ARI SHAPIRO, host:
We have some sad news this morning from Mars. The Mars probe known as Phoenix has gone silent. NASA managers presume it's dead. Phoenix was basically a robotic chemistry lab capable of scooping up samples of Martian soil and ice and seeing what they were made of. It performed diligently since it landed last May, but no longer. NPR's Joe Palca has this remembrance.
JOE PALCA: Near the north pole on Mars in winter, the days are short and the weather is cold. How does spending the night at 150 degrees below zero sound to you? But that's what Phoenix had to do. Solar panels charged batteries which ran heaters. But about three weeks ago, one day all the juice drained from the batteries.
Mr. BARRY GOLDSTEIN (Project Manager, Jet Propulsion Laboratory): When the batteries reach zero, kind of like your laptop computer running out of juice when you're on an airplane, the vehicle would just shut down.
PALCA: Barry Goldstein is project manager for Phoenix. With the days getting shorter, the solar panels were only able to charge the batteries enough to operate the radio to contact Earth. But then, a week ago, there wasn't even enough power for that.
Mr. GOLDSTEIN: At this time, we're pretty convinced that the vehicle is no longer available for us to use. So we are actually ceasing operations, declaring an end of mission operations at this point.
PALCA: Unlike the two rovers that have been driving around on Mars for nearly five years now, Phoenix is stuck in one place. But John Mustard says Phoenix did something the rovers could not. Mustard is a planetary scientist at Brown University.
Professor JOHN MUSTARD (Geological Sciences, Brown University): What Phoenix did which was different was actually to take soil samples and ice samples and stick them into ovens or chemical analysis machines and to really do more manipulative experiments.
PALCA: Mustard says those are the kinds of experiments that will ultimately be needed to say whether life once existed on Mars. NASA sent the Phoenix probe to Mars to look for ice because ice is made of water, and water is what you need for life. A spacecraft orbiting Mars saw signs of ice beneath the soil near the north pole. But Mustard says a signal from orbit is one thing.
Professor MUSTARD: We all have a distrust - I don't know, that's the wrong word. We have a respect for - but it's kind of like what Ronald Reagan said, "Trust, but verify."
PALCA: Seeing it up close is always more convincing. Scientists also want to know the extent of the ice.
Professor MUSTARD: Is this ice just filtering in from the atmosphere and filling the pores in the soil, or was it a big chunk, therefore maybe representing quite a bit more water than we previously might have understood there to be.
PALCA: The Phoenix results don't say exactly how much ice is there, but it seems to be more like a big chunk, or several big chunks. Phoenix also showed it's not easy to get Martian soil into instruments. The soil is very clumpy. Future missions will have to figure out ways to deal with that. Samuel Kounaves of Tufts University is one of the lead investigators on the Phoenix wet chemistry lab. He says working on the mission has been an intense and satisfying experience.
Professor SAMUEL KOUNAVES (Chemistry, Tufts University): Every day, you know, my students and my staff would work on it. You know we'd prepare programs and, you know, transmit them up, have it do work and send back to us on a daily basis. It's like working with someone. And it's sort of sad to see it sort of drift off, lose energy, lose power. And so, you know, it's - I don't know, maybe hard to take in some ways. But again, it did its job exceedingly well, and so we couldn't have asked for more.
PALCA: But no grief counseling.
(Soundbite of audience laughter)
Professor KOUNAVES: No grief counseling.
PALCA: And besides, there is still plenty of data to analyze and scientific papers to write, so Phoenix will be a part of the lives of many scientists for months, if not years, to come. Joe Palca, NPR News, Washington.
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