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What Happened To the Martian Ocean and Magnetic Field? (theatlantic.com)
schwit1 writes with this story at The Atlantic that explores what may have destroyed the Martian atmosphere and ocean. The question of whether there is life on Mars is woven into a much larger thatch of mysteries. Among them: What happened to the ancient ocean that once covered a quarter of the planet's surface? And, relatedly, what made Mars's magnetosphere fade away? Why did a planet that may have looked something like Earth turn into a dry red husk? “We see magnetized rocks on the Mars surface,” said Bruce Banerdt, the principal investigator of the InSight mission to Mars, which is set to launch in March. “And so we know Mars had a magnetic field at one time, but it doesn't today. We would like to know the history—when that magnetic field started, when it may have shut down.”
... that because of Mars' small size, it cooled faster, thus freezing its outer core and shutting down its dynamo? Isn't Venus the far greater mystery? Nearly the same size as Earth, yet no magnetic field and what appears to be occasional whole-crust overturn rather than plate tectonics? Isn't that the one we need to solve?
... that because of Mars' small size, it cooled faster, thus freezing its outer core and shutting down its dynamo? Isn't Venus the far greater mystery? Nearly the same size as Earth, yet no magnetic field and what appears to be occasional whole-crust overturn rather than plate tectonics? Isn't that the one we need to solve?
Well, I think they have Venus figured out. Basically it was like us early on, complete with oceans and land and magnetic field. Back in the beginning of the solar system, the sun was cooler than it is today. As it ages it grows hotter, like in the next 1 billion years the sun will be 10% hotter. Well, as it grew hotter back then, Venus's oceans started to evaporate into the atmosphere, and the H20 became lost to space. Leaving an ever growing thick atmosphere that held in the heat and increased the pressure on the surface. Being closer to sun, as it grew hotter, it also was moving closer to the edge of the habitable zone, which was moving outward as sun grew hotter. Without water on the surface anymore, plate tectonics stopped completely. When this happened, you no longer get a nice moderate release of volcanism, you get trememdous pressure building up and then released in huge amounts all at once probably every 400 million years that covers the planet in liquid hot magma. Also, it looks like Venus got hit hard by another proto planet that unlike what happened to the earth, which was a glancing blow at angle, Venus got hit straight on, slowing down it's spin a lot, It's one of(maybe the slowest), slowest spinning bodies in our solar system. I think you couple that with the lack of water to keep plate tectonics moving, you end up disrupting it's dynamo in the core and you have a very weak magnetic field now. The Earth is going to become Venus as the sun grows hotter and the habitable zone moves out further. It's a long time from now, but it will happen.
"I don't which is worse, that everyone has a price, or that the price is always so low"--Hobbes
How could you, guys, miss this opportunity to refresh the fear in the hearts of your followers? If you keep burning fossil fuels, our planet too will become an airless desert devoid of life
Tell me, what's the carbon footprint of burning a straw man?
SJW n. One who posts facts.
It's this exactly. Without a magnetic field, the solar wind dried out the planet and blew away a large amount of the already thin atmosphere. The low gravity didn't help any. The planet had a lot going against it from the beginning and was probably never a good place for complex life to appear. Barring some sort of cosmic change like how we got our moon and added a huge amount of iron and mass, Mars was always doomed to end up freeze-dried.
We currently have no way of fixing this problem so all the grand plans to terraform Mars won't work, unless they also restart the magnetic field, which we don't know how to do. It might take slamming a proto-planet into Mars to get things going again, which we can't currently do, and which would also make the planet essentially unusable for hundreds of millions of years, at least.
It also risks all kinds of other issues like disturbing other planets and introducing a lot of chaos into the solar system. But luckily we don't know how to knock planets into each other. And I suppose if we DID and we had that sort of tech, we would not need to bother with Mars. We'd just find a suitable planet elsewhere, which is probably easier.
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