NASA's next
mission to Moon will not merely orbit the gray satellite, but crash two
vehicles into its South Pole to hunt for water ice, the space agency said
Monday.
In addition
to mapping the Moon to support future astronaut
missions, NASA's Lunar
Reconnaissance Orbiter (LRO) spaceflight will also aim a spent fuel
stage and impactor probe at a southern crater rich in hydrogen and, possibly,
ice.
"I think
aggressively touching the Moon is an understatement," said Scott Horowitz,
NASA's associate administrator for the Exploration Systems Mission Directorate,
in a Monday press conference. "What this mission buys is an early attempt to
know what some of the resources we're going to have...we know for sure that for
human exploration to succeed we're going to have to essentially live
off the land."
Astronomers
know that hydrogen exists in some form on the permanently-shadowed crater
floors along the Moon's polar regions from past lunar
orbiters. The Pentagon's Clementine spacecraft hinted at water ice in a
crater called Shackleton in 1994, while NASA's Lunar Prospector unmistakable
signs of hydrogen on the Moon's surface.
NASA hopes
its LRO and crash missions will provide solid answers on the presence water ice
on the Moon, and whether it exists in forms that may prove useful for future
astronauts. Under the space agency's exploration vision, a four-astronaut Moon
mission is slated for no
later than 2020.
Lunar
smash-up
Set to
launch with LRO in October 2008, the $73 million Lunar Crater Observation and
Sensing Satellite (LCROSS) is a bare-bones spacecraft designed to use cameras
and spectrometers to watch its 4,409-pound (2,000-kilogram) upper stage slam
into hydrogen-rich Shackleton
Crater, mission managers said.
"It's got
the mass of an SUV and we'll send it into the South Pole of the Moon," LCROSS
project manager Daniel Andrews, of NASA's Ames Research Center, said of the
upper stage. "We will create a substantial plume [and] excavate some sample
material, some of which we think will be water ice."
The
1,940-pound (880-kilogram) LCROSS probe will fly through the resulting plume
and use its instruments to scan for water while taking photographs, then - 15
minutes after the upper stage booster's impact - the "shepherding" satellite
will also crash into the crater floor, Andrews said.
"We know that
we can steer it sufficiently to sample another region of the crater," Andrews
said, adding that smashing into the same place twice would likely not yield
additional valuable data.
A network
of ground-based observatories will observe the impact and plume from Earth
while LRO, India's Chandrayaan-1
lunar orbiter and other spacecraft examine the Moon crash from their
respective locations, LCROSS mission managers said.
Impact
science
Slamming
water-sniffing probes into objects is no strange feat for NASA.
The space
agency crashed
its Impactor probe into the comet Tempel 1
on July 4, 2005 while its parent Flyby craft and other space and ground-based
observers looked on during the Deep
Impact mission. NASA's Lunar Prospector orbiter also crashed
into the Moon in July 1999, also in the hope of stirring up water ice, though
researchers believe it may have hit at too shallow an angle to do much science.
"The models
show that it kicked up a lot of material but mostly skidded on the surface,"
said Butler Hine, NASA's Robotic Lunar Exploration Program manager, of the
earlier Moon crash.
Europe's SMART-1
orbiter - currently circling the Moon - is also expected to crash into
the lunar surface later this year.
But LCROSS
mission managers expect their crash-destined duo to carve a Moon crater 16 feet
(4.8 meters) deep, about 100 feet (30 meters) wide and toss up about
2.2-million pounds (1,000 metric tons) of lunar material.
That's
enough lunar material to fill 10 space shuttle payload bays to the brim,
Andrews said, adding that the plume could reach up to 40 miles (64 kilometers)
above the lunar surface.
Lunar
piggyback ride
The LCROSS
mission is a late
add-on to NASA's LRO mission.
Horowitz said
the secondary payload became possible when NASA decided to switch to a larger
rocket booster to allow extra safety and design margin for LRO.
LCROSS was
chosen after a brief competition among 19 contenders, each of which were
restrained by a 2,204-pounds (1,000-kilogram) spacecraft weight cap and a cost
of no more than $80 million.
NASA
finally chose LCROSS out of four finalists, which included a similar Moon
impact proposal that did not make use of the rocket's upper stage, an orbital
microsatellite and a small, hopping lunar lander, Horowitz said.
The key to
LCROSS lies in its Moon crashing fate. Unlike LRO, which is expected to
generate extremely detailed maps, the LCROSS effort will actually bite into the
lunar surface at a speed of 5,592 miles per hour (or about 2.5 kilometers per
second).
"You never
quite know what's there for sure until you touch it," said Hine of the Moon's
surface. "And once we get the answer to that, it will help us plan out
future human missions."
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