In January 1980, NASA announced a contract to develop a kit for astronauts to repair damaged heat shield tiles on the space shuttle. No such kit has been flown on a shuttle in recent memory, but the release makes for interesting reading in light of the shuttle Columbia's catastrophic breakup during re-entry Feb. 1. Here is the text of the Jan. 22, 1980, news release:

RELEASE NO: 80-004
For Release Upon Receipt

MARTIN RECEIVES TPS REPAIR CONTRACT

NASA has signed a letter contract with Martin Marietta Aerospace, Denver Division, for the development and production of a Space Shuttle on-orbit thermal tile repair kit. The kit is designed for use by Shuttle crews to repair possible damage to any of the thousands of ceramic-based tiles which cover the Orbiter and protect it from intense heat during entry into the Earth's atmosphere.

The kit will not be flown on the first test flight but will be held in reserve for possible use on later flights where the launch environment approaches design conditions. The letter contract with Martin Marietta is preliminary to an official contract award and authorizes the aerospace firm to proceed with immediate design and development of the tile repair kit. Estimated value of the contract is $2.1 million.

The contract follows studies conducted by four aerospace firms for the NASA Johnson Space Center, Houston. Proposals for the production contract were received from General Electric Company, Philadelphia, Pennsylvania, and Martin Marietta Aerospace.

The contract calls for Martin to design and fabricate three repair kits for delivery to NASA. Two of the units are for flight use and the third is for astronaut training. The kit weighs about 300 pounds and will be stored atop the Auxiliary Equipment Storage Assembly in the Orbiter cargo bay.

There are two separate types of repair material: blocks of precured ablative material to fill in large holes and ablative paste which will be used as an adhesive for the replacement blocks as well as a cure-in-place filler to repair areas smaller than tile size. Each kit will contain 160 replacement blocks. Each block will be approximately six-by-six inches in size with varying thicknesses of 3/4-inch to 1.5-inch.

The blocks are principally made of silicone rubber which will ablate when subjected to the heat of reentry. The actual Orbiter tiles do not ablate during the heat of entry. The cure-in-place ablator is a paste-like substance with a silicone-rubber base. It will be applied with an applicator which resembles a conventional caulking gun. Eight applicator guns are included in the repair kit.

If necessary to perform repairs, a spacesuited astronaut would don a backpack maneuvering unit in the Shuttle cargo bay, inspect the outside of the Orbiter, and if necessary, use the kit to apply the ablative materials.

The backpack referred to above was the Manned Maneuvering Unit, or MMU, a large jet backpack developed and tested before the 1986 Challenger disaster. It has not been used since. A smaller jetpack known as SAFER (Simplified Aid for EVA Rescue) is currently available to space station construction crews as an emergency device for getting back to the station or a shuttle in the event a spacewalker somehow became untethered.

Whether a repair kit like the one described above is an option for future shuttle flights is not yet known. And still unresolved is how a spacewalking astronaut could make repairs on the belly of the shuttle where there are no anchor points or handholds.