Is It Safe?

Air & Space Smithsonian - - In The Museum -

Peo­ple have been trav­el­ing into the strato­sphere by bal­loon since 1931, when Au­guste Pic­card and Paul Kipfer rode in a pres­sur­ized gon­dola (Pic­card’s in­ven­tion) to 51,775 feet. A se­ries of Navy and Air Force pro­grams in the 1950s and 1960s used pres­sure ves­sels or pres­sure suits to get bal­loon­ists higher, some to above 100,000 feet. Sky­diver Ni­cholas Piantanida set an un­of­fi­cial record—123,500 feet— in 1966, but a later at­tempt went awry when his hel­met de­pres­sur­ized. His team brought the gon­dola down, but Piantanida suf­fered brain dam­age from lack of oxy­gen. He died four months later.

High-al­ti­tude bal­loon­ing had claimed other lives over the years, and the elab­o­rate life sup­port sys­tems cre­ated for both re­cent suc­cesses—fe­lix Baum­gart­ner’s well-pub­li­cized leap from 127,852 feet and Eus­tace’s later, higher one—make clear that as­cents to the strato­sphere re­quire care­ful plan­ning and pro­tec­tion. Aero­space engi­neers have pretty much mas­tered the “shirt sleeves” en­vi­ron­ment for air­planes and space cap­sules. Even in the worst-case life sup­port sce­nario, the cap­sule can al­ways de­tach and de­scend quickly back to breath­able air, says Taber Maccal­lum, the chief tech­nol­ogy of­fi­cer at World View. “The con­se­quences of a cat­a­strophic fail­ure in a bal­loon,” he says, “are sim­ply that you fly home.” In a sud­den de­com­pres­sion, he says, there is more than enough emer­gency oxy­gen on board. Zero2in­ifinty’s cap­sule will seal off af­fected sec­tions.

The ab­sence of oxy­gen and lack of pres­sure are the gravest threats, but not the only prob­lems. At high al­ti­tude, the tem­per­a­tures are frigid. In the vac­uum of space a cap­sule en­coun­ters no air mol­e­cules, so it loses heat rel­a­tively slowly through ra­di­a­tion. But when a bal­loon ris­ing to very high al­ti­tudes en­coun­ters in­creas­ingly colder air (as low as -112 de­grees Fahren­heit), heat is trans­ferred from the cap­sule’s sur­face to cooler air mol­e­cules just out­side, and strong wind quickly re­places the now-heated air mol­e­cules with cold ones. Prop­erly in­su­lat­ing the cap­sule is one of the trick­ier en­gi­neer­ing chal­lenges ahead, as is bal­anc­ing pas­sen­ger com­fort against avoid­ing prob­lems like win­dows fog­ging up.

Though it may seem coun­ter­in­tu­itive, the least safe por­tion of a stratospheric bal­loon flight is right af­ter launch, when the bal­loon is still close to the ground. If any­thing goes wrong, there isn’t much time for the pi­lot to open a para­chute and steer the cap­sule to a safe land­ing. One way to mit­i­gate the risk of trou­ble early in the flight is to take care that the ul­tra-

thin poly­eth­yl­ene bal­loon doesn’t tear, so World View will use a crane to stand the bal­loon up be­fore in­flat­ing it, by­pass­ing the tra­di­tional pro­cesses of un­rolling the bal­loon as it in­flates or lay­ing it out on the tar­mac, both of which are more likely to lead to a tear.

Both World View and Zero2in­fin­ity are plan­ning a fur­ther safe­guard against early bal­loon fail­ure: Open the cap­sule’s para­chute early, per­haps even be­fore liftoff. With the para­chute al­ready de­ployed, a fail­ure even at a few hun­dred feet would re­sult in the same drift­ing land­ing as if the cap­sule were de­scend­ing from on high. And the pas­sen­gers won’t feel a jolt when the cap­sule de­taches from the bal­loon. Still, both com­pa­nies plan to pack sev­eral backup chutes (those, should they be needed, would come with the cus­tom­ary jolt).

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