SAFER backpack test. Astronaut Mark Lee seen testing the Simplified Aid for EVA Rescue (SAFER) system during Shuttle Mission STS64. At left is part of the interior of the Shuttles payload bay. SAFER is a scaleddown version of the Manned Manoeuvring Unit (MMU) used in previous Shuttle space walks, and is intended to provide emergency freeflying mobility or a selfrescue capability to astronauts during extravehicular activity (EVA). SAFER clips around the normal life support backpack, and is powered by 24 fixed nitrogen thrusters. The nitrogen supply may be replenished during an EVA from the payload bay. STS64 flew on 920 September 1994.
