Destiny Awaken

MOUNTAIN VIEW, Calif. — Scientists who slammed a bus-size projectile into the Moon on Friday, hitting exactly the spot they were aiming for, say it will take weeks to figure out what they did, and did not, see.

More than 230,000 miles from Earth, the Lunar Crater Observation and Sensing Satellite hit a bull’s-eye — two, actually — on the Moon. But the initial images at least, both from the spacecraft and telescopes on Earth, failed to capture expected plumes of debris rising out of the impacts.

At 4:31 a.m. Pacific time (7:31 a.m. Eastern time), one piece of Lcross slammed into the bottom of a crater, excavating hundreds of tons of the Moon. Trailing four minutes behind, a second piece sent its observations back to Earth before it also slammed into the same crater.

The absence of a visible plume disappointed the hundreds of enthusiasts who braved a chilly evening outside at the NASA Ames Research Center here, which operated the spacecraft, to watch the live images transmitted from the spacecraft.

But Anthony Colaprete, the mission’s principal investigator, was ecstatic. “We got the data we need to address the questions,” he said at a news conference.

Of greatest interest is whether there is water ice hidden in the crater’s perpetual darkness and frigidness. The data could play into the debate over where NASA’s human spaceflight program should aim next, whether to return to the Moon or head elsewhere in the solar system neighborhood. The presence of large significant amounts of water could make it easier to set up future settlements with the ice providing water and oxygen.

Data from NASA’s Lunar Reconnaissance Orbiter has already confirmed the presence of hydrogen deep within permanently shadowed craters near the Moon’s poles, and hydrogen is most likely in the form of water.

Lcross (pronounced L-cross) is a $79 million companion mission to the Lunar Reconnaissance Orbiter, sharing the same rocket into space in June. The mission designers took advantage of what would have otherwise been space junk — the rocket’s two-ton, second stage — and turned it into a projectile to hit the Moon, shepherded by a car-size spacecraft.

While the orbiter entered orbit around the Moon, Lcross swung into a wide polar orbit around the Earth that, by design, would intersect with the Moon’s path four months later at 5,600 miles per hour, or twice the speed of a bullet.

The target of Lcross was Cabeus crater, about 60 miles wide near the south pole.

Dr. Colaprete said the Lcross spacecraft captured a flash of light as the upper stage hit the bottom of Cabeus and then captured a thermal image of the resulting crater, about 60 to 65 feet wide, close to what had been predicted.

What was missing was the plume of debris that was knocked out by the impact. “We saw a crater. We saw a flash,” Dr. Colaprete said. “Something had to happen in between.”

Ground-based telescopes that had been pointed to that crater at the bottom of the Moon also failed to spot the theatrics, at least at first glance of their images.

“As far as I can tell from our quick processing, we did not see any plume,” said William C. Keel, a professor of astronomy at the University of Alabama who was operating a telescope at the Kitt Peak National Observatory in Arizona.

If the expended rocket stage hit a rocky area or a slope, the debris may not have been tossed high enough to reach sunlight and thus not have been seen.

But Lcross’s spectrometers — instruments that break down light into wavelengths and detect subtle changes, perhaps from vapor or fine particles not visible to the eye — did observe changes before and after the impact. Dr. Colaprete said the spectrometer data could identify the water and other molecules. “When I saw actually the spectra, I was like, “We got something,’ ” he said.

The analysis will take at least a few days and maybe weeks.

“We’re going to take our time” Dr. Colaprete said, “and build up a case for water and the ejecta, if it’s there or the case against it if it’s not there.”

While Lcross itself had the best view of the first impact, a host of telescopes in space and on Earth, including the Hubble Space Telescope and the Keck telescope in Hawaii, were also gazing at the Moon. The other telescopes also tried to observe the second impact of the Lcross spacecraft.

Several hundred people spent a chilly night on a grassy lawn at the Ames Research Center. They listened to Charlie Duke, one of the Apollo 16 astronauts, and watched three space-themed films — “Fly Me to the Moon,” “The Dish” and “October Sky” — projected on a 40-foot screen.

Then they watched the same NASA coverage of the mission, streamed over the Internet, that they could have watched at home.

“It’s adventurous and nerdy at the same time,” said Karin Atkins of Sunnyvale, Calif., one of those pulling an outdoors all-nighter.