NEW YORK - Some observers hoping for a big blast from NASA's
moon-slam experiment Friday were a bit disappointed.
Though NASA officials say they're thrilled with the impact
of the LCROSS probe into the moon, some scientists and members of the
public were left wondering why there was no obvious debris plume after the
crash.
"I don't know about you, but I didn't see
anything," said Columbia University astronomer Arlin Crotts, who was
watching the impact on NASA TV with a group of scientists and students gathered
at a "viewing party" for the event.
"I wanted an
explosion," a Columbia graduate student said.
Instead the screen showed footage
from the spacecraft as it moved closer and closer to the lunar surface.
Then, suddenly, the screen went white. When footage came back, it showed the
moon seemingly unperturbed.
Some SPACE.com readers also expressed disappointment.
"This was anti-climactic at best - there was absolutely
no visible
clue of any impact," wrote commenter HanShotFirst.
"Maybe they should change the headline from 'KAPOW!' to
'bloop' - I saw no evidence of an impact at all," wrote user gahmuret.
But NASA scientists stressed that just because the
preliminary footage didn't show an obvious debris cloud, that doesn't mean
there wasn't one. The goal of LCROSS's crash was to kick up material from the
lunar surface and analyze the signature for signs
of water or other interesting chemicals present in the moon dirt. NASA predicted
the probes would create a plume of material 6.2 miles (10 km) high.
"I'm not convinced we haven't seen the ejecta,"
said LCROSS principal investigator Tony Colaprete during a post-crash press
conference. "I want to go back to those images and look at them carefully.
You just never know how these things are going to go."
Colaprete explained that the footage broadcast on television
wasn't as high resolution as the direct data available from the orbiting Lunar
Reconnaissance Orbiter (LRO), which launched in June alongside the the LCROSS
shepherd spacecraft and its separate impactor probe. Plus, he added, the main
data scientists are interested in are not the visual images, but the spectra,
which are taken with an instrument that separates light into its constituent
wavelengths.
"I saw variations in the spectra," Colaprete said.
"I'm thrilled, that's a very good sign. The spectra is where the science
is."
NASA officials said they were elated by the results so far.
"It's been an exciting period," said NASA
administrator Charlie Bolden, who called LCROSS "the third big event"
to occur since he took on NASA's top post in July. The first two momentous
occasions were the Apollo 11 40th anniversary and the recent rejuvenation of
the Hubble Space Telescope.
The LCROSS mission was recently dedicated to the late journalist
Walter Cronkite, who reported on many great events in space history, including
the first U.S. moon landing. Cronkite's son Chip was on hand with reporters and
NASA officials watching the LCROSS impact at Washington, D.C.'s Newseum Friday
morning.
Cronkite called the event "fantastic" and said he hoped
the results reveal water ice on the moon. He said his father "would loved
to have been able to cover all these next missions," including possible
future human trips to the moon.
SPACE.com senior writer Andrea Thompson contributed to
this report from Washington, D.C.
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