EVA RETRIEVER FACT SHEET

Johnson Space Center (JSC)

March 25, 1988

     The EVA Retriever concept is an autonomous free flying robot 
for retrieving equipment or a spacewalking astronaut drifting in 
separated flight near the Space Station.  The device combines the 
proven manned maneuvering unit (MMU) with a robot latched in 
where an astronaut normally would be.  The MMU was flown eight 
times from the Space Shuttle's cargo bay in test flights and for 
satellite repair spacewalks.  

     Responding to voice commands from the Space Station crew, 
the EVA Retriever would activate and check itself out, search for 
and lock onto the "target," thrust toward, rendezvous with and 
grapple the target -- automatically avoiding any obstacles en 
route such as Space Station structures.  After grappling the 
target, the EVA Retriever would search for the Space Station and 
finding it, return home.  

     A ground-based prototype of the EVA Retriever is under 
development at JSC.  The project has just completed the first 
year of a 2-year program.  

     Television tracking and laser radar ranging signals are used 
by "smart" software in an onboard computer to plan and command 
search and rendezvous maneuvers in a simple environment without 
obstacles.  Robotic arms and hands are used to grapple the target 
when in range.  

     The developmental EVA Retriever currently is using nine 
words of a 200-word vocabulary to which it responds:  activate 
and quick-activate, search (tool, astronaut, home), rendezvous, 
reach (extend arm with open hand), grapple (close hand), manual 
(allows operator to modify Retriever's automatic sequencing), 
wait and shutdown.  Not only does the EVA Retriever carry out the 
commands it hears but it also acknowledges those commands with a 
human voice.  

     In JSC ground tests, the EVA Retriever is "flown" in two 
dimensions on a 3-thousandths-inch layer of compressed air on the 
Precision Air-Bearing Floor.  

     If the EVA Retriever is approved and funded for space 
operations, the device first would be tested from Space Shuttle's 
cargo bay before signing on for permanent employment aboard the 
Space Station in the 1990's.  

     The EVA Retriever is a joint development of the JSC Tracking 
and Communications Division, Crew and Thermal Systems Division, 
Systems Development and Simulation Division and Avionic Systems 
Division.  

     Industry participants in the EVA Retriever development 
are:  Martin Marietta Aerospace, MMU; Odetics, 3-D imaging laser 
radar; McDonnell Douglas Astronautics Co., video tracking system; 
Inmos Corp., central computer; Votan, voice control system; 
Remote Technology Corp., robot arms/hands; and JSC (in house), 
software, retriever body and hands.

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