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© Copyright 1996, Jim Loy
When I was a child, I wrote a story about a space mission to Mercury. They undershot their target and plunged into the sun. The story was terrible, and so was the science.
Sitting on a launching pad on earth, a space ship has a huge amount of energy, as the earth races around the sun. It is hard enough to lose enough energy to get to Mercury. But it is much harder to get to the sun. It takes less energy (more time) to go to a distant star than it takes to get to the sun.
Pretend that you're driving a bobsled (our space ship) around a curve. It is much easier to turn toward the outside of the curve and hurtle off into the woods (a distant star), than it is to turn toward the inside and actually ride to the center of the curve (the sun).
In order to travel to Mercury, space craft actually slingshot around the moon. Maybe using Mercury or Venus as a further slingshot could actually cause a space craft to plunge into the sun.
Ah, now I can rewrite the story so that the science is better. But the story is still terrible.
The science in the movie Journey to the Far Side of the Sun was just as bad as the science in my story. In that movie, an anti-earth was discovered in the same orbit as earth, but on the opposite side of the sun (not a stable point in relation to earth). Nearly identical astronauts took off from each planet simultaneously, and traveled to the other planet. Their superiors accused them of aborting their missions and turning back (virtually impossible in a trajectory around the sun). They didn't seem to be tracking the two spacecraft with radar, or even communicating with them by radio. I suppose they had some kind of interference.
Anyway, these two earths would be co-orbital planets, and they would behave like the co-orbital moons of Saturn, as described in my article on co-orbital moons.
The moon is getting farther away from the earth. I suppose the earth and moon will eventually become co-orbital planets. In fact, some of the moons of Saturn may have had little moons of their own at one time.
I have since found out that the orbit of the moon probably oscillates from near to far and back to near, over and over.
Incidentally, when I was a child, I predicted that we would eventually find more moons around Saturn than around Jupiter, as I equated a large ring with larger chunks of debris. It turned out that I was right. But, I predicted lots of other things that turned out to be false.
Addendum:
The fifth episode (Sunprobe) of Thunderbirds, a Brittish science fiction television series starring marionettes, is about an ill-fated expedition to the Sun. The series was apparently popular because of the many technological gadgets that the puppets used. This episode was ridiculous when it came to scientific accuracy. The story:
Sunprobe, with its three-man crew, fly to the vicinity of the sun. They fire retros to go into close orbit around the Sun. Then they launch a probe into a solar prominence and retrieve the probe. Brain, one of the star puppets on Earth, deduces that Sunprobe will suffer a disaster; their maneuver to retrieve the probe will aim them directly toward the Sun, and solar radiation will disable their control of their retro rockets. NASA tries to fire the retros by radio, from Earth. But the Sun's radiation is too strong. Our heros from International Rescue (which is a secret rescue organization, so they can pick and choose who they rescue) can help, and have two different plans. First they send a rocket toward the Sun to fire the retros by radio. And second, they send a strong radio to the top of a mountain on Earth, where they can perhaps do better than NASA can. The first idea succeeds, and saves Sunprobe. But, they get too close to the Sun and all pass out from the heat. Their retros won't fire because they have failed to turn off the radio which is using too much power. The team on the top of the mountain is able to turn on the retros by radio, and the first team is saved.
That's all pretty stupid, which was perhaps intentional.