|Shooting for Safety: Ballistics Team Helps Return Shuttle to Flight||
Aerospace engineer Matt Melis takes his work personally. He plays a key role in ensuring the safety of Discovery, the Space Shuttle that will carry his friend "Charlie" to orbit on a mission planned for this July. |
Melis met Mission Specialist Charles Camarda more than 20 years ago when they were both engineers. Today, Camarda is one of seven astronauts scheduled to fly on STS-114, the first Shuttle mission in more than two years.
"What could be more rewarding," Melis asked, "than to work on a mission that's so important to our nation and our space program and to know that one of your friends is flying on that mission?"
Image left: Melis and Camarda pose for a quick picture with the STS-114 patch and CD. Credit: Evannne Juratovac
Melis is team lead for NASA's Glenn Research Center Ballistics Impact Lab, where engineers test Shuttle parts for their ability to withstand hits from debris.
Built in 2000, the ballistics lab boasts three enormous gas guns that can shoot projectiles at speeds up to 3,000 feet per second -- that's more than 2,000 miles per hour. Despite their destructive tools, the engineers in this lab work hard to make sure such damaging blows won't occur when Discovery launches.
"We've performed thousands of tests over the past two years to identify all of the dangers that could impact the Shuttle wings, window and tank so that NASA can reduce those risks," Melis said. "This is an enormous responsibility, and we are deeply concerned about doing our best work."
Melis' team started testing Shuttle components in Feb. 2003 after Columbia broke apart while re-entering Earth's atmosphere. Launch videos showed that a piece of insulating foam the size of a briefcase had fallen off the External Tank and hit the Shuttle Orbiter wing. Accident investigators suspected that the foam had knocked a hole in the Reinforced Carbon-Carbon (RCC), a lightweight heat-shielding material on the leading edge of the left wing.
To test that theory, Melis and teammates Mike Pereira, Duane Revilock, Kelly Carney and Santo Padulo began a series of experiments that helped determine how foam and Reinforced Carbon-Carbon react to impacts.
The team shot small pieces of foam at reinforced carbon-carbon strips at speeds ranging from 1,500 to 1,900 feet per second. As the foam whizzed down the gun's long steel barrel, a high-speed digital camera captured the collision at 30,000 images per second. The photos showed the foam glancing off of the carbon as its layers bent, cracked and separated.
"In ballistics, intuition is rarely correct," Melis said. "I was amazed that a 2-gram piece of foam could break a reinforced carbon-carbon strip."
Three months later, at Southwest Research Institute near San Antonio, researchers were even more amazed to see what happened when they performed a full-scale ballistic impact test using a 1.7-pound piece of foam and an actual Orbiter wing. The foam shot a hole the size of a large pizza in the wing panel, prompting a collective gasp.
"I don't think anyone really expected to see a 16-inch square hole," Matt said. "In the blink of an eye, there it was, and hundreds of people immediately came to terms with how much damage a piece of foam can do."
Image left: Mechanics Jeff Hammel (left) and Jim Sexton (right) prepare a ballistics impact gun for testing as Aerospace Engineer Mike Pereira looks at a computer monitor that will display photos of the blast taken by a high-speed camera. Credit: NASA
Once the cause of the accident was determined, NASA switched its focus to redesigning the Shuttle fleet so that an accident like this would never happen again. The Glenn ballistics team continued to study the effects of foam, ice and other types of Shuttle debris on carbon-carbon panels, Orbiter windows and External Tank panels.
As a result of these tests and others across the Agency, NASA redesigned Discovery's External Tank, removing large pieces of foam, and added a heating system to prevent ice formation.
Data from the tests were used to create software that will help NASA predict the degree of damage if the Space Shuttle is hit by debris. Experts will use the analysis, combined with images from new cameras on the Shuttle, to determine a course of action.
Image right: On a recent trip to the Kennedy Space Center, Melis stood at the base of Discovery between its two towering Solid Rocket Boosters. Credit: NASA
In July, Melis will watch with pride as "Charlie" and the rest of the Discovery crew soar 250 miles above Earth's surface and begin a new era in space exploration. As for his teammates, they're happy just knowing that they've helped NASA return the Space Shuttle to flight.
"We're just proud to be a part of the whole process of finding out what happened in 2003 and returning the Shuttle to flight," Revilock said. "I'm sure we'll be very proud once it launches, knowing that we were a big part of helping the crew return safely."
Jan Wittry, (SGT, Inc.)
NASA's Glenn Research Center