Exploring Space on the Cheap

By Frederic Golden

Compared to the space station, balloons seem positively retro, something out of Jules Verne. Even today's sophisticated high-altitude models are little more than helium-filled sacs with gondolas swinging beneath them, rising no more than 20 or 25 miles, barely twice as high as military jets and complete captives of the wind. Yet while ballooning may seem the antithesis of the space age, it is exciting renewed interest as a low-cost alternative to costly orbital labs.

Nowhere was this more evident than last week at the Goddard Space Flight Center in Greenbelt, Md., where several dozen space scientists gathered to consider a new generation of so-called superpressure balloons. Floating to the very edge of the earth's atmosphere, these gossamer giants (as tall as 60-story buildings) will remain aloft up to 100 days. That's enough time to look for such elusive phenomena as planets in other solar systems, black holes and remnants of the Big Bang. Says astrophysicist Josh Grindlay, leader of a Harvard-Smithsonian group that uses balloons to map distant X-ray sources: "For some science, they're going to give the shuttle or space station a run for the money."

That's not just hot air. "You'll not only be able to send up instruments cheaper than by rocket (for less than $2 million, vs. $40 million for the least expensive Delta launcher)," says astronomer Jack Tueller, program scientist for NASA's balloon project, "you'll also be able to assemble and launch your package quicker and carry more weight--up to 3,000 lbs.--and the instrument isn't subjected to vibrations or high Gs." Moreover, the scientific gear (though not the balloon) will be recoverable, drifting back to earth by parachute at the end of a mission. Scientists, to be sure, have been flying high-altitude balloons since the 1950s. But there was always a major drawback: as the balloons rose, the sun's heat expanded their gas, and helium had to be vented to keep the balloon from exploding. Then, as the sun set and the gases contracted, ballast had to be dropped to keep it aloft. Missions rarely saw more than one or two sunsets.

With skins of an ultrathin, steely composite of polyester and polyethylene ("like sandwich bags," says Tueller), the new balloons will withstand pressures created by stratospheric solar heating and retain enough helium to circle the globe five to 10 times. The first of NASA's smaller trial balloons is to be launched in March 1999, to be followed a year later by a demonstration flight carrying a Washington University cosmic-ray detector. Over the horizon Tueller sees more astronomy and astrophysics experiments as well as Earth monitoring, such as observing the ozone hole, and perhaps even semipermanent balloons to replace some of the cellular-phone towers dotting the landscape. Assuming, of course, there's any money left over from the space station.

--By Frederic Golden