LADEE set to enter lunar orbit after transit from Earth
BY STEPHEN CLARK
Posted: October 5, 2013
One month after a dazzling late-night launch from Virginia sent NASA's LADEE mission into orbit, ground controllers in California are readying the lunar probe for a make-or-break rocket burn Sunday to put the modest spacecraft into orbit around the moon.
The $280 million Lunar Atmosphere and Dust Environment Explorer launched Sept. 6 aboard a Minotaur 5 rocket from Wallops Island, Va., putting on a Friday night pyrotechnic sky show for observers along the U.S. East Coast.
The five-stage launcher put LADEE in a high-altitude transfer orbit, and the bullet-shaped spacecraft completed three loops around Earth over the last month, using its rocket thrusters to nudge itself higher to set up for an intercept with the moon's orbit Sunday.
"On the third pass, we're hanging out there in space right around where the moon is going to come by," said Butler Hine, LADEE's project manager at NASA's Ames Research Center, in a prelaunch press conference. "It swings by, whips us around behind it, and then once we come out from behind the moon, we do a big braking burn with our main engine. That braking burn is what captures us around the moon."
LADEE's main engine, built by Space Systems/Loral, fired several times in September to change the probe's trajectory on the way to the moon. Sunday's lunar orbit insertion maneuver is the longest planned engine firing in LADEE's mission.
The mission's arrival at the moon is not impacted by the partial shutdown of the federal government, which furloughed 97 percent of NASA's civil servant workforce because Congress failed to pass a budget for the new fiscal year.
LADEE's operations are not affected by the shutdown because the mission is in a critical phase, said Rachel Hoover, a spokesperson at NASA's Ames Research Center, before the shutdown.
Sources said NASA had no plans to communicate the outcome of LADEE's insertion burn to the media or the public because the agency's public affairs staff is not at work.
Two more rocket firings are planned for Oct. 9 and Oct. 12 to lower LADEE's lunar orbit to an altitude of 155 miles. The spacecraft will initially be in an elliptical 24-hour orbit after Sunday's insertion maneuver.
During the mission's 30-day commissioning phase, due to begin in mid-October, ground teams will activate the spacecraft's research payload and deploy covers on LADEE's three science instruments. The sensors all appeared healthy during aliveness checks after LADEE's launch.
The spacecraft, which stands 7.7 feet tall and stretches about 4.7 feet in diameter, also hosts a laser communications package to demonstrate next-generation high-speed data links between Earth-based antennas and deep space probes.
The laser communications demo is scheduled to kick off later this month, and LADEE's laser payload - built by MIT Lincoln Laboratory - will connect the spacecraft with ground terminals in New Mexico, California and the Canary Islands.
LADEE will try to send and receive data packets transmitted through a laser beam connecting the spacecraft and the ground terminals at a range of about 250,000 miles.
Officials say laser communications on future missions could enable 3D videos and high-resolution imagery to be beamed from Mars to Earth at fiber-optic speeds, limited only by the one-way light time, the time it takes for a signal to travel from distant destinations back to Earth.
Then LADEE will begin its 100-day science mission, dipping as low as 12 miles above the moon's surface.
"LADEE has two main science goals: To understand the lunar atmosphere as well as the dust environment around the moon," said Sarah Noble, LADEE's program scientist.
The orbiter's three instruments - a lunar dust experiment, neutral mass spectrometer and ultraviolet spectrometer - will scoop up dust particles and analyze the composition and variability of the moon's tenuous atmosphere.