March 8, 2012
GRAIL Science Collection Phase Officially Begins
NASA's twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft officially entered the science collection phase of their mission on Tuesday, the U.S. space agency has announced.
This portion of the mission, which will last 84 days and conclude on May 29, officially began on March 6 at 8:15pm EST (5:15 PST), NASA officials announced in a press release Wednesday.
During that time, the twin spacecraft will provide scientists with a high-resolution map of the moon's gravitational field, which will not only provide them with an "unprecedented" look at its internal structure but will also shine some light on how Earth and similar planets were formed and evolved over time.
"The initiation of science data collection is a time when the team lets out a collective sigh of relief because we are finally doing what we came to do," Maria Zuber, the principal investigator for the GRAIL mission at the Massachusetts Institute of Technology (MIT), said in a statement. "But it is also a time where we have to put the coffee pot on, roll up our sleeves and get to work."
"We are in a near-polar, near-circular orbit with an average altitude of about 34 miles (55 kilometers) right now," added David Lehman, GRAIL project manager from NASA's Jet Propulsion Laboratory (JPL). "During the science phase, our spacecraft will orbit the moon as high as 31 miles (51 kilometers) and as low as 10 miles (16 kilometers). They will get as close to each other as 40 miles (65 kilometers) and as far apart as 140 miles (225 kilometers)."
According to information posted to the GRAIL Mission website, the two washing machine sized spacecraft will be transmitting radio signals to indicate exactly how far apart they are from one another.
That distance will change slightly during locations of greater or lesser gravity, caused by "mountains, craters and masses hidden beneath the lunar surface." Between now and May 29, the moon's gravitational field will be mapped a total of three times, NASA added.
The two probes, which were built by Lockheed Martin and entered the moon's orbit on December 31 and January 1 respectively, had previously been known as GRAIL A and GRAIL B. However, following a recent contest which involved 11,000 students from 45 states, Puerto Rico, and Washington D.C., they were re-christened Ebb and Flow.
That winning entry was submitted by a fourth-grade class at the Emily Dickinson Elementary School in Bozeman, Montana, and according to NASA, they were one of 900 classes which participated.
As previously reported here on RedOrbit, the spacecraft returned its first video from the far side of the moon at the beginning of February. According to NASA, that video showed the lunar north pole, and also showcased the mare Orientale, a 560-mile wide crater that lies on both the near and far side of the moon.
Those images were captured during a test of Ebb's MoonKAM, which allows students to take their own photos using cameras on board each of the twin GRAIL spacecraft. According to former astronaut Sally Ride, director of the MoonKAM program, more than 2,500 schools across the U.S. had signed up as of February 2 to participate in the project. The project's website says that it will officially begin on Monday, March 12.
Image Caption: Artist concept of GRAIL mission. GRAIL will fly twin spacecraft in tandem orbits around the moon to measure its gravity field in unprecedented detail. Image credit: NASA/JPL
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