TMCnet
03/10/06
Researchers Still Tackling Shuttle Foam Problems
(Space Daily Via Thomson Dialog NewsEdge)Iowa State University researchers
are studying how X-ray backscatter imaging and computer simulations can help
NASA examine the insulating foam on the space shuttle's giant external fuel tank
to find any defects that could threaten future missions.
Unlike traditional X-rays that make images by transmitting radiation through an
object to a detector, backscatter technology makes images based on the
electromagnetic radiation deflected back by the objects examined.
Pieces of foam fell from shuttle Columbia's tank during its January 2003 launch,
causing serious damage to the spacecraft's left wing and resulting in the shuttle's
destruction when it re-entered Earth's atmosphere on Feb. 1. The accident killed
all seven astronauts aboard and grounded the shuttle while NASA engineers
worked to solve the foam problem.
When shuttle Discovery finally lifted off last July, more foam chunks fell from the
main fuel tank and sent engineers looking for more answers. The problem
threatens to delay the next scheduled launch of Discovery in May.
Late last year, NASA asked Joe Gray, of Iowa State's Center for
Nondestructive Evaluation, and his research team, to do a three-month study
to answer two lingering questions about NASA's foam testing: They wanted to
know more about the ability of X-ray technology to detect bubbles when layers of
shuttle foam curve around corners, and they wanted to know more about the
technology's ability to see any bubbles near the foam's layer lines.
The spray-on foam that insulates and protects the shuttle's super-cold external
fuel tank is applied in thin layers. The top of the layer dries to a bumpy crust,
marking each layer like rings mark a tree trunk.
The researchers have been taking X-ray images of foam samples and loading
that information into a computer simulation program. Then they ran simulations
that model the X-ray technology's ability to find defects in the foam.
Gray said he expects to send NASA a final report of the research results later
this month.
Our job has long been to do research, find new inspection technologies and
develop a better understanding of those technologies, said R. Bruce Thompson,
the center's director. Now we're seeing those technologies put into practice on a
real and national problem.
For the past four years, CNE researchers have been working on 17 NASA
research projects that have focused on finding new technologies to monitor and
inspect spacecraft.