Three robotic
paparazzi orbiting the planet Mars are adjusting their flight paths to track an
incoming NASA probe due to land on the red planet in late May.
The plan
marks the first time that three orbiters will follow a landing on Mars and is
expected to return an unprecedented level of coverage throughout the entry,
descent, and landing of NASA's Phoenix Mars Lander on May 25.
"We
will have diagnostic information from the top of the atmosphere to the ground
that will give us insight into the landing sequence," said David Spencer,
deputy project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Such information would help deal with landing problems, and lead to
improved designs for future landers.
Launched
on Aug. 4, 2007, Phoenix is aiming for a site farther north than any
previous mission to Mars. There, the lander will use its robotic arm to sample
the surface for soil and ice, as well as scan for conditions that could support
microbial life.
The three
orbiters - NASA's Mars Odyssey, Mars Reconnaissance Orbiter (MRO) and Europe's
Mars Express - are maneuvering to be in the right place at the right time when
Phoenix enters the Martian atmosphere at more than 12,750 miles per hour
(20,519 kph).
"We
have been precisely managing the trajectory to position Odyssey overhead when Phoenix
arrives, to ensure we are ready for communications," said Bob Mase, the
mission's manager at JPL. "Without those adjustments, we would be almost
exactly on the opposite side of the planet when Phoenix arrives."
NASA's MRO
spacecraft will make bigger adjustments, with one firing of thrusters on Feb. 6
and at least one more course correction planned in April. The European Space
Agency's Mars Express orbiter, meanwhile, has also positioned itself to record
transmissions from Phoenix during the landing.
Even NASA
rovers Spirit and Opportunity, currently exploring the martian surface, have helped
out by simulating transmissions from Phoenix to rehearse the orbiters'
operations for the big day.
On that
day, Odyssey will turn its robotic eyes from the heavens to point an ultrahigh-
frequency antenna towards the descending Phoenix. A high-gain antenna will
stream information back to Earth as Odyssey watches Phoenix slow itself through
heat-shield friction, a parachute, and then firing descent rockets. That allows
the lander to hit the Martian surface on three legs at just 5.4 miles per hour
(2.4 m/s).
MRO and
Mars Express will start recording Phoenix transmissions
as backup data "about 10 minutes before landing," according to Ben
Jai, mission manager at JPL for MRO.
Until then,
all three orbiters are scoping out Mars for a suitable landing site.
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