NASA scientists and engineers are using high-tech components aboard the space shuttle Discovery to painstakingly inspect the spacecraft for launch-related damage as concerns linger about a piece of insulating foam that broke away from the craft's external fuel tank during liftoff.
Two laser sensors, a black-and-white camera and a 50-foot extension boom added to the shuttle's robotic arm allow NASA engineers to carefully peruse every square inch of the spacecraft's outer surface for flaws that could endanger its return to Earth after its 12-day mission.
So far, NASA officials have said that they don't believe that the 2.5-foot-long piece of foam struck or damaged the shuttle as it fell off the external tank during Tuesday's launch. But the inspections are being done to rule out any damage.
Also adding to NASA's worries is the apparent loss of a 1.5-inch section of one of the shuttle's thousands of ceramic heat shield tiles. The piece that dislodged is near the craft's front landing gear door. That area of the spacecraft is also being carefully reviewed by engineers back on Earth using the images from the sensors.
Since Tuesday's launch, the shuttle crew and the astronauts in the International Space Station have been taking photographs and laser images of the shuttle to allow engineers on Earth to evaluate its condition. The new lasers and boom extension were added to the shuttle after the shuttle Columbia was lost on re-entry in February 2003. On that flight, launch-related damage from a piece of foam that smashed into the leading edge of a wing caused a hole that allowed hot gases to enter and burn the ship from the inside upon re-entry, destroying the vehicle and killing all seven astronauts on board.
The exterior inspections of Discovery are being conducted as part of the mission's original schedule, said Debbie Rahn, a spokeswoman for the space agency, which is providing updated flight information online. "Obviously, we want to understand the state of the vehicle before the crew returns," she said. Images received so far by NASA have been very clear, helping engineers study the condition of the vehicle, she said.
The boom extension was built by the Brampton, Ontario-based space missions group of Canadian technology vendor MacDonald, Dettwiler and Associates Ltd., using spare parts from the original robotic arm. Herb Goettmann, an engineer at MDA, said the specialized laser sensors and camera positioned at the end of the extension can be operated by the shuttle crew to collect detailed images of tiles and protective panels. The data is then downloaded to engineers on Earth.
The extension doubles the length of the shuttle's robotic arm, and the camera and sensors each have a particular use. For example, NASA's Intensified Television Camera includes an adjustable zoom lens and can take black-and-white pictures in lighting conditions ranging from very dim to bright.
Another component is a Laser Dynamic Range Imager (LDRI) that was designed and built at Sandia National Laboratories in Albuquerque. NASA said the LDRI produces 2-D and 3-D image data as the sensor scans the shuttle surfaces. In 3-D mode, the scanner colors the images like a Doppler weather radar image, with each color representing the depth of surface irregularities.
The third device on the boom is a laser camera from Neptec Design Group Ltd. in Ottawa that scans the shuttle's surface and records data that can be used to create an image model of the surface. The camera uses the reflection of laser light beamed against the surface to measure the depth and other characteristics of any imperfections, said Iain Christie, Neptec's director of research and development.
NASA Administrator Michael Griffin pointed to the new technology in a statement on Wednesday announcing that the shuttles won't fly again until the foam-loss issue is corrected.
"As with any unexpected occurrence, we will closely and thoroughly evaluate this event and make any needed modifications to the shuttle before we launch again," Griffin said. "This is a test flight. Among the things we are testing are the integrity of the foam insulation and the performance of new camera equipment installed to detect problems. The cameras worked well. The foam did not."