Martian rock reveals evidence of water

The rock, blasted off Mars some 700,000 years ago by an asteroid or comet impact, also bears traces of the planet’s atmosphere, say scientists.

Martian meteorites allow scientists to study the planet’s geology on Earth without having to mount expensive space missions, however most are not found until long after their arrival, allowing them to be spoiled by Earthly contamination and chemicals.

The latest example, known as Tissint, is one of only five so-called fall meteorites to be collected after being spotted falling to Earth.

Having broken up in the atmosphere, fragments of the rock landed on a desert region of southern Morocco near the town of Tissint on July 18 last year.

The pieces were analysed by scientists including experts at London’s Natural History Museum, where a 1kg lump, measuring about 12 cms across, is now on display.

The museum’s meteorites curator Dr Caroline Smith said scientists on Earth could analyse the rock with a precision not possible using robots such as the rover Curiosity, which recently landed in a Martian crater.

She explained there was absolutely no suggestion of any sign of Martian life in the meteorite, adding: “I can say hand on heart that people have not found anything indicative of little green men or little green bugs,” she said.

The meteorite does, however, contain large amounts of black glass, created by heat from a shock impact melting rock, and scientists know that elements found inside the glass cannot have resulted from contamination from Earth.

One is cerium, an element from the Martian surface. The unusual levels of cerium suggested they had been deposited by a leeching process involving water.

The research, conducted by 20 scientists in five countries, is reported in the journal Science.