Launch Updates - Analytical Graphics, Inc.

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New Launch: 2011 September 10, 1308 UTC
Site: Air Force Eastern Test Range, Florida, USA
Launcher: Delta II
International Designator(s): 2011-046A, 2011-046B
SSC Name Owner
37801 GRAIL-A US
37802 GRAIL-B US

"Catching a break from the weather, a United Launch Alliance Delta 2 rocket blasted off Saturday and successfully boosted two NASA science satellites into space on looping, round-about trajectories to the moon, the first step in an ambitious US$496 million mission to map the cratered satellite's gravity and internal structure.

"By precisely measuring the distance between the two spacecraft as they orbit the moon—and thus the subtle effects of the moon's gravity as they sail over visible and sub-surface geologic structures—scientists will be able to determine the nature of the moon's enigmatic core and perhaps confirm or refute theories about how the moon formed some 4.5 billion years ago."

"It also may help inspire school kids to take more of an interest in science. Each satellite is equipped with four cameras sponsored by former shuttle astronaut Sally Ride's science education company that can be used by students around the world to photograph the lunar surface."

"Saturday's launching was virtually flawless and one hour and 20 minutes after liftoff, the GRAIL-A satellite was released from the Delta 2's second stage, followed a few minutes later by GRAIL-B. Both spacecraft will follow looping 2.6-million-mile [4.2-million-km] trajectories to the moon, a low-energy approach that allowed the use of a less expensive, medium-lift rocket."

"The flight plan calls for the GRAIL-A spacecraft to brake into an elliptical 11.5-hour orbit around the moon's poles on New Year's Eve with GRAIL-B following the next day. Over the next two months, flight controllers will carefully maneuver the two satellites into the same circular orbit at an altitude of about 34 miles [55 km].

"If all goes well, science operations will begin around March 8. Flying in formation at distances ranging from about 46 [74] to 140 miles [225 km], the two spacecraft will send radio pulses and timing signals back and forth to precisely measure the distance between them.

"Sailing over buried mass concentrations, craters, mountain ranges, basins and other geologic features, the satellites will ever so slightly speed up and slow down, one after the other. The ranging system is accurate enough to detect differences of as little as one micron, or the width of a red blood cell.

"By carefully analyzing those changes, scientists can determine the distribution of mass within the moon to gain insights into its hidden interior structure and the nature of its core."

"The three-month science mission is sandwiched between eclipses in December and June. The solar-powered satellites are not expected to survive the latter and flight controllers expect the spacecraft will lose power and eventually crash.

But by that point, GRAIL's mission will be complete, and the "results are expected to be a giant leap for lunar research. A major objective is to confirm or rule out theories about the moon's formation and evolution and, by extension, improve understanding of the early histories of other terrestrial planets."

[Note: This notification was delayed due to delays by USSTRATCOM in identifying these objects.]

Source: Spaceflight Now, "From the Earth to the Moon: GRAIL spacecraft blast off"

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© 2011 Analytical Graphics, Inc.  |   220 Valley Creek Blvd. Exton, PA 19341

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