Experimental Picosatellites Launched from Space Shuttle
EL SEGUNDO, Calif. (12/18/02) -- Experimental miniature satellites built by The Aerospace Corporation in collaboration with the Jet Propulsion Laboratory are serving as pathfinders for a new capability that might become the standard for conventional satellites: autonomous inspectors.
The miniatures, a pair of picosatellites that measure 4-by-4-by-5 inches and weigh only 2.2 pounds each, were launched from space shuttle Endeavour on December 2 as part of a series of test flights researchers hope will result eventually in autonomous "ridealong" spacecraft that can be released on command to inspect parent satellites.
Inspectors
As envisioned, these inspectors will feature an onboard imaging capability and other sensors, which will enable them to assess spacecraft damage and provide rapid feedback to spacecraft operators on the ground, thus helping to ensure continual service to users and optimum spacecraft longevity.
The series of MEPSI missions leading to this capability is funded by the Defense Advanced Research Projects Agency (DARPA). MEPSI stands for microelectromechanical systems (MEMS)-based picosat inspector.
The project, spearheaded by Dave Williamson of the Air Force Research Laboratory's Information Directorate at Rome, New York, calls for incremental advances that will result in autonomous and fully functional inspector satellites comprising MEMS components, such as radio frequency switches, gyros, accelerometers, and thrusters. The principal payload aboard the picosats launched December 2 consisted of inertial measurement units comprising MEMS angular rate sensors and accelerometers.
Deploying Tiny Satellites
The diminutive satellites, connected by a 50-foot non-conducting tether to facilitate detection by ground-based radar and emulate formation flying, were ejected from a spring-loaded launcher built by The Aerospace Corporation and installed in Endeavour's cargo bay.
The launch demonstrated the capability of deploying picosat-scale satellites (one kilogram, or 2.2 pounds, and under) on virtually any shuttle flight.
"This (launch) capability is extremely valuable for low-cost ready access to space by anyone developing technology to picosat scale," said Ernie Robinson, Aerospace principal investigator.
During the three-day mission the picosats transmitted signals to the ground station at Menlo Park, California, and performed inertial measurement unit exercises.
The Johnson Space Center Office of the Air Force Space Test Program, a unit of the Space and Missile Systems Center at Los Angeles Air Force Base, was a key participant in this mission, enabling shuttle flight operations, supporting the integration of picosat hardware onto the shuttle, and supporting ground operations.
Successful missions employing DARPA-funded, Aerospace-built "first-generation" picosats, measuring 1-by-3-by-4 inches and weighing one-half pound each, were completed in 2000 and 2001. They were aboard parent satellites launched by Air Force Orbital/Suborbital Program "Minotaur" launch vehicles.
A pair of picosats was deployed from a Stanford University student satellite in February 2000 and another pair was deployed from the Air Force Research Laboratory's MightySat 2.1 technology satellite in September 2001.
