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[Centaur]

A BBC News article posted today reports:

"A chemical study of Martian meteorites implies that the planet has always been cold and was rarely above freezing. Writing in Science, US researchers say they are able to determine the maximum temperature the rocks experienced. There is no evidence they were ever warm, the team says, as the meteorites would have recorded near-surface conditions for four billion years. The water erosional features seen on Mars must have been made during very brief periods, they conclude."

For the full article, click below:

news.bbc.co.uk/2/hi/science/nature/4703055.stm

[Maddad]

centaur said:

The other part of the research addressed the long-term thermal history of the rocks while they resided on Mars. The scientists did this by estimating the total amount of argon still remaining in the samples.

Something about this article bothers me. It's not just that our current understanding of the formation of the planets doesn't work if Mars was never hot; that I could live with. The initial estimates were base on rock history in the last 15 million years. That is harder to live with because it has nothing to do with temperatures for dating back 300 times longer that they're extrapolating their data to. Then for the rest of the time they're concluding temperatures never rose any higher because of their estimatep, not a measurement, of remaining argon? They're assuming that only the processes producing argon that they're familiar with on Earth can work on Mars, which may not be a good estimate when you're dealing with 4,000 million years. For instance, they're assuming that argon diffuses free of the crystaline structure on Mars at the same rate that it does on Earth when the rate on Mars should be much higher because the atmospheric pressure is so much lower. This higer pressure influence diffusion rate would result in less argon remaining in the minerals, and therefore make them appear to have experienced a lower average temperature.

[Chicago Astronomer - Astro Joe]

Then it implies that the meteorites were not from Mars...which I really never believed they were in the first place. It was a great presumption when it was announced...and I scoffed.

Either that or I had something caught in my throat.

Thanks for the link.