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- Hacker News
- I have always wondered about this with regard to Newton's Third law:
So if a craft departs from rendezvous with another craft it must do so by pushing away from that other craft. That means it is equally pushing on both crafts. If the rendezvous was in orbit does that mean departing from rendezvous pushes both crafts out of orbit? If so does the other craft have to correct for this to reestablish orbit or is orbit self-correcting as if in a third body scenario?For every action there is an equal and opposite reaction.I ask because Earth is an third body scenario between the sun and Jupiter. Jupiter has enough gravity to occasionally pull the Earth slightly (not significantly) out of orbit from the Sun, but Earth's orbit to the Sun is self-correcting due to the difference in mass between the Sun and Jupiter. Quick web searching reveals Jupiter's pull on Earth is only approximately 0.005% of the Sun's after accounting for both mass and distance, but that number rises to 0.011% after accounting for syzygy with the moon.
- Buzz Aldrin (who was the second person to walk on the moon) wrote his MIT thesis on methods for astronauts to handle the complexities of orbital dynamics when performing rendezvous maneuvers in orbit:by ubj
- I know it's a bit worn out but if you want to learn about practical orbital mechanics and have fun doing it, Kerbal Space Program is the best tutor there is. It's a simplified physics model so stuff like Lagrange points don't work, but there's no better way of getting an intuitive understanding of how bodies move in space.by noodlesUK
- For anyone who is remotely interested in this, a considerable chunk of the Gemini program was all about solving some of the practicalities involved with Rendezvous, and it is quite interesting even hearing some of the astronauts come to grips with some of the physics while orbiting in space trying the various types of rendezvous and docking maneuvers that were attempted.by ChicagoBoy11
- As Larry Niven wrote in The Smoke Ring and The Integral Trees...
"West takes you In, In takes you East, East takes you Out, Out takes you West, North and South bring you back again."
by lproven - I always thought this was unnecessarily made to sound counterintuitive, and I think there is a way to explain it simply without trying to make it sound like rocket science.
Instead of "speed up to slow down", it's "speed up to go higher". I think anyone can get on board with that. You'll come back to the same point you were when you accelerated, but later than before since you went into a higher orbit.
I like the included animations, since it also makes it clear that accelerating or decelerating from a circular orbit makes it elliptical. Your don't just jump to a higher or lower circular orbit.
by hydrogen7800 - Orbital mechanics can be counterintuitive. There was a fairly basic orbital mechanics problem that caused some debate among physicists back in the 1970s. The problem went like this:
You are in a spacecraft orbiting the Earth. You distribute a bushel of apples throughout spacecraft so that they are at rest with respect to the spacecraft. After a long time, where do the apples end up?
Hannes Alfvén (more famous for Alfvén waves) argued that they would bunch up together in the middle of the spacecraft. But Michel Hénon (correctly) proved that half would end up in the bottom front corner, and the other half in the top back corner.
I wrote up a blog post explaining the solution a few years ago: https://joe-antognini.github.io/astronomy/apples-in-a-spacec...
by antognini