The University of Maine (Orono, Maine, USA) says that its Bridge-in-a-Backpack comopsite technology has triggered interest from NASA, which is considering a similar technology for use in its Hypersonic Inflatable Aerodynamic Decelerator (HIAD). HIAD could one day help deliver astronauts to the surface of Mars.
HIAD, a spacecraft nose-mounted “giant cone of inner tubes” stacked like a ring toy, is designed to slow the craft as it enters a planet's atmosphere. The technology, says NASA, is intended to make it possible for a spaceship large enough to carry astronauts and heavy loads of scientific equipment to explore Mars and beyond.
Bill Davids, Joshua Clapp, Andrew Goupee and Andrew Young — engineers with University of Maine's Advanced Structures and Composites Center — are working with NASA to accomplish that mission.
UMaine's patented Bridge-in-a-Backpack, which has earned the American Association of State Highway and Transportation Officials' certification, is made of light, portable carbon fiber tubes that are inflated, formed into arches and infused with resin. Concrete is poured inside the carbon fiber tubes, which protect the concrete from water and other natural elements, thus extending the bridge's lifespan to double or triple that of a traditional bridge.
Ager the emergence of Bridge-in-a-Backpack, Davids, chair of the civil and environmental engineering department and the John C. Bridge Professor, led a UMaine group that worked on portable, lightweight, rapidly deployable inflatable fabric arch-supported structures for the U.S. Army Natick Soldier Systems Center. Designed for military forces, the tents that are supported by inflatable arches also can be used for disaster relief shelters, temporary medical facilities and storage.
The research involving inflatable fabric arch-supported structures caught the attention of NASA scientists several years ago. NASA officials working on HIAD inflatable technology contacted Davids about possible research collaboration. Ultimately, Davids' research proposal on the structural investigation of the HIAD technology to NASA-EPSCoR through the Maine Space Grant Consortium was accepted. UMaine is now about 18 months into the three-year, $750,000 project funded by NASA and EPSCoR.
“Our role is to fill in holes in NASA's technical knowledge,” says Davids. “They have developed the technology; we help them advance it through testing the structures in the lab and analyzing stresses and deformations in the HIADs.”
Davids and Clapp say the HIAD technology is viewed as one of the most-feasible options for a successful human spaceflight to Mars. It has the potential to allow landing at higher elevations on the planet, carrying more payload, or both. Payloads that have landed on Mars to date have had a mass less than 1 metric ton; 40-80 metric tons likely will be required for a mission that includes people, says Clapp, a doctoral student and research engineer.
Also, all Mars landings thus far have been below -1.4 km Mars Orbiter Laser Altimeter (MOLA) elevation due to the vertical distance required for deceleration. A number of scientifically interesting sites are at higher elevations, Clapp says.
UMaine researchers are working on a 6m/19.7-ft diameter HIAD tested at NASA's National Full-Scale Aerodynamics Complex — the largest wind tunnel in the world — in Moffeo Field, Calif., USA.
“The 6m HIAD created the most air blockage of anything ever tested in the wind tunnel and pushed the limits of the equipment to the maximum,” Clapp says. “The HIAD diameter needed for a manned mission to Mars is estimated to be on the order of 20m [65.6 ft], therefore we will not be able to conduct aerodynamic testing in a wind tunnel, which makes a reliable predictive tool (i.e., the finite element models that we're all working on) that much more important.”
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