No. 74: Mar-Apr 1991
H.L. Helfer, University of Rochester, noting the absence of extensive cratering on the northern plains of Mars, suggests that some 2-3.5 billion years ago these plains were covered with oceans. These ancient seas, perhaps as much as 700 meters deep, protected the plains from direct impacts. Further, crater density counts for Chryse and the Martian highlands imply that Mars possessed a fairly dense atmosphere until about 1.5 billion years ago. In his Abstract Helfer speculates as follows:
"With both early Earth and early Mars having similar atmospheric compositions and not too dissimilar atmospheric structures, it is reasonable to suppose that the warm Martian oceans, like the ancient oceans of Earth, would develop anerobic and aerobic photosynthesizing prokaryotes and structures like stromatolites. Their development might have changed the Martian atmosphere. Their fossils might be found along the fringes of the old oceans, the northern lowland plains."
(Helfer, H.L.; "Of Martian Atmospheres, Oceans, and Fossils," Icarus, 87:228, 1990.)
Comment. The Gaia influence is seen in the molding of the Martian atmosphere into something more conducive to the development of life. One can also speculate that, if life did develop on Mars, it could have seeded the earth via bits of debris blasted off by meteorite impacts. Several meteorites picked up in Antarctica are thought to have come from Mars originally.
Reference. Data suggesting Martian life are cataloged in AME14 in The Moon and the Planets. For ordering information, visit: here.