Today is when the first set of papers about Yellowknife Bay are published. There are six, and they are about the sediments, minerals, the age of the sediments, the geochemistry and the radiation environment. I am a co-author on the geochemistry paper and my collaborator Dr Susanne Schwenzer is a co-author on the radiometric dating paper.
The papers (published in the journal Science) summarise how we know that there was a habitable environment in the Yellowknife Bay mudstones. The temperature (<100 oC), pH – near neutral, and the nutrients needed for life were all present. This can be worked out from the mineralogy, and we are now working on understanding the fluid history in more detail and comparing to terrestrial analogues in our second round of papers.
The radiometric dating – led by Ken Farley et al. – is based on the known decay rate of the isotope Potassium 40. It shows an age of 4200 million years for the mudstones, confirming their ancient origin in what is called the Noachian era. The oldest known life on Earth is algal mats (stromatolites) of about 3500 million years age. However, older rocks on Earth have largely been metamorphosed or destroyed, so the most ancient rocks (and perhaps life) may have been preserved on Mars rather than the Earth.
Other work being presented at the American Geophysical Union in San Francisco includes ChemCam analyses to find the origin of the grains within sediments. ChemCam offers the chance to make individual mineral analyses with the laser, and we are comparing the analyses to martian meteorite minerals to give us an idea of the type of rock that the sediments were derived from.
Meanwhile our mission continues…
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