Friday, October 10, 2008

ATK unveils future aerospace solar array


In the spotless white bay of Alliant Techsystems’ Goleta site, the next generation in aerospace solar array technology slowly unfurled like an Oriental fan.
The lightweight and high-strength prototype, in the midst of initial testing, is being developed for use on NASA’s future space exploration vehicle, Orion.

Due to its unique design, the circular array being developed by Alliant Techsystems (ATK) is four times lighter and smaller in terms of storage space than standard rectangular solar arrays.
“Space flight is a lot like backpacking,” said Jim Spink, senior program manager at ATK. “Weight and space is at a premium.”
During a test deployment opened to local officials and media yesterday, a team of engineers demonstrated how the panels expand from a narrow package into a shallow umbrella-like shape 18 feet in diameter.
“It has to be very small because that’s the only way they can fit it into the rocket to get it up into space,” said Steve White, principal investigator on the project. “…There is limited space in the nose cone.”
While the size of the array presents new challenges, engineers have been working on the accordion-style design and lightweight frame, known collectively as UltraFlex technology, since the early 1990s.
In fact, earlier versions of the array in smaller forms have been used on the Mars Surveyor Lander in 2001 and the Phoenix Mars Lander that touched down on the Red Planet earlier this year.
“It’s producing more power than they expected,” Spink said of the Phoenix array, adding that the mission has already been extended three times as a result.
The Orion space vehicle will utilize two ATK arrays, each of which will provide approximately 7,000 watts of energy. As the replacement to the current space shuttle program, Orion is being developed by Lockheed Martin and is expected to make its first launch by 2015.
Brad Fiebig, a principal engineer with Lockheed Martin, said solar panels are a critical component of the next-generation space capsule. During the Apollo era of two-week trips into space, astronauts could get away with using fuel cells, he said, but no longer.
“When we go back to the moon with Orion, we’re going to be there for six months,” Fiebig said. “Our guys are going to be camped out on the south pole of the moon.”
Solar panels will be necessary to keep Orion in orbit for half a year, he said.
He also praised the strength of the ATK arrays, explaining that they will need to withstand powerful rocket bursts while deployed. The solar panels can handle up to 2.7 Gs and are 10 times stronger than standard arrays.
As White directed engineers to start the test deployment, he pointed out the carbon fiber panels sandwiching what he termed the “blankets” that hold individual solar cells.
A small motor slowly reeled in a high-strength steel tape much like an elbow tendon, pulling the array open in approximately three minutes.
White noted the panels can only be opened and will be shed by the capsule during reentry, burning up in the atmosphere.
“It’s kind of nice for us because they’re disposable and we get to build them for each Orion mission,” he said.
ATK officials have plans to build and test three more prototypes before developing the actual arrays that will accompany Orion on its first trip to the International Space Station.
Fiebig said Orion is expected to return to the moon in the 2025 timeframe and to Mars in the 2030 timeframe.
“It’s pretty cool that we’re already demonstrating this technology,” he said. “…You want to make sure when you get those guys up into space that those arrays are going to deploy, because you don’t want to have to turn right back around and come home.”

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