On November 20, 2012, Curiosity’s chief scientist John Grotzinger told NPR that the Mars rover had made a discovery “for the history books” (Palca, 2012). However, he was unable to elaborate on what exactly Curiosity has discovered because a team of NASA scientists still need to analyze and double-check the significance of the data (Gayle, 2012). Hypotheses of what Curiosity discovered are varied. Everything from presence of methane to the discovery of Martian life is a possibility (Hoover, 2012).
What Do We Know?
At the moment we know that Curiosity had been exploring the Rocknest area of the Gale Crater. This site was covered with water at some time in the distant past (Gayle, 2012). We also know that whatever the discovery was, it was made with the Sample Analysis at Mars (SAM) instrument which is designed to sample Martian rock, soil or air and find out what it is composed of (Hoover, 2012). We also know that the Curiosity Rover itself is teasing us via Twitter:
What If It Is Life?
I personally believe that this discovery could be of microbial life. If Curiosity found water, traces of methane or chemical conditions suitable for past and/or present life on Mars, those would all be great discoveries, however would they be discoveries “for the history books?” Probably not. Don’t get me wrong, they would be massive discoveries, but only the discovery of life on Mars would definitely be “for the history books.” That statement, coupled with knowledge that Curiosity was exploring Rocknest and the SAM instrument could detect microbial life all indicate that NASA will announce the discovery of the first extra-terrestrial life ever discovered. The announcement will be made in between December 3-7 at the fall meeting of the American Geophysical Union.
If Curiosity found life on Mars, what will it be composed of? To me, this is the most significant question. All life on Earth is composed of DNA. If life on Mars turns out to be based on a different code that would be proof life independently evolved on another planet. The ramifications of such a finding are far reaching. The discovery would permanently dismantle any notion that our planet is the center of life in the universe. Also, if microbial life evolved independently on Mars, there is increasing likelihood that life is abundant in the universe. There would be an increased probability of finding life on other planetary bodies in our solar system (e.g., Europa, Titan, Venus), as well as increased probability of finding chemical signs of life on Earth-like exoplanets within the goldilocks zone of their parent star.
However, if life on Mars is based on DNA, this probably indicates that Earth and Mars share an extended biosphere. Most scientists were surprised to find out that all life on Earth stemmed from one DNA-based common ancestor. The chance of two forms of DNA-based life forms evolving independently on two different neighbouring planets is mathematically implausible. It would be much more likely that at some point in the distant past Earth seeded Mars or Mars seeded Earth. There are several extremophiles that can survive within rock and can withstand the environmental pressures of space, planetary entry, and impact (Impey, 2007). If we find out that Earth seeded Mars, then it would be interesting to discover when that happened. More interesting, if we find out that Mars seeded Earth, it could revolutionize the way we understand life on our planet. It is possible that early in the Earth’s history DNA-based life forms were transported from Mars to Earth. If this happened it seems evident that they outcompeted any complex organic compounds present and took over the early Earth’s biosphere.
Of course, I am getting way ahead of myself. The Curiosity may not have made the biggest scientific discovery of our generation. Astronomer Phil Plait has wisely suggested that we shouldn't speculate. He also said he doesn't want to make any predictions of what was found. But if it is the biggest discovery of our generation I want to make a prediction. So here it is:
DNA-based microbial life, seeded from Earth (prediction 22/11/11)
I know that is the safe, and least interesting answer. But I also think it is the most plausible.
Gayle, D. 2012. Mars Curiosity rover team set to announce 'major discovery' on surface of Red Planet that 'will be one for the history books'. Daily Mail. Accessed November 22, 2012. http://www.dailymail.co.uk/sciencetech/article-2236333/Curiosity-team-set-reveal-major-discovery-Martian-soil--just-yet.html
Hoover, N. 2012. Mars Mystery: Here's What We Know. Information Week. Accessed November 22, 2012. http://www.informationweek.com/government/information-management/mars-mystery-heres-what-we-know/240142491
Impey, C. 2007. The Living Cosmos. New York: Random House.
Palca, J. 2012. Big News From Mars? Rover Scientists Mum For Now. NPR. Accessed November 22, 2012. http://www.npr.org/2012/11/20/165513016/big-news-from-mars-rover-scientists-mum-for-now?utm_source=NPR&utm_medium=facebook&utm_campaign=20121119