MAVEN Ready To Launch Today 55
An anonymous reader writes "Mars seems to have gone from being a warm, wet planet with a liquid core (with magnetic fields strong enough to maintain an atmosphere) to a cooled frozen desert-like surface. By gathering information about the Mars upper atmosphere and its magnetic field scientists hope MAVEN can help explain what happened and where the water went."
Pretty easy to speculate... (Score:1, Interesting)
... and this IS slashdot, after all.
I think Mars, being small, ran out of natural radio-decay heat sources in its crust and core. Not having enough mass, or enough tectonic activity to churn things up and generate heat, the core solidified, the magnetic field went away, and solar radiation finished them off.
Re:Pretty easy to speculate... (Score:5, Interesting)
The radioactive decay present in the core would continue at the same rate it does on earth ... it's just that it would have started with less, and would still to this day have less.
But Mars probably started with less radioactive material. The density of Earth is 5.5 kg/l. The density of Mars is 3.9 kg/l. So something in the early solar system caused more dense elements to end up on Earth rather than Mars. Most geothermal heat is caused by the decay of Thorium. Thorium is very dense, and is probably present in significantly higher concentrations on Earth, compared to Mars.
Re:Not Magnetic Fields (Score:4, Interesting)