You’ve all seen the iconic picture of the US astronaut riding gracefully upon his NASA-built MODOK chair. That astronaut was Bruce McCandless II, Houston’s capsule communicator during the moon landing mission, Challenger crew member, and the driving force behind America’s ability to conduct operations outside of the stuffy confines of space shuttles and international stations. Without McCandless, there’s no guarantee the US would have EVA capabilities today. Wonders All Around, exhaustively researched and written by McCandless’s son, Bruce III, explores McCandless the elder’s trials and tribulations during NASA’s formative years and his laser-focus on enabling astronauts to zip through space unencumbered by the mass of their ships.

Wonders All Around cover
Greenleaf Book Group

Copyright @ 20201 Bruce McCandless III. Published by Greenleaf Book Group Press. Distributed by Greenleaf Book Group. Design and composition by Greenleaf Book Group and Kimberly Lance. Cover design by Greenleaf Book Group, Shaun Venish, and Kimberly Lance. Cover image courtesy of NASA, photographed by Robert L. “Hoot” Gibson

In his long leaden days of waiting for a spaceflight, my dad found the route to redemption on the back of an aging cartoon character. From the afternoon in December 1966 that he first tried out the Manned Maneuvering Unit in a Martin Marietta simulator, he was hooked on a vision of a gas-propelled jetpack that would allow astronauts to operate outside their spacecraft. This vision had an obvious pop-culture antecedent. In the 1920s a comic-strip character named Buck Rogers — a rock-jawed, All-American World War I veteran — succumbed to the effects of a mysterious gas he encountered while working as a mine inspector. He fell into a deep sleep and woke after five centuries of slumber to a strange new world of spaceships, ray guns, and Asian over-lords. Though he initially traveled this new world via an antigravity belt, a device that allowed him and his best gal, Wilma, to leap great distances at a time, Buck eventually acquired a svelte and evidently omnidirectional jetpack. He eventually ventured into space in an adventure called Tiger Men from Mars, and his exploits in the cosmos changed America’s vision of the future forever. Millions followed Buck’s adventures in the funnies, on radio, and in movie serials. Among Buck’s imitators and spiritual heirs are Flash Gordon, Brick Bradford, John Carter of Mars, and Han Solo.

A host of talented men and women spent significant amounts of time and money to wrestle that jetpack out of the funny papers and into the space shuttle. None worked harder, though, than Bruce McCandless and his chief collaborator, an Auburn-educated engineer and Air Force officer named Charles Edward (“Ed”) Whitsett, Jr. Whitsett was a pale, bespectacled individual, mild-mannered but tenacious. He had a head start on my father. He’d been thinking and writing about jetpack technology as early as 1962. In a sense, he was trying to solve a problem that didn’t exist yet: Namely, how could an astronaut venture outside his or her spaceship and perform constructive tasks in an environment with no oxygen, with extreme temperature fluctuations, and in an orbital “free fall” that would leave the spacefarer lolling in the practical equivalent of zero gravity? Alexei Leonov of the Soviet Union and American Ed White had proven that extravehicular activity was possible, that men could survive outside of their space capsule, but basically all they’d done was float. How could a man move from one part of a spaceship to another, or from one spacecraft to another craft, or from a spacecraft to a satellite, in order to make inspections or repairs? None of these needs really existed in the early sixties, when the programs of both nations were still just trying to fire tin cans into low Earth orbit and predict, more or less, where they would come back down. But clearly the needs would eventually arise, and various methods were proposed to address them.

In the mid-sixties, the Air Force assigned Whitsett to NASA to supervise development of the Air Force’s Astronaut Maneuvering Unit. Gene Cernan’s failed test flight of the AMU on Gemini 9 in 1966 — the “space-walk from hell,” as Cernan called it — set the jetpack project back, but it never went away. McCandless, Whitsett, and a NASA engineer named Dave Schultz worked quietly but assiduously to keep the dream alive. They enlarged and improved the AMU all through the latter half of the decade and into the seventies. In the “Forgotten Astronauts” wire story that portrayed him as a washout in 1973, my dad mentioned the reason why he wanted to stay in the manned space program despite not having won a crew assignment on either Apollo or Skylab. “McCandless,” said the article, “has helped develop the M509 experimental maneuvering unit. The Skylab astronauts strap it on like a backpack and propel themselves Buck Rogers — like around the Skylab interior. [He] wants to build a larger operational unit to perform space chores outside the shuttle.” And that’s exactly what he did.

Though the Skylab M509 tests in 1973 and 1974 were a resounding success, resulting in the triumph of the jetpack concept over both rocket boots and the handheld maneuvering unit, Whitsett and McCandless didn’t rest on their laurels. Over the next several years, using whatever time and funding they could scrape together, the team made multiple upgrades — eleven, by one count — to what was now being called the “manned maneuvering unit,” or MMU. The bulbous nitrogen-gas fuel tank of the ASMU was replaced with two streamlined aluminum tanks in the rear of the unit, each of which was wrapped in Kevlar. The number of propulsion nozzles was increased from fourteen to twenty-four, positioned around the jetpack to allow for six-degrees-of-freedom precision maneuvering. Smaller gyroscopes replaced those used on the ASMU, and, as space historian Andrew Chaikin has noted, the ASMU’s “pistol-grip hand controllers, which were tiring to operate in pressurized space suit gloves, were replaced by small T-handles that needed just a nudge of the fingertips.” The MMU’s new arm units were made to be adjustable, to accommodate astronauts of all sizes. Painted white for maximum reflectivity, the unit was built to survive the 500-degree fluctuation in temperatures (from a high of 250 degrees F to a low of minus 250 F!) that an astronaut might encounter in space.

By 1980 the machine weighed in at 326 pounds. Like the AMU and the ASMU before it, the MMU was designed to fit with or “over” the astronaut’s pressure suit. Shuttle astronauts wore a newly designed suit called the Extravehicular Maneuvering Unit, or EMU, a two-piece marvel of textile engineering made up of fourteen layers of Nylon ripstop, Gore-Tex, Kevlar, Mylar, and other substances. Power for the jetpack’s electronics was supplied by two 16.8-volt silver-zinc batteries. Two motion-control handles — the translational hand controller and the rotational hand controller — were mounted on the unit’s left and right armrests, respectively, and a button activated an “attitude-hold mode,” which used motion-sensing gyroscopes to direct the firing of the thrusters to maintain an astronaut’s position in space.

The machine had been tested in every way its designers could imagine. A representative of a local gun club visited Martin Marietta and shot the MMU’s nitrogen fuel tank with a .50 caliber bullet to ascertain whether the tank would explode if pierced. (It didn’t.) The jetpack was run through hundreds of hours of simulations. At my father’s urging, a gifted and intense Martin Marietta project manager named Bill Bollendonk subjected the device to space-like conditions in the company’s thermal vacuum facility. The MMU was no longer a “far out” experiment, as Mike Collins once called it. It was now a promising space tool. Unfortunately, for the moment, it was still an unused space tool. American astronauts remained on Earth, as NASA struggled to produce its next-generation orbital workhorse, the space shuttle.

All products recommended by Engadget are selected by our editorial team, independent of our parent company. Some of our stories include affiliate links. If you buy something through one of these links, we may earn an affiliate commission.

Source link

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.