Press Release

Mission Complete: APL-Operated Midcourse Space Experiment Ends

After more than 12 years of successful operations and contributions to two diverse defense missions, the APL-built and -operated Midcourse Space Experiment (MSX) satellite is retiring. Having operated well beyond its designed four-year life span, ground crews from APL and the Air Force shut the spacecraft down on July 10, turning off transmitters and draining its batteries, and are verifying the spacecraft's inoperable status this week.

In January, several of the spacecraft's remaining operational systems began to fail, rendering it too "sick" to continue, says MSX Program Manager Glen Baer, of The Johns Hopkins University Applied Physics Laboratory (APL) Space Department. Its remaining horizon sensor failed; the attitude processor, used since launch to safely "drive" the spacecraft, locked up and didn't recover. While switching to the other attitude processor - no trivial task, says Baer - the battery nearly froze and then a gyro failed, as expected.

Shutting a spacecraft down isn't an overnight process. "Through July 10, we verified various Air Force regulatory processes and procedures used to disable the spacecraft," Baer says. "Using MSX's Space-Based Visible [SBV] sensor, we also collected data to test some theories and concepts for the Space-Based Surveillance System Pathfinder, the follow-on to the SBV sensor for detecting and tracking deep-space objects."