Preventing Another Space Shuttle Disaster

NASA engineers are using a new 3-D wireless scanner to inspect the space shuttle's heat-insulation tiles for flaws.

NASA engineers have developed a new 3-D wireless scanner to detect and measure damage to the space shuttle's heat-insulation tiles--the type of damage that led to the 2003 Columbia disaster. Both before the shuttle's launch and after its return, the handheld device can quickly scan the surface area of a tile, map it in 3-D, and if there is a crack or ding, calculate its dimensions. The data is wirelessly transmitted to an onsite laptop where engineers can assess the damage more accurately and efficiently than was previously possible and determine whether or not the affected tiles need to be replaced or repaired.

Tile inspection: NASA engineers are using a 3-D wireless scanner to inspect the tiles on the space shuttle for imperfections. The scanner weighs about two and a half pounds and measures six by five by seven inches. It creates a 3-D surface map of a nine-square-inch area, which it wirelessly transmits to an onsite laptop. The scanner calculates the dimensions of any crack or ding it finds, so engineers can reliably assess the damage and determine how to repair it. Credit: NASA

The scanner was used for the first time to inspect the space shuttle Endeavour preceding its launch on August 8, 2007, from NASA's Kennedy Space Center. "The longest, biggest, and most tedious job engineers have is the inspection of the thermal protection system before, during, and after a mission," says Joe Lavelle, a senior engineer at NASA Ames Research Center and the project manager. But for the safety of those on board, he says, it's also one of the most important.

Currently, an engineer who finds a flaw on a tile, like a crack or ding, must measure it with a ruler in order to estimate the extent of the damage. For the foreseeable future, engineers will continue to perform visual checks--which remain faster than dragging the scanner across the entire surface of the shuttle--but the scanner will give them extremely precise measurements of any imperfections, so they can better decide whether a tile needs to be replaced or just repaired.

The scanner weighs approximately two and a half pounds and is about the size of a heavy-duty flashlight, making it small and light enough for an engineer to carry around during inspection. It is also wireless and thus has no encumbering cables. When an engineer notices a damaged tile, she places the scanner over it and with the press of a button produces a 3-D scan of a nine-inch-square area and also calculates the dimensions--length, width, area, and volume--of the defect.

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The resulting 3-D surface map is wirelessly transmitted to an onsite laptop so engineers can immediately review the data. The speed of the scanner saves time, and its accuracy makes measurements more reliable, says Lavelle. "Replacing and repairing tiles is a vital function in the maintenance of a spaceship because you have to have a thermal protection system that has integrity. Otherwise, you are going to have major problems, like accidents that we have had," he says.