Date: Tue, 09 Apr 2002 12:16:37 -0500
From: Earl Wajenberg <[EMAIL PROTECTED]>
Subject: Chlorophyll on Mars?

Life on Mars hopes raised

Pathfinder's view of Mars: A lot more work needs to be done

By Dr David Whitehouse BBC News Online science editor

Scientists have found "intriguing" new evidence that may indicate there
is life on Mars.

An analysis of data obtained by the Pathfinder mission to the Red Planet
in 1997 suggests there could be chlorophyll - the molecule used by
plants and other organisms on Earth to extract energy from sunlight - in
the soil close to the landing site.

Researchers stress their work is in a very preliminary state and they
are far from making definite claims.

Even so, the work is attracting much attention in the scientific
community and will come under intense scrutiny when it is presented to
an astrobiology conference in the US next week.

Dr Carol Stoker, from the American space agency's (Nasa) Ames Research
Center, confirmed the findings to BBC News Online but cautioned that
they were "not ready for the big time".

Early data

Mars Pathfinder mission touched down in the Ares Vallis region of Mars
in July 1997. It took many images of the surrounding area and released a
small rover to sample rocks.

A detailed analysis of the images of the landing site now reveals two
areas close to Pathfinder that have the spectral signature of
chlorophyll.

According to experts it might be highly significant - or could be just a
patch of coloured soil.

Dr Stoker's team scrutinised the so-called Superpan, which is a
high-resolution, highly processed series of superimposed images produced
by Pathfinder's camera.

It is a multispectral panorama of the landing site recorded in 15
regions of the spectrum, and contains a wealth of information about rock
types, colours and textures.

Knowing the spectral signature of chlorophyll, the researchers wrote a
computer program that systematically scanned the Superpan for any pixels
of interest.

Specifically, the program looked for the spectral signature associated
with red light absorption by chlorophyll.

Previous searches for evidence of chlorophyll in Pathfinder's pictures
were carried out shortly after it landed.

Some tentative indications were seen but they were later dismissed as
"possible image misregistration".

Two patches

In Dr Stoker's study six regions of the Superpan matched positive for
the chlorophyll signature.

For each of the regions, a full spectrum was plotted out and their exact
position in the Superpan was then carefully examined.

All of the detections occurred close to the camera. This is to be
expected say the researchers, as these are the areas where the camera
has the highest sensitivity and resolution.

Close examination revealed that four of the cases occurred on the
Pathfinder spacecraft itself. But two regions showed a chlorophyll
signature in the soil around Pathfinder.

Given the controversial nature of their findings and the early stage of
the research, the scientists want to hold back any claims about what
they may have found until they have done more work and prepared a
detailed paper for submission in a scientific journal.


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