Guy Norris/EDWARDS AFB
NASA has revealed outline studies of three promising candidates for future experimental vehicles as part of its Pathfinder series of demonstrators that encompasses the X-34 and X-37 reusable launch vehicles.
Showing the potential low-cost demonstrators at a reusable launch vehicle (RLV) technology exposition at Dryden Flight Research Center, Edwards AFB, California, on 22 June, Future-X Pathfinder programme manager John London said the "future possibilities" emerged from a series of in-depth staff studies.
They include an advanced crew escape system, a reusable, glideback booster stage and a "Lunar tug" that could transfer payloads to the moon.
"One of the key findings was the need for a more robust crew escape system," says London, who adds the study is nicknamed "Little Joe III" after previous "Little Joe" escape systems developed for the Mercury and Apollo programmes. The project, if launched, could involve the development of a common, low-cost airframe to test an escape system that would be adaptable to both the Space Shuttle or a forthcoming crew transfer vehicle.
Tests would probably involve recovery of the Little Joe from the water, with tests expected to take place from the Kennedy Space Center, Florida, where the site is equipped to recover and refurbish the used solid-rocket boosters after each Shuttle launch.
The reusable glideback stage, dubbed "Fastpac", is based on a concept developed at Langley Research Center, and would support future second generation Shuttle studies as well as all-new RLVs. "If we build one, we might want to add an expendable upper stage to demonstrate the dynamics of separation as well as carry a payload into a transfer orbit," says London.
The more unusual looking Lunar tug study is designed to test aero braking technology and the concept of in-space refuelling. It is being seen as a potential precursor to an operational tug and, for cost reasons, is configured to fit within the Shuttle payload bay and attach to the X-37.
"It could move payloads from low-Earth orbit to geostationary orbit, or possibly to the International Space Station. It could even have the capability of putting a nominal payload out to the moon and would go into a free trajectory around the moon," adds London.
He also confirms that NASA is looking at changes to the X-34 as a fall-out of studies made after recent Mars mission failures. "In the wake of those failures, we have made a reassessment of the X-34 and one of the areas we've been looking at is avionics. We're coming to the conclusion that single string [little or no redundancy because of cost] is not adequate."
He adds that a main propulsion test article, which will test the X-34's novel MS-1 (formerly Fastrac) engine on the ground, is being considered. "I anticipate we will decide over the next few months to do these things."
Source: Flight International
