SBS-3 satellite with PAM-D stage inside the space shuttle
PAM-D stage in assembly
The Payload Assist Module (PAM) designed and built by McDonnell Douglas Astronautics Co., Huntington Beach, Calif is a modular upper stage operated with Thiokol Star series solid propellant engine, used with the Space Shuttle, Delta, and Titan launchers. The rocket was used to carry satellites from a low earth orbit to a geostationary transfer orbit or an interplanetary course. The payload was spin stabilized by being mounted on a rotating plate. Originally developed for the Space Shuttles, different versions of the PAM followed:
- PAM-A (Atlas class), development terminated
- PAM-D (Delta class), uses a Star-48B rocket motor
- PAM-D2 (Delta class), uses a Star-63 rocket motor
- PAM-S (Special) as a kick motor for the space probe Ulysses
The PAM-D module, used as the third stage of a Delta II rocket, is the only version in use today.
Saudi officials inspect the crashed PAM-D module.
On January 12, 2001, a PAM-D module reentered the atmosphere after a "catastrophic orbital decay". The PAM-D stage, that had been used to launch a GPS satellite in 1993, crashed in the sparsely populated Saudi Arabian desert, where it was positively identified.