Phoenix Lander Planned To Blast Off In Early August
NASA's next Mars mission will look beneath a frigid arctic
landscape for conditions favorable to past or present life.
Instead of roving to hills or craters, NASA's Phoenix Mars
Lander will claw down into the icy soil of the Red Planet's
northern plains. The robot will investigate whether frozen water
near the Martian surface might periodically melt enough to sustain
a livable environment for microbes. To accomplish that and other
key goals, Phoenix will carry a set of advanced research tools
never before used on Mars.
First, however, it must launch from Florida during a three-week
period beginning August 3, then survive a risky descent and landing
on Mars next spring.
"Our 'follow the water' strategy for exploring Mars has yielded
a string of dramatic discoveries in recent years about the history
of water on a planet where similarities with Earth were much
greater in the past than they are today," said Doug McCuistion,
director of the Mars Exploration Program at NASA Headquarters,
Washington. "Phoenix will complement our strategic exploration of
Mars by being our first attempt to actually touch and analyze
Martian water -- water in the form of buried ice."
NASA's Mars Odyssey orbiter found evidence in 2002 to support
theories that large areas of Mars, including the arctic plains,
have water ice within an arm's reach of the surface.
"Phoenix has been designed to examine the history of the ice by
measuring how liquid water has modified the chemistry and
mineralogy of the soil," said Peter Smith, the Phoenix principal
investigator at the University of Arizona, Tucson. "In addition,
our instruments can assess whether this polar environment is a
habitable zone for primitive microbes. To complete the scientific
characterization of the site, Phoenix will monitor polar weather
and the interaction of the atmosphere with the surface."
With its flanking solar panels unfurled, the lander is about 5.5
meters (18 feet) wide and 1.5 meters (5 feet) long. A robotic arm
2.3 meters (7.7 feet) long will dig to the icy layer, which is
expected to lie within a few inches of the surface. A camera and
conductivity probe on the arm will examine soil and any ice there.
The arm will lift samples to two instruments on the lander's deck.
One will use heating to check for volatile substances, such as
water and carbon-based chemicals that are essential building blocks
for life. The other will analyze the chemistry of the soil.
A meteorology station, with a laser for assessing water and dust
in the atmosphere, will monitor weather throughout the planned
three-month mission during Martian spring and summer. The robot's
toolkit also includes a mast-mounted stereo camera to survey the
landing site, a descent camera to see the site in broader context
and two microscopes.
For the final stage of landing, Phoenix is equipped with a
pulsed thruster method of deceleration. The system uses an
ultra-lightweight landing system that allows the spacecraft to
carry a heavier scientific payload. Like past Mars missions,
Phoenix uses a heat shield to slow its high-speed entry, followed
by a supersonic parachute that further reduces its speed to about
217 kilometers per hour (135 miles per hour). The lander then
separates from the parachute and fires pulsed descent rocket
engines to slow to about 9 kilometers per hour (5.5 miles per hour)
before landing on its three legs.
"Landing safely on Mars is difficult no matter what method you
use," said Barry Goldstein, the project manager for Phoenix at
NASA's Jet Propulsion Laboratory, Pasadena, CA. "Our team has been
testing the system relentlessly since 2003 to identify and address
whatever vulnerabilities may exist."
Researchers evaluating possible landing sites have used
observations from Mars orbiters to find the safest places where the
mission's goals can be met. The leading candidate site is a broad
valley with few boulders at a latitude equivalent to northern
Alaska.