In the December 8, 2006 issue of Science, a report was published suggesting that water had flowed on the surface of Mars in recent decades. A reexamination of the data led to the publishing of a new report in the September 21, 2007 issue of Science, claiming that most, if not all, of the evidences from the initial article could also be explained as dry gravel rather than water flows (see here for a discussion of this report).
Now, in a news release from the University of Arizona, Jon Pelletier and coauthor Alfred McEwen have reported on a further study of the surface-flow images that led to the original claim of water flow. Using new higher resolution images from NASA’s Mars Reconnaissance Orbiter (MRO), they have performed simulations of what the flows would look like if they were caused by water or by dry granular flow, such as sand or gravel. To their surprise, the dry flow better represented the image data than water flow. The team could not rule out mud flows, but felt that the simpler explanation was dry flow.
This report comes on the heels of another result discussed in a previous TNRTB, where researchers have concluded that if Mars did have surface water in its past, this water was probably so salty that only a few bacterial life-forms that exist here on Earth could survive in it.
In May of this year, NASA’s new spacecraft Phoenix will land on the north pole of Mars. The goal will be to examine the frozen material there and to dig down three feet below the surface in search of evidence for water and microorganisms.
The search for water and the possibility of life on Mars has not been straightforward or easy. Yet there’s a tremendous advantage in carrying out this search on the Red Planet because it is a relatively close neighbor and has a benign environment that enables us to examine many of its details. The search will be much harder for more distant Earthlike exoplanets, if such are discovered. Ultimately, RTB scholars expect that any life found on Mars will be identified as having originated on Earth.