Venus, Mars Share Rare Molecule Options

[cndwrld]

Planetary scientists have detected a rare molecule in the atmospheres of both Mars and Venus. The molecule, an exotic form of carbon dioxide, could affect the way the greenhouse mechanism works on Venus.

More information is available at the ESA Venus Express web site at:

http://www.esa.int/SPECIALS/Venus_Express/SEMF8BV7D7F_0.html

[dvandorn]

Unfortunately, Nick, Venus' mass is very nearly exactly that of Earth -- close enough that I wouldn't expect to see any statistical differences in atmospheric gasses related to escape velocity.

When I look at Venus, Mars and the Earth, and ask myself what atmospheric condition is shared by the former two and not by the latter, the only thing that comes to mind is direct interaction between the atmosphere and the solar wind. Earth's magnetic field wards off the direct solar wind, but Venus and Mars both endure direct impact of the solar wind into their upper atmospheres.

This continual "spalling" of the atmosphere is what has supposedly accounted for the reduction in Mars' atmosphere to such a pitiful remnant at this point in geological time. If Venus has been sans magnetic field for most of its history, you'd have to think it's regenerating its air a lot more robustly than Mars ever could.

But, in any event -- could this unusual concentration of rare isotopes be the result of high-energy interactions between the solar wind and the upper atmosphere? The only other thing I can imagine that would account for it would be differentiation in the solar nebula -- but for that to be the case, you'd have to have a relative abundance of certain isotopes and a "desert" of such isotopes in the band of the nebula from which Earth accreted. Occam's Razor would suggest we're looking at a post-accretion effect and not a question of solar nebula composition.

-the other Doug