"The results suggest that water was incorporated during the formation of Mars and that the planet was able to store water in its interior during the planet's differentiation, " Hauri said.

MSN: Scientists say parts of Mars interior are as wet as Earth's

One last point: Airbnb has accumulated what they are calling one of the largest collections of interior photography on the planet, including about a million professional property shots.

FORBES: Move up http://i.forbesimg.com t Move down

To do this, they used computer models of the planet's interior and computed the possible combinations of elements and compounds that could yield the observed characteristics.

BBC: Oddballs: The strange worlds beyond our Solar System

"It's been puzzling why previous estimates for the planet's interior have been so dry, " co-author Erik Hauri of the Carnegie Institution of Washington said in a statement.

MSN: Scientists say parts of Mars interior are as wet as Earth's

Held in a scoop on the rover's mechanical arm, the tablespoon of pulverized gray rock offers planetary scientists their first sample from the planet's interior, where it may have been sheltered from the harsh surface chemistry and ultra-violet radiation.

WSJ: Rover on Mars Extracts First Rock-Core Sample

This is the theory that life is not merely a surface scum which clings to the outside of planet Earth, but that living things, in the form of so-called extremophile bacteria which can tolerate infernal heat, penetrate several kilometres into the planet's interior.

ECONOMIST: Obituary

Moreover iron, which gives the planet its characteristic hue, would naturally cling to the varnish, protecting interior organisms from the harmful effects of intense ultraviolet radiation from the sun.

CNN: Researcher: Mars rock varnish hints of life

Plate tectonics, the formation of faults and the moving of the continental crust over a molten interior, is a characteristic unique to Earth and it meant that minerals evolved far beyond those on any other planet in the Solar System.

ECONOMIST: Minerals