Editing Explorer II (section)

==Background==
In January 1934, the [[National Geographic Society]] (NGS) and the [[United States Army Air Corps|U.S. Army Air Corps]] decided to collaborate on a program to build and launch a manned balloon to the then record altitude of {{Convert|15|mi|km|abbr=on|disp=flip}}. This vehicle would be capable of carrying a crew of three in an airtight capsule, along with a laboratory of instruments. The hydrogen balloon, named ''Explorer'', was completed by July at a cost of around $60,000; {{Inflation|US|60000|1934|fmt=eq}} currency.<ref name="Ryan2003"/>

The balloon was launched from a canyon in the [[Black Hills]] of [[South Dakota]]—dubbed the [[Stratobowl]]—on July 28, 1934 and reached a near-record altitude of {{Convert|60613|ft|m|abbr=on|disp=flip}}<ref name="Shayler2000"/> before tears in the fabric led the crew to begin reducing their altitude. A rupture in the balloon resulted in a precipitous descent, followed by a spark that caused the hydrogen to ignite and destroy what was left of the balloon, leaving the capsule to plummet toward the ground at [[terminal velocity]]. The crew just managed to escape using their parachutes, with the last man bailing out at {{convert|500|ft}} above the ground. Their capsule was almost completely destroyed upon impact.<ref name="Ryan2003"/><ref name="AmExp"/>

The crash resulted in a national embarrassment, leading Captain [[Albert W. Stevens]], the scientific observer on board the ''Explorer'' balloon, to lobby for another attempt with an improved balloon to be named ''Explorer II''. But news of the [[Osoaviakhim-1|fatal crash of a Russian stratospheric attempt]] in 1934 left President [[Gilbert Hovey Grosvenor|Gilbert H. Grosvenor]] of the NGS sobered by the risk.<ref name="DeVorkin1991"/> A review of the crash by the [[National Bureau of Standards]]<ref name="DeVorkin1991"/> (NBS) was held between July and September, revealing that the balloon had not opened symmetrically during the ascent, causing stresses that led to the fabric tears. A month-long delay prior to launch had allowed the rubberized cotton to stick together, which created the uneven expansion. The hydrogen explosion followed when the gas in the bag mixed with the oxygen in the atmosphere.<ref name="Shayler2000"/>