The Disposition of the Service Module of the Unmanned Space Experiment Recovery System (USERS) Spacecraft after the Completion of the Mission
- Paper number
IAC-07-A6.3.04
- Author
Dr. Koichi Ijichi, Institute for Unmanned Space Experiment Free Flyer (USEF), Japan
- Coauthor
Mr. Atsuo Ushikoshi, Institute for Unmanned Space Experiment Free Flyer (USEF), Japan
- Coauthor
Mr. Shuji Nakamura, Institute for Unmanned Space Experiment Free Flyer (USEF), Japan
- Coauthor
Mr. Tatsuro Ono, Institute for Unmanned Space Experiment Free Flyer (USEF), Japan
- Coauthor
Mr. Hiroshi Kanai, Institute for Unmanned Space Experiment Free Flyer (USEF), Japan
- Year
2007
- Abstract
The Unmanned Space Experiment Recovery System (USERS) Project has been completed with full success at February 25, 2005, and the Service Module (SEM) was properly disposed to the maximum extent as possible according to the IADC debris mitigation guideline. The USERS Spacecraft was self-return unmanned space experiment system, and consisted of the Re-entry Module (REM) and the SEM, and was launched on September 10, 2002. The REM was separated from the SEM and returned to the earth with on-orbit experiment results on May 30, 2003 while the SEM kept its operation on orbit with its own mission till end of January 2005. The SEM disposition at the end of the mission was not considered at the design phase, but fortunately the SEM has capability to change orbit, and more, the residual propellant was enough to lower the orbit and to set the attitude adequate for the SEM to enter the atmosphere within 25 years. The SEM disposition operation was performed according to the guideline as much extent as possible from February 1 to 25, 2005. The SEM disposition operation started from the orbit change operation. The orbit was lowered to approximate 470 km from 570 km orbit, and the operation to dissipate the residual propellant until it reached the minimum amount required to maintain necessary attitude. The tilt angle of the solar paddles was selected to supply the minimum power necessary to maintain bus system attitude control even in the worst case of the attitude. Finally, the attitude was set to the Sun Pointing Mode with rotation around the direction of the Sun, and the transmitter has been turned off at the end of the disposition operation. The current altitude of the orbit of the SEM is about 350km in February 2007 and expected to re-enter the atmosphere in the Middle of coming June 2007. In the presentation, after brief description and operation outline of the USERS Project and the spacecraft, the comparison analysis of the current guideline under discussion, the results of survivability and casualty analysis will be mentioned. Then, the actual strategy and the results of the disposition will be explained. USERS showed excellent example of realizing debris mitigation purpose in spite of originally unintended design baseline.
- Abstract document