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I wonder whether Neptune or Uranus could be used to 'aerobreak' in order to get a probe into an orbit around Pluto. I'm guessing with Pluto's eccentric path the

I wonder whether Neptune or Uranus could be used to 'aerobreak' in order to get a probe into an orbit around Pluto. I'm guessing with Pluto's eccentric path there should be points in time where it is close to one of these planets, but it is probably a window that only opens up on a timescale of hundreds of years?

dredmorbius 12y ago
You might also be interested in the actual trajectory and positions of other planets for this mission: https://www.youtube.com/watch?v=78U0_XcFP_I https://www.youtube.com/watch?v=78U0_XcFP_I
dredmorbius 12y ago
That's a possibility, but the bigger problem is simply the size of the solar system. Uranus is 2.88 billion km from the Sun. Neptune is 4.5 billion km from the Sun. Nearly twice as far as Uranus. Pluto is 5.9 billion km from the Sun on average. It varies a lot, from inside the orbit of Neptune to nearly double the distance - 4.4 to 7.3 billion km. New Horizons will be reaching it at one of its nearer approaches. Pluto is also significantly inclined to the solar plane, unlike the planets. By contrast Jupiter is less than 1 billion km away: 0.779 billion km. Saturn is 1.4 billion km -- twice as far as Jupiter. Note that if you managed to slow yourself down at Neptune on your way out to Pluto, you'd still have the distance from the Sun to Saturn to traverse. Say you cut half your speed -- it would take you nearly six and a half years to reach Pluto, rather than the 3.2 of the current mission trajectory. You're trading speed and time here. And you'd still have to lose some 20,000 km/h of velocity when you arrived. Space is big. Really big. You won't believe just how vastly, hugely, mind bogglingly big it is. Then there's the orbital periods. Neptune's year is nearly 165 Earth years, Uranus is 84 years, Pluto's is nearly 248 years. This means that Pluto, discovered in 1930, won't have completed a full orbit of the Sun until 2177. Neptune, discovered in 1846, completed its first full orbit since only in 2010.
- m_mueller 12y ago
  That's what I meant with eccentric path though: As far as I know Pluto is not always that far out, there are points in time where it's closer to the sun than Neptune - which should be a good moment when either Uranus or Neptune could be used to aerobreak. Edit: but only when they also line up correctly, which is why I think it would take hundreds of years of waiting. Edit2: After watching the linked video, Uranus would be out, since Pluto is never close to it, but Neptune might work at some point in time when these planets are close.
  - dredmorbius 12y ago
    The Neptune-Pluto alignment is one that might be interesting to explore on a solar system simulator. I suspect you might have to wait a fair fraction of a thousand years for that though, at a minimum.
    - m_mueller 12y ago
      I actually tried to find a good simulator for that reason, but all the web simulators I've found didn't have a reasonable time slider UI.
      - dredmorbius 12y ago
        There's a KDE astronomy simulator I've used that seems pretty good, though I haven't played with it for a while. Celestia IIRC: http://www.cyberciti.biz/tips/celestia-astronomy-linux-program.html http://www.cyberciti.biz/tips/celestia-astronomy-linux-progr...

dredmorbius 12y ago

You might also be interested in the actual trajectory and positions of other planets for this mission: https://www.youtube.com/watch?v=78U0_XcFP_I https://www.youtube.com/watch?v=78U0_XcFP_I

dredmorbius 12y ago

That's a possibility, but the bigger problem is simply the size of the solar system. Uranus is 2.88 billion km from the Sun. Neptune is 4.5 billion km from the Sun. Nearly twice as far as Uranus. Pluto is 5.9 billion km from the Sun on average. It varies a lot, from inside the orbit of Neptune to nearly double the distance - 4.4 to 7.3 billion km. New Horizons will be reaching it at one of its nearer approaches. Pluto is also significantly inclined to the solar plane, unlike the planets. By contrast Jupiter is less than 1 billion km away: 0.779 billion km. Saturn is 1.4 billion km -- twice as far as Jupiter. Note that if you managed to slow yourself down at Neptune on your way out to Pluto, you'd still have the distance from the Sun to Saturn to traverse. Say you cut half your speed -- it would take you nearly six and a half years to reach Pluto, rather than the 3.2 of the current mission trajectory. You're trading speed and time here. And you'd still have to lose some 20,000 km/h of velocity when you arrived. Space is big. Really big. You won't believe just how vastly, hugely, mind bogglingly big it is. Then there's the orbital periods. Neptune's year is nearly 165 Earth years, Uranus is 84 years, Pluto's is nearly 248 years. This means that Pluto, discovered in 1930, won't have completed a full orbit of the Sun until 2177. Neptune, discovered in 1846, completed its first full orbit since only in 2010.

m_mueller 12y ago
That's what I meant with eccentric path though: As far as I know Pluto is not always that far out, there are points in time where it's closer to the sun than Neptune - which should be a good moment when either Uranus or Neptune could be used to aerobreak. Edit: but only when they also line up correctly, which is why I think it would take hundreds of years of waiting. Edit2: After watching the linked video, Uranus would be out, since Pluto is never close to it, but Neptune might work at some point in time when these planets are close.
- dredmorbius 12y ago
  The Neptune-Pluto alignment is one that might be interesting to explore on a solar system simulator. I suspect you might have to wait a fair fraction of a thousand years for that though, at a minimum.
  - m_mueller 12y ago
    I actually tried to find a good simulator for that reason, but all the web simulators I've found didn't have a reasonable time slider UI.
    - dredmorbius 12y ago
      There's a KDE astronomy simulator I've used that seems pretty good, though I haven't played with it for a while. Celestia IIRC: http://www.cyberciti.biz/tips/celestia-astronomy-linux-program.html http://www.cyberciti.biz/tips/celestia-astronomy-linux-progr...