Demonstration and validation of formation flying algorithms in the microgravity environment of the International Space Station
Objectives
The objective of the SPHERES-JPL Guest Scientist Program is to allow TPF-I to test formation flying algorithms on the SPHERES satellite formation flight laboratory on-board the International Space Station (ISS). The formation algorithms to be demonstrated include optimal formation reconfiguration and optimal reactive collision avoidance, both critical for the operation of TPF-I.
Testbed Description
SPHERES is a satellite formation flight laboratory developed by the Massachusetts Institute of Technology Space Systems Laboratory. SPHERES is operable either in two translational dimensions on a terrestrial flat floor or in three translational dimensions inside the Destiny Module on the International Space Station (ISS). Each twenty-centimeter diameter SPHERE has the full functionality of a nano-satellite with twelve cold-gas thrusters for propulsion, ultrasonic and infrared transmitters and receivers for position sensing, on-board processing, wireless communications, and power storage.
Prior to testing on the ISS, the TPF-I formation algorithms will be tested in the ground-based SPHERES laboratory at MIT. Test sessions on the ISS will occur approximately every three months. Therefore, researchers from the TPF-I Project will nominally have four test sessions on the ISS per year, resulting in eight test sessions over two years. Within each test session, ~20 minutes of testing time is available. This estimate is conservative based upon past operational experience with SPHERES on the ISS. If more test sessions become available, more test time can be provided to TPF-I.
The Principal Investigator for SPHERES is Prof. David W. Miller, the Director of the MIT Space Systems Laboratory (MIT-SSL) and the Principal Investigator for Formation Flying Algorithms is Dr. Fred Hadaegh of the Jet Propulsion Laboratory.
Progress to Date
Six SPHERES have been built. Three remain on the ground for the SPHERES terrestrial testbed. As of December 2006, three SPHERES are also on the International Space Station. At the ISS, MIT has tested its own algorithms for slew, docking, and station-keeping as well as two-SPHERES formation control, attitude tracking and position following. In April
2007 MIT performed the three-SPHERES formation rotation test shown in the video (right).
In 2007, JPL is adapting TPF-I formation algorithms to run on-board the SPHERES nano-satellites to test aspects of formation guidance and collision avoidance.
External Links
References
A. Saenz-Otero and D. W. Miller, "SPHERES: a platform for formation-flight research,"
UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts II, Proc. SPIE 5899, 58990O (2005).
E. M. Kong, M. O. Hilstad, S. Nolet, and D. W. Miller, "Development and verification of algorithms for spacecraft formation flying using the SPHERES testbed: application to TPF," New Frontiers in Stellar Interferometry, SPIE Proc 5491, 308-319 (2004).
E. M. Kong, A. Saenz-Otero, S. Nolet, D. S. Berkovitz, and D. W. Miller, "SPHERES as a Formation Flight Algorithm Development and Validation Testbed: Current Progress and Beyond," 2nd International Symposium on Formation Flying Missions & Technologies, September 14-16, 2004, Washington, DC.
J. Enright and M. Hilstad, "The SPHERES Guest Scientist Program: Collaborative Science On the ISS," 2004 IEEE Aerospace Conference, Big Sky, Montana (2004).
Miller, D.W., Kong, E.M.C., and Saenz-Otero, A., "Overview of the SPHERES Autonomous Rendezvous and Docking Laboratory on the International Space Station," 26th Annual AAS Guidance and Control Conference, Breckenridge, CO, 5-9 February, 2003.
