A pair of identical probes orbiting the moon
for nearly a year will be sent crashing into the lunar surface on
Monday after completing their scientific mission, NASA said Thursday.
The probes, nicknamed Ebb and Flow, are being prepared for what
NASA called a "controlled descent and impact" on a mountain near the
moon's north pole. NASA set the time of the crash as 2228 Monday GMT.
"It is going to be difficult to say goodbye," said Maria Zuber,
principal investigator of the project known as the Gravity Recovery
and Interior Laboratory (GRAIL).
Zuber said the goal of the 496-million-dollar mission was to
unlock the secrets of the interior of the moon.
The probes - Ebb first, then Flow 20 second later - will hit the
surface of the moon traveling 1.7 kilometres per second, NASA said.
No photos of the impact will be made because the region will be in
shadow at the time.
The two probes, each about the size of a washing machine, began
flying in formation around the moon on January 1. Their prime mission
was to generate a gravity field map that NASA says will provide a
better understanding of how Earth and other rocky planets in the
solar system formed and evolved.
Ebb and Flow were able to detect minute changes in the distance
between them as they flew over lunar mountains, craters and other
topography, according to space.com. Scientists used these
ultra-precise measurements to construct a map of the lunar gravity
field.
The map reveals that the moon's crust is almost completely
pulverized, suggesting the moon was pounded by impacts far more
violently than previously believed, researchers said last week during
the American Geophysical Union in San Francisco, according to
space.com.
