SPHERES Flight Operations Testing and Execution

Paper number

IAC-07-A2.6.03

Author

Ms. Swati Mohan, Massachussets Institute of Technology (MIT), United States

Coauthor

Mr. Steven Sell, Payload Systems Inc., United States

Coauthor

Dr. David Miller, Massachussets Institute of Technology (MIT), United States

Year

2007

Abstract

SPHERES (Synchronized Position Hold Engage Reorient Experimental Satellites) is a formation flight testbed consisting of a set of three satellite operating inside the International Space Station (ISS).  The goal is to use the long term microgravity environment to mature formation flight and docking algorithms.  The operations processes have also matured over the course of the first five test sessions; the planning for each test session building on and streamlining the previous methods.  This paper describes the evolution of the SPHERES program operations processes from conception to implementation to refinement through flight experience.  

The conception of SPHERES operation was initially formulated to begin in 2003, when the original launch was scheduled for May 2003 on STS-116.  However, due to the Space Shuttle Columbia accident, operations were indefinitely postponed.  In March 2006, the SPHERES team received word that the first satellite would launch in April, with operations beginning on May 18, 2006.  Planning consisted of three major aspects: procedures, test plan/flight note, and graphical user interface content.  Each of these aspects was developed for a specific purpose for the first test session.

The modifications to these major sections were based on experience and feedback from Marshall Space Flight Center, USAF Space Test Program office at Johnson
Space Center, and the crew of Expedition 13 (first to operate SPHERES on station).  Important modifications include limiting information passed to the crew, creating a test “success Mark”, and developing generic criteria for when a test should be re-run. 

The maturation of the processes can be tracked through the level of effort in creating each test session.  The amount of effort for the first two sessions involved the entire flight team preparing the files for the preceding month prior to delivery.  By the fifth test session, the process was streamlined to a little under two weeks, with the equivalent full time effort of half of the flight team.  The paper evaluates each test session as a case study, and describes the change in processes and the impact on the outcome of the test session.  SPHERES had very successful initial test sessions in that they allowed for modification and tailoring of the operations processes to streamline the code delivery and to tailor responses based on flight experiences. 

Abstract document

IAC-07-A2.6.03.pdf

Manuscript document

IAC-07-A2.6.03.pdf (🔒 authorized access only).

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