Another Martian Life Flap

A British newspaper, the Sun, has reported that NASA scientists have announced the discovery of life on Mars. NASA, and the scientists involved, absolutely deny anything of the sort-- and of course they're right. Had NASA made that announcement, it would have been done in such a way as to leave no doubt about what was said. The story would be front page news in every newspaper in the world.

In fact, in 1996, NASA did precisely that. A team of NASA researchers announced what it thought was strong evidence for life on Mars found in a meteorite that originated on Mars. Since then, most scientists have rejected that claim, but the NASA team is still working to strengthen its case.

Then there is the controversy surrounding Viking in 1976. Two landers successfully reached Mars and carried out a set of three separate tests searching for life. Before the missions, scientists agreed that a positive result in any of the three tests would be evidence of life. Well, one test seemed to get positive results, but the science community backed away from making any historic claim. NASA did not claim to have found life in that instance, but the principal investigator of the test in question certainly did.

Deciding exactly what constitutes "proof of life" has been more difficult than even most scientists expected forty years ago.