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High-Altitude Drop Tests Rocket U. Engineers
08.16.12
 
The capsule as it starts fall Image above: The capsule and instruments built by Rocket University participants begins its descent to Earth from 105,000 feet. Photo credit: NASA
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The high-altitude balloon pops Image above: The high-altitude balloon that carried the capsule 19 miles inot the air pops, releasing the capsule to fall back to the Earth. Photo credit: NASA
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An engineer shows capsule for drop test. Image above: Ron Sostarick shows the capsule built by Kennedy's Rocket University team before it is sent aloft and dropped from a high-altitude balloon. Photo credit: NASA/Jim Grossmann
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The high-altitude balloon and drop capsule Image above: The rig set up by Rocket University linking a high-altitude balloon with a mechanism to carry and then release an aerodynamic capsule for an evaluation of its handling characteristics. Photo credit: NASA/Jim Grossmann
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An engineer shows capsule for drop test. Image above: Leandro James, left to right, Alejandro Azocar, Ron Sostaric and Chris Iannello discuss a high-altitude balloon flight for the Rocket University program. Photo credit: NASA/Jim Grossmann
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An experimental payload went 25,000 feet higher than planned during a recent test flight but still performed well and will be the basis for a larger flight test next year.

"I think avionics-wise it went beautifully," said Chris Iannello, part of the team at NASA's Kennedy Space Center in Florida that launched a high altitude balloon to the edge of the atmosphere and then tracked an instrument package they built as it free fell back to Earth. "We were all real pleased with it."

The engineers intended for a shoebox-sized capsule loaded with instruments to be carried under the balloon to about 80,000 feet and dropped to test the stability of the capsule's aerodynamic design.

But when a wire didn't burn through correctly, the package held onto the balloon as it floated up to 105,000 feet. The balloon burst at that height, sending the instrument package into a terminal velocity free-fall before automatically deploying its parachute.

"It sent data all the way, recorded data on board, changed collection rates as programmed during descent, and performed its automatic chute deployment spot on," Iannello said. Teams that launched the payload from Melbourne Beach recorded the instrument readings and tracked the package as it descended, eventually landing near Kissimmee.

Johnson Space Center in Houston designed the capsule to find out whether it can work as a design for returning payloads safely from space.

Kennedy teams built the large scale version of the capsule and the electronics inside that would control the flight. These electronics, which were test flown on this small scale launch included components to measure navigational data such as attitude and position and a camera. These sensors were connected to a central control processor that was programmed to carry off tasks at an appointed time. An SD card slot was also included. The team also had to write the software that would handle the electronics and transmit the data to tracking groups.

"Prior to Rocket University, I had no experience making controllers," said Kelvin Ruiz. "It gets real personal when it's in the air."

Known more for their work with rockets, the engineers who built the instruments and launched the balloon are taking part in Rocket University, a program designed to challenge NASA engineers. Rocket University, or just "Rocket U," lets engineers perform hands-on work they might not otherwise do, and requires them to work with other centers and apply techniques to different disciplines.

"I thought balloons were going to be the least exciting," said Leandro James, adding that rocket payloads have to be built robust to handle launch loads for missions lasting only a couple minutes. "But to me it's been the most exciting. We have to plan for three- to four-hour (flights)."

The balloon flight was the second major test flight for the Rocket University group at Kennedy. The first one, with a smaller set of instruments, was also successful. This time, the instrument requirements were more precise, the capsule was bigger and the balloon and other parts had to be larger, too.

The demands for precision were also greater, without being suffocating. In other words, if things went wrong, the engineers didn't have to worry about losing an expensive mission. It was large scale flight project like experience gained on a small scale, low cost, and low risk platform.

"The first flight was a lot of 'just get it to work,' " said Nicole Otermat, who took part in both missions but had just given birth when the first flight took off. "I have an appreciation for why you go through months of design and systems hardware."

The payload demands will increase again on the Rocket U participants as they prepare a 200-pound capsule to fly on a much larger balloon next year provided by NASA's Wallops Flight Facility from a launch site in New Mexico.

Before that, the team plans to work with unmanned aerial vehicles and rockets. The work calls for payloads to be tested on low-altitude rockets first, then higher-performance launchers up to sounding rockets and perhaps orbital craft.

"We're learning by doing, working our way up through hardware and methods," Iannello said. "We're doing it in the logical progression with the next step begin real time operating systems and from there Field Programmable Arrays with soft-core processors."

 
 
Steven Siceloff
NASA's John F. Kennedy Space Center