Designing the First Manned Spacecraft
Designing a spacecraft from scratch was not an easy task. The basic shape—the truncated cone—was already decided upon, but there were many other factors up in the air. For one…the heatshield. Should it be a solid heat sink like the current ICBM reentry vehicles, or an ablating heat shield, that is, one that the material turns from solid to gas under extreme heat, and carries the heat away from the capsule? There were proponents for both, and not a lot of give on either side.
Eventually the ablating shield won out, especially when, in a test, the heat sink was detached from the capsule and fluttered down like a leaf, actually coming back to hit the capsule.
Less contentious was the escape system for emergencies to take the space craft away from the booster in a catastrophic failure. There was no argument, this was required. Two types of systems were proposed. One used solid rockets at the back of the capsule to push it away from the booster. The other used solids on a tower at the front of the capsule to pull the craft away from a distressed booster.
The latter offered clear advantages. It did not impact the booster, and was simpler to eject once the capsule was on orbital insertion mode.
But the most contentious factor was the role of the pilots. Engineers had designed the Mercury to be totally automatic. The pilots would merely be passengers. When the seven astronauts toured the factory and were briefed on the design and their role, they, to a man, balked. They were pilots. They intended to fly this thing.
Fortunately, there were a few engineers who agreed with them, and saw man as an integral part of the package. And to everyone’s surprise, the psychiatrists and psychologists evaluating the astronauts agreed. Man could, and had to be, in control of the craft.
The engineers went back to the drawing boards in a hurry. They designed two astronaut controlled systems—a fully manual system and a ‘fly-by-wire system’. Fly-by-wire sends commands to a computer that then controls the reaction control jets. A ‘joy stick’ controller was designed, so the astronaut could exercise control with one hand, even under the rigors of reentry.
The Astronauts decided to give names to their individual spacecraft, and to commemorate the seven of them, put '7' in the names.
Meanwhile, the escape and recovery systems were being tested at Langley Research Center’s Wallops Island launch facility on a solid booster called Little Joe. Almost as a warning of things to come, the first Little Joe flight was a pad disaster. Thirty minutes before launch time, the escape tower motors suddenly ignited and took to the sky.
Subsequent Little Joe flights were more successful, proving the efficacy of the escape and recovery systems.
It was now on to the real thing.