SPHERES tethered formation flight testbed: Advancements in enabling NASA?s SPECS mission

Soon Jo Chung, Danielle Adams, Alvar Saenz-Otero, Edmund Kong, David W. Miller, David Leisawitz, Enrico Lorenzini, Steve Sell

Research output: Chapter in Book/Report/Conference proceedingConference contribution


This paper reports on efforts to control a tethered formation flight spacecraft array for NASA's SPECS mission using the SPHERES test-bed developed by the MIT Space Systems Laboratory. Specifically, advances in methodology and experimental results realized since the 2005 SPIE paper 4 are emphasized. These include a new test-bed setup with a reaction wheel assembly, a novel relative attitude measurement system using force torque sensors, and modeling of non-ideal tethers to account for tether vibration modes. The nonlinear equations of motion of multi-vehicle tethered spacecraft with elastic flexible tethers are derived from Lagrange's equations. The controllability analysis indicates that both array resizing and spin-up are fully controllable by the reaction wheels and the tether motor, thereby saving thruster fuel consumption. Based upon this analysis, linear and nonlinear controllers have been successfully implemented on the tethered SPHERES testbed, and tested at the NASA MSFC's flat floor facility using two and three SPHERES configurations.

Original languageEnglish (US)
Title of host publicationAdvances in Stellar Interferometry
StatePublished - 2006
Externally publishedYes
EventAdvances in Stellar Interferometry - Orlando, FL, United States
Duration: May 25 2006May 30 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6268 I
ISSN (Print)0277-786X


OtherAdvances in Stellar Interferometry
Country/TerritoryUnited States
CityOrlando, FL


  • Formation flight
  • Space tether
  • Stellar interferometer

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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