Luna 24 was launched on August 9th, 1976 and landed on the lunar
surface in the Mare Crisium (Sea of Crisis)
on August 18th. The probe collected 170.1 grams of lunar samples and
returned to Earth on August 22nd.
Clementine
Clementine, a joint project of the Strategic Defense
Initiative Organization and NASA, was designed to test a variety of sensors by
mapping the surface of the Moon. The probe was launched on January 25th, 1995 and, after two flybys
of the Moon, entered lunar orbit on February 21st. Over two months,
Clementine took images of the lunar surface in a variety of wavelengths,
including ultraviolet, infrared, and visual light. It also conducted laser
ranging altimetry, and charged particle measurements to ascertain the surface
mineralogy of the Moon. In May, Clementine blasted out of lunar orbit for an
attempted flyby of the asteroid Geographos, but a software fault caused the
probe’s engines to expend all of its fuel, making the maneuver impossible.
One of the great discoveries of Clementine was of
indications of frozen water ice in the permanently shadowed lunar north and
south poles. If this discovery is confirmed, it will have profound implications
for future lunar settlers.
Lunar Prospector
Lunar Prospector was one of the first probes to be operated
under NASA’s “faster, better, cheaper” policy and was a follow up to
Clementine. In was launched on January
7th, 1998 and entered lunar orbit on January 13th.
Its orbit was lowered to a 100 kilometer polar orbit on January 16th.
After conducting data collection from this orbit for nearly a year, the probes
orbit was lowered to a 15 by 45 kilometer orbit for higher resolution studies.
In July, 1999, Lunar Prospector was deliberately crashed into a permanently
shadowed crater at the lunar south pole in hopes of creating a plume of water
vapor. None was detected however.
Nevertheless, Lunar Prospector’s instruments showed an
unusual concentration of hydrogen at the lunar poles, indicating water ice. The
instruments also showed concentrations of iron, titanium, and rocks rich in
potassium, rare earth elements and phosphorus. There were also indications of
thorium and uranium.