Re: Rust?
Not only that, but the only reason there *is* more than trace atmospheric oxygen on Earth is life. Biotic processes are what separate the Oxygen from the rocks (Iron and Calcium, predominantly). Otherwise, Earth would look rather a lot like Mars, with much of our oxygen tied up in the rocks.
Of course, it's spectacularly unlikely that Mars (or Earth) formed with all the Iron being iron oxide. Oxygen is a very common element, but to reach the all-pervasive nature of iron-oxide on Mars there would have had to have been atmospheric oxygen on Mars at some point...and for quite a while too.
"Mars had an Oxygen atmosphere" isn't exactly news. Proof that it didn't would be novel. Alternately, proof that there was once enough Nitrogen on Mars to serve as a buffer gas would be interesting. If there was that much at one point, where'd it all go? Mars should be able to hold on to Nitrogen...I think? Hmm...now I have to go look that up...
Biting the hand that feeds IT
