Much has been debated concerning whether or not Mars once hosted geography akin to that of Earth. For example, scientists have uncovered evidence that the planet had plenty of its own water supply billions of years ago, a trait that implied the existence of a denser atmosphere. Where, then, did all the air vanish to?
Utilizing its Sample Analysis at Mars instrument (SAM), NASA’s Mars Curiosity rover recently relayed new data suggesting that Martian atmosphere has been slowly diminished by the effects of particles from the sun. These particles, traveling at high velocities and electrically charged, have taken advantage of Mars’ lack of a planet-encompassing magnetic field. The atmosphere on its rocky, red surface is now 1 percent as dense as that of Earth’s.
How exactly did this happen? Scientists have long suspected the Sun was responsible for the red planet’s lack of an atmosphere, but SAM’s recent findings solidify the theory to a clearer degree. It was able to determine that the Martian atmosphere, made primarily of carbon dioxide, contained more of a lighter argon isotope—argon-36—than that of a denser one, or argon-38. Argon-isotope measurements of the sun and Jupiter reveal that Mars’ argon ratio is lower than the solar system’s original 5.5-to-1; light enough, then, to constitute a top-down erosion of the atmospheric isotopes by the Sun’s solar winds.
It is believed that nearly 95 percent of Mars’ original atmosphere has been sloughed away by this process. The reason the argon idea has garnered so much credibility is because of the isotope’s unreactive nature. The imbalance between argon-36 and 38 would be easily explained by the lighter isotope’s inability to stand against high-velocity solar winds as they passed over the Martian surface.
“We’ve been waiting for this result for a long time,” said Professor Sushil Atreya, a SAM co-investigator from the University of Michigan in Ann Arbor.
SAM was able to take such precise measurements through amplification of its argon samples via the removal of other gases. It is the first time the process has been attempted during Curiosity’s mission and goes on to clarify questionable measurements taken by the Viking spacecraft of the 1970s.
NASA plans to launch the Maven satellite at the end of 2013. The spacecraft’s purpose it to analyze Mars’ atmospheric loss to a larger degree and will hopefully complement Curiosity’s SAM findings.