MIT experiment flies on Atlantis
An MIT laboratory experiment that began in a swimming pool may help astronauts determine what it will be like to build a manned station in space before the turn of the century.
On Nov. 26, the astronauts of the space shuttle Atlantis blasted off into orbit with an experiment designed by the MIT Space Systems Laboratory (SSL) that examined the ability of humans to work outside the spacecraft.
Researchers at MIT hope that the experiment, called Experimental Assembly of Structures in Extra-vehicular activity (EASE), will provide valuable information needed to build the proposed space station currently scheduled for operation in 1993.
The EASE experiment is the<>
culmination of eight years of work by Prof. David L. Akin '74 and many MIT graduate and undergraduate students. Akin was a graduate student in the newly-founded SSL when he first started studying the productivity of humans in space.
The systems studies which he and other students performed on structures -- such as space stations, satellite solar power stations and space colonies -- all indicated that a person's productivity in space is a key parameter in the overall costs of projects. There was, however, little extra-vehicular activity (EVA) productivity data available.
The swimming pool
Akin designed a simple experiment as a graduate student under the direction of Prof. James W. Mar '41 and Prof. Rene H. Miller: the assembly of a pyramid-<>
shaped structure in the MIT Alumni Pool. The experiment consisted of eight six-foot-long aluminum beams with styrofoam flotation taped to them so that they would neither float nor sink, simulating the weightlessness of space.
The test subject, outfitted in<>
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scuba gear, assembled the structure while strapped in a harness which prevented him from swimming. The measured productivity was impressively high, so much so that the National Aeronautics and Space Administration (NASA) sponsored a series of experiments in NASA's Neutral Buoyancy Facility, a water tank 75 feet in diameter and 40 feet deep. The test subjects, MIT students, were able to wear space suits which better simulated the EVA environment.
The neutral buoyancy experiments showed that structural assembly in EVA is easier than the assembly of equivalent structures on earth. The simulated weightlessness improved the ability of EVA astronauts to assemble large space structures. The initial experiments showed the restraints for the astronauts were not necessary.
The astronauts could climb on the structure while assembling it, learning through experience how best to position themselves for the next task and adapting very quickly to the zero-gravity environment.
There was, however, little data for correlation between simulated EVA assembly in the neutral buoyancy facility on earth and actual EVA assembly in space. To take the final step, Akin proposed to NASA that it perform the identical experiment in space as on earth: assemble a tetrahedron.
On a warm, clear night late this November in Florida, EASE was launched into orbit aboard the maiden flight of space shuttle Atlantis, in a fiery display which could be seen 500 miles away, lighting the sky.
EASE was among four other shuttle payloads: three satellites and ACCESS, a comparison structural assembly experiment built by NASA. EASE consisted of six aluminum beams about 12 feet long, and four joint clusters which joined the beams together.
Astronauts Jerry Ross and Sherwood "Woody" Spring each took turns at the two work positions for assembling the tetrahedron during the two EVAs. The astronaut in the lower position was placed in foot restraints as he received the beams from the storage area in the shuttle cargo bay. He attached beams to the tetrahedron's vertex and passed them to the top of the structure where the second astronaut was positioned.
The second astronaut either held onto the structure or was attached to the Remote Manipulator System, which was controlled from within the shuttle by astronaut Mary Cleave. Ross and Spring were given basic assembly instructions for the EASE experiment, but were encouraged to adapt to their environment by modifying the procedures.
Learning and adaptation to the zero-gravity conditions were evident during the nine assemblies and disassemblies the astronauts completed. Correlation between neutral buoyancy tests conducted before the flight and the flight tests seem quite good, but the final results will not be known until all the data has been examined.
Akin stressed the involvement of MIT students in the SSL. The EASE experiment is the first safety-critical EVA experiment performed by NASA which was planned, designed and built by students. Under the direction of Akin and Research Associate Robert Wolf, graduate and undergraduate students were, and still are, involved in every aspect of EASE. When the video tapes of the flight are delivered to the SSL it will be students that examine and analyze the data.
The EASE flight is a first for the SSL, but not the last. There are many more future-looking student experiments currently under investigation which may progress to being flight experiments.
(Editor's note: Sarver is a graduate student in the Department of Aeronautical and Astronautical Engineering and is a member of the Space Systems Lab.)