NASA’s Curiosity rover has taken soil samples on Mars that may indicate life forms.
The NASA rover has been around for almost nine and a half years Curiosity landed on the Red Planet, where he has since explored an area of Gale Crater where ancient rock strata have been exposed.
In the samples from buried sediment, a carbon isotope found, taken from half a dozen exposed sites. For the origin of the carbon, it gives the researchers 3 plausible explanations: cosmic dust, ultraviolet breakdown of carbon dioxide, or ultraviolet breakdown of biologically produced methane, which would be indicative of life on Mars. As the researchers note in the Proceeding of the National Academy of Sciences, all of these scenarios are unconventional and different from processes that are common on Earth.
No evidence of biological origin
Further analysis needs to be done to determine its true origin. Like from a broadcast of the research team Christopher House from Pennsylvania State University, spectrographic analysis indicated a wide range carbon 12 and carbon 13-Shares. A portion was exceptionally poor in carbon 13 while other samples were carbon enriched.
On Earth, a severely carbon-13-depleted paleosurface signature would indicate that microbes have historically consumed microbially-produced methane. Ancient Mars may have had large plumes of methane released from underground. This released methane was then either consumed by microbes on the surface or reacted with ultraviolet light and deposited directly on the surface.
“The extremely carbon-13-depleted samples are somewhat similar to the samples from Australia, which come from 2.7 billion-year-old sediment,” House said. “These samples were caused by biological activity as methane was consumed by ancient microbial layers, but we can do that not necessarily say on Mars because it is a planet that may have formed from different materials and processes than Earth.” Thus, the evidence is not proof of life on the Red Planet.
cosmic dust
According to House, the solar system traverses every few 100 million years a galactic molecular cloud. “It doesn’t collect a lot of dust,” says House. “It’s hard to see such depositional events in the Earth’s record.”
In order to form a layer for Curiosity to sample, the galactic dust cloud would first have to lower the temperature on a Mars that still contained water and produced glaciers. The dust would have settled deposited on the ice and would have to remain in place after the glacier melted to leave a layer of dirt containing the carbon.
So far there is only few hints on former glaciers in Gale Crater on Mars. According to the researchers, this explanation is plausible but requires further investigation.
Converted CO2
Another possible explanation for lower levels of carbon 13 is the ultraviolet conversion of carbon dioxide into organic compounds such as formaldehyde. “There is work that predicts that UV radiation could cause this type of fractionation,” House said. However, further experiments are needed to assume or rule out this process.
“All three possibilities point to one unusual carbon cycle that doesn’t exist on Earth today,” House said. “But we need more data to figure out which of these is the correct explanation. It would be nice if the rover could detect a large methane plume and measure the carbon isotopes from it.” While there are methane plumes, most are small, and no rover has been able to collect a sample large enough to measure the isotopes.