of Michigan, who's on the PFS team and has thought about such things in the past, but for the time being he and his colleagues are staying quiet on the matter. They are working hard on a paper -- probably aimed at Science -- and don't want to do anything that might jeapordise its publication. Nor is it clear where the sinks are. Formisano says he hopes to have a story to tell on that subject by September, when an international Mars meeting will be held on Ischia.
Also not under open discussion at this session were the latest developments with Marsis. The Marsis radar is the greatest novelty on Mars Express -- the first ground-penetrating radar designed to look at the subsurface of Mars. To do this, though, it first has to deploy forty metres of antenna, and that deployment has now been delayed (at least once). The reason, apparently, is that a similar system built by the same company will be used to deploy the radar antenna for Sharad, the radar on NASA's 2005 MRO. When the models that have recently been developed to study the dynamics of the Sharad antenna's deployment -- how it would bend and whip round and so on -- were applied to the Marsis antenna, they suggested that its deployment might go quite spectacularly wrong, possibly putting the whole spacraft at risk.
The Sharad model is more recent than the model originally used to plan the Marsis deployment, and incorporates features the earlier model lacked, which is why this is a worry. However, as I understand it, although this new model probably works better as a model of the Sharad deployment than the old model works as a model of the Marsis deployment, it's not clear that the new model really works better as a model of the Marsis deployment than the old model did. As a result a series of modelling runs using a model that incorporates the new features but which is also specific to Marsis has now been started. People seem genuinely optimisitic that these runs will show that the worries raised by the first use of the Sharad model are not that grave. But it means that for the time being the deployment is on hold. This is a wonderful spacecraft, and no one is going to put it at risk if they can avoid doing so. (Update: around the time I was posting this, BBC Online ran a story giving more details)
One of the reasons for being especially protective of Mars Express is that many of its instruments have already been lost once. Much of the Mars Express payload was originally developed for the joint ESA/Russia Mars-96 mission, which crashed back to earth shortly after launch. The reflight of those instruments on Mars Express reflects the idea that, as Mars Express supremo Augustin Chicarro put it in his introduction to the session, "ESA recovers the science of its fallen comrades". That philosophy should be of help to the Beaglers; indeed there'll be a discussion of how to achieve Beagle's science aims (and those of the cancelled Netlander, too) later today.