Featured Research

from universities, journals, and other organizations

Curiosity confirms origins of Martian meteorites

Date:
October 16, 2013
Source:
American Geophysical Union
Summary:
Earth's most eminent emissary to Mars has just proven that those rare Martian visitors that sometimes drop in on Earth -- a.k.a. Martian meteorites -- really are from the Red Planet. A key new measurement of Mars' atmosphere by NASA's Curiosity rover provides the most definitive evidence yet of the origins of Mars meteorites while at the same time providing a way to rule out Martian origins of other meteorites.

Scientists identified meteorites, such as this one nicknamed "Black Beauty," as Martian in origin.
Credit: NASA

Earth's most eminent emissary to Mars has just proven that those rare Martian visitors that sometimes drop in on Earth -- a.k.a. Martian meteorites -- really are from the Red Planet. A key new measurement of Mars' atmosphere by NASA's Curiosity rover provides the most definitive evidence yet of the origins of Mars meteorites while at the same time providing a way to rule out Martian origins of other meteorites.

The new measurement is a high-precision count of two forms of argon gas -- Argon-36 and Argon-38-accomplished by the Sample Analysis at Mars (SAM) instrument on Curiosity. These lighter and heavier forms, or isotopes, of argon exist naturally throughout the solar system. But on Mars the ratio of light to heavy argon is skewed because a lot of that planet's original atmosphere was lost to space, with the lighter form of argon being taken away more readily because it rises to the top of the atmosphere more easily and requires less energy to escape. That's left the Martian atmosphere relatively enriched in the heavier Argon-38.

Years of past analyses by Earth-bound scientists of gas bubbles trapped inside Martian meteorites had already narrowed the Martian argon ratio to between 3.6 and 4.5 (that is 3.6 to 4.5 atoms of Argon-36 to every one Argon-38) with the supposed Martian "atmospheric" value near four. Measurements by NASA's Viking landers in the 1970's put the Martian atmospheric ratio in the range of four to seven. The new SAM direct measurement on Mars now pins down the correct argon ratio at 4.2.

"We really nailed it," said Sushil Atreya of the University of Michigan, Ann Arbor, the lead author of a paper reporting the finding today in Geophysical Research Letters, a journal of the American Geophysical Union. "This direct reading from Mars settles the case with all Martian meteorites," he said.

One of the reasons scientists have been so interested in the argon ratio in Martian meteorites is that it was -- before Curiosity -- the best measure of how much atmosphere Mars has lost since the planet's earlier, wetter, warmer days billions of years ago. Figuring out the planet's atmospheric loss would enable scientists to better understand how Mars transformed from a once water-rich planet more like our own to the today's drier, colder and less hospitable world.

Had Mars held onto its entire atmosphere and its original argon, Atreya explained, its ratio of the gas would be the same as that of the Sun and Jupiter. They have so much gravity that isotopes can't preferentially escape, so their argon ratio -- which is 5.5 -- represents that of the primordial solar system.

While argon comprises only a tiny fraction of the gases lost to space from Mars, it is special because it's a noble gas. That means the gas is inert, not reacting with other elements or compounds, and therefore a more straightforward tracer of the history of the Martian atmosphere.

"Other isotopes measured by SAM on Curiosity also support the loss of atmosphere, but none so directly as argon," said Atreya. "Argon is the clearest signature of atmospheric loss because it's chemically inert and does not interact or exchange with the Martian surface or the interior. This was a key measurement that we wanted to carry out on SAM."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Curiosity mission for NASA's Science Mission Directorate, Washington. The SAM investigation on the rover is managed by NASA Goddard Space Flight Center, Greenbelt, Md.


Story Source:

The above story is based on materials provided by American Geophysical Union. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sushil K. Atreya, Melissa G. Trainer, Heather B. Franz, Michael H. Wong, Heidi L. K. Manning, Charles A. Malespin, Paul R. Mahaffy, Pamela G. Conrad, Anna E. Brunner, Laurie A. Leshin, John H. Jones, Christopher R. Webster, Tobias C. Owen, Robert O. Pepin, R. Navarro-Gonzαlez. Primordial argon isotope fractionation in the atmosphere of Mars measured by the SAM instrument on Curiosity, and implications for atmospheric loss. Geophysical Research Letters, 2013; DOI: 10.1002/2013GL057763

Cite This Page:

American Geophysical Union. "Curiosity confirms origins of Martian meteorites." ScienceDaily. ScienceDaily, 16 October 2013. <www.sciencedaily.com/releases/2013/10/131016134028.htm>.
American Geophysical Union. (2013, October 16). Curiosity confirms origins of Martian meteorites. ScienceDaily. Retrieved August 27, 2014 from www.sciencedaily.com/releases/2013/10/131016134028.htm
American Geophysical Union. "Curiosity confirms origins of Martian meteorites." ScienceDaily. www.sciencedaily.com/releases/2013/10/131016134028.htm (accessed August 27, 2014).

Share This




More Space & Time News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) — The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Powered by NewsLook.com
Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Newsy (Aug. 21, 2014) — Russian cosmonauts say they've found evidence of sea plankton on the International Space Station's windows. NASA is a little more skeptical. Video provided by Newsy
Powered by NewsLook.com
Space to Ground: Hello Georges

Space to Ground: Hello Georges

NASA (Aug. 18, 2014) — Europe's ATV-5 delivers new science and the crew tests smart SPHERES. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
Powered by NewsLook.com
Tiny Satellites, Like The One Tossed From ISS, On The Rise

Tiny Satellites, Like The One Tossed From ISS, On The Rise

Newsy (Aug. 18, 2014) — The Chasqui I, hand-delivered into orbit by a Russian cosmonaut, is one of hundreds of small satellites set to go up in the next few years. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins