The Payload Assist Module (PAM) is a modular upper stage designed and built by McDonnell Douglas (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. 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

• PAM-D (Delta class), uses a Star-48B rocket motor, designed for satellites up to

• PAM-DII (Delta class), uses a Star-63 rocket motor, designed for satellites up to

• PAM-S (Special), uses a Star-48B as a kick motor for the space probe Ulysses

The PAM-D module was used as an optional third stage of the classic Delta rocket. The PAM-D was discontinued after the Challenger accident. A simplified 3rd stage using the STAR-48 motor was employed on Delta II.

2001 re-entry incident

On January 12, 2001, a PAM-D module re-entered the atmosphere after a "catastrophic orbital decay". 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.

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References

External links

• Payload Assist Module at the NASA Shuttle Reference Manual

• Payload Assist Module at GlobalSecurity.org