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How much water DID Mars once have? Analysis of oldest meteorite from red planet reveals world likely held 'small seas'

  • Study done by University of California, Nasa and Smithsonian Institution
  • They looked at ALH84001 which was found in Antarctica 30 years ago
  • They believe something liquid - probably water - seeped through pores in Martian rock and deposited globules of carbonates and other minerals
  • But analysis remaining minerals suggests Mars did not have vast oceans 
  • Last week, Nasa announced another potential whiff of Martian life in the form of methane sniffed by the rover Curiosity 
An ancient rock, found on Earth 30 years ago, is believed to have been created from a Martian volcano that erupted four billion years ago.
The meteorite fell on Antarctica around 13,000 years ago, and has since been analysed to discover whether life once flourished on the now barren landscape of the red planet.
Now, a new study of the oldest meteorite from Mars has added evidence to the theory that the red planet likely held smaller seas that allowed life to flourish.
Allan Hills 84001, also known as ALH84001, is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984. The rock has been dated to about 4.5 billion years - the period when Mars formed
Allan Hills 84001, also known as ALH84001, is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984. The rock has been dated to about 4.5 billion years - the period when Mars formed
Scientists from the University of California, San Diego, Nasa and the Smithsonian Institution recently took a fresh look at the minerals within the ALH84001 rock.

'[They] hold a snapshot of the planet's ancient chemistry, of interactions between water and atmosphere,' said Robina Shaheen, a project scientist at UC San Diego.
Scientists believe something liquid - probably water - seeped through pores in the rock and deposited globules of minerals.
The meteorite was found 30 years ago in Allan Hills. This is a group of hills, mainly ice free and about 12 nautical miles long, lying just north-west of the Coombs Hills
This team measured a pronounced ozone signal in the carbonates within the meteorite, suggesting that although Mars had water in its early days, but vast oceans were unlikely
The carbonates in the rock vary subtly depending on the sources of their carbon and oxygen atoms. Both carbon and oxygen occur in heavier and lighter versions, or isotopes.
Mars's atmosphere is mostly carbon dioxide but contains some ozone.
The balance of oxygen isotopes are strikingly weird with enrichment of heavy isotopes as first described by co-author Mark Thiemens, a professor of chemistry at UC San Diego, 25 years ago.
'When ozone reacts with carbon dioxide in the atmosphere, it transfers its isotopic weirdness to the new molecule,' said Dr Shaheen.
When carbon dioxide reacts with water to make carbonates, the isotopic signature continues to be preserved.
The degree of isotopic weirdness in the carbonates reflects how much water and ozone was present when they formed. The more water, the smaller the weird ozone signal.
This team measured a pronounced ozone signal in the carbonates within the meteorite, suggesting that although Mars had water back then, vast oceans were unlikely.
Last week, Nasa announced another potential whiff of Martian life in the form of methane sniffed by the rover Curiosity.

ALLAN HILLS 84001: KEY FACTS

Allan Hills 84001, also known as ALH84001, is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984.

The potato-shaped meteorite is 4.3lbs (1.93kg) and made headlines when scientists thought it may contain fossilised bacteria.

The rock has been dated to about 4.5 billion years - the period when Mars formed.  It is believed to have originated underneath the Martian surface from an volcano.

It may have been fractured by impacts as meteorites hit the planets in the early inner solar system.

Between 3.6 billion and 4 billion years ago, a time when it is generally thought that the planet was warmer and wetter, water is thought to have existed in this region.

Since the water was saturated with carbon dioxide from the Martian atmosphere, carbonate minerals were deposited in the fractures. 

Scientists are now analysing minerals within the rock to find out more about the red planet's early climate - and whether life may have existed on Mars.


The meteorite was found 30 years ago in Allan Hills. This is a group of hills, mainly ice free and about 12 nautical miles long, lying just north-west of the Coombs Hills
The meteorite was found 30 years ago in Allan Hills. This is a group of hills, mainly ice free and about 12 nautical miles long, lying just north-west of the Coombs Hills

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