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Shuttle Radar Topography Mission



The SRTM mast provided the baseline distance between the main antenna and the outboard antenna. In space, the mast with the outboard antenna attached to its end deployed from its canister in the payload bay to a full 60 meters (200 feet). The SRTM mast is the largest rigid structure ever to have flown in space.

Mast deployed and suspended from cable
Mast fully deployed at AEC Able. Shown from tip end.
Mast in canister
Mast with first few bays deployed from canister at AEC Able.
The mast used on the SRTM mission is the Able Deployable Articulated Mast (ADAM) built by the AEC-Able Engineering Company, Inc. of Goleta, California. The mast is a truss structure that consists of 87 cube-shaped sections, called bays. Unique latches on the diagonal members of the truss allowed the mechanism to deploy bay-by-bay out of the mast canister to a length of 60 meters (200 feet). The canister housed the mast during launch and landing, and it also deployed and retracted the mast.

The mast was deployed and retracted by a motor driven nut within the mast canister. This nut pulled the mast from its stowed configuration and into its deployed configuration. An astronaut inside the space shuttle initiated the mast deployment. The mast could have also been deployed manually using a hand-held motor.

See the AEC-Able SRTM web page for detailed information about the mast used on the SRTM mission.

Mast deploying from canister
Mast deploying from canister
AEC Able worker checks the mast cabling
AEC Able worker checks the mast cabling

Once in space and after Shuttle Endeavour's payload bay doors were opened, the mast was deployed to it's full 60 meter (200 foot) length. The outboard antenna, which remained in its stowed position atop the mast, was then slowly flipped over the end of the mast into its operation position. Mapping operations commenced shortly after.
Shuttle cargo bay with mast visible
The first few feet of the mast as photographed from Shuttle Endeavour's aft window
Photo of the mast and outboard antenna in space
The 60 meter mast with the outboard antenna in space
QuickTime Movies
  • Mast Animation: Animated version of the mast deploying in space. Includes "flip-over" of outboard antenna. (1.6M)
  • Mast Begin Deploy: The actual mast beginning to deploy from its canister in the Shuttle payload bay. (2.3M)
  • Mast Deploy: The mast deploys in this footage from space. (1.6M)
  • Mast Retract: The mast retracts into Shuttle Endeavour's payload bay. (1M)
Animated Gif Photos