Curiosity Rover Samples Air for a Flavor of Mars Heritage
LASER BEAMS: A laboratory demonstration of the sample chamber in the Curiosity rover’s Tunable Laser Spectrometer, one of the two instruments returning new data on Mars’s ambiance.
It’s time to update the list of ingredients in Martian air.
In late 2012 NASA’s Curiosity rover drew air into its onboard laboratory and analyzed Mars’s atmospheric composition with a pair of spectrometers. The results of the investigation, revealed July 19 in Science, revise decades-outdated data on the makeup of Red Earth air and paint a wide photograph of how the atmosphere has changed because the planet’s formation.
The diaphanous layer of gas enveloping Mars, the place the atmospheric strain is only about 1 per cent of Earth’s at sea stage, is predominantly carbon dioxide, with considerably scaled-down contributions from nitrogen and argon. Jointly these three gases constitute much more than ninety nine per cent of the atmosphere. (Earth’s atmosphere is also dominated by three gases: nitrogen, oxygen and argon, in that get, in addition a variable quantity of drinking water vapor.)
But NASA’s Viking mission in the nineteen seventies detected a significantly bigger contribution from nitrogen than argon—2.7 p.c nitrogen to one.six p.c argon. The new measurements from Curiosity’s Sample Examination at Mars spectrometers demonstrate that the two gases are present in almost equivalent amounts. In simple fact, argon (1.93 percent) appears to be slightly more common than nitrogen (1.89 %). The precision of the new measurements leaves little area for uncertainty, though long term information from Curiosity will help constrain any seasonal variants in the atmospheric make-up.
The rover is currently investigating more time-timescale modifications to Mars’s atmosphere by measuring which gases are present and which nuclear isotopes are in those gases. (Isotopes are atoms of the identical element with different atomic masses.) Researchers can then examine the isotopic measurements with historic gases trapped in Martian rocks that, freed from the floor by impacts, have fallen to Earth as meteorites.
“It tells us for the very first time the atmospheric composition to an accuracy which is higher ample to make immediate comparisons to the meteorites in all our labs,” states experimental atmospheric scientist Chris Webster of the NASA Jet Propulsion Laboratory in Pasadena, Calif., guide author of one particular of the new rover scientific studies.
The ratio of isotopes in carbon dioxide molecules, for instance, can reveal how a lot of the Martian ambiance has been dropped to space—whether blown away by meteor strikes or stripped by solar wind. Carbon dioxide molecules manufactured with operate-of-the-mill carbon-12 (the most widespread kind of that element) are lighter than molecules that contains the large isotope carbon-13 and escape to place simpler. As a result, atmospheric reduction leaves a planet’s carbon dioxide reservoir depleted in carbon-12 and reasonably enriched in carbon-thirteen.
Compared with earlier missions these kinds of as Viking and NASA’s Phoenix lander, Curiosity has unveiled a higher function for carbon-13, supporting the idea that Mars after had a significantly richer environment. Intriguingly, the Curiosity knowledge carefully match analyses of a meteorite referred to as Allan Hills 84001, which shaped on ancient Mars ahead of being ejected into place and subsequently landing in Antarctica. (The Allan Hills meteorite rose to fame in 1996, when experts made the highly controversial suggestion that it may include fossilized continues to be of Mars lifestyle.)
“We know that the Allan Hills meteorite is four billion years aged,” Webster claims. “It traps gas from that early Martian atmosphere.” Curiosity, on the other hand, can decide the exact makeup of the atmosphere nowadays. “So we now have ample confidence and ample accuracy in the measurements to make that comparison. The overarching end result is that the ambiance has modified quite tiny in 4 billion a long time.” In other words, it appears the bulk of Mars’s ambiance was lost reasonably shortly soon after the planet’s formation four.five billion many years in the past.
That does not imply there hasn’t been any modern variation. Methane, a gasoline that some planetary experts count on to modify tremendously more than time, is notably absent from the new scientific studies. In current many years, measurements from Earth have indicated the appearance and disappearance of methane plumes on Mars that may possibly spew from geologic—or even biological—sources. These observations have stirred controversy, which Curiosity ought to help settle. The rover has yet to detect the gasoline, but that does not always indicate it is absent from the Martian atmosphere. The specific higher limits on methane abundance that rover scientists can infer from Curiosity’s nondetection will show up in a later on research.
“That’s a large story, so we determined to independent it,” Webster claims. “We have a result that’s extremely exciting,” he adds, which has been submitted to Science for publication. “We have no definitive detection of methane—I can inform you that.” It continues to be to be seen if Curiosity’s limits on methane abundance strongly conflict with the ranges expected in the existence of seasonal methane belches from the Red Planet. If they do, the supposed plumes of mysterious origin may possibly be consigned—alongside the purported fossils in the Allan Hills meteorite—to the long record of Martian mirages, much to the dismay of optimistic astrobiologists and an excited public. “It’s not a information people want to listen to,” Webster claims. “They really do not actually want to listen to that there’s no methane on Mars.”