The ERBS spacecraft was deployed from
Space Shuttle Challenger on October 5, 1984 (first day of flight) using the Canadian-built RMS (Remote Manipulator System), a mechanical arm of about 16 m in length. On deployment, one of the solar panels of ERBS failed initially to extend properly. Hence, mission specialist
Sally Ride had to shake the satellite with the remotely-controlled robotic arm and then finally place the stuck panel into sunlight for the panel to extend. It had a design life of two years, with a goal of three, but lasted 21 years suffering several minor hardware failures along the way. The command memory was subject to random bit flips since launch. The ERBE scanner failed in 1990. There was a partial memory failure in October 1993. One of two Digital Telemetry Units failed in April 1998. In September 1999, a failure in the elevation gimbal of the non-scanner instrument suspended solar measurements for the solar monitor. Measurements resumed on December 22, 1999, when a new command sequence was defined. Only one of the five gyros was still functioning at the end of the mission, and thruster performance was unstable. During decommissioning, it was discovered that the fuel tank bladder had failed. By the end of the mission, battery 2 had experienced 5 cell failures and been disconnected from the main bus; and battery 1 had experienced 3 cell failures. In 2002, the satellite's perigee was lowered more than 50 km to ensure that the vehicle would naturally decay within 25 years after its end of mission. This proved to be wise, because when the spacecraft was finally decommissioned in 2005 the propulsion and attitude control systems had become so degraded that the risks associated with eliminating the remaining fuel by performing post-science mission delta-V maneuvers were deemed too significant, and therefore those maneuvers were not performed.
Decommissioning and re-entry The order to decommission the satellite was issued on July 12, 2005, and efforts began at that time. The instruments were turned off in August and the active steps began in September. During decommissioning, the last of the fuel was depleted, the batteries were discharged, the tape recorder was played back one last time, on-board memory was scrubbed and the solar arrays were disconnected from the battery. On the final ERBS contact, during its 114,941st orbit, the attitude and momentum control system was disabled and the power system was put in discharge. The final commands opened the thrusters to allow the remaining fuel to seep out, and the transponders were powered off for the last time. The satellite is believed to have
re-entered the Earth's atmosphere on January 8, 2023, at 6:04 PM
HAST over the
Bering Sea near the
Aleutian Islands. Most of the satellite is believed to have been burned up in the atmosphere, but some large pieces may have survived and fallen to the sea. Prior to re-entry, NASA had estimated the odds that the falling debris would cause any injury at about 1-in-9,400. ==Discoveries==