Surfing the Moons of Jool for Fun and Profit

[NeilC]

Have you ever wondered just how far gravity assists can take you? Well, this challenge is all about finding out.

The Goal:

See as much of the Joolian system as you can using as little delta-V as possible.

The Rules:

- Only craft with 600 delta-V or less in their final stage are allowed

Preferably as measured by MechJeb in the VAB for consistency, but other info mods or hand calcs are allowed, too.

EDIT: Apparently MechJeb doesn't measure dV properly in the VAB and is more accurate in flight. My reference craft has 612 dV in flight, so you too can create a craft with up to 612 dV as measured in flight.

This figure must include ALL propulsion on your craft: RCS, xenon, EVA packs if your kerbal ever leaves the craft, whatever else you can think of. Everything combined must add up to less than 600 delta-V. this is the whole point of the challenge, please don't look for loopholes.

- No staged craft allowed into the Jool system. Only your final stage with <600 dV may enter Jool's SoI, and nothing can be jettisoned after that point.

- No refueling

- No resource providing mods (kethane, etc - basically, no refueling by ANY means)

- Balanced mods are allowed. No imbalanced mods compared to stock parts

- No infinite fuel/RCS cheating, whether by mod parts or debug menu

- No getting any extra dV in any other way (infiniglide, etc). This challenge is all about using gravity assists, not rawpower.

- If you're still thinking of a brilliant loophole to get extra dV, that's not allowed either.

- Screenshots of each achievement required, including the following elements so I can verify continuity:

- the mission timer in the top left corner

- the fuel indicator in the lower left corner

- if you're using MechJeb, the "delta-V stat" window, since this makes it a lot easier to verify your burns

The Scoring:

1pt for each dV remaining after you declare your mission complete

2pts for each dV below 600 in your vehicle as it arrives in the Jool system

150pts for each non-consecutive encounter with a moon, doubles count but no points for repeating the same encounter chain over and over **

500pts for each orbital capture by a moon (must be a stable orbit. instantaneous ones during aerobraking don't count)

500pts for each orbital escape from a moon

500pts for impacting a moon (probe pod is destroyed)

1000pts for landing on a moon (probe pod survives)

2000pts for re-establishing a stable orbit after landing

100*(n^2) bonus points, where n is the number of moons you encountered:

1 moon = 100 pts

2 moons = 400 pts

3 moons = 900 pts

4 moons = 1600pts

all 5 = 2500pts

** - spirit of this rule is to promote planning repeat fly-bys during long missions, but not give infinite points for dancing in and out of a moon's SoI, or sitting in an elliptical orbit that approaches one moon's orbit at peri and another's at apo, and then just barely grazing the same 2 moons again and again. As long as you're keeping it interesting, you get points for repeated encounters.

LEADERBOARD

metaphor - 5600

SunJumper - 4000

NeilC - 2354

The Reference Craft:

I have provided a reference craft and lifter for your convenience only. Feel free to make your own as long as it conforms to the rules. These are all stock parts, I removed MechJeb before saving the linked files so you're not forced to use it.

Download the payload only

Download the lifter

Edited May 4, 2013 by NeilC

[SunJumper]

I quite like the idea of this. A single kerbal has about 550m/s of delta-v, so keep this in mind. You can theoretically do this in a 31kg "craft".

Also, might an imbalanced mod still count if you still had 0.6km/s delta-v in the final stage?

[NeilC]

Here's an album narrating my journey.

I aerobraked into a Jool orbit intersecting with Pol's, but Tylo got in the way before I could encounter Pol. Used the Tylo encounter to shift orbit to Bop, and encountered it. Then got lucky and hit the inner 3 planets at resonance, encountering all 3. I intended to aerobrake into Laythe orbit and land to finish it all off, but I didn't have enough dV to get that close and wound up diving straight into Jool at 9km/s.

Scoring:

No dV left at end of mission

4 points for unused dV, since mechJeb thought my craft had 598dV in the VAB. It later thought the identical craft had 614dV in Jool orbit, but we're using VAB figures.

Encounters: Tylo, Bop, Tylo, Vall, Laythe

5*150 = 750

No orbital captures or escapes, no impacts or landings (Jool doesn't count, not a moon).

Bonus: 4 moons encountered, +1600

TOTAL: 2354 points

Not bad for a first attempt, I'll give it another go if someone beats me. I'm looking at you, tavert.

Edited May 3, 2013 by NeilC

[NeilC]

Beat me to the first reply, you hoser!

I did have that in mind when I set the limit at 600 dV. I didn't mention it because I was hoping the first realization of that fact would come in the form of pictures of a Kerbal slingshotting around Tylo. Since you spilled the beans, SunJumper, I demand you produce this screenshot.

[SunJumper]

You know, I could probably beat your score by aerobraking and landing on Pol. This challenge should probably be more about emulating the Galileo probe (Atmo entry probe optional)

[NeilC]

If you can find an atmosphere around Pol to aerobrake with, you deserve to beat me! (I know, you probably meant aerobrake around Jool)

Pol's low mass is a double-edge sword: the ease of landing/takeoff on Pol is offset by the difficulty of being captured by it. The system map puts it at 900dV from low Jool Orbit - you wouldn't need that much, but you'd still need a significant burn to match Pol's speed from a highly elliptical Jool orbit.

I tried to do this first, but big fat Tylo had to get in my way and throw me out of Pol's orbital plane.

[SunJumper]

I'd rather emulate Galileo with this. With that in mind, can we decouple an atmo entry probe and have it impact Jool, with the remaining craft having 600m/s of delta-v?

Also, although Galileo probably had much more delta-v (the mass ratio was 1.83, compared with 9 for KSP's fuel tanks). It had an Isp of approximately that of the Space shuttle's manoeuvering thrusters, 316s, making for an approximate delta-v of 1.87km/s. Then again, Jool is much smaller with the moons much closer.

Edited May 3, 2013 by SunJumper

[NeilC]

You can jettison an atmospheric probe if you really want, with the following conditions:

- Your final stage, including the probe, must have less then 600m/s dV when it enters Jool SoI. Not after jettison.

- The probe cannot have an engine or fuel tanks of any kind

- You will get no points for the probe's activities

I guess you can use "imbalanced" mods as long as you don't break any of the other rules - I just mean to exclude anything that magically produces fuel or gives you extra dV in any way.

[tavert]

FYI: MechJeb's delta-V numbers are more reliable in flight than in the VAB. Some parts like cubic struts are massless in flight, and MechJeb often miscalculates the mass in the VAB. Your probe actually had 612 m/s delta-V, as shown in flight.

Not bad for a first attempt, I'll give it another go if someone beats me. I'm looking at you, tavert.

Hah, I didn't even read this before I posted. You give me too much credit, planning gravity assists is not exactly my forte.

And looking through your pictures, MechJeb 2 does do aerobrake predictions, it even shows them with a maneuver node so you can get a good idea of what your post-aerobrake orbit should look like. It's under Landing Guidance.

Edited May 3, 2013 by tavert

[SunJumper]

You can jettison an atmospheric probe if you really want, with the following conditions:

- Your final stage, including the probe, must have less then 600m/s dV when it enters Jool SoI. Not after jettison.

- The probe cannot have an engine or fuel tanks of any kind

- You will get no points for the probe's activities

I guess you can use "imbalanced" mods as long as you don't break any of the other rules - I just mean to exclude anything that magically produces fuel or gives you extra dV in any way.

This gives me an idea on how to do this...

Actually, I'm thinking this wrong. 600m/s before jettison means more than 600m/s after jettison. I am planning on releasing the probe before conducting the main mission.

Edited May 3, 2013 by SunJumper

[metaphor]

Can we enter Jool's SoI at any velocity and angle? and is there a time limit?

[SunJumper]

Can we enter Jool's SoI at any velocity and angle? and is there a time limit?

I would believe so.

Edit: So far, by your rules, I have 2250 points. And how much delta-v do I have left? 400m/s!

Edited May 3, 2013 by SunJumper

[NeilC]

You're right. I was tired!

You must be under 600m/s at all times in your flight.

[NeilC]

Thanks for the info! OP modified to allow others up to 612 dV. Fair is fair!

I didn't realize MJ could help me aerobrake, that would have saved me an hour or two and a dozen or so reloads.

[NeilC]

No time limit, you're free to intercept Jool however you'd like. Just don't bring your transfer stage into the Joolian System.

[SunJumper]

Does the make orbit bonus still count if it is only for a few seconds (ie Laythe aerocapture?)

Regardless, I've captured into a semistable Tylo Orbit, and am about to impact. The impact was beautiful.

Also, by semistable, I mean the apoapsis was close to the SOI edge, and IRL, the probe would very quickly be nudged somewhere. The orbit was perfectly stable with KSP physics (so long as you don't 100,000x at Kerbin or something).

Edited May 3, 2013 by SunJumper

[NeilC]

Nope, that bonus is for stable orbit. If you impact without orbiting or aerobrake right into a landing, no orbit points.

[metaphor]

I did it with just Jeb. I hear the Kerbals' pack has around 550 m/s delta-v, so that should be under 600. Took a couple of hours with lots of F5/F9 but it was pretty fun.

Here's the album

So let's see, these are the moon encounters I had:

Pol

Bop

Laythe

Vall

Tylo

Vall

Tylo

Laythe orbit

Vall

Tylo

Score: 10 encounters * 150, 1 orbital capture * 500, 1 orbital escape * 500, 1 impact * 500, 5 moons visited = 2500, 50 less delta-v started with * 2 (not sure about this one)

So that's a total of 1500+500+500+500+2500+100 = 5600 (I think)

Playing around in Jool orbit is really fun. You can get a lot of encounters by just waiting in an elliptical orbit and only changing your orbit so you don't impact or get slingshotted out of the system. The earlier you change your orbit the less delta-v it takes.

[SunJumper]

What happens if we get chucked back into solar orbit,

And return to orbit Jool?

This did not happen to me.

[NeilC]

In terms of points? Nothing at all.

But if your craft shows more than 612dV at any point in that chucking, you're disqualified.

[NeilC]

Well done metaphor! 2 months in a space suit, Jeb must smell.... interesting.

I'll double-check your score and add you to the leaderboard after work.

Now I've got the motivation to try this again... I'll still stick to my unmanned probe, though. I can't stomach crashing poor innocent Jeb into a moon.

Edit: Your score checks out. We'll standardize on the assumption that EVA packs have 550m/s delta-V, unless someone can prove that wrong.

Edited May 3, 2013 by NeilC

[SunJumper]

Well done metaphor! 2 months in a space suit, Jeb must smell.... interesting.

I'll double-check your score and add you to the leaderboard after work.

Now I've got the motivation to try this again... I'll still stick to my unmanned probe, though. I can't stomach crashing poor innocent Jeb into a moon.

Edit: Your score checks out. We'll standardize on the assumption that EVA packs have 550m/s delta-V, unless someone can prove that wrong.

Whoever uses this method should make sure they have no mannable pods in the Jool system....

Also, my entry is uploading soon. I have:

Visited Laythe, Vall, and Tylo;

Flybys of (Hold your breath!):

Laythe

Vall

Laythe

Laythe

Tylo

Laythe

Laythe

Vall

Vall

Tylo

Tylo

Tylo

Vall

Vall

Tylo (Capture and impact)

I'll post a link to the album when its ready.

http://imgur.com/a/s0ZEt#0

Edited May 4, 2013 by SunJumper

[NeilC]

Good work, Sunjumper!

I do have a nit to pick here, though: most of your screenshots have no timer or fuel indicator. I found it a little hard to follow, and there's no way for me to verify that those pics aren't a collage of several different missions.

I don't mean to cast doubt on your achievement, and I trust you! Your score counts. But to everyone else: from here on, to claim the winning slot your screenshots must include at least the mission timer and fuel indicator, and I've amended the rules as such.

I didn't know there was a way to turn the HUD stuff off or I would have specified from the start - thanks for teaching me about F2, SunJumper!