LCROSS gathered strong spectroscopic signals, but officials were expecting a dramatic visible ejecta plume from the Centaur impact that was not obviously observed by any sensor. Instruments also detected an unexpected sodium flash in the data.
Ground telescopes also observed suspected spectral data, but saw no apparent sign of a debris cloud.
"We have a tremendous amount of data gathered through observation campaign, both ground-based and space-based," said Jennifer Heldmann, coordinator of the observation campaign.
"That, by itself, may constitute enough information to answer some fundamental questions," Colaprete said.
"That, by itself, may constitute enough information to answer some fundamental questions," Colaprete said.
"There was an impact," Colaprete said. "We saw the impact. We saw the crater."
Meanwhile, the 21-foot MMT Observatory in Arizona is also reporting no obvious detection of an impact ejecta plume.
The Gemini North Observatory and the Keck Telescope on Mauna Kea both used spectroscopy to detect the ejecta plume and potential water vapor expelled by the impacts.
Peter Michaud, public outreach manager at Gemini's 26-foot telescope, said their results are inconclusive so far, but analysis is continuing in the wee hours of the morning in Hawaii.
"It wasn't obvious from anything that I saw there," Michaud said.
Diane Wooden, an LCROSS science team member at Keck, said that facility's giant 33-foot telescope was looking for signs of water vapor emission lines in coordination with Japan's nearby Subaru observatory.
"We're optimistic, but we can't give you any conclusions until we finish analyzing the data," Wooden said.
Wooden said there were some tentative signs of potential detections, but it may be at least Tuesday before more is known.
"We didn't see anything in a quick glance at the images, but it's going to take a while to know for sure if we saw anything," said Nancy Chanover, assistant professor of astronomy at New Mexico State University.
Apache Point's 11.5-foot telescope was collecting visual frames and a 3.3-foot telescope took video at the time of impact, Chanover said.
A Keck spokesperson would not comment on if any ejecta was actually observed, referring to the upcoming press conference in one hour.
"Within this $79 million cost cap, the experiment had been optimized to produce the largest possible impact plume. So I remain confident that this is our best opportunity to date to measure (water) on the moon," Bicay said.
"Alright, all stations, great job," flight director Rusty Hunt just said.
The LCROSS payload will be put in "flash mode" in one minute to begin its fast-paced sequence of observations.
The precise impact point is now in view of cameras on LCROSS.
"We have to live within a very constrained bandwidth, so that limits how much data we can actually get down," said Tony Colaprete, LCROSS principal investigator
"If your goal is to extract water in a resource sense, then you want to go where the water concentration is the highest," said Michael Bicay, director of science at Ames Research Center.
The Centaur is expected to hit the moon at a velocity of 5,600 mph, about twice the speed of a rifle bullet. It will carve a crater 66 feet across and 13 feet deep, kicking up 350 metric tons of lunar dust, potentially including water or other hydrogen-bearing minerals.
All of the video imagery, plus the crucial data from the LCROSS spectrometers, will be sent back to Earth with just a few seconds delay because the shepherding spacecraft itself will be destroyed during its own impact four minutes after Centaur.
"We're looking at, on average, a couple of frames per second on all the cameras," Colaprete said.
LCROSS has a visible camera provided by Ecliptic Enterprises Corp., two near-infrared cameras and two thermal infrared cameras.
"Right at impact, when there's a flash, we turn off our visible camera and we go solely to our near-infrared camera, which is better for detecting the flash because the near-infrared portion of the flash lasts longer," Colaprete said.
A photometer will take 1,000 measurements per second to characterize the brightness of the impact flash.
"We then go a different series where we go back to the visible camera and the near-infrared and thermal cameras to image the ejecta curtain," Colaprete said.
"My expectations are that the near-infrared camera and the thermal cameras are going to be the best for viewing the flash and the ejecta curtain."
"At a minute until shepherding spacecraft impact, so this is three minutes after the Centaur impact, we go into what we call crater phase. And that's where the ejecta has pretty much settled out and its gone, and what we're doing is flying through the vapor cloud."
"The last thing we're doing is looking at the sun with our side-looking spectrometer to measure total water concentration and ice concentration that's left there in the vapor cloud."
"And also using our thermal cameras, we image the crater we made with the Centaur. So we'll actually be able to see, just before we impact ourselves, the crater we made with the Centaur. At least that's what we're hoping. We'll get a few pixels across the crater, which is astonishing to me. It's going to be incredible," Colaprete said.
Scientists switched the LCROSS target crater from Cabeus A to Cabeus proper late last month based on a new analysis of data from Lunar Reconaissance Orbiter and Japan's Kaguya spacecraft.
"We convinced ourselves that Cabeus proper was a better target. There are a couple reasons for that. We've always known that Cabeus has had a lot of hydrogen associated with it. And as the time went on, that association became more and more definitive, more and more clear. The signal just got stronger," said Tony Colaprete, LCROSS principal investigator.
The extreme topography surrounding Cabeus concerned scientists enough to select the adjacent Cabeus A crater when NASA first announced the impact site selection in early September.
"Right on the side that faces Earth, there's a large mountain about 3 or 4 kilometers tall. All in all, we were afraid that being such a deep crater and having this range, we would have trouble getting ejecta to sunlight and actually in view of Earth," Colaprete said.
But the latest round of data calmed those fears.
"We (found) a really serendipitous situation for us. For our particular impact date, tomorrow morning, the sun will be shining in through a cleft, a valley, right along the rim of the crater," Colaprete said.
Ejecta from the Centaur impact will be illuminated by the time it reaches 1 kilometer in altitude. A small saddleback in the mountain blocking the view from Earth will also allow earlier observations.
"With those two factors being resolved, the fact that we can actually get ejecta into sunlight very soon and get the ejecta in view of Earth relatively soon, Cabeus was just that much more attractive," Colaprete said.
Shadows form the backdrop of the crater as viewed from LCROSS and Earth, providing a high contrast background. This maximizes the ability to resolve the dust kicked up by the impact, officials said.
Centaur will hit the moon at 1131:20 GMT (7:31:20 a.m. EDT) at 84.674 south latitude and 311.302 east longitude. The shepherding satellite's impact is set for 1135:36 GMT (7:35:36 a.m. EDT) at 84.731 south latitude and 310.522 east longitude.
NASA has also released very precise impact time forecasts. The Centaur is expected to slam into Cabeus at 1131:19.56937 GMT (7:31:19 a.m. EDT) and the shepherding spacecraft should hit the moon at 1135:38.79007 GMT (7:35:38 a.m. EDT).
The impact coordinates for the Centaur are 84.675 degrees south latitude at 311.275 degrees east longitude. The LCROSS mothership will smash into the moon at 84.729 degrees south latitude and 310.64 degrees east longitude.
Workers are also changing shifts inside the LCROSS control center at Ames Research Center in California. The incoming team of flight controllers will oversee the impact events.
Engineers will generate a revised impact plan overnight based on the latest navigation data available. This update will focus on fine-tuning the hundreds of spacecraft maneuvers planned to keep the science instruments turned toward the Centaur collision flash and the resulting plume of debris, according to Paul Tompkins, an LCROSS flight director.
Other activities over the next few hours will include disabling most of the probe's fault management system and uploading the new impact sequence commands to the spacecraft.
The impact phase begins shortly after 1000 GMT (6 a.m. EDT).
LCROSS will fire thrusters for four minutes, enough to create a separation time of four minutes, or almost 400 miles, at the moment of impact.
The attitude control system will be re-activated with new software parameters shortly after separation. The first task will be to re-orient the probe 180 degrees to point cameras at the departing Centaur, according to Paul Tompkins, LCROSS flight director.
During the three-minute maneuver, the data-handling unit aboard LCROSS will be switched on to collect imagery of the Centaur to be sent back to Earth live.
"During the separation event, we will essentially be inheriting a whole new spacecraft with entirely different dynamics," the flight director just told his team of controllers.
That's because more than half of the mass of the LCROSS/Centaur stack is being let go at separation. The Centaur weighs nearly 5,000 pounds, while the LCROSS shepherding satellite has a mass of about 1,500 pounds.
Flight controllers already uploaded the command sequence for the release, but engineers are monitoring telemetry to ensure physical separation occurs as planned. The team is ready to halt the commands if separation is not detected.
The shepherding satellite's attitude control thrusters will be temporarily disabled before commands are executed to fire relays that will unlock LCROSS from the Centaur.
Heavy-duty compressed springs will then push the vehicles apart at a relative velocity of about 2.3 feet per second.
The separation device is an off-the-shelf clampband system used by the Centaur on normal Atlas launches, according to Dan Andrews, LCROSS project manager.
"Those separation systems are not expected to hang around and wait to do their thing as long as we have," Andrews said.
It has been 112 days since LCROSS launched aboard its Atlas 5 rocket. The separation systems are usually used within minutes or hours of liftoff.
Andrews said the LCROSS team, NASA's Launch Services Program and United Launch Alliance, the rocket's contractor, analyzed the clampband system's performance in a wide range of temperature and flight environments to ensure it would work as planned.
"We found that the performance will be satisfactory for this long a time, including the very wide excursions in temperature during the course of the mission," Andrews said.
"It's a pretty simple system," Andrews said. "It's a series of compressed springs axially located around the spacecraft, and then a release mechanism that has some fail-safes in it to simply push the two vehicles apart."
Just in case LCROSS does run into problems in the separation sequence, the control team at Ames has planned some contingency operations to overcome potential problems.
"In the very unlikely scenario that we get a partial separation or no separation at all, we have some contingency operations plans in place. But we consider that a very low likelihood," Andrews said.
LCROSS also just finished maneuvering to the correct attitude for separation from the Centaur rocket stage left over from its June launch aboard an Atlas 5 rocket.
The shepherding spacecraft is due to release the Centaur at 0150 GMT (9:50 p.m. EDT).
"It's not going to be a grand spectacle that you can go outside in your backyard and see with your bare eyes, or even a good pair of binoculars. It's just going to be too faint."
Scientists say you will need at least an 8-inch telescope to have much hope of seeing debris kicked up by the collision.
"It will last, at its brightest, about 30 seconds, and it will be about a factor of 5 or 10 times dimmer than the surface of the moon itself," Colaprete said.
"What somebody looking through a 10- or 12-inch telescope might see is potentially a sparkling or shimmering across this black space on the moon," he said. "You'll see the blackness get less black as the ejecta moves in front of it and then falls out back to the surface."
Colaprete said the most sure way to watch the early morning fireworks is to follow it online or visit one of 50 observing parties planned across the United States.
"You can go to your nearby observatory, or planetarium, or science center, or amateur astronomy group and observe the LCROSS impacts yourself," said Jennifer Heldmann, coordinator for the LCROSS observation campaign.
Heldmann said the best viewing conditions will be in an area west of the Mississippi River to Hawaii, where the sun is still below the horizon and the moon is high in the sky.
Check out NASA's list of public events for more information.
According to Colaprete, the toughest part for an amateur looking at the moon will be finding the impact site. LCROSS is aiming for a precise point inside the 60-mile-wide Cabeus crater where sunlight and shadows meet to provide the best possible illumination of lunar dust.
"It takes practice finding a crater on the moon. And in particular, finding a particular shadow next to a crater on the moon."
Dan Andrews, the mission's project manager said systems were green across the board.
"And that is good," Andrews said. "The spacecraft has been performing admirably, and everything is going as it should."
LCROSS was about 40,000 miles from the moon and closing the distance at about 2,000 mph, according to Andrews.
Officials have cancelled a final trajectory correction maneuver this afternoon because the last burn on Monday night put LCROSS right on track for its impact point inside Cabeus crater.
The next milestone will be separation of the LCROSS shepherding spacecraft from the Centaur upper stage at 0150 GMT (9:50 p.m. EDT). The probe will fire its thrusters for a braking maneuver at about 0230 GMT (10:30 p.m. EDT) to further separate the two vehicles.
Impact of the Centaur at Cabeus crater remains scheduled for 1131:19 GMT (7:31:19 a.m. EDT) tomorrow. Another navigation update after Centaur release could change that time by a few seconds.
"There is hydrogen down in that crater and we're going to go dig some of it up," said Tony Colaprete, the mission's principal investigator.
Based on the results from Monday night's trajectory correction maneuver, engineers project the Centaur will slam into the moon at 1131:19 GMT (7:31:19 a.m. EDT) Friday. That is about 11 seconds earlier than previously announced.
The shepherding spacecraft impact is expected at 1135:45 GMT (7:35:45 a.m. EDT).
The latest navigation information indicates the Centaur impact site will be at 84.675 degrees south latitude and 311.275 east latitude inside Cabeus crater.
The LCROSS probe will hit the moon at 84.729 south latitude and 310.64 east latitude, according to the NASA update.
Another tweak to the impact times and locations is expected early Friday, after the Centaur jettisons and the shepherding satellite conducts a braking burn to further separate from the rocket stage.
The maneuver moved the impact site by about 9 kilometers, or 5.6 miles, to a new location inside Cabeus based on the latest lunar mapping data, according to a blog posting by Paul Tompkins, an LCROSS flight director.
The burn should put LCROSS within a navigation envelope with less than a mile of error, Tompkins said.
If the maneuver is accurate enough, managers could elect to skip a final trajectory correction maneuver before the shepherding spacecraft releases the Centaur rocket stage for its plunge into the moon.
Impact of the Centaur remains set for 1131:30 GMT (7:31:30 a.m. EDT) Friday, and the shepherding satellite will smash into the moon about four minutes later.
Those times are still preliminary and could change based on the results of Monday night's burn.
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