NEW evidence has made it more likely that remnants of Martian microbes were transported to Earth in a meteorite, it was revealed today.

A study by scientists from the American space agency Nasa has found chemical signatures in the rock strongly associated with life.

The discovery strengthens the case for believing that worm-like structures in the meteorite are 'microfossils' of ancient Martian bugs.

Sceptics have pointed out that similar-shaped structures could be formed from non-biological processes.

Another unanswered question is whether the microfossils were the result of contamination by Earthly bacteria. This was originally ruled out by Nasa but has raised doubts in the minds of other experts.

The meteorite, catalogued as Allen Hills (ALH) 84001, crashed onto the frozen wastes of Antarctica 13,000 years ago and was recovered in 1984.

Scientists believe the rock was blasted off the surface of Mars by an asteroid or comet, reaching Earth after floating through space for around 16 million years.

It would have formed part of the planet's crust at a time billions of years ago when many experts believe water flowed on the surface of Mars, and conditions were suitable for life.

In 1996 Nasa and the White House made the explosive announcement that the rock contained traces of Martian bugs.

Photographs were released showing elongated segmented objects that appeared strikingly lifelike.

However, the excitement did not last long. Other scientists questioned whether the meteorite samples were contaminated. They also argued that heat generated when the rock was blasted into space may have created mineral structures that could be mistaken for microfossils.

The new study was conducted using advanced high resolution electron microscope techniques which were not available 13 years ago.

News of the findings, expected to be released soon by Nasa, was leaked to the space news website Spaceflight Now and picked up today by the Sun newspaper.

The research was led by Dr Kathie Thomas-Keprta and members of the original team at the Johnson Space Centre in Houston, Texas, that claimed to have found evidence of life in the meteorite.

It focused on a more detailed analysis of magnetite crystals - tiny magnetic particles - and carbonate discs within the rock.

Certain bacteria on Earth are known to contain magnetite crystals, which they are believed to use as tiny compasses to help them navigate.



Originally published as Martian bugs crashed to earth