Hunting for Biosignatures
Any hunt for biosignatures will include the rover’s suite of cameras, especially Mastcam-Z (located on the rover’s mast), which can zoom in to inspect scientifically interesting targets. The mission’s science team can task Perseverance’s SuperCam instrument – also on the mast – to fire a laser at a promising target, generating a small plasma cloud that can be analyzed to help determine its chemical composition. If those data are intriguing enough, the team could command the rover’s robotic arm to go in for a closer look.
To do that, Perseverance will rely on one of two instruments on the turret at the end of its arm. PIXL the Planetary Instrument for X-ray Lithochemistry) will employ its tiny but powerful X-ray beam to search for potential chemical fingerprints of past life. The SHERLOC (the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) instrument has its own laser and can detect concentrations of organic molecules and minerals that have been formed in watery environments. Together, SHERLOC and PIXL will provide high-resolution maps of elements, minerals, and molecules in Martian rocks and sediments, enabling astrobiologists to assess their composition and determine the most promising cores to collect.
An enduring hope of the science team is to find a surface feature that couldn’t be attributed to anything other than ancient microbial life. One such feature could be something like a stromatolite. On Earth, stromatolites are wavy, rocky mounds formed long ago by microbial life along ancient shorelines and in other environments where metabolic energy and water were plentiful. Such a conspicuous feature would be difficult to chalk up to geologic processes.
“Yes, there are certain shapes that form in rocks where it’s extremely difficult to imagine an environment devoid of life that could cause that shape to form,” said Williford. “But that said, there are chemical or geologic mechanisms that can cause domed layered rocks like we typically think of as a stromatolite.”
Enter Perseverance’s sample caching system. The steamer-trunk-size collection of motors, planetary gearboxes, and sensors is among the most complex, capable, and cleanest mechanisms ever sent into space. With it, the science team will collect the most intriguing samples they can find, store them in samples tubes, and, later, deposit them so that future missions can collect the sample tubes and fly them back to Earth for analysis.
“The instrumentation required to definitively prove microbial life once existed on Mars is too large and complex to bring to Mars,” said Bobby Braun, the Mars Sample Return program manager at JPL. “That is why NASA is partnering with the European Space Agency on a multi-mission effort, called Mars Sample Return, to retrieve the samples Perseverance collects and bring them back to Earth for study in laboratories across the globe.”
And when that happens, samples from Mars’ Perseverance rover may tell us that at one time billions of years ago life existed elsewhere in the universe. But they also may indicate the opposite. And what then?
“We have strong evidence that Jezero Crater once had the ingredients for life. Even if we conclude after returned sample analysis that the lake was uninhabited, we will have learned something important about the reach of life in the cosmos,” said Williford. “Whether or not Mars was ever a living planet, it’s essential to understand how rocky planets like ours form and evolve. Why did our own planet remain hospitable as Mars became a desolate wasteland?"
Perseverance may not provide the final word on if the Red Planet ever contained life, but the data it collects and the discoveries it makes will play a key role whenever that result is reached.
Humanity has been focusing on Mars since Galileo became the first human to see it through a telescope in 1609. Did it once have life? The answer may be awaiting us somewhere in Jezero Crater. NASA’s Perseverance rover will begin the process of finding out tomorrow.
More About the Mission
A key objective of Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith.
Subsequent missions by NASA in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.
The Mars 2020 mission is part of a larger program that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with returning astronauts to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through NASA’s Artemis lunar exploration plans.
JPL, which is managed for NASA by Caltech in Pasadena, California, built and manages operations of the Perseverance rover.
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