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

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

Revealing the potentially habitable climate of ancient Mars is a key 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 at the Red Planet.

To mark the occasion, here are five of the most significant discoveries that scientists have made using Curiosity’s Sample Analysis at Mars (SAM) instrument suite. SAM is one of NASA’s most powerful astrobiology 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 components that scientists use remotely to test Martian samples.

1. Detection of organic compounds on Mars

Charles Malespin and Amy McAdam, SAM’s principal and deputy principal investigators at Goddard, very much agree on SAM’s most significant finding: SAM detected organic molecules in rock samples collected from Mars’s Gale Crater. Organic molecules (those containing carbon) could be used as building blocks and “food” for life. Their presence on Mars suggests the planet once could have supported life, if it ever was present.

While the isotopes in carbon dioxide and measured during some SAM sample analyses could be consistent with ancient biological activity producing the organics observed, importantly there are also non-life-based explanations—for example, this isotopic signal could be a result of an interaction between ultraviolet light from the sun and carbon dioxide in Mars’s atmosphere producing organics that fall to the surface, no life required.

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

2. Methane variability

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 gathers samples. On Earth, most of the methane present in the atmosphere gets there thanks to processes from life and varies as a result of changes in biological processes, but we do not know whether this is the case on Mars.

Curiosity isn’t equipped to determine whether or not the methane it has detected originates from biological processes, but the host of Red Planet 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 bit more than a year when, thanks to SAM, scientists determined both the formation age and the exposure age of a rock on the surface of another planet for the first time.

The rocks around the rim of Gale Crater were formed about 4 billion years ago, then transported as sediments to Yellowknife Bay. “Here they were buried and became sedimentary rocks,” McAdam said. From there, weathering and erosion slowly broke down and exposed the rocks to surface radiation about 70 million years ago. Apart from providing insight into Mars’s erosion rates, knowing how long a sample was exposed enables scientists to consider possible radiation-induced changes to which could affect the ability to identify potential biosignatures.

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

4. Homing in on the history of water on Mars

SAM has also shed light on Mars’s wetter past and how the planet has dried out. Water is vitally important to life as we know it, and “multiple lines of evidence indicate that the rocks of Gale Crater record a rich history of ,” Malespin said. Part of that evidence is the presence of jarosite, a ruddy-yellow mineral only formed in watery 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 surface of Mars was becoming dry, some liquid water remained below the surface in the Gale Crater environment, extending the period of habitability for any Martian microbes that might have existed.

In addition, analyses by SAM provided insight into the loss of Mars’s atmosphere that led its long-term evolution from the early warm and wet state to the current cold and arid state. Water, H2O, contains two hydrogen atoms and one oxygen atom. The hydrogen can be swapped for a heavier form of itself, called deuterium. Through 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 useful nitrogen

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

SAM detected fixed nitrogen in the form of nitrate in rock samples it analyzed in 2015. The finding indicated that biologically and chemically usable nitrogen was present on Mars 3.5 billion years ago.

“While this nitrate could have been produced early in Martian history by thermal shocks from meteor impacts,” McAdam said, “it is possible that some could be forming in the Martian atmosphere today.”

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

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Do winners cheat more? New research refutes previous high-profile study

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Credit: Pixabay/CC0 Public Domain

New large-scale research led by the University of Leicester shows that winning does not cause people to cheat, in stark contrast to a previous high-profile study.

A 2016 paper by Israeli researchers reported a series of experiments, which claimed that winners of skill-based competitions are more likely to steal money in subsequent against different opponents, as opposed to losers or people who did not see themselves as winners or losers.

This highly-cited study of relatively small sample sizes proposed that competitive winning induces a sense of entitlement that encourages cheating.

But now, an expanded and enhanced study by researchers at the University of Leicester (UK) and the University of Southern California (U.S.), published today in the journal Royal Society Open Science, has refuted the original findings.

The international team of researchers found that people with a strong sense of fairness cheat less—regardless of whether they had previously won or lost.

They examined the behavior of 259 participants in a lab-based dice-rolling game—identical to the original study—and 275 participants undertaking a basic coin-tossing game in an additional online experiment. The results were then analyzed using standard statistics plus a mathematical technique called structural equation modeling.

Researchers found that a small but significant amount of cheating occurred for the financial rewards on offer, just as in the original study. However, winning did not increase subsequent cheating or increase people’s sense of entitlement—and neither did .

Instead, the only factor investigated which could account for the small (but significant) amount of the cheating that occurred was low “inequality aversion.”

People with inequality aversion dislike unequal outcomes. Those with a strong sense of fairness tend to be inequality averse, and they avoid cheating because they view the practice as a form of unfairness.

Andrew Colman is a Professor of Psychology within the University of Leicester’s Department of Neuroscience, Psychology and Behavior, and also served as lead author for the new study.

Professor Colman said, “Cheating and general dishonesty are of growing concern in the light of academic dishonesty in the digital age, problems of tax avoidance and evasion by wealthy people in developed economies, and more generally effects of widening inequality in wealth and income on corruption and crime.

“We were surprised by the findings in the 2016 study, and that’s why we wanted to replicate it with substantial sample sizes. The original study’s small samples do not have the statistical power to generate firm conclusions.

“We were amazed when it turned out that neither nor losing had any effect on cheating although a significant amount of occurred. We have at least provided scientifically sound data that give a clear answer to the question.”

More information:
Does Competitive Winning Increase Subsequent Cheating?, Royal Society Open Science (2022). DOI: 10.1098/rsos.202197.

Do winners cheat more? New research refutes previous high-profile study (2022, August 2)
retrieved 3 August 2022

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