Professor Aron Vecht and researcher Terry Ireland from the university's School of Chemical & Life Sciences say that the special structures -- which are shaped like flowers and spheres -- could have been formed on the cold surface of Mars from minerals commonly occurring there. Their findings cast grave doubts on the possibility of Martian life.

In a paper published today (Tuesday, August 1 2000), Vecht and Ireland show that vaterite, a rare form of calcium carbonate found in the meteorite, can be made easily.

It occurs when carbon dioxide is bubbled through a solution of calcium chloride in the presence of ammonia at room temperature (about 25 degrees Celsius) -- conditions that may well have existed on Mars in the past.

Other forms of calcium carbonate, such as calcite and aragonite, can be formed at higher temperatures, around 65 degrees Celsius.

"Any junior school laboratory in the country could replicate these results using a very simple process," says Professor Vecht.

"It came as a great surprise that, under the electron scanning microscope, the structures we had made bore very great similarities to those reported in the Martian meteorite, as these have been used as the best/only evidence for the existence of primitive life on Mars.

"Our findings cast grave doubts on the possibility of Martian life, especially as we used minerals readily available on Mars," said Vecht

The discovery came about while the team was investigating the properties of different forms of calcium carbonate (chalk) as part of an ongoing research project into phosphor compounds which have luminescent properties.

The Centre for Phosphors & Display Materials at the University of Greenwich carries out leading research on the preparation, study and improvement of phosphors which are widely used in electronic display and flat screen technology including TVs, computers, oscilloscopes and medical equipment such as X-ray screens.

It is hoped that the research which led to this discovery may be extended to the investigation of fossil structures that have been attributed to previous life forms on Earth.