COLORADO SPRINGS, Colo.
The lunar-crashing secondary payload that will share an Atlas 5 launcher with NASA’s Lunar Reconnaissance Orbiter, has entered comprehensive performance testing about a month ahead of schedule. That payload, the Lunar Crater Observation and Sensing Satellite (LCROSS), is designed to gather data to help researchers determine how much water-ice might be contained in lunar surface material.
Besides promising to put on an impressive show when two separate pieces of hardware
into one of the Moon’s permanently shadowed craters in early 2009 at a speed of more than 9,000 kilometers per hour, the
mission has been providing a great hands-on training experience for a new generation of engineers.
LCROSS beat out 19 other proposals in April 2006 to win $79 million in funding that was accompanied by
a strict 1,000-kilogram mass allowance.
The ultimate goal of the mission is
to find out once and for all whether the Moon’s permanently shadowed regions
contain the water ice hinted at by findings from the Clementine and Lunar Prospector missions of the 1990s.
To do this resourcefully, NASA Ames Research Center and its industrial partner, Northrop Grumman Space Technology, designed a
mission that will send the Atlas 5’s spent Centaur upper stage hurtling into the lunar surface while LCROSS – a standard payload adapter ring cleverly transformed into a fully functional science satellite – observes the impact, flies through the resulting plume of debris, and then finally crashes into a different part of the crater. Just four minutes will separate the impact of the Centaur upper stage from the impact of LCROSS.
A similarly compressed schedule has defined the mission from the beginning. The LCROSS preliminary design review was held in September 2006, just shy of five months from the selection. LCROSS passed its mission confirmation and critical design reviews in February 2007. Just under a year later, the LCROSS instrument payload, after being assembled and tested at Ames, was shipped to Northrop Grumman’s Redondo Beach, Calif., campus for integration with the spacecraft.
Dan Andrews, the LCROSS project manager at Ames, said one of the keys to keeping to such a tight schedule has been NASA’s willingness to let the LCROSS team take more risks than the agency usually tolerates. LCROSS formally is designated a Class D mission. Whereas NASA’s human missions and multi
billion-dollar planetary flagships are considered Class A missions, Class D missions, Andrews said, “are at the other end of the spectrum. They are very risk tolerant. D is as tolerant as the agency gets.”
Andrews said the Class D designation gives LCROSS latitude to do less mission assurance and “lighter, more strategic testing” in order to keep the mission within its cost and schedule box.
To keep overall mission risk in tow, Andrews said, the LCROSS team has striven to keep the spacecraft design as simple as possible and use high heritage hardware wherever it can.
“If you take a look at our avionics, at our star tracker, at our core sun sensors and all of our payload instruments … these have all either flown spaceflight missions, or are [Defense Department] proven [equipment] in the case of the payloads,” Andrews said. “We’ve even got some automotive industry industrial devices that are being used on this that we have then flight qualified on our own.”
Steve Hixson, Northrop Grumman Space Technology’s vice president of advanced concepts, in an April 10 interview here with Andrews, credited the involvement of young engineers on LCROSS with the project’s success to date.
“They don’t have any preconceived notions as to how long things take,” he said. “They haven’t been told it cannot be done.
From a work-force development point of view, Hixson said, LCROSS is providing a great training opportunity for the new generation of engineers the aerospace industry sorely needs.
“The neat thing about these kinds of missions is a young engineer can get the experience of all phases of a program – the design phase, the fabrication of equipment, the integration and test – in two years rather than 10 years,” he said. “For the Gen Y’s and millennials that are entering our industry, they are pretty impatient in that regard, so these kind of missions are very attractive from the point of view of training a work force fairly quickly.”
“And a Class D mission is an excellent training ground for that,” Andrews added.
The core of the LCROSS mission is the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA), a rugged aluminum ring roughly 1.5 meters in diameter designed by the U.S. Air Force as a way of fitting up to six tiny satellites into an Atlas 5 or Delta 4 below the rocket’s primary payload. The ESPA ring made its debut in March 2007, carrying four military microsatellites into orbit beneath the larger Orbital Express spacecraft.
Hixson said LCROSS marks the first time that an ESPA ring has been outfitted with a propulsion system, effectively transforming the aluminum ring into a standalone spacecraft.
“So that is very exciting to us,” he said. “It is now Air Force policy that every EELV launch will have an ESPA ring and I think their
hope is that these sort of things will be leveraged as additional launch capability is available.”
already has been thinking about how the approach taken with LCROSS could be applied to other mission needs.
“We’ve looked at all sorts of things,” said Dave Ryan, Northrop Grumman Space Technology’s vice president for civil space programs. Adding additional avionics would give an ESPA-based spacecraft the added redundancy it would need to do longer duration missions, Ryan said, including Earth-observation and planetary treks and “conceivably even a similar kind of mission where we might direct a projectile into Mars and find out more about the crust construction of the planet.”
“There’s a lot of flexibility using the ESPA ring type of architecture and the attractiveness that most of these missions could be done in a couple of years. They could be rapid response missions and with some of the additional things we’ve learned doing LCROSS be even longer lived.”
For now, at least, Ames and Northrop are focused on making LCROSS a success.
Hixson said the spacecraft is fully assembled except for its fixed solar array, which is ready to be installed once the spacecraft’s performance tests conclude in the weeks ahead. After that, LCROSS will undergo a couple months of environmental tests before shipping out to Cape Canaveral, Fla., in late July or early August – several weeks ahead of schedule.
“There were some naysayers on various sides when we started doing this,” Hixson said. “Whether or not we’d be able to do this quickly was a real question.”
Although it appears to be a moot point given that LCROSS is closer to shipping out than the Lunar Reconnaissance Orbiter (LRO), NASA would have no qualms about leaving LCROSS on the ground if it was not ready to go when LRO lifts off. Nonetheless, Hixson said
that push come to shove NASA would fly ballast in place of LCROSS has helped keep the team motivated.
“The choice is do you fly this or do you fly a mass simulator … that drives decisions along the way, and it also drives the work force – both on the government side and on the contractor side – to team together and sometimes just out of pride and say ‘well, they’re not going to fly a mass simulator instead of us
,’” Hixson said. “We’ve got a very energized, very motivated work force on both sides.”