As the sun dips
lower in the Martian sky with each passing day, NASA's solar-powered Phoenix Mars Lander
took time this week to send a postcard of sorts to scientists on Earth after
more than three months studying the red planet.
Phoenix beamed
home a view of its trench-filled worksite after surpassing the 90-day mark of
its initial mission to hunt for water ice buried beneath the barren arctic
plains of Mars. While the Martian days, or sols, are getting colder and the sun
expected to dip completely below the horizon tonight for the first time since Phoenix
landed in late May, the probe itself is in fine health, mission managers said.
"It's doing
fabulously," said Barry Goldstein, NASA's Phoenix project manager at the Jet
Propulsion Laboratory in Pasadena, Calif. "But I've made it clear to the
science team that the warranty's over."
Goldstein
told SPACE.com Thursday that Phoenix scientists are using the spacecraft
to collect as much data as possible through the end of September, when its
mission extension concludes, and have submitted a proposal for a second
extension through mid-November should the probe survive that long. Researchers at the University of Arizona in Tucson are overseeing the mission.
"The
vehicle is not going to tip over and die," Goldstein said. "But we're getting
to the point where we're going to start seeing the creaks and groans."
Phoenix
landed in the northern Vastitas Borealis region of Mars on May 25 and began
a planned three-month mission to search for water ice using a shovel-tipped
robotic arm and a science tool kit that included eight small ovens and a wet
chemistry lab with four beakers, each the size of a teacup. Researchers hoped
that those tools and a Canadian-built weather station would find definitive
proof of local water ice and help determine if the Martian arctic could have
once served as a welcome oasis for primitive life.
Since that
time, Phoenix has successfully scooped, touched and tasted bits of
actual Martian ice even as mission scientists race to collect more
information from the probe's arctic landing site before winter closes in on
Mars.
The days,
Goldstein said, are steadily growing colder.
During
Phoenix's first 50 days on Mars, the lander experienced temperatures that dipped down
to minus 80 degrees Celsius (minus 112 degrees Fahrenheit) at their coldest. Now,
the probe is experiencing temperatures as low as minus 85 degrees C (minus 121 degrees
F) and its going to keep getting colder, Goldstein added.
The amount
of power generated by Phoenix's two solar arrays is also on the decline, with
the probe currently generating about 2,500 watt-hours each day - or about 1,000
watt-hours less than when it landed - because of waning sunlight. The absolute minimum needed for Phoenix to
perform the most basic operations is about 1,000 watt-hours, mission managers
said.
"We're
predicting that's the end of mission," Goldstein said, adding that current
projections put that power benchmark in November.
But for
now, the $420 million Phoenix is
forging ahead to study the Martian arctic, and is expected to use one of its
two remaining wet chemistry lab beakers to study a sample of Mars this
Saturday, Goldstein added. There are also four remaining ovens that stand ready
to bake Martian samples and determine their composition, but it may be a
challenge to fill all of them before the current mission extension ends next
month, he said.
"We're in
that mode now where we're collecting a lot of data," Goldstein said. "Everybody
is so busy trying to make hay as the sun shines, literally and figuratively,
that we haven't had a chance to take a breath to see what the biggest science find
has been."
Goldstein
also worked on NASA's long-lived Mars Exploration Rovers (MER) Spirit and
Opportunity, which have been exploring different parts of the red planet since
January 2004, and said it's a somewhat sad and weird feeling to know that those
older spacecraft will outlive Phoenix.
But while Spirit
and Opportunity, the latter of which began
climbing out of the vast Victoria Crater this week, have returned thousands
of images of Martian days and evenings from the planet's equatorial regions, Phoenix's
views from the planet's arctic circle stand apart.
"We have
those shots from MER of Martian sunsets and sunrises, but its something about
the arctic," Goldstein said. "There's just something about that."
advertisement
