Mars on ice: I'll believe it when I take a drink of the local water

Congratulations to the Phoenix Lander team on its apparent discovery of ice near the north pole of Mars. Dig the color-photo evidence:

It took me a bit of looking to figure out what was going on with this picture of the trench dug by the Phoenix's eight-foot arm.

The idea is that some small chunks disappeared over a four-day period, indicating that they were made of ice that (I think) warmed up and then sublimed, because the Red Planet's extremely thin atmosphere causes water to boil immediately.

If I'm reading the picture correctly, the chunks are located in the bottom-left end of the trench. They were churned up by Phoenix as it dug for a soil sample. It's likely they came from the same layer of white stuff (which sure looks like ice) we see a bit of in the middle of the picture.

And as you can see in this photo, the chunks seem to be gone four days (or sols) later.

That's a pretty good indication of something, and an interesting locked-room mystery. But in a way I'd feel more confident if this discovery were based on evidence I couldn't so easily understand. The Rovers found varied evidence for historical water on Mars — such as erosion patterns in some rocks and the dispersal of the famous hematite "blueberries." But I don't believe water itself, in any form, has yet ended up in the hands of any robot. Phoenix's mission is to dig up some soil, cook it and examine it with the Thermal and Evolved-Gas Analyzer, or TEGA. It has so far not found any water through that means, so the sublimed-ice eureka, while interesting, doesn't necessarily move us beyond where we were.

So I decided to play Stupid Columbo and wonder aloud just how solid the evidence is for H2O on Mars. In an email, Cornell professor Steve Squyres, principal investigator for the Rover program and author of "Roving Mars" — a book you must read if you have even a passing interest in this stuff — says the evidence is absolute:

And it has been for decades. The Mariner 9 and Viking missions in the '70's produced compelling evidence that water once flowed across the martian surface, and that there is ice at the martian poles today. We often describe what the rovers and Phoenix are doing as "searching for evidence of water" or "searching for ice", but that's a gross oversimplification. That question was settled back when I was in college, and I'm in my 50's now. What we're doing today is adding the next level of detail.

He also notes that one hoped-for result of the Phoenix work would be a better understanding of the composition of the ice. "The ice could, for example, help preserve organic compounds," he writes.

Stupid Columbo again: But should we be hoping to find organic compounds, or for that matter water? I'm partly reacting here to news coverage that frequently characterizes scientists as "disappointed" or "not disappointed" or "pleased." I'm wondering whether the focus on organic materials, water, etc. might be part of a geocentric fallacy; after all, there wouldn't be much excitement about Mars if we discovered it really had nothing in common with us or our planet. Squyres' book treats in great detail the politics of research and discovery, the need for expectations management and the temptation to see what you want to see, so I asked him about that as well. His response:

Well, it's something you have to be very careful about. There's a saying that I've heard scientists use: "I wouldn't have seen it if I hadn't believed it." That's a trap you don't want to let yourself fall into. If you go to Mars with hopes or expectations for what you'll find, you can easily be led astray by those hopes. Mars is what it is, and it's asking too much for it to conform to our wishes. What you want to do instead is design a good experiment, look at the data you collect objectively, and let the data take you wherever they take you.

I put a variant of this question to JPL director Charles Elachi last year, while interviewing him for a profile. Quotes:

Tim: Is the prospect of life the only, only thing we're always after here?

Charles: That's the main focus. I mean, people are particularly intrigued... I mean you say: Wow people are excited about Mars. Mainly there are two reasons. One, you see it's a planet similar to ours; we can learn a lot about the geology and so on and learn about how our planet works. Really a key objective. But also the question: could life have evolved. That tends to have a broader public attention. At least, their impression. Because people, you know, they don't get excited when say you found a volcano. Yeah there will be lots of people excited, but if today you found a little bit of water on Mars, I think that's going to get a lot of attention. A number of years ago there was a possibility that a meteorite that was discovered in Antarctica might have life on it, and President Clinton wanted to make the announcement. But when we discovered a volcano on Io I don't think — that was a long time ago — I don't think the president made a point of wanting to announce that there was a volcano on Io...

So now you've spent more time with one of my hobgoblins than you probably cared to. And I don't want to be mulish about my skepticism. (These fancy scientists have no horse sense, I tell ya!) So again, I say to the Phoenix team: Congratulations, and keep digging.

Photos courtesy of NASA.