New York
—
Scientists said June 20
they have “found proof” of water ice on Mars away from the polar ice caps
.
The finding, discovered by NASA’s Phoenix Mars Lander, is a crucial first step toward learning whether the ground on Mars is hospitable, because all life
requires water. Now scientists can proceed
with the
studying the chemistry of Mars dirt in more detail.
Phoenix photographed dice-sized crumbs of bright material in a trench informally called “Dodo-Goldilocks” June 16. When the probe
went back to look at the trench, they had vanished. The disappearing act convinced scientists the material was frozen water that vaporized after digging exposed it.
“It must be ice,” said Phoenix principal investigator Peter Smith of the University of Arizona, Tucson. “These little clumps completely disappearing over the course of a few days –
that is perfect evidence that it’s ice. There had been some question whether the bright material was salt. Salt can’t do that.”
The mission was designed to investigate whether the arctic plains environment could have been habitable to microscopic life.
Researchers knew there was abundant water ice at the polar caps, and there is strong evidence for water ice below the surface away from the poles, based on satellite observations.
“What this tells us is we found what we’re looking for,” said Mark Lemmon, a Phoenix co-investigator from Texas A&M University in College Station. “This tells us that we’ve got water ice within reach of the [robotic] arms, which means that we can continue the investigation.”
Phoenix made another potentially exciting discovery June 19.
While digging in a different trench, called “Snow White 2,” Phoenix’s Robotic Arm connected with a hard surface that also may turn out to be an icy layer.
Bruce Jankosky, a geologist at the University of Colorado, Boulder, who has been involved with past missions to the red planet, called the discovery a “significant result” that allows the Phoenix mission to go forward with its wet chemistry experiments, analyzing the soil for the history and composition of the ice.
The next questions to answer are what chemicals, minerals and organic compounds might be mixed in with the water.
“Just the fact that there’s ice there doesn’t tell you if it’s habitable,” Smith said. “With ice and no food it’s not a habitable zone. … we have to have carbon chain materials that we ingest into our bodies to create new cells and give us energy. That’s what we eat and that’s what has to be there if you’re going to have a habitable zone on Mars.”
Mission scientists plan to put samples of ice into Phoenix’s oven instrument, the Thermal and Evolved-Gas Analyzer
, which is designed to bake
martian dirt and analyze the vapors it emits to detect its composition. They also plan to use the onboard Microscopy, Electrochemistry and Conductivity Analyzer
instrument, a wet chemistry lab that measures levels of acidity, minerals and conductivity in dirt samples.
Prior to the discovery, Phoenix had suffered a few glitches, including recent memory loss. While these issues may give the mission the appearance of a rocky start, they are par for the course, mission managers said. In fact, Phoenix
already has been successful enough to merit a one-month extension to its planned 90-day mission, they said.
Barry Goldstein, Phoenix project manager at NASA’s Jet Propulsion Laboratory
in Pasadena, Calif., said the spacecraft’s troubles were the type of issues that could be expected for the complex $420 million
mission.
“We knew it was going to be difficult to operate on the surface of Mars, so we designed the mission such that we could guarantee that we’d meet our full mission success even if we lost one out of every three days on the surface,” Goldstein said
. “We’re now on sol [m
artian day] 24 and we’ve lost one. So by that metric we’re way ahead of schedule.”
Phoenix successfully landed in the flat Vastitas Borealis region of the martian arctic
May 25 and subsequently deployed its robotic arm to begin scratching for frozen water ice beneath the dirt-covered surface.
But the probe lost some science data last
week when its memory got clogged with housekeeping information regarding its computer functions. Engineers traced the problem to a pair of software bugs that caused the spacecraft’s file-saving algorithm to run on an endless loop
that created heaps of data – about 45,000 data packets when they normally expect only a few.
The glitch caused Phoenix to overwrite some science observations it had gathered the day before, though all this data was low priority and can be collected again. The issue also prevented mission managers from uploading Phoenix’s science commands June 18
, the 23rd sol of the mission.
“We feel we have taken all the necessary steps to mitigate the problem. We won’t have any overwritten science data anymore based on the corrective action we’ve taken,
” Goldstein said.
Jeremy Hsu contributed to this article from New York.