More than 40
years after the last Apollo astronauts left the moon, NASA is preparing
to launch a small robotic spacecraft to investigate one of their most
bizarre discoveries.
Crews reported seeing an odd
glow on the lunar horizon just before sunrise. The phenomenon, which
prompted a notebook sketch by Apollo 17 Commander Eugene Cernan, was
unexpected because the airless moon lacked atmosphere for reflecting
sunlight.
Scientists
began to suspect that dust from the lunar surface was being
electrically charged and somehow lofted off the ground, a theory that
will be tested by the U.S. space agency's upcoming Lunar Atmosphere and
Dust Experiment.
The spacecraft,
known as LADEE, is scheduled to be launched at 11:27 p.m. EDT on Friday
from NASA's Wallops Flight Facility on Wallops Island, Virginia.
"Terrestrial
dust is like talcum powder. On the moon, it's very rough. It's kind of
evil. It follows electric field lines, it works its way in equipment.
... It's a very difficult environment to deal with," said LADEE project
manager Butler Hine of NASA's Ames Research Center in Moffett Field,
California.
In addition to studying
fly-away lunar dust, LADEE will probe the tenuous envelope of gases
that surrounds the moon, a veneer so thin it stretches the meaning of
the word "atmosphere."
Instead,
scientists refer to these environments as exospheres and hope that
understanding the moon's gaseous shell will shed light on similar
pockets around Mercury, asteroids and other airless bodies.
"LADEE
is part of a much broader scientific exploration of the solar system,"
said John Grunsfeld, NASA's associate administrator for science.
The
$280 million mission also includes an experimental laser optical
communications system that NASA hopes to incorporate into future
planetary probes, including a Mars rover scheduled for launch in 2020.
The
prototype is based on technology used in terrestrial fiber-optic
communications systems, such as Verizon's FiOS. NASA says the system
should be at least six times faster than conventional radio
communications. Also, its transmitters and receivers weigh half as much
as similar radio communications equipment and use 25 percent less power.
"On
the Earth, we've been using laser communication and fiber optics to
power our Internet and everything else for the last couple of decades,"
Grunsfeld said. "NASA has really been wanting to make that same
technological leap and put it into space. This is our chance to do
that."
LADEE's optical
communications system, which includes three ground stations in addition
to LADEE, will be tested before the probe drops into a low lunar orbit
to begin its science mission about 60 days after launch.
Just
getting to the moon will take LADEE 30 days - 10 times longer than the
Apollo missions due to the probe's relatively low-powered Minotaur 5
launcher.
The rocket is comprised
of three refurbished intercontinental ballistic missile motors and two
commercially provided boosters. The Minotaur 5 configuration will be
flying for the first time with LADEE.
The
use of decommissioned missile components drove the decision to fly from
NASA's Wallops Island facility, one of only a few launch sites
permitted to fly refurbished ICBMs under U.S.-Russian arms control
agreements.
REUTERS