h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The extinct vocanoes on Mars suggest that the planet once had heat at it's centre, such heat is caused by gravitational stress,the moon IO is a typical example.The moons of Mars do not have the mass to cause such stress. Is it possible that Phobos and Deimos are the remains of a much larger moon? Did Mars once have plate techtonics?

I have posed this question to experts but so far nobody has answered

Regards.

phredz.

Hi there fred,

I’m no expert but I’ll try to answer your question.

Phobos and Deimos are almost certainly captured asteroids and that happened within the last billion years. As you say, they do not have sufficient mass to have materially affected Mars’ internal heating or even to pull themselves into a globular shape. They are not likely to have been part of a larger body as their composition shows them to be similar to asteroids in the outer reaches of the solar system.

There is no evidence that Mars now has any tectonic plates in the same manner as the Earth. Whatever formed Mars' surface it was mainly volcanic or impact action. Its lithosphere is thicker than the Earth’s showing that it has cooled to the point where it is a single entity and the underlying mantle has also cooled to the point where it is no longer fluid enough to create a magnetic field.

Mars may have had some tectonic plate action in its early history before its internal heat production waned and the lithosphere thickened. There are residual magnetic lines, similar to those in Earth’s mid-Atlantic ridge, where its southern highland crust spread apart from a plate boundary. But for all practical purposes Mars’ lithosphere is now a solid orb of rock.

Deke

Hi Deke, Thankyou for your comments, it's nice to know someone is interested. communicating through this medium is frustrating for a beginner.
kind regards
phredz.

If you're interested in things astronomical, you could pop along here A413876 and subscribe to the page. Although not as active as it used to be, the h2g2 Astronomy society still has the occasional conversation about suchlike.

Also Galaxy Babe U128652 writes a monthly column on space related subjects for the h2 paper The Post. You'll find her column 'Babe Among the Stars' in the Post's index (two weeks out of four). The link is on the h2 front page. The back issues are at A31616958 .

Did you catch 'Wonders of the Solar System' on BBC2 last night? Much of it was about the comparison between Earth and Mars. If not catch up with it here:
http://www.bbc.co.uk/programmes/b00qyxfb

Deke

HiDeke, thanks once again, yes i did see prof. Cox, I seldom miss this kind of programme or any of Attenborough's.I am fotunate to live only 3 miles from Creswell Crags, another of my interests
CHEERS
pHREDZ