Scientists discover massive underground ‘thermal anomaly’ on Mars– www.space.com

New research into the interior of Mars further emphasizes that the Red Planet is a world of two very different halves.

Deep inside the southern hemisphere of Mars, the temperature is up to 750 degrees Fahrenheit (400 degrees Celsius) warmer than beneath the northern hemisphere, deepening the mystery of the strange dichotomy between the Red Planet’s flattened north and craggy southern highlands.

“Scientists usually assume that the interiors of planetary bodies are generally spherically symmetric, but this is not necessarily true,” said Alexander Berne, formerly of Caltech and now at the University of Arizona, in a statement. Berne is the lead author of a new research paper revealing the discovery of the strange southern hotspot.

Berne and his team went back and looked at archival data from three NASA spacecraft – Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter – to look for subtle changes in their orbital velocity that might reflect variations in Mars‘s gravitational field. Using a technique developed by Berne called ‘tidal tomography’ that also accounts for the sun‘s varying gravitational influence on Mars as the Red Planet progresses around its elliptical orbit, he and his team were able to infer a model of the interior structure and temperature of Mars.

How the gravitational field that the various spacecraft experienced changed over time differs substantially from what would be expected were Mars’s interior perfectly spherically symmetrical. To explain this difference, the mantle beneath Mars’s southern hemisphere must be between 390 and 750 degrees Fahrenheit (200 and 400 degrees Celsius) warmer than the mantle in the north, and indeed it is so warm that it could still be partially molten. This could have repercussions for both Mars’s habitability and how long Mars remained volcanically active.