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At 9:28 p.m. (EST) on January 6, 1998, Lunar Prospector (LP)
blasted off to the Moon aboard a Lockheed Martin solid-fuel, three-stage
rocket called Athena II. It was successfully on its way to the
Moon for a one year, polar obit, primary mission dedicated to
globally mapping lunar resources, gravity, and magnetic fields,
and even outgassing events.About 13 minutes after launch, the
Athena II placed the Lunar Prospector payload into a "parking
orbit" 115 miles above the Earth. Following a 42 minute coast
in the parking orbit, Prospector's Trans Lunar Injection (TLI)
stage successfully completed a 64-second burn, releasing the spacecraft
from Earth orbit and setting it on course to the Moon, a 105-hour
coast. The official mission timeline began when the spacecraft
switched on 56 minutes, 30 seconds after liftoff. Shortly after
turning the vehicle on, mission controllers deployed the spacecraft's
three extendible masts, or booms. Finally, the spacecraft's five
instruments -- the gamma-ray spectrometer, alpha particle spectrometer,
neutron spectrometer, magnetometer and electron reflectometer
-- were turned on. On Sun., January 11, at 7:20 a.m. (EST), Lunar
Prospector was successfully captured into lunar orbit, and a few
days later began its mission to globally map the Moon.
Lunar Prospector is a small* spin-stabilized spacecraft in a
polar orbit with a period of 118 minutes at an altitude of 100
km (63 miles). Since the Moon rotates a full turn beneath the
spacecraft every lunar cycle (~27.3 days) as it zips around the
Moon every 2 hours, Prospector visits a polar region every hour
and completely covers the lunar surface twice a month. Prospector's
one year long primary mission with an optional extended mission
of a further 6 months at an even lower altitude enables large
amounts of data to collect over time. For some science instruments,
a significant amount of time is required to obtain high quality
usable data. Thus, Prospector's polar orbit and long mission time
render it ideal from the standpoint of globally mapping the Moon.
*(1.3m in diameter X 1.4m tall bus with three 2.5 meter science
masts carrying its five science instruments and isolating them
form the spacecraft's electronics)
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