'Mars dust resembles seawater'
2008-10-01 08:32
Washington - Nasa extended the mission
of the busy Phoenix lander on Monday, saying it will operate
until it dies in the cold, dark Martian winter.
The lander found evidence that the chemical makeup of the
dust on the surface of Mars resembles that of sea water, adding
to evidence that liquid water that once may have supported life
flowed on the planet's surface.
The Phoenix lander already has operated far longer than
expected when it was dropped onto the Martian surface in May,
and its controllers said they would squeeze every drop of life
they could out of the solar-powered lander.
"We are literally trying to make hay as the sun shines,"
Barry Goldstein, Phoenix project manager at the Jet Propulsion
Laboratory in Pasadena, California, told reporters.
Scheduled to last just 90 Martian days, known as sols, the
lander has already operated for more than 120.
But the sun will soon dip below the horizon until April.
Already the lander is getting less power, after a summer of
light-filled days akin to the months of daylight at Earth's
poles in the summer.
Perchlorate
In July, the Phoenix team reported definitive proof of
water after the lander scraped up ice.
It also found
perchlorate, a chemical compound used by plants and microbes
and it has sent back the first image of a speck of red Martian
dust taken through an atomic force microscope.
The latest analysis shows evidence of a carbonate chemical,
likely calcium carbonate, best known as limestone, said William
Boynton, who leads a team operating the lander's Thermal and
Evolved-Gas Analyser at the University of Arizona.
And, said JPL's Michael Hecht, further analysis shows the
Martian dust is about as alkaline as seawater, with a pH of
8.3, more evidence that life could have existed on Mars.
Mars weatherman Jim Whiteway of the University of Toronto
said the lander has seen snow, frost and clouds forming.
"This is now occurring every night," he said - although it is not
yet clear whether any snow reaches the surface.
Habitable zone
Peter Smith, Phoenix principal investigator at the
University of Arizona, said Mars wobbles more than Earth does
as it spins, so sometimes its poles point directly at the Sun.
They would be warmer then, perhaps warm enough to melt ice that
Phoenix has confirmed lies just below the red dust.
"If you were to sweep away this thin soil layer on what
looks like this flat plain you would find it is more like a
skating rink," Smith said.
"Is this a habitable zone on Mars? I think we are
approaching this hypothesis," he added.
Smith said the scientists plan to turn on a microphone that
was supposed to record the lander's descent in May but did not.
"We are going to try and turn on this microphone and try to
listen to Mars for the first time," he said.