Curiosity Sniffs Mars' BO to Learn About its Past

Ever wonder what Mars smells like? Researchers have long known that the average aroma of a planet can tell you a lot about its atmosphere. Now, experts are commanding the Mars curiosity rover to take a long sniff of the Red Planet's 'body odor' to learn more about its history.

This is the ongoing objective of the Mars-roaming robot - a mission that started even as the rover concluded geological analyses of rock layers around the "Pahrump Hills" in Gale Crater this past winter.

While the rover was drilling into Martian stone, Curiosity's Sample Analysis at Mars (SAM) experiment analyzed xenon in the planet's atmosphere. Xenon is a noble gas, and like all noble gasses, it does not bond  or react with other substances in the Martian air or ground. That makes it a perfect gas to trace back into Martian history.

"Xenon is a fundamental measurement to make on a planet such as Mars or Venus, since it provides essential information to understand the early history of these planets and why they turned out so differently from Earth," Melissa Trainer, one of the scientists analyzing the SAM data, recently explained in a statement.

Xenon also exists naturally in nine different isotopes that widely range in mass. This special characteristic allowed researchers to better see when Mars began to most violently lose its atmosphere - as removing gas from the very top of an atmosphere removes lighter isotopes more readily than heavier ones, affecting the ratio of isotopic masses seen today.

The SAM xenon measurement traced a very early period in the history of Mars when a vigorous atmospheric escape process was pulling away even the heavy gas. The lighter isotopes were escaping just a bit faster than the heavy isotopes, tilting the ratio.

"We are seeing a remarkably close match of the in-situ data to that from bits of atmosphere captured in some of the Martian meteorites [that fell to Earth]," SAM Deputy Principal Investigator Pan Conrad added.

He explained that this first test simply shows that Curiosity's nose can get the job done, proving just as accurate as laboratories back on Earth. Now experts can trust SAM's data in the future, as they continue to investigate the decline of Mars' atmosphere.

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