NASA's Maven Mission Solves the Mystery of Mars' Lost Atmosphere

StartsWithABang writes: If you came to the Solar System some 500 million years after its formation, you would've found two world with oceans of liquid water, continents and all the conditions we know of for life to begin thriving: Earth and Mars. But unlike our own world, Mars' organic history was cut short when it lost its atmosphere and became a barren, desert wasteland. While we had some pretty compelling theories as to how this happened, it was only with the advent of the Maven mission and its first science results that we discovered exactly how, how fast and when Mars lost its atmosphere. One cool discovery: aurorae appear diffuse and all over the entire night sky on Mars!

Comments

Summary missing information

[JoshuaZ]

The summary is missing important information. As TFA discusses, the primary issue was (as already strongly suspected) the loss of the magnetic field around Mars. With only a very weak magnetic field nothing protected the planet's atmosphere from the solar wind which blasted the atmosphere away over a time span probably in the hundreds of millions of years. This last result, the slow loss of the atmosphere is a genuinely novel and important discovery because as TFA discusses this makes it more plausible that if there was life on Mars that it would have had time to evolve to survive the gradually harsher environment. The research also suggests that Mars will become completely airless in around 2 billion years.

Re:Summary missing information

[Geoffrey.landis]

And the magnetic field stopped why?

Mars, being half the diameter of Earth, has a higher surface to volume ratio. Thus, it cooled faster. Presumably the liquid core froze, or at least, enough of it froze to stop the dynamo of molten metal that creates the magnetic field

Re:Summary missing information

[Anonymous Coward]

Gravity. Venus has about 0.8 the mass of the Earth. Mars has about 0.1 of the mass. That's a big difference. Without that extra mass, Mars doesn't have the gravity to hold in the atmosphere, so the solar wind is strong enough to strip it away. On Venus, there's plenty of mass to generate gravity which keeps the atmosphere in place with more force than the solar wind has to strip it. On Earth, there's even more gravity plus a magnetic shield that negates the solar wind completely.