Developing Launch Vehicles for the Mercury Space Program and Manned Spaceflight
Frustration, Then Finally Success
But of course, as Robert Burns observed, the best laid plans of mice and men–and even rocket scientists—‘gang aft a-gley’ (oft times go awry, in English).
The first flight test of a Mercury Redstone vehicle—MR-1—did not go as planned. The Redstone ignited and lifted about an inch off the pad. Then the engine shut down, the vehicle settled back on the pad, and the escape tower rockets ignited, but it did not pull the capsule off the rocket.
So nothing worked as it should have.
The Redstone was replaced with another vehicle, and the same capsule mated to it. Engineers determined the shutdown was caused by a booster tail plug that pulled out early. This was reworked, and MR-1A was readied for launch.
It was time to see if a living being could perform in space.
A chimpanzee named Ham got the job. MR-2 lifted off from the pad perfectly, but its trajectory was at a slightly high angle. And the engine was producing too much thrust. As a result, the vehicle exceeded the design velocity, subjected Ham to 17 Gs acceleration, and ran out of LOX (liquid oxygen) too soon. The good news was that all the safety systems worked. They sensed the low pressure in the engine and shut it down. The capsule abort system sensed the engine failure and immediately separated the capsule from the booster. A man would have been safe.
And how did Ham fare through all this? He was as happy as a chimp in the jungle. He performed every task he had been programmed for perfectly. Through the high acceleration he just went on as if everything was normal. Not even being weightless bothered him. Maybe men could survive in space after all.
But NASA wanted one more MR flight to make certain the booster was ready for manned flight. The causes of problems with MR-1A and MR-2 had been found and addressed. There was not another spacecraft available, so a boilerplate model was mated to the Redstone, now dubbed MR-BD.
The bird lifted off flawlessly, and flew a flawless trajectory. The Mercury Redstone was ready to put a man in space.
While engineers were man-rating the Mercury Redstone, other rocket scientists were attempting to man-rate the Mercury Atlas. They were having a more difficult time.
MA-1 lifted off perfectly, but 58 seconds into the flight, exploded catastrophically. The cause turned out to be the design of the Atlas
vehicle. The Atlas used ‘integral tankage.’ That is, the vehicle’s fuselage was the outer skin of the fuel tanks. A major weight saving measure, but with the 4300 lb Mercury craft atop an extended nose section, the thin fuselage flexed severely, causing the tanks to rupture.
To repair this problem, engineers installed trusses in the nose section of MA-2. This worked and MA-2 flew a successful suborbital mission. NASA was ecstatic and ready for an orbital test.
Their ecstasy was short lived.
MA-3, using an Atlas without integral tankage, was designed to orbit the spacecraft for one orbit. It lifted off flawlessly, but 40-seconds into the flight failed to execute its roll program. The Range Safety Officer destroyed it.
The spacecraft itself performed well, with a few glitches—that an astronaut could have easily solved.
It now was time to put Americans into space.
Credits
Mecury Redstone: NASA
Disaster on the pad: NASA
Mercury Redstone liftoff: NASA
Mercury Atlas: NASA
Mercury Atlas liftoff: NASA
This post is part of the series: The Mercury Manned Spacecraft Program
The U.S.’s first manned space program was Project Mercury. Seven Astronauts were chosen to fly the craft, six actualy did. John Glenn was the first American to orbit the Earth. Gordon Cooper was the last to fly in Mercury, orbiting for 22 orbits
