GUY RAZ, HOST:
It's WEEKENDS on ALL THINGS CONSIDERED from NPR News. I'm Guy Raz.
This past week, the director of NASA's Jet Propulsion Laboratory spoke at a conference in Rome where he said preliminary data shows the possibility - and I emphasize the word possibility - that the Mars rover has found signs of carbon-containing molecules on the Red Planet.
It set off a frenzy of speculation and excitement about what that could possibly mean. NASA's scientists will explain the latest findings at a much-anticipated news conference tomorrow. But NPR's Joe Palca says that we should scale back our enthusiasm just a bit.
JOE PALCA, BYLINE: I know it's not typical to start a news story by saying what the news isn't, but in this case, I think I have to. There will be no announcement on Monday that the rover has found carbon-containing molecules - at least that's what a news release from NASA's Jet Propulsion Laboratory said.
So no major announcements. But as the JPL director said this week, the rover science team is continuing to try to verify that one of its instruments has seen signs of carbon-containing molecules. And why is finding these molecules of such great interest?
JOHN GROTZINGER: It's a substance that's consistent with biological materials.
PALCA: John Grotzinger of the California Institute of Technology is the chief scientist on the rover team. Now, don't start thinking that because some carbon-containing compounds are associated with biological materials Grotzinger's talking about life on Mars here.
GROTZINGER: It doesn't have to be biological materials.
PALCA: There are plenty of these carbon-containing compounds that have nothing to do with life. But finding certain of these carbon molecules would be exciting because of what it might say about the Martian environment where the rover is sitting at the bottom of Gale crater. If one kind of carbon can survive there, it might just be a place where carbon molecules that are related to living organisms could also survive as a kind of chemical fossil.
GROTZINGER: There wouldn't be a field of paleontology unless you found the hot spots where things get preserved.
PALCA: Grotzinger says the rover is looking for those hot spots, places where carbon-containing chemicals, also called organic chemicals, consistent with life might exist.
GROTZINGER: We're using the rover to move around and find those places where these organics might get preserved. And even if they have nothing to do with life, at least it tells us that this is the kind of environment that might have been favorable for preservation of something that could be a biological material.
PALCA: It's funny in a way that even the possibility of finding carbon compounds on Mars causes excitement. It's certainly not true for every planet. In the current issue of the journal Science, researchers reported that they were virtually certain they had found large deposits of organic compounds on the planet Mercury, and that wasn't front-page news. Maria Zuber of the Massachusetts Institute of Technology is one of the Mercury researchers. She also works on Mars.
MARIA ZUBER: I can tell you anytime when you find anything with Mars, it's a frenzy.
PALCA: Mars just seems to have that effect on people. Joe Palca, NPR News, Washington.