Aliens!

[m_huber]

Usually is a problem word. For example, the Martian meteorites which were thought to be possible evidence of life contain structures "usually" only formed in the presence of life. Unfortunately, they also form without life, it's just more unusual. Evidence that says something was either caused by life or not caused by life isn't very helpful, as evidence goes. As for studies of the actual surface of Mars by various rovers, there is nothing even as conclusive as that.

Amino acids are no big deal. They're exist pretty much everywhere in the universe, even in cold, diffuse nebulae. They were also one of the first pre-life molecules to be artificially synthesised. Amino acids are easy, it's getting anything more than that which is the hard part.

I'm actually not referring to the meteorites, but rather to Martian sulfate minerals. These have been imaged by Spirit and Opportunity. They show the exact same structure as terrestrial sulfates that have high quantities of organic compounds, so they may represent the leftovers of ancient bacterial life (see Aubrey et al, Geology, 2006). The presence of amino acids isn't the significant thing, because they are found in space also (I think it takes something like 200 sq. meters to get enough amino acids to make a bottle of wine). However, the presence of fairly large amounts of sulfate minerals that contain organic compounds may be significant.

Also, Robert Folk has imaged different types of rust, and has concluded that some forms of rust form only in the presence of bacteria, and those forms of rust have been imaged by the rovers.

Some deposits on Mars definitely show evidence of fluvial process, though some definitely show evidence of dry movement. There is also confirmation of ice in the form of rock glaciers. Comparison of images taken months apart shows that there is movement on the surface of the planet consistent with ice being there.

If we accept the notion of "where there is water, there is life," then Mars and Europa both should have had life at some point. The evidence for that notion is only terrestrial up to this point, though.

As for Io, the magma it is spewing is higher density than the bulk chemistry of the planet, which it couldn't have been doing for very long, because they will eventually settle to the core of the moon. If it continues at the rate that it is going, it will indeed have its surface overturned, but it hasn't been doing that for its whole lifetime, else the magmas reaching the surface would have a lower density composition.

Of course, if we had found conclusive proof of life on Mars or anywhere else, it would have been all over the news already, just like it was when we thought we had it pegged with the meteorite. Even Bill Clinton made a statement. Even though we don't have proof, I personally am convinced that the evidence will turn up.

At the very least, I think it is much more likely that we will find evidence of life on Mars than life in Heaven.