They're the ones thinking outside the space capsule.
- By James Oberg
- Air & Space magazine, November 2003
NASA Langley Research Center
(Page 3 of 5)
The inflatable wing spars were made of nickel-chromium alloy mesh. For thermal protection, the mesh was saturated with liquid silicone and covered with another layer of silicone rubber. A vehicle returning from orbit would experience more heating than IMP had during its suborbital flight, and vacuum chamber tests showed that this material could handle temperatures of more than 2,000 degrees Fahrenheit. The wing material, says Keville, “resembled a lightweight burlap.” At first he had trouble finding a textile company that could handle the tricky job of weaving metal yarn, but he finally found one called Prodesco, in Perkasie, Pennsylvania. Keville spent weeks in the small town, which had “only one general store and a Quaker church.”
The FIRST lifeboat was designed to be folded up in a small container on the outside of a spacecraft. An astronaut abandoning ship would enter the pod through a small hatch leading to the outside. After inflating the paraglider with nitrogen fed through a hose or from gas bottles, the escapee would fire solid rockets in the central spar to deorbit the craft. The fall from orbit (400,000 feet) down to 120,000 feet would take half an hour, with attitude control jets used for maneuvering. Once it became aerodynamic in the lower atmosphere, the paraglider could be steered by changing the pressure within the inflatable spars to achieve a kind of wing-warping. The landing would take place anywhere within a footprint 450 miles wide and 1,400 miles long.
Five years of research convinced the FIRST engineers that the concept was feasible. Unfortunately, by the late 1960s it was no longer wanted. Neither Apollo nor Skylab, NASA’s first space station, were in the market for a bailout system, and the Department of Defense was already starting to back away from plans for its own station. Inflatable lifeboats had become the answer to a question no one was asking.
From the beginning, Brodsky had had grander things in mind for FIRST, based on futuristic schemes that Wernher von Braun and others were espousing at the time. “[FIRST] was begun to meet an apparent need for a wheel-like rotating space station,” he says. “It was terminated when it was apparent that we were too early. The idea of a [large] manned space station was no longer in vogue.”
That hadn’t stopped other engineers from exploring similar bailout concepts, though. Other companies had learned of the FIRST project, and throughout the 1960s they came up with various ways to improve on it. General Electric produced probably the most famous concept, called MOOSE (the acronym originally stood for Man Out Of Space Easiest, but the name was later changed to the more sober Manned Orbital Operations Safety Equipment). Instead of inflating the structure with gas, MOOSE engineers used fast-setting polyurethane foam to hold a conical shape; the hardware, which fit in a suitcase-like container and weighed 200 pounds, was even tested on a spacesuited volunteer.
Douglas Aircraft had a similar concept: Paracone, an inflatable shuttlecock-shaped structure made of Teflon-coated Rene-41 alloy fabric. The reentry vehicle was slowed to about 25 mph at impact, so no parachute was required, although the astronaut experienced about 10 Gs of acceleration.
The inflatable designs often were met with the same reaction from potential customers and other outsiders. “They were skeptical,” says Robert Kendall, who worked on Paracone at Douglas in the 1960s. He tried to overcome the doubts by pointing to inflatable structures used by the U.S. Navy: “I mentioned common, everyday inflatable structure applications such as truck tires, bags around payloads, vessel-side protective balloons.”
It was still a tough sell, and remains so, even though the idea has resurfaced more than once since then. In Russia, engineers at the Babakin Space Center in Moscow turned to inflatables in the 1980s to produce lightweight vehicles for descending to Mars. The Mars 96 mission included an inflatable aerobraking system to slow down two small atmospheric-entry probes meant to study the Martian weather. But the spacecraft went off course immediately after its launch in 1996, crashing down into the Andes Mountains.