A NASA spacecraft
wielding a trench-digging robotic arm is poised for a Saturday launch towards the
north pole of Mars to find out whether the icy region sports an environment
suitable for microbial life.
The
three-legged Phoenix
Mars Lander is set to launch at 5:26:34 a.m. EDT (0926:34 GMT) atop a Delta
2 rocket from the Cape Canaveral Air Force Station in Cape Canaveral, Florida. It's
destination: the arctic martian
plains of Vastitas Borealis.
"Is this a
habitable zone? This is really a major question for us," said Peter Smith, the
Phoenix mission's principal investigator at the University of Arizona, during a
Thursday briefing. "One that we hope to answer."
Icy
quarry
Observations
from spacecraft orbiting Mars have shown Phoenix's planned landing site to be rich in subsurface ice, a
tantalizing target for researchers tracking the history and role of
water on the red planet. Phoenix is designed to use its robotic arm-mounted
scoop to dig into and collect samples of Mars' surface, then scan them with a
host of onboard instruments.
But reaching
Mars has historically been tough, particularly since the planet is rather unforgiving
to small errors. More than half of all the missions sent to Mars have ended in
failure.
NASA's ill-fated Mars
Polar Lander, for example, suffered an apparent early shutdown of its
descent rocket engines in 1999, likely sending the craft plummeting to its
destruction on the martian surface. Phoenix carries many of the same instruments
as its polar-bound predecessor in an effort to recoup some of that lost
science.
"It's
challenging, no doubt. Anytime you try to land on Mars, it's a challenge," said
Doug McCuistion, director of NASA's Mars Exploration program. "But the payoff
is worth the risk."
The $420
million Phoenix mission is expected to land on Mars on May 25, 2008 for an
initial 90-Martian day expedition. NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, California will manage the expedition.
If successful,
Phoenix's Mars landing next year will be the first soft touchdown since NASA's
Viking missions in the 1970s, mission managers said.
Sampling Mars
Built by
Lockheed Martin, the 772-pound (350-kilogram) Phoenix lander is NASA's
first Mars Scout Program mission to explore the red planet with small,
relatively low-cost robots.
"We're
there to study the air, the dirt and the ice in this northern polar region," said
Leslie Tamppari, NASA's Phoenix project scientist at JPL, of the probe's
mission.
Much of the
spacecraft and its seven instrument suites draw on equipment built for NASA's
canceled Mars Surveyor 2001 Lander and the lost Mars Polar Lander.
"Phoenix
had an inherent advantage in that it had a lot of inherited hardware," said Ed
Sedivy, Phoenix Spacecraft Program for Lockheed Martin, adding that the probe
has undergone a barrage of tests to ensure it will work properly. "It really
gave us a leg up in driving the risk down."
Folded away
aboard Phoenix is its eight-foot (2.4-meter) robotic arm, which carries a
camera and instruments to study martian soil, as well as a spiked scoop strong
enough to bite into ice as hard as concrete.
Lining the
probe's top, or deck, are more cameras, a wet chemistry laboratory, eight miniature
ovens and other tools to determine the chemical makeup of Mars' ice and soil
with a special focus on the presence of organic compounds. Such complex compounds
and liquid water are thought to be among the requirements needed to support
primitive life, Phoenix researchers said.
Each tiny
oven can only be used once and will cook just a pinch of martian soil -- about 30
microliters -- and then analyze the leftovers.
"When the
oven is heated...it gives off vapor just like cookie dough in your kitchen," said
the oven instrument's lead scientist William Boyton, of the University of
Arizona. "And we use that to see what's going on."
Red
planet weather station
Phoenix is
also equipped to serve as the first polar weather station on Mars.
The lander's
four-foot (1.2-meter) meteorology mast gives the probe a total height of just
over seven feet (2.2 meters) and carries a series of heat sensors to measure
atmospheric temperature at different heights. A small cylinder tethered to the
top of the mast will indicate wind direction, Phoenix researchers said.
A laser
detection and ranging (lidar) tool will beam light into the martian sky, then
measure the amount reflected back to track atmospheric particles and clouds.
"I'm
excited about finding Earth-like clouds at Mars," Deborah Bass, NASA's deputy
Phoenix project scientist at JPL, told reporters Wednesday.
While Mars
researchers are targeting a 90-Martian day mission for Phoenix, they don't
expect the lander to last as long as NASA's hardy
rovers Spirit and Opportunity, which are currently hunkered down to weather
a massive dust storm in their fourth year of an initial three-month mission.
"Once
winter approaches, we will be immersed in solid carbon dioxide ice," Smith
said. "It will certainly not survive that kind of winter."
NASA
will broadcast the Phoenix Mars Lander's launch live on NASA TV beginning at
about 3:30 a.m. EDT (0730 GMT).
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