Pluto and Back!

[Carlo]

Hi all! I need some help to solve this problem: I want a flag on Pluto!

I'm using Real solar system+Realism Overhaul and all the consequent mods.

1- A very fast fly-by is possible within 10-14 years with reasonable Dv, one way, no return, so no crew on-board ^^ (New-Horizon style)

2- An orbit is achievable with a reasonable amount of Dv "only" taking like 50 to 70 years, one way... to come back you can aerobrake on Earth so maybe it could take like 10-15 years.... total 65 to 85 years... not realistic with a crew on-board (I hope I'm wrong on that "only", and that someone will tell me another way ^^)

3- It is probably possible to calculate the departure to be in a time window when another celestial body (let's say Uranus) can help you to gravity-aero brake and then redirect yourself to Pluto, but I'm not good enough with math to do that ^^, if someone have a tip for me to do that in an easy way, you are welcome!

4- It is quite hard to Bring there enough Dv to come back, but this is just about planning a good ship.

Any tip/advise is very welcome! This is my obsession today ^^

P.s. Excuse me for my poor english, I hope you all understood what I need

[Wallygator]

I cannot give you an answer, but reading your question makes me want to switch from stock to RSS.

I think I'll give it a try this week.

[temporalExile]

Two words: Kraken Drive

[timsfitz]

Park a refueller at Jupiter and top off the tank.

[Starwhip]

Two words: Kraken Drive

But that's cheating!

Anyway, he's asking for the alignment of the planets. I say just wing it (Quicksave so you can go back a few years, if needed). If you can get a Uranus intercept, that's a start. Then try planning maneuvers inside Uranus' SOI (Before you leave Kerbin! (Or Earth. )) by focusing your view on it in Map mode.

As for the mathematical alignment, I could theoretically do it, but I really don't have the time right now.

[regex]

If you have Windows or iOS, check this out: http://forum.kerbalspaceprogram.com/threads/36476

Otherwise, my suggestion is to use a separate save and practice with a tiny satellite slinging yourself around using gravity assists.

[magico13]

Can't KSP TOT use RSS' settings for the planets? Then you could really easily calculate gravity assists. I don't follow it very closely, so I'm not 100% sure it works with RSS.

[r_rolo1]

Basing on RL stuff, it is probably possible to do a Venus->Jupiter->Pluto flyby chain ( with optional landing there ) that could maybe have enough fuel for a return, but regardless follow Starwhip advice: keep handy a save, because the more favorable alignments can take centuries to come by, due to the big orbital period of Pluto...

Edited March 5, 2015 by r_rolo1

[regex]

Can't KSP TOT use RSS' settings for the planets?

http://forum.kerbalspaceprogram.com/threads/36476?p=1520004#post1520004

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions.

Also, your English is fine.

[Streetwind]

Isn't that more of a mod affairs thing though, Vanamonde?

Anyway: you're probably not going to get around throwing some serious dV at the problem. If you want a short travel time, you need a high energy transfer, which costs a lot of dV. If you want to plant a flag, you need to capture into orbit. If you have a high energy transfer and want to capture into orbit, you're going to have to brake hard, which costs a lot of dV. Gravity assists can save some of that dV, but they also cost extra time in return again.

This is why IRL, the Dawn probe is such a big deal. It's not flying high energy transfers, but it is going around, orbiting one body, leaving, then reaching another body and orbiting that too. Two orbit missions in one. That's expensive. RL spacecraft don't do such a thing, generally, precisely because it's so prohibitively costly in terms of dV. In Dawn's case, they're using solar electric propulsion. In your case, that's not a valid choice because there's no sunlight worth mentioning out there at poor Pluto. You could, however, use nuclear electric or nuclear thermal propulsion, provided you have the technology (and the necessary part mods).

If you have neither... well. You already mentioned New Horizons. Maybe you can not only throw your spacecraft on such a trajectory, but also the propulsion stage required to slow it back down at Pluto... of course, it would be a one-way trip for the Kerbal. Unless, perhaps, the propulsion stage could be undocked and a fresh one docked in Pluto orbit. You'd have to throw the fresh one onto the same trajectory, along with a third one to slow that back down at Pluto... That's the Tyranny of the Rocket Equation for you.

[Kibble]

It might be possible to shorten the trip time by initially launching on a Solar escape trajectory, and then doing a flyby of Neptune and/or Uranus to slow down to an elliptical transfer orbit (or you could even aerobrake!). Then as you approach Pluto you can use an ion drive to slow onto orbit. Then from there you launch into another solar escape trajectory, that intersects Earth's orbit. It'll be easier at Pluto because of lower escape velocity this far from the Sun, but it'll still require a huge hypergolic rocket stage. Then aerocapture at Earth, and the mission only took maybe 20 or 30 years. It would take a really, really, way-too-big rocket to launch the stack though. Also there are at least a hundred catastrophic failure modes. Also you'd need nuclear power, and a greenhouse, and a bunch of other futuristic junk.

Edited March 5, 2015 by Kibble

[magnemoe]

It might be possible to shorten the trip time by initially launching on a Solar escape trajectory, and then doing a flyby of Neptune and/or Uranus to slow down to an elliptical transfer orbit (or you could even aerobrake!). Then as you approach Pluto you can use an ion drive to slow onto orbit. Then from there you launch into another solar escape trajectory, that intersects Earth's orbit. It'll be easier at Pluto because of lower escape velocity this far from the Sun, but it'll still require a huge hypergolic rocket stage. Then aerocapture at Earth, and the mission only took maybe 20 or 30 years. It would take a really, really, way-too-big rocket to launch the stack though. Also there are at least a hundred catastrophic failure modes. Also you'd need nuclear power, and a greenhouse, and a bunch of other futuristic junk.

Remember that an Neptune operation depend that they are in the correct position. Install KSP interstellar or similar mods you need an high ISP engine, something better than vasmir.

An orion would make the mission plausible and let you travel in some style.

[Rusty6899]

TO do this, I have to have a rough estimate of your delta-V budget and a rough estimate of a realistic time frame.

To brake at Uranus to get to Pluto is problematic, because it takes decades to travel between the two, so you would be saving a couple of years between Earth and Uranus, but still travelling at a snails pace during the most time consuming part of the trip. I don't think the two bodies' respective orbits are very conducive to such a transfer either; your solar orbit during the transfer to Uranus will be too eccentric to get a useful reduction in svelocity. Uranus' orbit will be almost perpendicular to your direction of travel, whereas you want to be travelling parallel to its orbit to reduce your velocity (and to achieve that would take an insane amount of time or delta-V).

Using a Earth-Venus-Jupiter-Low Solar-Pluto set of Hohmann transfers, meeting Jupiter at the Pluto-Jupiter AN/DN to use Jupiter's gravity to perform your inclination change, and meeting Pluto at Periapsis, you could get there in maybe 35-40 years and your circularisation burn around pluto would cost around 6-7 km/s (Disclaimer: That was a complete back of a napkin calculation and I accept no liability for its potential inaccuracy).

I'm not prepared to give a predicted DV cost of the entire trip, but you would be able to save a lot of DV with the suggested gravity assits.

It also would require a near miraculous aligning of the planets and execution of the transfers. Any minor blip in your Sun-Pluto transfer could cost you years.

Edited March 5, 2015 by Rusty6899

[cantab]

Well really you're going to have to pick. A fast flyby, a slow mission that can land and return, or an insanely huge mission that can land and return quickly.

Getting an assist from one of the gas giants can help reduce your capture burn at Pluto, but at the cost of taking *even longer*. You'd be looking at in excess of a century each way for a fuel-optimal flight. To find such assists, look for Earth-giant windows and giant-Pluto windows that more or less coincide in time.

[NathanKell]

I haven't done this myself, but using TOT or another one of those trajectory tools is your best bet.

Also, Check out metaphor's trip.