Gemini 4 launched on this date in 1965, and almost immediately Jim McDivitt gave us our first practical lesson in orbital mechanics:
[R]endezvous in space is a kind of puzzle, where you have to start at the ending and work backward. If there’s a space station in orbit, and I want to get my spaceship to it, where do I have to put my spaceship so that as I either slow down or speed up, the space station gets closer and closer to me, and we are able to meet at a point in space?
That is just the start of the weirdness of navigating in space. Your human intuition—based on 30 or 40 years of living on Earth and rendezvousing with things all the time: a doorway, the curb, freeway entrance ramps—is not only useless in space but it also tells you to do the wrong thing.
...In the early days of spaceflight, rendezvous wasn’t just hard and counterintuitive; it was scary. NASA feared that a failed rendezvous at the Moon, for instance, would leave two astronauts in the lunar module, orbiting in the wrong place, out of fuel—and therefore, doomed.
NASA’s first effort to use astronauts to rendezvous failed, and failed spectacularly, in just the way one might have imagined for a species of gravity-bound, novice space travelers.
...McDivitt and White were the first astronauts—Russian or American—to attempt a rendezvous in space. Their goal was to rendezvous their capsule with the used second stage of the Titan rocket that had helped launch them. Just after separating from the booster, as they entered orbit, McDivitt made a first stab at rendezvous. The official NASA history of the Gemini program, On the Shoulders of Titans, tells what happened: “McDivitt braked the spacecraft, aimed it, and thrusted toward the target. After two bursts from his thrusters, the booster seemed to move away and downward. A few minutes later, McDivitt pitched the spacecraft nose down and the crew again saw the rocket, which seemed to be traveling on a different track. He thrusted toward it—no success—and stopped. McDivitt repeated this sequence several times with the same luck.”
To mission control, McDivitt reported, “The booster fell away quite rapidly and got below us like there was a considerable difference in our velocity.” The booster wasn’t moving away, of course; it was McDivitt’s spaceship that was moving away, following the laws of orbital mechanics.
...McDivitt estimated that he started out a few hundred feet from the booster. After 45 minutes of trying to get to it, he radioed CapCom Gus Grissom at mission control: “I think we ought to knock it off, Gus. It keeps falling. It’s probably three or four miles away, and we just can’t close on it.”
“Right, knock it off,” Grissom replied. “No more rendezvous with the booster.” It was a four-day flight. In the first 90 minutes, McDivitt had used up half his capsule’s maneuvering fuel futilely “chasing” the booster in defiance of the laws of physics and motion.
...NASA would perform a successful rendezvous between two Gemini spacecraft just six months later. McDivitt would go on to command Apollo 9, the first test flight of the lunar module in orbit with astronauts at the controls. Apollo 9 was a huge success. McDivitt flew the lunar module 111 miles away from the command module in Earth orbit and then returned for a pinpoint docking.
Sometimes failure is not an option; sometimes it is a good learning opportunity.
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