This story was updated at 2:23 p.m. EDT.
A NASA probe that slammed into the moon's south pole Friday
managed to spot the artificial crater carved into the pristine lunar terrain
minutes earlier by its partner craft, but scientists have not yet confirmed if
the two crashes kicked up a giant plume containing any signs of water ice a
main goal.
NASA's LCROSS
spacecraft slammed a 2.2-ton empty rocket stage the equivalent of a sport
utility vehicle into a crater called Cabeus at 7:31 a.m. EDT (1131 GMT) and
recorded the resulting explosion just before making its own
death dive and crater four minutes later.
But in those four crucial minutes, the five cameras and four
other instruments on the LCROSS shepherding spacecraft recorded
the flash of the rocket stage's impact and a telltale sign of the leftover
crater. What remains to be seen is whether the crashes created the vast plume
of moon dirt that scientists predicted would blast out of the crater up to
heights of 6.2 miles (10 km), where it could be lit up by the sun and visible
to observers on Earth.
"We saw a crater. We saw a flash," NASA's
principal investigator Tony Colaprete told reporters after the $79 million
lunar impacts. "So something had to happen in between."
Colaprete said he's thrilled, rather than disappointed like
some observers not with the mission team, and had some thoughts on the
missing plume.
The plume may have ejected out on an unexpected angle or not
risen high enough to be spotted by spacecraft and observers on Earth, Colaprete
said, adding that researchers will know more after an in-depth look at the
data. The crater left by the Centaur upper stage is about the same size as
scientists predicted around 66 feet (20 meters) wide.
Lunar smackdown
Colaprete and other LCROSS researchers repeatedly warned
that the LCROSS impacts would be difficult to spot from Earth. On Thursday,
they described it as seeing "blackness get less black" as the plume
exploded outward.
"I'm not convinced it's not in our data yet,"
Colaprete said. "We've got to go look."
Scientists hoped to be able to scan that portion of the
plume from space and Earth to determine if any water ice was present in the
debris cloud. Finding proof of buried water ice long suggested by the
presence of hydrogen-bearing material at the lunar south pole could be a boon
for NASA since it could be a potential resource for future astronauts.
Last month, scientists announced definitive proof that small
amounts of water exist elsewhere on the moon in a molecular form attached
to lunar dirt. NASA launched LCROSS short for Lunar Crater Observation and
Sensing Satellite in June along with a powerful orbiter to seek out evidence
of water and ice on the moon.
"The moon we thought we knew is not the moon we know
now," NASA's chief lunar scientist Mike Wargo told SPACE.com after the
LCROSS crashes. "The results that we'll
get from LCROSS are an important piece in the puzzle of something that is
pretty darn new, the hydration cycle on the moon."
And there are already some other intriguing details puzzling
LCROSS scientists.
While no obvious sign of a debris cloud have been confirmed,
spectra measurements taken in non-visible wavelengths of light indicate a
signal that suggests an ejecta cloud occurred, Colaprete said. More time is
needed to analyze the spectra findings, he added.
During the four minutes between the Centaur crash and the
shepherding spacecraft's impact, there was also a strong sodium signal, hinting
at some interaction between the impact and the moon's tenuous exosphere of
surface material.
"I've got to say that I was blown away by how long this
little spacecraft lasted," Colaprete added.
The view from Earth
About 21 professional observatories and a host of amateur
skywatchers stretching across the western United States, Hawaii and some
overseas sites had fair weather to spot the cloud, but have not yet
reported a visible confirmation of the plume.
"We're just looking at the very preliminary images to get
a sense of the types of data that have been collected," said Jennifer
Heldmann, head of the LCROSS observation campaign. "But it's too early to
tell, to make that determination."
Some observatories have already released their early images
of the LCROSS lunar crash. Others recorded videos of the Centaur rocket stage
and the target crater Cabeus, a 68-mile (98-km) crater partly covered by a
permanent shadow because of its location at the lunar south pole.
The Hubble Space Telescope and other satellites and
spacecraft, including NASA's Lunar Reconnaissance Orbiter that launched with
LCROSS and is currently circling the moon, are also tracking the aftermath of
the lunar crashes.
Heldmann said that right now, NASA is awash in data from the
moon crashes, especially since all the sites reported pristine viewing
conditions.
"We have images. We have video. We have graphs with
wavy lines that scientists love," Heldmann said. "We have something
for everyone."
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