Crowd gathers at Chabot to see NASA’s rocket and probe crash into moon
on October 10, 2009
The planetarium was quiet at 3:30 Friday morning yet nearly every seat was occupied, as 184 pairs of eyes stared up at an enormous computer-generated moon rotating in the center of the domed ceiling. A smaller, secondary screen broadcast grainy black and white images resembling a cratered surface over 230,000 miles away.
Some attendees slept in the near-darkness, until a voice rang out, “Five minutes!” The audience inside the planetarium came alive, with people stirring and stretching. Hoots and hollers sounded. “Bomb the moon!” someone cried. After nearly four months of spaceflight, the Lunar Crater Observation and Sensing Satellite (LCROSS) mission was about to sacrifice itself for science and the audience at Oakland’s Chabot Space and Science Center was going to experience the impact live.=
At approximately 4:30 a.m. Friday, a high-energy Centaur booster rocket and the LCROSS probe flew directly into the surface of the moon’s south pole. The impact was intended to kick an estimated 250 metric tons of lunar dust more than six miles above the moon’s surface, creating twin plumes visible for astronomers watching from Earth, who were looking for signs of one of life’s fundamental building blocks: water.
The Chabot Center’s science staff had planned to record the lunar impact using “Nellie,” their state of the art, 36-inch, computerized telescope perched high in the Oakland hills. “Unfortunately,” says chief astronomer Conrad Jung, “the bay’s fog took care of that” rendering their optical telescopes useless in the cloud cover. Instead, Chabot tapped into NASA’s streaming web TV, broadcasting a live video feed from the LCROSS probe as it sped toward its inevitable destruction.
NASA redirected the orbiting Hubble Space Telescope toward the moon’s south pole in an attempt to catch the blast. A dozen terrestrial observatories around the United States — including the Lick Observatory near San Jose — along with hundreds of amateur telescope operators around the world, trained their lenses at the moon’s southern rim to watch, record, and analyze the light filtering through the lunar dust.
Flight Control at NASA’s Ames Research Center near Mountain View, California flickered across the planetarium screen. “Go-no-go for launch,” said the flight director at his desk, seeking status reports from the mission’s various departments. “Go for launch!” cried the audience in response. “Payload—go. Systems—go. Engine—go,” said the mission departments checking in. “Copy that,” confirmed the flight director. “Go for observing impact.” The planetarium was quiet in anticipation.
The recycled Centaur rocket would strike first, with the LCROSS probe following four minutes later. The mottled black and white infrared footage refreshed itself every few seconds as the probe, traveling at over a mile a second, sped toward the moon’s Cabeus crater.
“One minute to Centaur impact,” said NASA’s Flight Command.
NASA chose the moon’s south pole as LCROSS’ destination due to its relatively high concentrations of hydrogen — a key indicator of water — detectable on the surface. The steep sides of the lunar craters have blocked the sun, in some instances, for billions of years, maintaining temperatures at or below 300 degrees Fahrenheit. Upon coming in contact with sunlight, any particles of frozen water kicked up by the impacts would vaporize into their component elements: hydrogen and oxygen. A battery of equipment aboard LCROSS, as well as on terrestrial observatories, will have 90 seconds or less to measure light in the visible, infrared, and near-infrared wavelengths, gathering data as the light is absorbed by countless particles rocketing into the space.
“Mark, Centaur impact,” said NASA’s flight control. It’s 4:30 a.m. PST. A whoop goes up from the audience but the LCROSS imagery remains the same. No flash. No sign of a plume. It’s not immediately clear from NASA what had happened, but the lack of a flash turns out to be a good sign. During an interview broadcast a few moments later, Michael Bicay, Science Director at the NASA Ames Research Center, noted on NASA TV that despite the underwhelming theatrics, astronomers prefer not to see a brilliant flash upon impact. “You want a dimmer flash, indicating contact with regolith [lunar soil] and water vapor.” A brighter flash would indicate the probe hit solid lunar rock, which will travel shorter distances than dust and is far less likely to contain the water particles scientists were seeking.
The fuzzy image of the Cabeus crater continued to grow larger and larger, filling the screen as LCROSS followed the Centaur rocket’s path down the surface. 3, 2, 1 and then…
The screen turned solid white. At 4:35 a.m., the live feed went dead as the probe hit. A half-second of silence and then… “BOOM!” NASA TV’s on-air host provided his own extemporaneous sound effects to fill the void. The audience jumped and exhaled. “Is that it?” a voice cried out. Laughter and some clapping echoed around the planetarium as the lights slowly came up. Some stayed to watch NASA’s post-impact analysis, while many gathered their things to leave.
As the audience streamed out into the chilly morning air, there was a clear sense of bemusement about the event. Retired science writer Isla Bartlett said she found the show “terribly entertaining” and “not like some Disney production at all.”
Among the younger crowd milling about outside the observatory, sentiments were mixed. “Ultimately,” said 22-year old Oakland resident Erica Brown, “it was pretty disappointing.” “But,” she added, “I did come for the novelty of seeing it with a lot of people.”
The LCROSS mission, though lacking in theatrics during its final moments, could help set the stage for humankind’s eventual return, after a nearly 37-year absence, to the surface of the moon. “You’d have a kind of resource,” said Chabot’s Conrad Jung, as he held open an exit door for guests leaving the planetarium. “Water would allow astronauts working the surface of the moon to make energy.” It gives astronauts an ability to “live off the land,” as the Ames Science Director, Michael Bicay, put it in his NASA TV interview.
At a press conference later that morning with LCROSS mission staff, NASA’s principal investigator, Anthony Colaprete said that all instruments performed better than expected but it was too soon to know whether water was found in the dust plume. “Ultimately,” he said, “we got the measurements to address the question.”
Image: The moon’s south pole as seen from orbit by the LCROSS Probe. Image courtesy of NASA.
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