Whenever commercial aircrew fly, they're exposed to cosmic and solar radiation.
The exposure is even greater if they're flying across one of the poles — say, from Chicago to Berlin — where radiation levels are higher, or roughly equivalent to a chest X-ray.
"It's not too terribly much, it's not constantly life-threatening," said Kevin Daugherty, aerospace engineer at NASA Langley Research Center in Hampton.
But it's enough, he said, that commercial aircrew are classified as radiation workers, just as if they worked at a nuclear power plant.
This month, NASA Langley will be launching four instruments on a science balloon from Fort Sumner, N.M., to gather, Daugherty said, a "good, quantitative measure for exactly how much radiation that is."
The project is called the Radiation Dosimetry Experiment, or RaD-X, and it's the first time those four instruments — one on loan from the University of Surrey in England — will be flown together and at such altitudes. They'll also fly for the first time in concert with a research plane from NASA's German counterpart, the German Aerospace Center, to collect even more data.
The information they gather will be key to confirming the first physics-based analytical model to determine biologically harmful radiation levels in aviation in real time, NASA said.
The model is called NAIRAS, for Nowcast of Atmospheric Ionizing Radiation for Aviation Safety, and will be used to help enhance safety not only for those aboard aircraft but also for astronauts on Soyuz crew capsules and the International Space Station. NAIRAS is headed by Christopher Mertens at NASA Langley.
The largest instrument in RaD-X is an industry standard called the Tissue Equivalent Proportional Counter, or TEPC, that simulates the interaction of radiation with human tissue, Daugherty said. The other instruments use silicon similar to computer chips and regular electronics to interact with radiation and measure it.
According to Amanda Moore Cutright, RaD-X chief engineer, it's a "challenging scientific problem, putting together all the components that come together in order to do the science."
Their balloon launch is one of four scheduled out of Fort Sumner. The first launched Monday, and the last is set to go Sept. 17.
If weather and winds cooperate, RaD-X will launch around 8 a.m. Sept. 11 aboard the smallest balloon at the facility. But "small" is relative — it still comes in at a massive 4 million cubic feet, compared to the largest balloon of 40 million cubic feet, Daugherty said.
The largest has been compared in size to the volume of the Superdome in New Orleans, he said, and estimates the smallest would compare to the Hampton Coliseum.
The balloon is made of extremely lightweight clear plastic that will be infused with helium to only 1 percent of its capacity, as the gas will only expand in the thin atmosphere of 107,000 feet.
"One percent full would still be 40,000 cubic feet of helium," Daugherty said. "That's enough to lift the balloon off the ground."
It will float at that altitude for 10 hours, gathering radiation data. After sunset, the helium will cool and the balloon will start to descend naturally, helped along with valves strategically releasing helium until it drops to between 69,000 and 88,500 feet. There, it will sit for 10 more hours taking measurements.
By the time the sun rises again, the mission will be nearly over. The payload will be cut from the balloon to descend to Earth via parachute. A hole will be ripped in the balloon to force it to land in a "nice, safe desert region," Daugherty said.
Data and training
After they recover the payload, they'll begin processing the raw data. The goal, he said, is to release the first data sets to other scientists within a month, and to the public within three months.
The RaD-X mission also has a training component, said Cutright, offering others in NASA an opportunity to take on new roles or transition in their careers.
"The idea is that you learn best when you are actually doing and putting your hands on the hardware," Cutright said. "So for a lot of our team this was the first time they were generating an engineering design and presenting that and defending it with peers and for us to fabricate it, build it and then go fly it."
The mission also includes 100 small experiments from the agency's Cubes in Space program for students ages 11 to 18. Each cube measures only 4 centimeters, or about 1 1/2 inches.
"Students have proposed everything from little electronics experiments to see if the radiation up there affects little tiny computers, to flying seeds, to flying marshmallows, to flying just about everything they can think of," Daugherty said.
Dietrich can be reached by phone at 757-247-7892.