Life-Altering NASA Announcement of the Day: A few days ago NASA teased the world with a news conference to be held today at 2PM EST, in which an annoucement will be made concerning “an astrobiology finding that will impact the search for evidence of extraterrestrial life.” So, is there life on Mars as David Bowie has been demanding to know for years? Maybe. But that’s not what NASA wants to discuss.

According to the just-unembargoed research paper “A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus,” the much-debated possibility of a terrestrial “shadow biosphere” (that is, “a second genesis for life on this planet”) has allegedly been confirmed by scientists studying the microbes of California’s arsenic-rich Mono Lake.

From Cosmic Log:

In the paper published today, the researchers report that some of the bacteria could survive on arsenic and incorporate it into their cellular biochemistry. Instead of the usual phosphate-rich DNA, they observed arsenate-rich DNA. Heightened levels of arsenic also showed up in the cell’s proteins and fats. The scientists used mass spectroscopy, radioactive labeling and X-ray fluorescence to confirm that the arsenic was really being used in the biomolecules rather than merely contaminating the cells.

The long and short of it is that, if verified, this would be quite an exciting prospect for those actively searching for extraterrestrial life, because it opens up the possibility that undiscovered alien lifeforms could have a genetic makeup far removed from our own.

How cool is that?

[msnbc / slashdot / image: mono lake at dawn.]