Clementine:
Nation: U.S. (66)
Objective(s): lunar orbit
Spacecraft: Clementine
Spacecraft Mass: 424 kg
Mission Design and Management: BMDO and
NASA
Launch Vehicle: Titan IIG (no. 23G-11)
Launch Date and Time: 25 January 1994 /
16:34 UT
Launch Site: WSMC / SLC-4W
Scientific Instruments:
1) ultraviolet/visible camera
2) near-infrared camera
3) long-wave infrared camera
4) high-resolution camera
5) two star tracker cameras
6) laser altimeter
7) bistatic radar experiment
8) gravity experiment
9) charged-particle telescope
Results: Clementine was the first U.S. spacecraft
launched to the Moon in over twenty
years (since Explorer 49 in June 1973).
The
spacecraft, also known as the Deep Space
Program Science Experiment (DSPSE), was
designed and built to demonstrate a set of
lightweight technologies such as small imaging
sensors for future low-cost missions
flown by the Department of Defense.
Clementine carried fifteen advanced flight-test
components and ten science instruments.
After
launch, the spacecraft remained in a temporary
orbit until 3 February 1994, at which time
a solid-propellant rocket ignited to send the
vehicle to the Moon. After two subsequent
Earth flybys on 5 February and 15 February,
Clementine successfully entered an elliptical
polar orbit on 19 February with a period of 5
days and a perilune of 400 kilometers.
In the
following two months, it transmitted about 1.6
million digital images of the lunar surface; in
the process, it provided scientists with their
first look at the total lunar landscape,
including polar regions.
After completing its
mission goals over 297 orbits around lunar
orbit, controllers fired Clementine's thrusters
on 3 May to inject it on a rendezvous trajectory
in August 1994 with the asteroid 1620
Geographos. Due to a computer problem at
14:39 UT on 7 May that caused a thruster to
fire and use up all propellant, the spacecraft
was put into an uncontrollable tumble at about
80 rpm with no spin control. Controllers were
forced to cancel the asteroid flyby and return
the vehicle to the vicinity of Earth. A power
supply problem on 20 July further diminished
the operating capacity of the vehicle.
Eventually, lunar gravity took control of
Clementine and propelled it into heliocentric
orbit. The mission was terminated in June
1994 when falling power supply levels no
longer allowed clear telemetry exchange. On 3 December 1996, DoD announced that
Clementine data indicated that there was ice
in the bottom of a permanently shadowed
crater on the lunar south pole.
Scientists
estimated the deposit to be approximately
60,000 to 120,000 cubic meters in volumeýýý
comparable to a small lake that is 4 football
fields in surface area and 5 meters deep. This
estimate was very uncertain, however, due to
the nature of the data.
Editor's Note: This mission profile was originally published in Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, by Asif A. Siddiqi, NASA Monographs in Aerospace History No. 24.
