SPHERES: An ISS facility for On-Orbit Validation of Advanced Spacecraft Control Algorithms

The MIT Space Systems Laboratory, in conjunction with NASA, DARPA, and Aurora Flight Sciences, developed and operates the SPHERES (Synchronized Position Hold Engage and Reorient Experimental Satellite) system to provide a safe and reusable zero gravity platform to test sensor, control and autonomy technologies for use in satellites, especially in the area formation flight. Developing these technologies enables new types of satellite systems to be developed.

The satelites are capable of rotation and translation in all directions. Twelve carbon dioxide thrusters are used for control and propulsion, and allow the satellites to manuever with great precision in the zero gravity environment of the station. Ultrasound beacons in the test area and ultrasound recievers on the satellites allow the SPHERES to determine their relative positions. There are three SPHERES satellites currently onboard the International Space Station, and there have been over sixty test sessions using the devices.

The original three SPHERES launched to the International Space Station in 2006. In the years since, the SSL has developed new hardware, such as a camera attatchment and a docking port. These projects expand the capablities of the SPHERES and allowing new and exciting research to be done with the platform. Additionally, SPHERES is the only free floating experiment onboard the station, and is used by a range of guest scientists for experiments which require movement in three dimensions unconstrained by gravity.

In the decade and a half since its inception, over thirty five graduate students and more than a hundred undergraduates have worked on the project, along with many engineers and reaserchers at Aurora Flight Sciences and Ames Reasearch Center.