Chlorophyll or just green dots? She asked what the Pathfinder spacecraft really found in 1997
6.4.2002
The scientists found challenging new evidence this week that may herald the existence of life on Mars. An analysis of data collected by the Pathfinder spacecraft in 1997 indicates the existence of chlorophyll - the molecules that plants use on Earth to absorb energy from sunlight - in sites close to the spacecraft's landing sites.
The researchers emphasize that the research is at an extremely advanced stage and that they are far from being able to make substantiated claims. But even so, the work has attracted the attention of the scientific community and it will be examined at an astrobiology conference in the US next week.
A pigment found in plants and some bacteria allows these creatures to capture sunlight. This energy is used to drive photosynthesis, a process in which carbon dioxide gas and water are turned into simple glucose molecules. Photosynthesis is the starting point of all life forms on Earth. The chlorophyll in leaves and other parts of plants make them appear green.
Dr. Carol Stoker of NASA's Ames Research Center confirms the findings but claims that they are not yet ready for publication.
Mars Pathfinder landed in the Ares Valley on Mars in July 1997. It was necessary to take many pictures of the environment around the landing area and send a small rover to collect rock samples. A more detailed analysis of the images from the landing area were recently released. These are pictures of two areas close to the spacecraft where there are signs of the presence of chlorophyll.
According to the experts, the photographs show a reasonable chance of chlorophyll, or they just show colored soil.
Dr. Stocker's team examines with a microscope and photographic equipment the images taken by the Pathfinder camera. A panoramic photograph of the landing area was produced in 15 colors, and included a lot of data on the types of ribs, colors and texture.
The SUV, Sojourner was used to get closer to the areas that interested the researchers.
Knowing the spectral signature of chlorophyll, the researchers wrote computer software that systematically scanned the images for interesting pixels. In particular, the software looked for spectral signatures associated with red light, the same light absorbed by chlorophyll.
A search of this kind was made shortly after receiving the images, but was then rejected on the grounds of "possible mis-combination of images."
In Dr. Stoker's research, the new study found six locations where the chlorophyll signature was felt. Each of these areas was examined in detail. All of the images appeared in the locations closest to the camera. This is to be expected, the researchers say, as the camera's sensitivity is highest in these areas. She discovered that four of these spots were on the Pathfinder spacecraft itself, but two areas showed that the chlorophyll signature was found in the soil near the spacecraft.
Being aware of the controversial nature of these findings and the preliminary state of the research, the scientists wish to postpone any claim about these findings until they perform additional work and prepare a detailed article for publication in one of the scientific journals.