Teapot-Sized Scanners Size Up Damage In Seconds
A new space shuttle tile inspection method using NASA-built,
wireless scanners is replacing manual inspection. The new process
begins with the upcoming shuttle mission, STS-118. Endeavour is
scheduled to launch from NASA's Kennedy Space Center in Florida on
Wednesday, August 8 at 1836 EDT.
Technicians have been using six new scanners to look for cracks
and other imperfections in some of the 24,000 tiles that cover
space shuttle Endeavour. The agency designed and built the new
tools at NASA's Ames Research Center in Moffett Field, CA. In the
past, workers at Kennedy 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."
The thermal tiles on the space shuttle protect it from the
extreme heat generated during re-entry into the Earth's 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 NASA's new
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 NASA's Johnson Space
Center in Houston. The unit should be completed in about two
months.