A Stowaway Mission to the Moon

NASA's LCROSS lunar impactor mission comes in on time and on budget

Illustration: NASA

moonbound

Lcross is set to smack into the moon.

Several months from now, the empty upper stage of an Atlas V rocket will slam into a shadowy crater near the north pole of the moon, tossing a plume of debris up into the sunlight. By then, the Atlas V will have delivered its main payload, the Lunar Reconnaissance Orbiter (LRO), and a smaller stowaway. That stowaway satellite will watch the spectacle unfold from above, looking for telltale signs that there’s water in the lunar soil, before it, too, crashes into the moon.

NASA’s current plan for manned exploration calls for establishing a base near a lunar pole, where indirect evidence suggests that frozen water is trapped in permanent darkness. Scheduled to launch in late April, the Lunar CRater Observation and Sensing Satellite mission, or LCROSS, aims to explore the nature of lunar water and determine whether it’s concentrated in small pockets or spread diffusely throughout the shadowed regions. Although these findings will help guide the strategy of lunar exploration, LCROSS is not a typical NASA mission—it wasn’t even on the drawing board three years ago.

”This was probably the ultimate mission of opportunity,” says LCROSS project manager Dan Andrews. ”Frankly, it was never supposed to happen.”

LCROSS owes its existence to the ballooning size of the US $500 million LRO, a lunar-mapping satellite that will scout future landing sites and requires a bigger rocket than originally planned. Even with a larger LRO, the new rocket has more than 1000 kilograms of payload capacity to spare. So, back in January 2006 NASA began canvassing the agency for ideas. Proposed missions had to cost less than $80 million, not interfere with the LRO, and go from concept to flyable spacecraft in less than 30 months.

NASA’s missions of opportunity normally involve adding an additional instrument, not building an entirely new spacecraft. So when NASA selected the LCROSS proposal by Northrop Grumman and NASA Ames Research Center in April 2006, the agency designated it a class D mission—one that’s allowed a ”medium or significant risk of not achieving mission success.” The LCROSS team soon realized that their classification, tight schedule, and significant constraints actually freed them from typical NASA methodology, which tends to be risk averse. ”We decided that this mission is not about ultimate performance,” says Andrews. ”It’s about cost containment.”

To that end, the LCROSS team leveraged proven parts, off-the-shelf components, and previously flight-tested instruments. To reduce the risk of failure, they relied on redundancy. When the empty rocket-stage belly flops onto the soft surface, its shepherding spacecraft will be watching with five cameras, three spectrometers, and one high-speed photometer.

To keep LCROSS as simple as possible, the engineers designed the satellite so that it would be free of moving parts. To point the antenna, for example, technicians will simply turn the entire body of the craft. And LCROSS has no onboard storage devices, so all data will be streamed back to Earth live, including a video feed available to the public.

So far, doing things differently has paid off: When the original launch date of October 2008 rolled around, LCROSS was on budget and ready to go. (Problems with the Atlas V rocket motor have held up the launch.) The agency’s ability to stick to schedule and budget is a rare feat that’s generated excitement within the space community.

”If LCROSS is successful, I think it’s likely that you’ll see more of this,” says Bruce Betts, the project director for the Planetary Society. But extra launch capacity is a rare luxury, and space exploration is inherently hard and expensive, he says. ”You can’t take this idea too far.”

Andrews agrees that there will always be a place at NASA for big projects. Without them, he says, the facilities and equipment that made LCROSS possible wouldn’t exist in the first place. But he hopes LCROSS will prove to the agency that other types of missions are possible.

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