An MIT-industry experiment scheduled to be launched aboard the shuttle Endeavor tomorrow (March 2) will test ways to improve the performance of small spacecraft by seeking to control the vibrations caused when the instruments they carry are operated.
The problem has been a constant one, dating to Explorer 1, the first American satellite. More recently, the Hubble Space Telescope's solar panel vibrated every time it was heated or cooled, producing additional vibrations in the telescope that made detailed observations impossible. The solar panel was replaced during last year's Hubble repair mission.
During Endeavor's scheduled 16-day mission, the crew--which includes MIT graduates Wendy B. Lawrence, the flight engineer, and John M. Grunsfeld, the mission specialist--will repeatedly assemble and disassemble a small, compact "spacecraft" inside the shuttle middeck. The spacecraft, a 5-foot-long flexible beam, has several simulated instruments attached to it. The instruments will be operated simultaneously and the experiment will examine ways in which they can function without their motions interfering with each other.
For example, one instrument will move back and forth in a scanning motion that might be used by an imaging device seeking environmental data from a large section of Earth. Another instrument will simulate the precise pointing and aiming that might be required by a camera designed to focus closely and tightly on one section of Earth. The vibrations caused by the back-and-forth motion of the scanning image could make it difficult or impossible to precisely point the other camera.
The results from each day's tests will be transmitted to the Johnson Space Center in Houston, where members of the MIT team will analyze the data and transmit new programmed tests to the space shuttle for additional studies.
Such disturbances are difficult to anticipate and "design out" working in Earth's gravity, and the experiment-the Middeck Active Control Experiment (MACE)-will evaluate methods the MIT team has designed to accomplish this feat.
Professor Edward F. Crawley and Principal Research Scientist David W. Miller, both of the Department of Aeronautics and Astronautics, are the principal investigators. Professor Crawley heads the department's Space Engineering Research Center.
The experiment has been developed over five years and has involved several PhD students. Currently the students are Mark Campbell, Simon Grocott and Roger Glaese, all of aero/astro, and Timothy D. Tuttle of Mechanical Engineering, all working with aero/astro post-doctoral associate Ketao Liu.
The company involved is Payload Systems, Inc., of Cambridge, founded by MIT alumni. The president is Javier de Luis, a 1988 aero/astro graduate. Lockheed Corp. also was involved in the project, which was funded by NASA's In-Space Technology Experiments Program (IN-STEP) and administered at MIT through the Center for Space Research. The program fosters small, innovative technology experiments that can be developed in a relatively short time and for a fraction of the cost of most space hardware programs.
A version of this article appeared in MIT Tech Talk on March 1, 1995.