It's not being announced at NASA Goddard's Space Flight Center, but NASA Monday will release what's being called a noteworthy finding by the Curiosity rover now investigating the surface of Mars.
Rumors began flying after chief Curiosity scientist John Grotzinger was quoted by NPR as saying that the rover had recently gathered data "for the history books."
However, NASA downplayed expectations in a statement Friday.
"Rumors and speculation that there are major new findings from the mission at this early stage are incorrect," officials at NASA's Jet Propulsion Laboratory wrote. "At this point in the mission, the instruments on the rover have not detected any definitive evidence of Martian organics."
JPL officials added that the announcement, set for noon at the fall meeting of the American Geophysical Union in San Francisco, would "be an update about first use of the rover's full array of analytical instruments to investigate a drift of sandy soil."
Jeffrey Kluger, science editor for Time Magazine, told CBS News Saturday his suspicion is the rover found some traces of methane, a byproduct of metabolism, but he said that could be produced geologically and not necessarily biologically.
But he said such a finding is "not insignificant."
The Huffington Post will have live streaming video of the announcement and provide live updates.
In August, Mars rover fans spilled over onto the floor and stood along the walls in the wee hours at NASA Goddard's Visitor Center in Greenbelt to watch Curiosity as it first descended toward the Red Planet..