As Rick Sterling has kindly pointed out in the comments, there's been movement on the Formisano front. Jenny Hogan at New Scientist reports that he is now claiming very large amounts of formaldehyde have been picked up by the Planetary Fourier Spectrometer that he runs on Mars Express. He thinks the formaldehyde is being made as methane is oxidised, and that the formaldehyde level he sees is equivalent to an annual production of 2.5m tonnes of methane. It's near impossible to see how that much methane could be made by any process other than life. This is presumably the stuff he was keeping quiet about on Ischia. He's going to be talking about these results at an ESA meeting this coming week.
I've posted on the formaldehyde story before. And, even more now than then, I think Formisano is making a mistake. As Jenny points out, so do a number (quite possibly, from what I hear, all) of his colleagues on the PFS, including those who have more experience modelling atmospheric chemistry and interpreting spectrometer data than Formisano has. I don’t want to rehash everything in the earlier post on the subject, but the gist is that a) formaldehyde is expected to have a very short lifetime in the atmosphere, and thus it is very hard to explain how there could be so much of it and b) earth-based telescopes have looked for the stuff and found no evidence for it even at levels far lower than those that Formisano appears to see.
In addition, I’ve spoken to someone who’s seen the data and has a quite good theory as to what might be up. While no one else thinks there’s any formaldehyde in the atmosphere, everyone agrees that there’s carbon dioxide -- the atmosphere is almost entirely composed of the stuff. And carbon dioxide has some complexities. Since there are two stable isotopes of carbon (12 and 13) and two stable isotopes of oxygen (16 and 18) there are in fact six different possible types of carbon dioxide molecule, all with very slightly different spectral features and present in the atmosphere at very different levels. In the area of the spectrum that Formisano is looking at, around 3.7 microns, you’d expect some little features due to minority isotopes, and it seems plausible that this explains what Formisano is seeing. I believe this has been pointed out by reviewers of a paper Formisano has written on the subject, which may be why it hasn't appeared anywhere yet.
Another relevant point here is that there are two different regions where formaldehyde signals might be looked for in the PFS data. The 3.7 micron region is where one would expect a weak signal; the 5.1 micron region is where one would expect a stronger one. But Formisano seems to have said nothing about a signal in the 5.7 micron region, even though, at the sort of formaldehyde levels he’s talking about, you’d expect something quite visible there.
I think Formisano has put together a very good instrument, and that he’s also a nice guy. But on the issue of formaldehyde, he seems mistaken.
I’ll try and post on the Carol Stoker and Larry Lemke story (mentioned in comments here) a bit later, but for the time being it seems to me that that comment thread sorts out the story pretty well. Take note of this, a comment on the matter by Carol, relayed to us by Penny Boston and Phil Plait, and provided in the comments here yesterday by Bruce.