The search for ancient life on Mars has been ongoing since NASA’s first successful rover mission to the planet in 1997. Now, new photos taken by the Curiosity Rover have provided clues about what scientists are looking for when it comes to ancient fossils or other evidence of past microbial life.
Mars has always been an attractive target for scientists hoping to learn more about our ancient past. The planet is the closest in proximity to Earth, and its size and composition are similar to that of Earth which makes it a good candidate for study. However, with so many years of research, you would think there would be some hard evidence of life on Mars, and you would be wrong.
For years scientists have focused their efforts on the red planet’s surface looking for fossils or other evidence of past life forms that may have existed billions of years ago when Mars was a much different world than the one we know today. Unfortunately despite all this effort, there has been no concrete evidence found. While this may seem like a dead-end, scientists are planning to take a closer look at the Martian atmosphere for possible clues.
While it is possible that microbes once populated Mars, in our current search for life on Mars we have not yet found an organic matter that is unambiguously from life, said NASA Jet Propulsion Laboratory astrobiologist, Jennifer Eigenbrode.
We have not yet found the smoking gun of life on Mars, but organics are difficult to find with Curiosity because these are highly reactive chemicals that would likely degrade when exposed to ultraviolet radiation or cosmic rays over millions or billions of years, she said.
To find evidence of past life on Earth in our planet’s ancient past, scientists find organic material like fossilized microbes or plant life that has been covered over time by sediment and rock. The same idea applies to Mars as those layers of rock would help protect evidence of possible Martian life from solar radiation which is why now scientists are taking a closer look at the atmosphere.
To search for clues about past life on Mars, the Curiosity rover has been fitted with a new instrument called SAM Sample Analysis at Mars, which can heat the soil and ice samples to about 935 degrees Fahrenheit 500 Celsius to release organic chemicals.
The first soil samples heated by SAM revealed some of the strongest evidence yet that water flows on present-day Mars. However, no organic compounds were detected which means they are still searching for evidence of past or present life on Mars.
While this is not the result that scientists have been looking for, it does provide some valuable information about how habitable Mars recently was and could help direct those future missions that will search more thoroughly for fossils, organics, and other possible signs of ancient life.
NASA’s next rover to Mars is set for launch in 2020 and will include the hardware necessary to search directly for evidence of past life on the red planet.
Until then, scientists continue their search for organic matter that could be attached to grains of sediment which would indicate that life once existed there. The absence of these finds has not stymied the search for life on Mars, but it has created a new approach using Curiosity’s Sample Analysis at Mars SAM instrument to look at the Martian atmosphere and see if there’s organic evidence of past or present microbial life.
That is what Professor of Geochemistry and Planetary Sciences at Brown University, Kevin Cannon, and his team have done. Using the latest technology, they have developed a new method of detecting organic compounds in Mars’ atmosphere.
Their initial results found hints of 20-plus organic chemicals that make up only a small fraction of the gases spewed by volcanoes on Earth. This suggests that Martian volcanoes are not an ideal habitat for microbes to grow.
However, Cannon and his team identified a chemical in the Martian air that has not been seen previously.
It can be toxic to life at high concentrations, but we also see it at the parts per trillion level, which is interesting because microbes can grow on Earth in places with very low concentrations of organics in the water, Cannon said.
I’m confident that there are organics on Mars, but we need to be focused on how to find them and look at the right periods with this ancient greenhouse gas that may be uniformly distributed and also could potentially form these organic particles in the atmosphere, he added.