Spatula
A PUTTY knife which drifted out of space shuttle astronaut Piers Sellers' tool kit as he did repairs is being tracked through space by Nasa.
The £1,100 spatula is being watched by military radars at 20 sites worldwide as it hurtles at 25 times the speed of sound towards Earth, orbiting the planet every 90 minutes.
But Nasa dismissed fears the tool could be a hazard to the shuttle or the international space station saying: "We have no concerns."
Shuttle commander Steve Lindsey filmed the spatula as it floated over Discovery and into space.
Mission controllers teased British-born Sellers by making him count his other five spatulas before he was allowed back aboard the spacecraft.
This image made from NASA TV, shows a close-up view of several carbon-carbon tiles and astronaut Mike Fossum's hands as he works with a test material and spatula in Discovery's payload bay .
Text Source: Mirror.co.uk / Photo: AP
Development of the repair techniques began soon after the fatal breakup of the shuttle Columbia in 2003, which was blamed on damage to the shielding from falling fuel tank foam insulation during the launch.
The results of the mock repairs will be returned to Earth aboard Discovery for experts to analyze.
The spacewalk was the third in five days for Sellers and Fossum. They worked from the open payload bay of the shuttle Discovery, floating before a work bench with a collection of tools that included caulk guns, putty knives, spatulas, thermometers and cameras.
"I'd call that a chemical engineer's dream day," quipped astronaut Julie Payette, who served as Discovery's liaison in Mission Control.
"I don't know about that, but it was kind of fun," Sellers said.
"It was the kind of day we were looking for," added Fossum.
But there were some glitches. One of the spatulas floated away from Sellers. One of Fossum's two safety tethers came unlatched.
"It looks like the spatula is gone, gone, gone," Sellers said. "I don't think anyone is going to find it."
Fossum re-latched his tether almost as soon as Discovery pilot Mark Kelly spotted the lapse as he watched through a shuttle window. Fossum was never in jeopardy, NASA spokesman Kelly Humphries said.
Sellers and Fossum dispensed a black-grey sealant from a pair of caulk dispensers, working the material into the cracked samples with spatulas and the putty knife. Their major challenge was overcoming the temperature swings that accompany the shuttle's constant cycling between sunlight and darkness as the astronauts orbit the Earth.
The spacewalkers used the sunlight to heat up the putty, a sealant mixed with a carbon-silicon carbide powder, after it was dispensed onto a palette. They mixed the material vigorously with their tools while trapped air and moisture boiled from the putty in the vacuum of space.
Then, they spread the goo rapidly over the cracks before the fluid became too thick as the temperatures dropped in the darkness.
"The crew did a great job," said NASA's Tomas Gonzales-Torres, who developed the spacewalk.
As a final task, Sellers and Fossum scanned their handiwork, as well as Discovery's wings, with a new camera equipped with temperature sensors that can detect internal damage not apparent from the surface of the heat shielding.
Discovery lifted off July 4 with a crew of five men and two women on only the second shuttle mission since Columbia's loss.
This week, mission managers announced Discovery hurtled into orbit without significant damage from falling foam or other forms of debris that would require repairs.
Text: mark.carreau@chron.com