The search for life beyond Earth is a primary driver of many missions to explore the Red Planet and in this new video, a NASA scientist takes a closer look at the question that drives it all: Is there life on Mars?
NASA has a number of missions running on Mars that are intensely involved in searching for traces of life. Major such missions include the Curiosity rover, which landed on Mars in 2012, and Perseverance, which launched on Mars in 2021. The latter has been collecting rock cores from Jezero Crater where traces of life might be minuscule. Trapped.
“Now we’re getting tools on Mars that can help us understand these potentially habitable places and we can ask deeper questions about the habitability of those rocks,” Heather Graham, an astrobiologist at NASA’s Goddard Space Flight Center in the city, said. Greenbelt, Maryland, in a minute-long video posted Dec. 28. (Opens in a new tab). “We have been searching for life on Mars for a long time.”
Related: How Martian microbes can survive in the Red Planet’s salty pools
NASA scientist Heather Graham is an organic geochemist and researcher based at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, studying the connections between biotic and abiotic systems. Her research focuses on “agnostic biosignatures,” which NASA describes as evidence of living systems that may have little in common with life on Earth.
Graham’s research has focused on developing tools and techniques that can help us identify evidence of living systems that may have biochemistry different from life on Earth, also known as “indicative biosignatures.”
As they explore Mars and aim to study other planets in the solar system for traces of life, scientists need detection methods that assume a common heritage with life on Earth. These methods can also help scientists understand life deep underground as life can be very different from that on the surface of the planet as a result of following different evolutionary lines over billions of years.
Graham explained: “While NASA has not found any evidence of life now, we have found a lot of evidence that Mars could have supported life in the past. The ocean on Mars and the atmosphere that could have supported life.”
One of the most important pieces of evidence that Mars could once have supported life is the fact that the now dry and arid planet once harbored an abundance of water, an essential ingredient for life.
The fact that the 45-kilometre-wide (28-mile-wide) Jezero crater was flooded and was home to an ancient river delta is the reason NASA chose it as the landing area for the Perseverance rover.
About 4 billion years ago, river channels at Jezero spilled over the crater walls to form a lake, also filling it with clay minerals from the surrounding area. If microbial life was present on Jezero during these wetter Martians, signs of this life may remain in lake bottom or beach sediments. Thus, signs of this past life could be found in samples of Martian rocks and soil collected by Perseverance.
On Earth, our magnetic field prevents harmful radiation from stripping the atmosphere and protecting life on the planet’s surface. Mars is believed to have lost its water when it lost its magnetic field about 4 billion years ago. Without an atmosphere, there would have been nothing to prevent the Martian water from evaporating and then being lost to space. This radiation also made life on Mars impossible.
However, there is a possibility that liquid water could still exist under the surface of the planet, and thus Graham believes that if life persists on Mars, it will also be under the outer layers of the planet. The advantage of subsurface habitation is the layers of rock and soil that provide protection from harmful solar radiation once connected by the Red Planet’s magnetic field.
“There are places that could be habitable, like the deep substratum. There are places underground that could have liquids or organisms could live in, and they would be shielded from very harmful radiation at the surface,” Graham explained. “So, is there life on Mars? We haven’t found it yet, but there’s still a lot of Mars to explore.”
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