Astronauts test the Simplified Aid for EVA Rescue (SAFER) system some 130 nautical miles from Earth. The pair were actually performing an in-space rehearsal or demonstration of a contingency rescue using the never- before flown hardware. One wears the small back-pack unit with its complementary chest-mounted control unit, and the other is anchored to Discovery's Remote Manipulator System robot arm, took turns using the SAFER hardware during their shared space walk of Sept 16, 1994.