Spaceflight Now: Breaking News

Pounds peel away with inflatable space structures
Posted: June 26, 2000

Engineers prepare inflatable membrane for testing in the AFRL Directorate's Structures and Controls Laboratory. Looking a lot like a giant contact lens, this experimental lightweight device may pave way for future, inexpensive weight-saving technologies that enable large space structures. Photo: Air Force
The latest Air Force Research Laboratory (AFRL) brainchild to reduce the bulk and weight of future space systems looks, well, kind of like a huge contact lens for a myopic Jolly Green Giant or a transparent flying saucer.

"But what you're really seeing here at AFRL's Space Vehicles Directorate is a potential solution to an important, ongoing problem in the space business: How to shrink the weight of spacecraft and, as a result, lower expensive launch costs."

That is what AFRL project manager for inflatable space structures Bob Acree tells the sometimes awestruck visitors when they first see the experimental, inflatable membrane for large, space-based structures towering over them in the high-bay of the Directorate's Structures and Controls Laboratory.

"We, and our commercial partners at SRS Technologies in Huntsville, Alabama, are also examining the inherent possibilities of inflatable technology to reduce the volume of stowed payload in launch vehicles," Acree explained. "By using thin-film, NASA-developed plastics like this membrane, we can shrink payload weight and the pre-launch mass of some fairly large structures -- antennas, radar dishes, sensors, telescope optics -- down to a few hundred pounds rather than the thousands of pounds comparative metal structures weigh today. Then, once the system is in orbit and ready for deployment, an inert gas will re-inflate the structure, like a life raft."

When considering spacecraft design, weight and volume have always been critical limitations, not only for the Air Force, but also for the space industry at large. The standard cost estimate commonly used for every pound placed into orbit is $10,000. Consequently, the lighter and smaller the payload, the cheaper class of launch vehicle can be used.

Moreover, by developing technologies that both compress a payload's volume -- either by folding or collapsing -- for launch, and then unfolds, or in this case inflates, the payload back to its operational size and configuration once in orbit, AFRL enables placement of much larger -- not heavier -- structures in orbit.

"And in space, size dominates, especially if you want to find relatively small things on earth and see them clearly by using space-based radar, sensors, or a telescope," said Acree.

"If you are designing structures for, say, high-altitude surveillance missions, you want to put up the largest system you can. And the bigger the structure, the bigger, more detailed picture you get of objects on and above the ground. But we must work within reasonable cost limitations," explained Acree.

"Here at the lab, our thin-film, inflatable technology has potential to be about 10-times cheaper and 10-times lighter than current structures, and also permit payloads that are at least 10-times smaller in volume than today's mechanically deployed structures," said Acree. "Right now, we think inflatable membranes hold genuine, efficient possibilities for such spacecraft as solar orbit transfer vehicle concentrators and radio frequency antennas."

Acree said AFRL is planning a demonstration flight for AFRL's thin-film inflatables within the next six years.