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Five of the top discoveries aboard NASA’s Curiosity rover on Mars

Curiosity Rover

This self-portrait from NASA’s Mars rover Curiosity combines dozens of images taken by the rover’s Mars Hand Lens Imager (MAHLI) during the 177th Mars day, or sol, of Curiosity’s work on Mars (February 3, 2013), plus three images captured during Sol 270 (May 10, 2013) to update the appearance of some of the ground next to the rover. Credit: NASA

Revealing the potentially habitable climate of ancient Mars is an important part of NASA’s mission to explore and understand the unknown, to inspire and benefit humanity – and for 10 years the Curiosity rover has been on the case. been to the Red Planet.

To mark the occasion, here are five of the most significant discoveries scientists have made using Curiosity’s Sample Analysis at Mars (SAM) instrument suite. SAM is one of NASA’s most powerful astrobiological instruments on Mars. Designed and built at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, SAM searches for and measures organic molecules and light elements, which are important to life as we know it. To complete this task, SAM carries with it components that remote scientists use to test Mars samples.

1. Detection of Organic Compounds on Mars

Charles Malespin and Amy McAdam, SAM’s principal and deputy principal investigators at Goddard, strongly agree on SAM’s key finding: SAM detected organic molecules in rock samples collected from Mars’s Gale Crater. Organic molecules (containing carbon) can be used as building blocks and ‘food’ for life. Their presence on Mars suggests that the planet could once have supported life, if it ever existed.

While the isotopes in carbon dioxide and methane measured during some SAM sample analyzes may be consistent with ancient biological activity producing the observed organics, it is important that there are also non-life-based explanations – for example, this isotopic signal may be the result of an interaction between ultraviolet light from the sun and carbon dioxide in the atmosphere of Mars, producing organics that fall to the surface, does not require life.

Taken together, these results motivate ongoing and future studies with SAM and the entire Curiosity suite of instruments, as well as other planetary missions seeking evidence of habitable environments and life beyond Earth.

2. Variability of Methane

Using SAM’s Tunable Laser Spectrometer, developed at NASA’s Jet Propulsion Laboratory in Southern California, scientists have detected fluctuations in the abundance of methane in the near-surface atmosphere where Curiosity collects samples. On Earth, most of the methane present in the atmosphere ends up there through processes from life and varies due to changes in biological processes, but we don’t know whether this is the case on Mars.

Curiosity isn’t equipped to determine whether or not the methane it detects comes from biological processes, but the Red Planet’s many missions continue to piece together the tantalizing puzzle.

3. Rock Formation and Exposure Age in Gale Crater

Curiosity had only been on Mars for a little over a year when, thanks to SAM, scientists first determined both the formation age and the exposure age of a rock on the surface of another planet.

The rocks around the rim of Gale Crater were formed about 4 billion years ago and then transported to Yellowknife Bay as sediments. “Here they were buried and became sedimentary rock,” McAdam said. From there, weathering and erosion slowly broke down, exposing the rocks to surface radiation about 70 million years ago. In addition to providing insight into Martian erosion rates, knowing how long a sample was exposed allows scientists to consider possible radiation-induced changes in organic compounds that could affect its ability to identify potential biosignatures.

“The age-dating experiment was not planned for launch,” McAdam said. “But flexibility in the design and operation of SAM, and the dedication of a team of scientists and engineers, has enabled it to be successfully implemented.”

4. Zooming in on the history of water on Mars

SAM has also shed light on Mars’ wetter past and how the planet has dried up. Water is vital to life as we know it, and “multiple lines of evidence indicate that Gale Crater’s rocks record a rich history of water,” Malespin said. Part of that evidence is the presence of jarosite, a ruddy-yellow mineral that forms only in aqueous environments, McAdam said. An age-dating experiment with SAM and another Curiosity instrument (APXS) found jarosite hundreds of millions of years younger than expected.

This finding suggests that even as much of the Martian surface became dry, some liquid water remained below the surface in the Gale Crater environment, extending the period of habitability for any Martian microbes that may have existed.

In addition, analyzes by SAM provided insight into the loss of the Martian atmosphere that led to the long-term evolution from the early warm and wet state to the current cold and dry state. water, huh2O, contains two hydrogen atoms and one oxygen atom. The hydrogen can be exchanged for a heavier form of itself called deuterium. By measuring the deuterium-to-hydrogen ratio in its samples, Curiosity uncovered evidence of a history of hydrogen escape and water loss on Mars.

5. Biologically usable nitrogen

On Earth, nitrogen is an essential ingredient in the recipe for life, but just nitrogen is not enough. Before most biological processes can make use of them, the nitrogen atoms must first be “fixed”: freed from their strong tendency to interact only with themselves. “Solid nitrogen is needed for the synthesis of DNA, RNA and proteins,” Malespin said. “These are the building blocks of life as we know it.”

SAM discovered solid nitrogen in the form of nitrate in rock samples it analyzed in 2015. The finding indicated that there was biologically and chemically useful nitrogen on Mars 3.5 billion years ago.

“While this nitrate may have been produced early in Mars’ history by thermal shocks from meteor impacts,” McAdam said, “it’s possible some could form in the Martian atmosphere today.”

No finding from SAM or other Curiosity instruments can provide positive evidence for past life on Mars, but more importantly, these discoveries don’t rule it out. Earlier this year, NASA extended Curiosity’s mission to at least 2025, allowing the rover and its mobile SAM chemistry lab to stay focused on the pungent matter of Mars’ habitability.

Curiosity rover inventories key life ingredient on Mars

Quote: Five of the top discoveries aboard NASA’s Curiosity rover on Mars (2022, August 4), retrieved August 4, 2022 from https://phys.org/news/2022-08-discoveries-aboard-nasa-curiosity-rover .html

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