Transcript – Ancient Organics Discovered on Mars
We want to know: has life ever existed on Mars? Do pockets of life persist on Mars today? NASA's approach to answering these questions is to break them down into smaller and smaller steps.
First, we need to know if ancient Mars was habitable. Did it once have the right climate, and the right chemistry to support life?
The Curiosity rover is investigating these questions by looking for organic molecules: containing carbon. Organic molecules are the backbone of all life on Earth, though they can also come from non-living sources. Today the surface of Mars readily destroys organics, making them difficult to detect.
Six years ago, Curiosity landed in Gale Crater, on an ancient lakebed. A few months after arrival, it drilled into sedimentary rocks and detected traces of organic molecules using an instrument called SAM.
Now, Curiosity is climbing the mound in the middle of Gale Crater, and SAM has made a subsequent detection of organics. This new detection is exciting because it comes from rocks that are billions of years old. That means that the organic material within them is extremely ancient.
Some of the organics that SAM has detected contain sulfur, likely introduced through geological processes. Sulfur can act as a preservative, binding organic molecules together to make them tougher, and protecting them from oxidation.
In fact, sulfur is the element that makes hair and fingernails tough, as well as vulcanized rubber. Martian sulfur has probably had a similar effect on these old organic molecules, helping to preserve them over geological timescales.
SAM made the new detections by heating samples of crushed rock to very high temperatures, above a thousand degrees Fahrenheit. This vaporized the samples and released several species of small hydrocarbons, like benzene and propane.
Because the hydrocarbons were released at such high temperatures, they may be the fragments of bigger, heavier molecules within the rock similar to kerogens. On Earth, kerogens are found in rocks like black shale and coal, and are the products of ancient plant and bacteria.
We don't know if the recently discovered organics on Mars are of biological origin, but it's exciting to find such old material preserved right at the surface. This finding is also encouraging for future exploration.
NASA and the European Space Agency are preparing to send the next generation of rovers to Mars in 2020, carrying new technologies to search for signs of microbial life.
In the distant past, Mars was much warmer and wetter than it is today. The rocks at Gale Crater tell us it was once an environment where life as we know it could have survived.
The discovery of ancient organic molecules shows that another ingredient of life was present at that time, and it broadens our understanding of habitability of both ancient and modern Mars.