Mars lost atmosphere due to radiation and solar wind
MAVEN principal investigator Bruce Jakosky and his colleagues by analyzing how much of two argon gas isotopes were present in the Martian atmosphere and on the planet's surface, in an attempt to see how much of this noble gas was lost in space over billions of years. Scientists predict that the loss was greater in the past, since the Sun was younger and more active, emitting far more intense ultraviolet radiation and winds.
This means the only way it can be lost from Mars' air is by being dragged away into space by the abrasive action of the solar wind - the billowing stream of charged particles constantly flowing from the Sun.
According to the latest MAVEN data, radiation and solar wind were responsible for the disappearance of much of Mars' atmosphere.
"As the planet cooled off and dried up, any life could have been driven underground or forced into rare surface oases". The significant loss of atmospheric gas would have played a role in Mars going from the warm and wet planet scientists believe it once was to the cold and dry landscape it is today. Earth's liquid metal core creates a magnetic field that deflects solar winds.
Looking at the abundance of two different isotopes of argon gas, they compared the relative amount of that found in the upper atmosphere with that at the surface to estimate what has been lost to space.
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Jakosky is lead author of a paper on this research to be published in Science on Friday. The present analysis uses measurements of today's atmosphere for the first estimate of how much gas was lost through time. The light version (argon-36) escapes more easily than the heavy version (argon-38), which leaves the gas remaining behind enriched in the more massive isotope. They focused on argon, a gas that nearly never chemically reacts with other elements. Jim began blogging about science, science fiction and futurism in 2004.Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch. For the record, argon is the most abundant element in the Earth's crust and the third most dominant gas in the atmosphere.
As a "noble gas" argon cannot react chemically, so it cannot be sequestered in rocks; the only process that can remove noble gases into space is a physical process called "sputtering" by the solar wind. The achievement took place on March 27, approximately 11 years after the MRO arrived on the planet's orbit. As soon as they determined how much argon had been lost by sputtering, they could use this data to determine the sputtering loss of other molecules and atoms, including CO2 (carbon dioxide).
"As a result, we know that the loss by sputtering represents just a small fraction of the total amount of Carbon dioxide that has been lost to space", Professor Jakosky said. Thanks to new data from NASA's MAVEN spacecraft, scientists now think they've finally figure it out.
CO2 is of interest because it is the major constituent of Mars' atmosphere and because it's an efficient greenhouse gas that can retain heat and warm the planet. "We determined that the majority of the planet's Carbon dioxide also has been lost to space by sputtering", Jakosky said. "Using measurements from both spacecraft points to the value of having multiple spacecraft that measure complementary things". "It's a marvelous vehicle that we expect will serve the Mars Exploration Program and Mars science for many more years to come", noted in a statement Dan Johnston, MRO project manager of NASA's Jet Propulsion Laboratory in Pasadena, California.
Recently, the spacecraft aided preparations for NASA's next mission to Mars, the InSight lander, which will launch next year on a mission to study the planet's deep interior.
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