Payload Assist Module

The Payload Assist Module (PAM) is a modular upper stage designed and built by McDonnell Douglas (now Boeing), using Thiokol Star-series solid propellant rocket motors. The PAM was used with the Space Shuttle, Delta, and Titan launchers and carried satellites from low Earth orbit to a geostationary transfer orbit or an interplanetary course. The payload was spin stabilized by being mounted on a rotating plate.[1] Originally developed for the Space Shuttle, different versions of the PAM were developed:

  • PAM-A (Atlas class), development terminated; originally to be used on both the Atlas and Space Shuttle, designed for satellites up to 4,400 lb (2,000 kg)
  • PAM-D (Delta class), uses a Star-48B rocket motor, designed for satellites up to 2,750 lb (1,250 kg)
  • PAM-DII (Delta class), uses a Star-63 rocket motor, designed for satellites up to 4,150 lb (1,880 kg)
  • PAM-S (Special) as a kick motor for the space probe Ulysses

The PAM-D module, used as the third stage of the Delta II rocket, was the last version in use. As of 2018, no PAM is in active use on any rockets.

2001 re-entry incident

On January 12, 2001, a PAM-D module re-entered the atmosphere after a "catastrophic orbital decay".[2] The PAM-D stage, which had been used to launch the GPS satellite 2A-11 in 1993, crashed in the sparsely populated Saudi Arabian desert, where it was positively identified.[2]

  • PAM-D stage in assembly
    PAM-D stage in assembly
  • SBS-3 satellite with PAM-D stage being launched from Space Shuttle Columbia
    SBS-3 satellite with PAM-D stage being launched from Space Shuttle Columbia
  • Saudi officials inspect a PAM-D module that re-entered the atmosphere in 2001
    Saudi officials inspect a PAM-D module that re-entered the atmosphere in 2001

References
  1. "Payload Assist Module (PAM)". Global Security. Retrieved June 8, 2012.
  2. "PAM-D Debris Falls in Saudi Arabia" (PDF). The Orbital Debris Quarterly News. NASA Johnson Space Center. 6 (2): 1. April 2001.
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