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If a spacecraft was accelerated to just above Earth's escape velocity, it would begin orbiting the sun with an orbit very similar to Earth's. Could the spacecraft then repeatedly perform a gravity assist with the Earth to increase it's apogee over and over until it left the Solar System, while only using a nominal amount of delta-v to perform deep-space maneuvers to fine-tune encounters with the Earth?

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  • $\begingroup$ several millennia per slingshot, once it passes beyond Sedna orbit, aside? $\endgroup$ – SF. Jul 6 '16 at 12:38
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    $\begingroup$ I might have to model this in KSP... $\endgroup$ – PearsonArtPhoto Jul 6 '16 at 13:07
  • $\begingroup$ Oh, and is a Jupiter flyby after initial Earth flybys okay? $\endgroup$ – PearsonArtPhoto Jul 6 '16 at 13:07
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    $\begingroup$ @PearsonArtPhoto for this question I want to know if leaving the Solar System is possible using only Earth flybys. $\endgroup$ – Thomas Jul 6 '16 at 19:42
  • $\begingroup$ I like this question - it reminds me a little bit of code golf - they look for fewest characters, here we can look for fewest flybys. $\endgroup$ – uhoh Jul 7 '16 at 9:25
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Juno did something similar to this, it went on an initial 2 year orbit, with a flyby of Earth 2 years after launch, after which time it went on to Jupiter, to orbit it.

I've been playing a bit with NASA's Trajectory Browser, and found this possibility:

  • Launch March 2016- 4.33 km/s beyond Earth Escape
  • Deep space maneuver 1 year later
  • Slight powered flyby of Earth 10 months later
  • Pick the correct course to flyby Jupiter, such that the flight will lead to interstellar space

Total ~ 5 km/s delta v.

enter image description here

If you want to do a purely Earth based escape, it is also possible, the trick is to periodically return to Earth. So the first return time would be in 2 years, the next might be in 4, and so on until you have left the Solar System. It might take a while, but it could be done.

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