Hydrogen is a great rocket fuel, but it can be tricky to handle. The tiniest and lightest atom in existence, it finds the tiniest cracks, possibly into places where its extreme flammability becomes a problem.
(HySense leak detection tape)
In the early days of the space program, inspectors held brooms to the pipes as they slowly walked the lines. If the broom’s head began to burn, they knew there was a leak burning. Later, during the launches of the 1980s and ’90s, they used ultraviolet sensors to detect flames; to find non-burning leaks they began utilizing electrochemical and combustible gas sensors.
The team of researchers started with a Japanese patent for a hydrogen-detection tape that changes color when exposed to the substance, but they wanted to make the color change more noticeable. The team tested different combinations of the two active chemicals in the tape, palladium oxide and titanium oxide, to find a mix that had the right color contrast, could create a fast reaction and could be applied to a silicone-based tape.
Two years later, another team of scientists and engineers from Kennedy improved the tape to make it robust enough to withstand harsh conditions ranging from shuttle launches to unruly weather.
The tape got its first real-world test with the launch of STS-118 in 2007, where it quickly proved its worth: Kennedy’s area sensors detected the presence of hydrogen on the launch pad, and the hydrogen tape pinpointed the exact location of the leak so that crews could address it. Afterward, the tape was used for every launch through STS-134 in 2011, the program’s penultimate mission.
NASA and FSEC entered into a Space Act Agreement and a licensing agreement to sell the tape commercially, resulting in the creation of Rockledge, Florida-based HySense Technology.
Science fiction writers have been thinking about this problem for a long time. Heinlein wrote about tagalongs in 1948 for use inside space stations and space habitats.
However, the great Leo Zagat described the following method of leak detection in his 1932 story The Great Dome of Mercury:
"Look!" he grunted, and jerked a grim jaw at one of the dials. The long needle was moving rapidly to the right. "I can't hold the air pressure!"
"Wow, what a leak!" Darl started forward. "How's it below, in the mine?"
"Normal. It's the Dome air that's going!"
"Shoot on the smoke and I'll spot the hole. Quick, man!"
Thomas' long legs shot him out of the headquarters tent. Just beyond the entrance flap was one of the two gyrocopters used for flying within the Dome. He leaped into the cockpit and drove home the starter-piston. The flier buzzed straight up, shooting for the misted roof.
The Earthman fought to steady his craft against the hurricane wind, while his gray eyes swept the three-mile circle of the vault's base. He paled as he noted the fierce speed with which the white smoke-jets were being torn from the pipe provided for just such emergencies. His glance followed the terrific rush of the vapor. Big as a man's head, a hole glared high up on the Dome's inner surface. Feathered wisps of tell-tale vapor whisked through it at blurring speed.