Two crucial tools for a successful landing of America's latest mission to Mars, the radar and UHF radio on NASA's Phoenix Mars Lander, have passed in-flight checkouts.
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 Aug. 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.
單字
1. crucial
Extremely significant or important
2. checkout
An investigation; an inspection
3. mount
To place oneself upon
4. jettison
To discard (something) as unwanted or burdensome
5. descent
A way down
6. trajectory
The path of a projectile or other moving body through space
7. maneuver
A controlled change in movement or direction of a moving vehicle or vessel, as in the flight path of an aircraft
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