NASA is evaluating potential in-orbit inspection and repair techniques for the Space Shuttle using a 10-camera motion capture system developed by OMG subsidiary Vicon Motion Systems.

The system consists of high-resolution, high frame-rate Vicon cameras, reflective strobe illuminators, a data station to control the cameras and the strobes, and software to process datastreams in real time. For the tests, the reflectors are fitted to the astronaut's spacesuits, backpack and tools, and the movement measured in a range of simulated zero-gravity manoeuvres.

"The idea was to develop procedures so that on future Space Shuttle missions the crew can perform an EVA [extra vehicular activity] to check for the depth of pitting in tiles and for other damage," says Vicon business development manager Jon Damush. "The second part was to work out ways of repairing any damaged tiles to make them good for one re-entry."

Tests were conducted in simulated zero-g environments by Johnson Space Center's anthropometry and biomechanics group using the agency's Precision Air-Bearing Floor (PABF), and the Boeing KC-135 parabolic zero-g test aircraft. The PABF is a frictionless steel floor over which heavy objects slide on a film of compressed air. The suited astronauts tried out combinations of approach angles, force and speed.

"They calculate from this how much fuel they need in the jetpack to resist the reaction forces, and that impacts the duration of the planned EVA," says Damush, adding that the PABF test series was repeated in the KC-135, which can replicate zero-g for up to 30s. A second framework for the Vicon camera system, identical to that surrounding the PABF, has been installed in the KC-135 and is being retained for future experiments.

Source: Flight International