When NASA introduced the Mercury astronauts to the country during a press conference in 1959, getting them to space wasn’t a problem. The Redstone and Atlas rockets were on their way to being man rated and the agency had settled on a blunt body capsule for the Mercury spacecraft over competing spaceplane designs. Landing the capsule was a different matter. How to bring the astronauts back from space alive was much less straightforward.
Rocket launches weren’t new. One of the earliest recorded uses of rocket technology making something fly is by the Greek Archytas. Sometime around 400 B.C., he was known to amuse citizen of his native Tarentum by using steam to propel a wooden pigeon suspended on wires. It was a very early proof that every action has an equal and opposite reaction. In the modern era, American Robert Goddard pioneered the use of liquid fuels to send rockets to high altitudes. Hermann Oberth’s written accounts of rockets used for spaceflight inspired many young German engineers, among them Wernher von Braun who developed the V-2 and later the Jupiter, Redstone, and Saturn family of launch vehicles.
In 1959, nothing sent into space had landed back on Earth. Early rockets were launched to gather data on flight characteristics; how the rockets landed was less important. In 1948 the US Air Force had begun launching rodents and monkeys on low sub-orbital missions on recovered V-2s and Aerobee sounding rockets, but the parachutes designed to bring the capsules to a soft touchdown didn’t always work. An unfortunate number of rats and monkey lost their lives when parachutes failed and they slammed into the ground from an altitude of about 40 miles.
The only things that had been recovered from orbit were film canisters as part of the CIA’s Corona Program. The canisters were jettisoned from orbiting satellites and were slowed by small parachutes on their fall towards the ocean. To avoid the film falling into the wrong hands, USAF aircraft flew above the canisters and snagged the parachutes with hooks to collect them in mid air.
When it came time to choose a landing system for Mercury, this was all the experience NASA had to build on. In 1960 the Space Task Group – the group behind the Mercury program – entertained proposals for different landing methods.
Some ideas from within NASA reflected the agency’s experience with parachutes with simple proposals using a parachute to slow the capsule’s fall to a soft touchdown on land or on the ocean. More complicated proposals sought to turn the capsule into a controllable spacecraft. Replacing the parachute with a parasail would give the astronaut inside some directional control over the capsule as it fell. The US Air Force proposed a multistage progressive landing system program in this vein that would see parachute controlled touchdowns develop into controllable parasail landings. One proposal took pilot control to the extreme and advocated adding small wings to the side of the capsule.
Engineer Francis Rogallo from the Langley research centre proposed an inflatable triangular paraglider wing. It would inflate after the capsule passed through the fiery atmospheric reentry, giving the capsule some lift during its descent. By pulling the cables that attached the wing to the capsule, the astronaut inside could gain directional control and land on a preselected runway. The US Navy proposed a similar inflatable paraglider wing that would enable astronauts to make a controlled landing on the ocean.
Some ideas stood out as less practical than others. Adding wings to the capsule, for example, was an expensive modification that would make the capsule too heavy for the Atlas launch vehicle. Land landings by parachute or parasail were equally problematic, demanding the capsule be reinforced to protect the astronaut for the shock of a land landing.
The Rogallo wing was the most intriguing idea. It combined the ease of a parachute descent with moderate directional control but took away the hard land landing a straight parachute descent would entail. But it was complicated. At the time there weren’t any full scale models complete and using the landing system risked putting the Mercury program further behind schedule and that wasn’t an option. The race to the Moon hadn’t begun, but there was certainly a race underway to get a man in space first.
With speed a key factor, splashdowns emerged as the best choice in the short term; letting the capsule fall from orbit and land on the wide yielding target provided by the Atlantic and Pacific oceans. It wasn’t a universal favourite landing method – the astronaut in particular hated being passengers during their landing – but it did the trick. It gave NASA a simple way to bring its astronauts home safely while allowing the agency to focus on the more pressing questions, like how men would cope with the physical and mental stresses of spaceflight.