Magdalena Ridge Observatory Records Lunar Impacts for NASA
Returning humans to the surface of the moon is among the goals of NASA scientists. American astronauts walked on the moon during six missions from July 1969 to December 1972. Since then, space exploration has focused on more distant planets, stars and celestial bodies.
In September 2005, NASA officials unveiled a $100 billion plan for a crew to land on the moon in 2018. The long-term goal is to establish a permanent science station on the lunar surface. Such an ambitious endeavor would require massive amount of resources. The LCROSS project aimed to answer one specific question about the moon subterranean composition: Is there water on the moon?
Astronomers suspect that water exists in the polar regions of the moon, but its presence is not certain.
“Finding water is the precursor to setting up human resources so we could live comfortably on the moon under artificial constructs,” Ryan said. “This mission will have a significant impact on where we go as a nation in the future. If we find water, that’s a huge step toward lunar exploration.”
The Shepherding Spacecraft and Centaur rocket were launched from the Lunar Reconnaissance Orbiter (LRO). The Shepherding Spacecraft first sent the 4,400-pound Centaur rocket toward the Moon at more than twice the speed of a bullet.
The Shepherding Spacecraft monitored and collected data on the rocket’s descent and impact. Four minutes later, the Shepherding Spacecraft followed
almost the exact same path as the rocket, descending through the plume and analyzing it with special instruments, then self-destructing in a kamikaze run at the moon. Scientists around the country – from New Mexico to Hawaii – monitored the impacts via optical, infrared and thermal instruments and spectrometers. The spectrometers will aim to detect the chemical composition of the plumes and, hopefully, determine whether water exists.
“This mission took a lot of preparation, so it’s good to see it finally come to a head,” Dr. Eileen Ryan said the day before the mission.
Eileen and Bill Ryan found that they had to learn new techniques – and use new instruments. In trial runs, they found that the moon is too bright for their standard camera, which is designed to see fainter objects.
They had to use additional filters on the main telescope, and also installed a charge-couple device, or CCD camera on the 2.4m’s wide-field acquisition telescope, so they could manually adjust the aperture and exposure. The CCD camera captured images that are clear and crisp, Eileen Ryan said.
The video camera they normally use on the acquisition telescope became oversaturated with light during trial runs, she said.. They also had to learn how to point the telescope by sight, as opposed to by coordinates.
“We had to learn how to navigate the moon,” she said. “Each observatory in the LCROSS mission had a cheat sheet and we helped each other find the impact site. Instead of using coordinates, we’d say, ‘Two hops left from Copernicus crater and one hop down.’ That’s something we didn’t expect.”
Through several trial runs, the astronomers became accustomed to finding the various craters near the lunar south pole and identifying the distinguishing features of the target site – a distinct bright area and its neighboring shadowed region.
They also conducted several test runs with NASA to ensure they could link digitally to mission control.
Anthony Colaprete, LCROSS principal investigator, said in a news conference Friday afternoon that the observatories successfully viewed the impacts and gathered interesting spectroscopic and visual data. He said the team gathered enough information to address the question of whether water exists on the moon. Space-based thermal cameras detected a flash, which scientists were hoping would indicate the presence of water vapor in the plume. However, Colaprete said his team would thoroughly analyze the data sets before definitely answering the question.
Hours after the impact, Ryan said the 2.4-meter telescope successfully viewed the impacts and captured scientifically significant images and video. On first study, she said the plume did not produce a flash of light, which would be a tell-tale sign of presence of water. However, NASA scientists will take several weeks to completely analyze the data.
Return to the Moon
NASA announced in March 1998 that data returned by the Lunar Prospector spacecraft indicated that water ice might be present at both the north and south lunar poles. The ice originally appeared to be mixed in with the lunar rocks, soil, and dust. Subsequent data from Lunar Prospector indicated the possible presence of near-pure water ice deposits buried beneath as much as 18 inches of surface material. Later work called this interpretation into question, so the LCROSS mission was designed to determine the extent of lunar ice.
Over the course of a lunar day (roughly 29 Earth days), all regions of the moon are exposed to sunlight, and the temperature on the Moon in direct sunlight reaches about 250 degrees F. Any ice exposed to sunlight for even a short time would be lost. The only possible way for ice to exist on the Moon would be in a permanently shadowed area.
The Clementine imaging mission of 1996 showed that such permanently shadowed areas do exist in the bottom of deep craters near the moon's poles, according to the NASA website. The permanently shadowed area near the moon’s north pole include a large water-bearing area at the north pole. At the moon’s south pole, much of the area is within the South Pole-Aitken Basin, a giant impact crater 2500 km (1550 miles) in diameter and 12 km deep at its lowest point.
Many smaller craters exist on the floor of this basin, permanently hidden from sunlight by the walls of the craters. Within these craters the temperatures would never rise above about -280 degrees F, according to the NASA website. Any water ice at the bottom of the crater could probably exist for billions of years at these temperatures.
The NASA website says, “Beyond the scientifically intriguing aspects, deposits of ice on the Moon would have many practical aspects for future manned lunar exploration.” Shipping water to the Moon for use by humans would be extremely expensive. Paul Spudis, one of the scientists who took part in the 1996 Clementine study, referred to the lunar ice deposit as possibly “the most valuable piece of real estate in the solar system.”
In addition to finding water, Rembold will use the findings to correlate the size of the plume to the size of the impacting object.
“This is pretty cool,” Rembold said. “This isn’t something you expect to get approached with out of the blue. Obviously, you’d hope to be doing something bit
Click here for more about the Magdalena Ridge Observatory.
Click here for more information about the NASA Lunar Impact mission.
like this, but I kind of expected it later in my career. It’s cool to have an opportunity come my way.”
Eileen Ryan enlisted Rembold in the LCROSS project precisely because his doctoral research focuses on examining meteor impacts on the moon. Rembold regularly aims his telescopes at the moon, searching for natural impacts. He will use LCROSS data to help him calculate the size of meteors that impact the moon.
“Right now, there’s not very many good means of estimating the size of a meteor hitting the moon,” he said. “There hasn’t been a lot of work done scientifically about the exact correlation between brightness of the plume and size of the asteroid or meteor that smashes into the surface. With this mission, we know how big the impactor is, so it will serve as a baseline for future impacts we see. We’ll be able to estimate how big they are. This is like a controlled meteor.”
Romero and Ryan said getting student involvement was a great bonus for the project. Ryan said this project shows prospective students that they can come to New Mexico Tech and have the opportunity to work with world-class instrumentation – and potentially study space missions with NASA.
“We have amazing opportunities for students,” Ryan said. “Students can get that close to working on a spacecraft mission and working on data in their research.”
“The great thing about this project is that a Tech student gets to do his graduate research based on this event,” said Vice President Romero, who earned two physics degrees at Tech. “Getting students involved is always a huge success.”
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