This story was updated at 6:52 p.m. EDT.
The moon is
due for a double whammy from two NASA probes Friday, with scientists assuring
some skeptics that smacking the lunar surface with spacecraft is really okay.
NASA's
LCROSS mission will slam
a spacecraft and an empty rocket stage into the moon's south pole Friday
morning at 7:31 a.m. EDT (1131 GMT) in a search for water ice buried in the
perpetual shadows of lunar craters.
Scientists
are eagerly awaiting the LCROSS crashes and hope they'll provide a definitive
answer on whether lunar water ice could be used to support future astronauts on
the moon. But at least one person novelist and screenwriter Amy Ephron has
spoken out against the $79 million mission on her Huffington Post blog and
launched a Twitter campaign ("helpsavethemoon") to save the moon from future onslaught.
"I'm not a
big fan of explosions, anyway. In Iraq or Afghanistan or the South Pole of the
Moon. But who does have a territorial prerogative there?" Ephron wrote. "Who
has jurisdiction? Who has the right to say that it's okay to blow up a crater
on the moon?"
Apparently, Mother Nature does. The moon is covered in craters, with new ones
like those to be created by the LCROSS probes popping up all the time by meteorites
that pummel
the lunar surface.
"The image
of this impact, what we're doing with the moon, is something that occurs
naturally four times a month on the moon, whether we're there or not," LCROSS
principal investigator Tony Colaprete told reporters Thursday.
The
difference with LCROSS is that it is specifically targeted at a certain spot, a
crater called Cabeus known to have vast stores of hydrogen-rich material a
potential sign of water ice hidden in shadowed regions that never see the
light of day. [Click
here to find out how to watch the LCROSS moon crashes in your area.]
It's that
lure of ice that drew the interest of LCROSS scientists. Such a resource could
be a boon for NASA's plan to return astronauts to the moon since it could be
used to support a lunar base.
Some
SPACE.com readers have expressed concerns over the possibility of the moon
crash destroying evidence of the very water ice LCROSS is hoping to uncover.
But mission
scientists say that shouldn't happen. The amount of hydrogen-bearing material
is vast within the Cabeus crater, which is 60 miles (98 km) wide and 2.4 miles
(4 km) deep. The impressions left by LCROSS and its Centaur rocket are expected
to be about 66 feet (20 meters) wide and 13 feet (4 meters) deep. The plume
should rise up about 6.2 miles (10 km) and be illuminated by the sun,
researchers said.
That's not
to say the LCROSS probes won't have any effect on the moon. The laws of
physics, Colaprete said, mean there will be a miniscule perturbation.
"The impact
has about 1 million times less influence on the moon than a passenger's eyelash
falling to the floor of a 747 [jet] during flight," Colaprete said.
That means
the impacts will be little more than a pinprick, if even that, to the moon. But
they will still be substantial blows on a human scale.
When LCROSS
and its Centaur stage hit, they are expected to kick up about 350 tons of moon
dirt. The Centaur stage, which weighs more than 2 tons about as much as a
sport utility vehicle will be first, followed by the smaller LCROSS shepherd
craft four minutes later.
The
shepherd craft will beam images and data of the impact plume to NASA's mission
operations center at the Ames Research Center in Moffett Field, Calif. A host
of Earth-based observatories and amateur astronomers, as well as satellites and
space-based assets like the Hubble Space Telescope, Sweden's Odin satellite and
NASA's powerful Lunar Reconnaissance Orbiter circling the moon, will also scan
the resulting plume for evidence of water.
Scientists
now know for sure that there are some traces of water on the moon. They
announced as much last month citing data from recent spacecraft that revealed the
signal for water across wide swaths of the lunar surface.
Rather than
steal the LCROSS team's thunder, the finding only bolstered the team's spirits
and excitement, Colaprete said.
"The one
thing we've learned about the moon is how much we really don't know about the
moon," he added. "And we are still learning and LCROSS is going to provide us
additional data to further understand it."
SPACE.com
is providing full coverage of the LCROSS moon crash. Click
here for a look at the mission and return to SPACE.com at 6:30 a.m. ET
(1030 GMT) for live crash coverage.
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