Gravity assist masters

[DennisB]

After my first challenge didn't get much resonance, here is the next one. It took so long, because I was busy with my Jool mission.
Since I play KSP, I saw many brilliant players, who did incredible gravity assist maneuvers. In most cases, the goal was fuel saving. I thought about a different challenge, which could be challenging even for them. That means, completing the mission with a vessel, which is far from ideal, with a fairly tight fuel budget, in the shortest time.

The vessel for the challenge is called the Dumb Probe. It's a ridiculous machine, I don't know, what the kerbal engineering team had in mind during the construction. Maybe... to make your life more difficult? 

It is powered by one RTG and one ion engine, has a huge amount of useless liquid fuel as ballast, and a probe core, which can't follow maneuver nodes. It has a total dV of 2247m/s, it can sustain maximum thrust for 126s with an acceleration of 0,49-0,52m/s² (61,9-65,1m/s), or 0,04m/s² with persistent thrust.

There are two different missions available.
Mission 1: Get the Dumb Probe to an escape trajectory from the solar system, with reduced fuel (empty one of the Xe-tanks, so you have only 1512m/s dV).
Mission 2: Do a Grand Tour, and visit the SOI of all celestial bodies of the solar system.

The date (not the mission time), when the mission is completed, will determine the ranking.
In mission 1, it is the date, when the probe is on an escape trajectory, and it isn't within and won't cross the SOI of any of the planets or moons.
In mission 2, it is the date, when the probe reaches the final SOI and isn't on a collision course with a celestial body.

To start the mission, download the Dumb Probe from KerbalX (https://kerbalx.com/DennisB/Dumb-Probe). Start a new game with CommNet switched off, because the probe doesn't have an antenna. If you try mission 1, empty one of the Xe-tanks. Except this, there are no further changes on the vessel allowed. Cheat the Dumb Probe into Kerbin orbit with Alt+F12. Both your PE and AP must be within 80-100km, within this range, you can set the orbital parameters, like you want. Switch the clock to Universal Time, and go. Don't forget to document your route and your maneuvers to show afterwards. You can use visual and information mods, but no flight assistant mods, because it's part of the challenge, to execute the maneuvers manually.

Spoiler

I tried to do some tests, to get the fuel levels right, unfortunately, I'm not good enough in gravity assists. I hope, the challenge isn't easy nor impossible.

 

Edited October 13 by DennisB

[JeDoesStuff]

Using the Mun, it is possible to get to anywhere you want using only 850m/s and whatever more you need in corrections. Once you reach Jool, escape trajectory is trivial. Obviously, time is of the essence here, so what would most likely be better is using one Mun assist on the way to eve, then assisting off of eve with slightly more relative velocity than usual, which should allow you to skip one of the Kerbin assists in the usual KEKKJ route. as for escaping from that point, I believe a Tylo assist should be enough, though I think you might need to do more than one Jool assist to properly escape.

As for challenge 2, there's a lot of interesting possibilities here. I've had occasions where in the process of setting up an assist, I get some miracle encounter with a different moon I wasn't aiming for. I think what would be best is setting up a gravity assist chain that forces contact with all of the bodies before getting to where you're going, so like passing by Gilly whilst flying by eve. As for time, I doubt this one can be done very quickly, but less than 20 years seems reasonable enough. If you were really dedicated and put some planning in I estimate less than 15 years might be doable.

The route for this, I think, would be to use the Mun and Minmus to get to Eve, where you assist (and hopefully grab a Gilly encounter) to get to Moho. Then, by way of Eve again, you assist back up and swing by Kerbin to bring apoapsis closer to Dres. A flyby of Duna and Ike could get you there, and the resultant encounter can set up an assist with Kerbin the next time around to reach Jool. Jool seems like the hardest part to optimize here, since theoretically you could encounter all of the moons in sequence one after another if you're lucky, but more likely than not you're going to need to capture. Lucky, once in the Jool system, it shouldn't take very long to encounter all the moons thanks to shorter orbital periods. Lastly, a direct course to Eeloo can be set up to take at the very most a year and boom all done. 

Obviously, I assumed a lot of assists that might be flat out impossible to set up or plan for with transfer windows. The initial assist off of Eve will mess up your AoP, which means it will necessarily take longer than a year to get another Kerbin encounter. Still, the fact that you need all these planets and moons to be in precise positions is an issue, and honestly it makes me wonder if you can modify the game files to just put them in ideal locations to start with. Not doing this would require you to wait thousands of years for the perfect transfer window, which is relatively unattractive.

[DennisB]

Thank you for sharing your thoughts about this. I'm happy to hear, that you think, the dV budgets are adequate to complete the missions.

14 hours ago, JeDoesStuff said:

Obviously, time is of the essence here

That's the point of the challenge. Not to find the most fuel efficient way, like you do normally, but to use the additional fuel to finish faster.

14 hours ago, JeDoesStuff said:

Not doing this would require you to wait thousands of years for the perfect transfer window, which is relatively unattractive.

I thought about this too, and that's the reason, why I decided to use the universal time and not the mission time for the results. Using all the available fuel should make it possible to finish the mission before the perfect constellation even occurs.