The Swiss cheese texture on Mars’ south pole is getting holier – so fast that the cheese will soon be gone.

Earlier this week, Shane Byrne, of the University of Arizona in Tucson, presented a model that explained the strange ice dynamics observed by HiRISE. At the south pole, there’s a thin layer of water ice overlain by a layer of frozen carbon dioxide ice that varies in thickness between two to 10 metres. There are pits in the dry ice — the so-called Swiss cheese textures — that tunnel down to the water ice. And observations have shown that the pits are growing.

Once they start to grow, the reflectivity of the dry ice is reduced, more heat is trapped, and the process accelerates. Some have proposed that Mars’ climate is changing. But Byrne asks the question: How can a residual carbon dioxide cap, with these pits, survive for us to observe? The process is so fast that we’d have to be awful lucky to observe the changes.

Byrne ran a model that doesn’t need to invoke any climate change. He starts with a very thin layer of dry ice with a certain degree of roughness. At first, the layer is smooth enough that reflectivity is high, and each winter, more ice condenses. But as the ice layer grows, its roughness increases. After about 30 years, instabilities occur in places with the highest slopes. Pits begin to form. Even as the pits grow, the overall height of ice table grows for while in the intervening flat areas.

But eventually, a tipping point is reached, and all the carbon dioxide disappears. At that point, a smooth, flat film of dry ice could condense to start the process all over again. The whole process, Byrne argues, is the inevitable consequence of starting with an ice surface that isn’t perfectly flat.

The poster was just one among hundreds, an analysis of craters bigger than 2.2 kilometres on the surface of Saturn’s moon Enceladus. But the author, Brian Karpes, was a bit more unusual.

On 14 February, Karpes, a geology graduate student at Northern Illinois University, was taking notes in a crowded lecture hall when a gunman burst in and began firing randomly with a shotgun and three handguns. The gunman, a former sociology student, killed five people before turning the gun on himself. Karpes was shot five times, including once in the head, and was taken by helicopter to the intensive care unit of a nearby hospital.

The LPSC poster was unattended, but dozens of colleagues had signed its border, wishing him well. There was a note in the middle of the poster: “Despite being shot FIVE times, Brian finished his LPSC poster Friday afternoon March 7, 2008. Because one bullet penetrated his skull and this wound has not yet fully healed, his doctors will not let him fly. He gets shot FIVE times and he still turns in his homework!!”

I wondered why everyone kept clustering around Tony Irving, of the University of Washington at Seattle. Then I realized: if you’re the guy holding a moon rock at a lunar science conference, you’re pretty popular. Here’s Tony with his 600-gram, 1-centimetre thick slice of the moon, taken from the 2nd largest lunar meteorite ever, an 11.5 kilo monster found in Morocco last summer. That’s just shy of “Big Muley,” an 11.7 kilo sample that was the biggest returned by the Apollo astronauts.

Meteorite hunting has become big business in the dry deserts of northwest Africa and the Arabian peninsula. You can buy moon rocks on eBay, where little flakes sell for hundreds and thousands of dollars. Randy Korotev, who maintains a wonderful lunar meteorite Web site at Washington University in St. Louis, estimates that, per gram, you pay more for moon than you would for diamond or gold.

Assuming a bargain basement price of $1,000 per gram, Tony’s slab would be worth half a million dollars, and the 11.5 kilo monster it came from would be worth more than $10 million. But Tony insists: “It’s a scientific treasure, not a financial treasure.”

The rocks are important because they represent a wider distribution of the types of rocks that exist on the moon. The Apollo missions only retrieved rocks from a few specific areas. Whereas the 56 known lunar meteorites, which result from random impacts, sample a far greater area. This one, Tony says, comes from highlands on the lunar far side. He says it’s an important rock because it contains bits of iron nickel metal that are exotic to the moon.

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The wonderfully named Wendell Mendell, manager for office of human exploration science at Johnson Space Center, talked at the end of the day about making sure that science capabilities were included in the lunar exploration architecture. His talk didn’t include many slides, but he did have one with three statements. Two, he said, came from official NASA documents. And one came from Mad magazine. Wendell wouldn’t reveal which was which, but I was still amused trying to guess.

A) The problem on landing on the lunar dark side is that terrain is usually dark.

B) Washout: high light angles do not allow reflected light to reach the eye.

C) Although the Moon is 1/49th the size of the Earth, it is farther away.

Here’s a meme you sometimes hear repeated in space science communities: The return of humans to the moon — formerly known as President Bush’s Vision for Space Exploration — has nothing to do with science. We’ve already been there. We already know everything. It’s just a waste of money — money that would be better spent elsewhere.

Now, to be fair, there are some reasons to be cynical about NASA’s human exploration program; the rocket builders who push people into space sometimes view science as something to be tacked on. And many space scientists argue that robots will always bring more science bang for the buck.

But to say that there aren’t space scientists who are excited to get another crack at understanding the moon — either via manned or unmanned missions — is just plain wrong.

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Maria Zuber often starts her presentations with a Maya Angelou quote: “There is no greater agony than bearing an untold story inside you.” If so, then the man in the Moon must be writhing in pain.

At an LPSC session on Tuesday, Zuber, of MIT, flashed a cross section showing what is known about the structure of the Moon’s interior. The answer is: not much. “There are a lot of question marks,” she says. “We don’t actually know that the Moon has a core.” She’s fairly sure the GRAIL gravity mapping mission will change all that.

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This is the first time that NASA Administrator Mike Griffin has spoken at LPSC — perhaps a sign of the growing importance of the conference. But there is also a valedictory air to Griffin’s talk tonight. Many doubt that he will survive the coming election and continue as administrator in a new US administration. It is the first time I have seen Griffin — always competent, ever irascible, seemingly indomitable — look weary.

The main conference hall is packed. People line the walls. Griffin begins reading from a prepared script. His speeches are always well written. But tonight, his delivery is flat. At one point, he offers perfunctory praise to the Mercury Messenger mission, and says he is looking forward to the next flyby. “I don’t know about you, but I can’t wait,” he says in a monotone.

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So I spoke too soon about the weather. After lunch, thunderclaps began to punctuate the talks, and it ended up raining all afternoon. But it cleared some of the humidity. And man, do I love the way Texas clouds roll in and out. Here’s the view from the conference center. Across the marina, in the distance, the folks at Johnson Space Center must be celebrating the successful launch of the Jules Verne ATV.

Monday is Mercury day at LPSC. It’s only been a month and a half since Messenger flew past Mercury, and the images and analyses keep on coming. I’m always surprised by the speed and volume of the work that occurs after these planetary missions. Messenger principal investigator Sean Solomon, of Carnegie, began the day’s sessions, and said the team got 500 megabytes of data from its instruments, and 1,213 images.

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Why did I bring sweaters? Too habituated to wintry weather in Washington, DC, I suppose.

The weather here in Houston, Texas (well, League City, actually) is expected to be in the mid-70s all week (that’s pretty warm for you Celsius types). I actually turned on the air conditioning in my hotel last night.

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