Spacecraft Has Traveled More Than 50 Million Miles So Far
Two crucial tools for a successful landing of America's latest
mission to Mars, the radar and UHF radio on the National
Aeronautics and Space Administration's Phoenix Mars Lander, have
passed in-flight checkouts.
NASA said this week the ultra-high-frequency radio won't be
turned on again until landing day, May 25, 2008, when it will relay
communications from Phoenix to orbiters already in service around
Mars. Since launch on August 4, 2007, and until the day it reaches
Mars, Phoenix is communicating directly with Earth via even higher
frequency X-band radio, mounted on a part of the spacecraft that
will be jettisoned shortly before Phoenix hits the top of the
Martian atmosphere.
The radar will monitor the spacecraft's fast-shrinking distance
to the ground during the final three minutes before touchdown on
Mars, triggering descent-engine firings and other necessary events
during the most challenging moments of the mission.
The Phoenix flight operations team tested the radar and UHF
radio on Aug. 24. Four days earlier, the team ran the first
in-flight checkout of a Phoenix science instrument. This test
focused on the Thermal and Evolved-Gas Analyzer, which will check
for water, carbon-containing molecules and other chemicals of
interest in the icy soil of Mars. The checkout verified the health
of an ion pump, which will be used during the transit to Mars to
remove most water vapor carried from Earth with the instrument.
Four additional science instruments are scheduled for checkouts
before the spacecraft's next trajectory correction maneuver,
planned for Oct. 16, according to the space agency.
As of September 1, Phoenix will have covered 50 million miles
422-million-mile flight to Mars. It is traveling at 76,000 mph in
relation to the sun. Meanwhile, careful preparations continue for
the white-knuckle minutes before landing and the potential
scientific discoveries at the landing site.
"Everything is going as planned. No surprises, but this is one
of those times when boring is good," said Barry Goldstein, Phoenix
project manager at NASA's Jet Propulsion Laboratory, Pasadena,
CA.
Phoenix will fly to a site farther north than any previous Mars
landing. The solar-powered lander will dig into underground ice and
will run laboratory tests assessing whether the site could have
ever been hospitable to microbial life. The instruments will also
look for clues about the history of the water in the ice. They will
monitor arctic weather as northern Mars' summer progresses toward
fall, until solar energy fades and the mission ends.