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Science Floats

What a satellite can do, balloons can do cheaper.

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Whatever the predictions, balloons can't be launched in anything but a calm. The team members sometimes get dispirited when they have a run of bad weather, says Klein, but when the weather turns favorable, "you can get two off in three or four days. Then the world looks a lot brighter. Before then it's, 'Oh, I'm never going to go home.' [Then] boom, you get one off and you see the light at the end of the tunnel.

"There are a couple of other balloon programs in the world," he continues, "but we are the best. We fly the biggest balloons, the heaviest payloads, for the longest durations at the highest altitudes. It's an incredible high when you get one off."

The scientists have a different perspective. Jonathan Grindlay describes the long waits for a launch as "painful." "You're not able to do as much with your finite grant dollars," he says.

Fortunately, it didn't take a month to get Grindlay's X-ray telescope in the sky over Ft. Sumner. Less than a week after the first attempt, the telescope, which weighed 4,800 pounds, made it up. "High-altitude winds blew it to the east, towards Texas," NASA manager Steve Smith recounts. "Then those winds changed and blew it to the west. It crossed Interstate 25 toward evening, in clear sky and at very high altitude. A lot of people saw it and started making phone calls. They thought they were seeing a UFO from Roswell."

For Grindlay, the launch was worth the wait. His team was able to evaluate the properties of a small prototype X-ray detector, and a larger instrument provided spectra for further study of the well-known X-ray source Cygnus X-1. And the launch, supported by the Astronomy and Physics Division of NASA's Office of Space Science, cost less than $200,000. The balloon, a standard 40-million-cubic-foot model, cost about $120,000, plus another $12,000 for the helium to fill it. The cost of payload integration and launch services, about $25,000, was also absorbed by NASA, as par of the operating costs of the agency's National Scientific Balloon Facility.

Had Grindlay launched his payload on a Delta II rocket, it would have cost between $40 and $50 million for the service. Yes, the payload would have orbited and returned data for years, as opposed to hours. But the low cost of a balloon launch places it well within the budget of university research groups of modest size, and recently, a few noteworthy discoveries made by such groups suggest that scientists look again at the humblest of launch vehicles.

Not only is a balloon cheap to launch, the culture of balloon science encourages thriftiness in the assembly of payloads as well. One researcher avoided paying $30,000 for a space-related video camera and used an ordinary $200 security camera, relying on bathtub caulking when he needed additional electrical insulation. A gamma-ray telescope built by a team at the California Institute of Technology in Pasadena used home-movie video cameras to store data during the flight. One group of scientists, needing to protect photomultiplier tubes from stray light, fashioned shields from beer cans.

At Raven Industries, a balloon manufacturer in Sulphur Springs, Texas, senior engineer Mike Smith points out that in the world of balloons, "you don't see clean rooms. The instruments are built by guys wearing T-shirts and jeans. Probably every NASA flight has plywood as part of its payload," rather than the titanium honeycomb or similarly exotic materials used in satellites.

According to Mike Zimmerman, Raven's chief of quality control, payloads can also be cheaper because balloons can carry odd shapes that would have to be folded to fit onto a rocket, then unfolded in space. With balloons, he says, "you can have solar panels sticking out. You don't have to withstand G-loads" or strong vibrations of a rocket launch. Designers avoid costly test programs, since they don't have to demonstrate that their instruments can withstand such forces. In fact, balloons have served as test platforms for instruments that were later space-rated and flown on satellites. The Compton Gamma Ray Observatory, on of NASA's premier astronomical satellites, is one that benefited from balloon tests. The satellite helped astrophysicists learn about violent events occurring near quasars, neutron stars, black holes, and supernovae, or exploding stars. Such events produce gamma rays and X-rays, which the orbiting observatory was able to detect. "Every instrument on the Compton was first developed on a balloon," says Jonathan Grindlay.

Yet for all their usefulness, balloons have an ongoing problem: They don't stay up very long. Most flights last between 12 and 24 hours. Those launched from Ft. Sumner are not allowed to cross the Colorado River, the state line of California, because they would pose hazards to air traffic if they descended near Los Angeles. Those launched from the National Scientific Balloon Facility's main base in Palestine, Texas, must come down before they cross the border of Mexico, only a few hundred miles away, because that country will not allow overflights. Ground controllers send a radio command to release the payload and its parachute if winds carry it toward the border. That action tears the balloon, which, venting helium, descends. Even balloons that fly in Australia, crossing the Outback and the Indian Ocean, stay up no more than a few days.

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