In a recent press release John Grotzinger, chief scientist for the Mars Curiosity rover has said they have made a discovery. Not just any discovery, though, this discovery is "one for the history books".

We don't know yet what that discovery is and that may upset some people (if you know something why don't you just tell us!!?!!), but that's how science works. Discoveries should be verified and peer-reviewed before an announcement is made. Otherwise we end up with a Pons/Fleischmann cold fusion debacle.

However, this isn't a peer-reviewed blog, so I can speculate all I want. I have a couple ideas of what could be announced and what I think that could mean - in order from least likely to most likely.

SAM (Sample Analysis on Mars) instrument

1. Evidence of current microbial/bacterial life
Ok, this would be awesome. From what I know of the rover's capabilities the evidence they would find of current microbial or bacterial life would things like large peptide and protein fragments. The Mars rover has lots of fancy instruments, but Grotzinger has said that the discovery was found using SAM, or Sample Analysis on Mars, which has a mass spectrometer. If some form of life is on Mars right now the mass spectrometer would most likely respond with peaks for all sorts of amino acids, peptides (several amino acids bound together), and proteins (lots of amino acids bound together). To be honest, this isn't looking very likely. If bacterial life was currently on Mars I think we would have seen evidence already.

2. Amino acids
Another possibility is that Curiosity has found individual amino acids. Amino acids are the building blocks of life. Finding them would be interesting because it would say something about how prolific life in the universe really is. The basic building blocks of life being found on two separate planets in the same solar system would be huge. I don't think this one is very likely either, though.

3. Methane
We know that Mars has an atmosphere of mostly carbon dioxide with some water, carbon monoxide, and oxygen. Finding methane would be a big deal as well. You may wonder why I'm just glossing over the fact that there is water in the martian atmosphere and focusing on methane. The reason that methane would be such an important find is that methane is the product of many carbon decomposition reactions. If life once existed on Mars, we should see methane. Living organisms would be broken down to their component parts, proteins would be broken down to peptides, peptides to amino acids, and amino acids to methane and other products. Finding methane would be a big deal, and if I were a betting man I'd put my money on methane.

4. Minerals
Minerals may sound like a boring thing to find, right? So what, you found a few rocks, what's the big deal?

I've been waiting to make a Breaking Bad reference. I just didn't think it would be this one...

Minerals have already been seen on Mars. We found hematite, the mineral form of iron (III) oxide. The presence of minerals on Mars would suggest that at one point there were large bodies of water on Mars. This wouldn't necessarily mean that life existed, but water is obviously one of the things needed for life.