Just In Time, NASA Develops New Scanner To Check Damaged Heat-Shield Tiles
Starting with the landing of Space Shuttle Endeavour from its STS-118 mission, technicians will have a new scanner to check for damage — which, coincidentally, occurred on the Endeavour orbiter vehicle heat shield tiles during launch last week. (Please see separate story.)
The new space shuttle tile inspection method using NASA-built, wireless scanners is replacing manual inspection.
Before Endeavour launched, technicians used six new scanners to look for cracks and other imperfections in some of the 24,000 tiles that cover the space shuttle.
The agency designed and built the new tools at Ames Research Center in Moffett Field, Calif. In the past, workers at Kennedy Space Center visually analyzed tiles and measured dings and cracks with small hand-held scales.
“The new method is much faster and more accurate because the depth and volume measurements of the flaws and their locations are wirelessly transmitted into a computer database,” said Joe Lavelle, a senior engineer and project manager at Ames. “This tool allows the inspectors to determine with very high confidence whether a shuttle tile needs to be replaced or just repaired.”
“When they made the measurements manually with the scales, they had to estimate the volume of flaws to a worst-case value because they could not precisely measure the volume with any accuracy,” Lavelle explained. “With this scanner, they will actually save tiles and the time-consuming process of replacing them.”
Thermal tiles on the space shuttle protect it from the extreme heat generated during re-entry into the atmosphere. After each shuttle lands, technicians go through a very rigorous and lengthy process to assess the surface of the tiles for any damage.
Each scanner weighs approximately 2.9 pounds and is about the size and shape of a small teapot. Technicians place the machine on the tile’s flaw to scan it. In about three seconds, the data are computerized and archived.
Engineers can scrutinize computerized 3-D pictures of the flaws. The images show the length, width and depth of the flaws on the surface of the tiles. Although engineers designed the instrument to scan space shuttle tiles, it also could scan reinforced carbon-carbon material used on the leading edges of the shuttle’s wings.
Engineers developing a heat shield system for the next-generation U.S. spaceship Orion already are using a larger, desktop version of the scanner to study heat shield samples tested at Ames.
NASA is building a second desktop scanner for use at Johnson Space Center in Houston.
The unit should be completed in about two months.
For high-resolution images of the scanner, visit: http://www.nasa.gov/mission_pages/shuttle/news/wireless_scanner.html