OAK RIDGE, Tenn. — The NASA shuttle Discovery, now circling the Earth on a 12-day space mission, was originally set to launch last November when a hydrogen leak and then multiple cracks in the fuel tank were discovered, grounding the mission.
The sleuth technology that helped detect the fuel tank fissures before liftoff was manufactured in East Tennessee and was put to work in the months since, readying the shuttle for last week’s takeoff. The Discovery is scheduled to return home Tuesday after its final voyage.
Nucsafe, headquartered in Oak Ridge, Tenn. supplied the equipment, which uses a technique known as X-ray backscatter imaging to inspect the shuttle’s fuel tank as well as carbon composites, heat shield material on the orbiter and spray-on foam.
In the intervening months, teams of Nucsafe employees have made trips to Florida to assist in the Discovery effort after the original mission was scrapped.
"We were doing inspections when they first found a problem all the way back in October and November," said Daniel Shedlock, scatter X-ray imaging director for Nucsafe. "They decided to roll the whole shuttle back into the assembly (area)."
Making trips in November and January, when more cracks were discovered, Nucsafe’s crews were sent to the Kennedy Space Center to support customer and NASA contractor United Space Alliance with additional equipment and staff for the shuttle inspections, Shedlock said, noting that at one point, Nucsafe had a two-man crew on site, pulling up to 12-hour shifts as they worked 24 hours a day to help ready the shuttle for flight.
Shedlock has been working with the space program using X-ray backscatter since 2003, following the disastrous Columbia mission when a piece of insulation foam dislodged from the shuttle on liftoff, damaging the wing and ultimately resulting in the loss of the shuttle and crew as the spaceship re-entered the Earth’s atmosphere.
Then a nuclear engineering student at the University of Florida, Shedlock helped launch the use of X-ray backscatter imaging for evaluating the integrity of the shuttles. X-ray backscatter equipment has been used to inspect spray-on foam insulation on the external tank of every shuttle to go in space since Columbia, Shedlock said.
Nucsafe, which got its start making equipment for detecting radioactive materials, licensed the technology from the university and brought Shedlock on board in 2007.
"It’s exactly the same thing you see all over the news for (airport) screening," he said. "You shoot out a beam of X-rays and you measure what’s bouncing back."
Unlike medical X-rays, "you don’t have to have a sensor or imaging panel on the other side," he said, allowing the X-rays to do their work while scanning just one side of an object. Nucsafe sells a high-resolution version of the technology for high-end inspections such as government and commercial aerospace. The machine is portable — the version used to inspect the shuttle measures about 18-by-30 inches — and can be manufactured in a variety of configurations, including a robotic option, depending on the need of the customer. In addition to United Space Alliance, customers include Lockheed Martin Space Systems, Boeing, Gas Technology Institute and several government agencies. The technology could at some point become part of the mission itself, Shedlock said.
"They’ve been entertaining the idea of putting X-ray into outer space. We haven’t gotten that far yet," he said.
The business brings Nucsafe several million dollars a year in revenue, and the company is beginning to more aggressively market the product.
"We’re hoping to hit more than $10 million this year," he said. "We’re getting more market recognition and (demand is) also growing."
As for Nucsafe’s space work, Shedlock admits he feels connected to the success of a shuttle launch knowing the company’s technology and expertise are a key part of the mission’s safety.
"You don’t want to make a mistake," he said.
But work, not nerves, kept Shedlock, who has watched previous launches, from seeing Discovery lift off last week.
"I was just really busy," he said.
Larisa Brass is a freelance contributor to the Knoxville News Sentinel.