From time to time, the Moon (or a portion of it) enters the Earth's shadow
in what is known as a
.The Moon is dimmed partially
or almost completely, depending on whether it passes through the less
dark part of the Earth's shadow, the
, or the darker part,
The Lunar Prospector relied on sunlight to recharge its batteries. Scientists
were concerned that whenever the Lunar Prospector was in the darkness
of the Earth's shadow, its batteries could have drained to the point where
they could not be recharged.
Prospector survived penumbral lunar eclipses on September 6, 1998, and
January 31, 1999, without damage. It also survived a much darker umbral
eclipse the following July.
In a video interview conducted just before the eclipse of September 6,
1998, Dr. Alan Binder, Principal Scientist for the Lunar Prospector, discusses
steps scientists took to protect the spacecraft.