The Hands-Free Mission Challenge

[Yakky]

Slowly doing the math, but I'm almost positive this is mathematically impossible, not even mentioning the complexity of the mission in it's own right (hitting bop and pol would be nigh impossible from a landing on anything but a perfectly flat surface).

I'm not going to bother dissecting the flight path of Tylo to Bop to Pol to Vall to Kerbin, we're going to assume it's possible, landing at perfect places at perfect times and allowing a couple extra keystrokes for transfer and landing (to close solar panels to stop overshoot and to land, because you've got to start and stop the ion engine).

So, we start with a probe core chair with 7 xenon tanks (6 of which can be ejected), with strut legs, and a parachute (poor Jeb is going to land on his head). Add some struts to give the decouplers something to bind to) and before you know it, we're at 1.6T that we have to get from Tylo to an intercept with Pol (remember, we're going to have to overshoot by a wide margin because it's going to take a long time to slow down to hit these moons with low enough speed to be considered a soft landing). To get that overshoot, we're going to need somewhere around 5000 total dV aimed precisely. Your launch vehicle weighs 18.25T once you ditch the landing gear and SAS you needed to control and absorb the landing.

Now to land that you need a 110T lander. You can't get this off of Laythe.

I've yet to figure out a way to do this, even with the added keystrokes.

Even a partial Jool tour would be an absolutely incredible achievement. Thinking about it from a simplicity standpoint rather than a delta-V standpoint, it seems to me that the obvious first landing has to be Laythe. It's the only one with an atmosphere and is therefore the only one with any kind of forgiveness in the targeting accuracy. Once you land on Laythe, you buy yourself a little bit of flexibility because you can wait around on Laythe's surface for the best departure time to take advantage of orbital conjunctions and phase angles.

Also take a look at Metaphor's very clever use of action groups in Post 48 above, which the judges have decided to allow (albeit on a very close split-decision vote -- see Post 50 for an explanation of why the judging committee decided to allow this approach). Basically he sets up each action group to propel him in a different direction, then he picks the one he actually needs. This could give you a little bit of aiming/targeting ability for making trajectory corrections to the other moons.

But all of that said, nobody has yet demonstrated the ability to do a hands-free landing on any celestial body lacking an atmosphere -- even the Mun or Minmus. Frankly that's a far bigger challenge than the delta-V budget or the trajectory design.

[Yakky]

I am proud to present the point-scoring system for interplanetary landings:

Scoring Rationale: Interplanetary landing scores will be based on minimum separation distance from Kerbin, divided by the relative size of the target planet's SOI compared to Kerbin's (since larger SOIs are easier to hit). Bodies having an atmosphere will be further divided by 10 since they are far easier to land on than bodies lacking an atmosphere.

On that basis, here's the score for Eve:

Minimum separation from Kerbin: 3.8 billion meters

Relative size of Eve's SOI compared to Kerbin's: 1.01

Atmosphere: Yes

Score = 3.8 billion / (10* 1.01) = 376 million

Well done!

Some representative point totals possible for various interplanetary landings:

Eve: 376 million (big SOI and handy atmosphere)

Duna: 1.25 billion

Eeloo: 54.2 billion

Laythe: 125 billion (far away, small SOI, but has atmosphere that makes the landing easier than other Jool moons)

Pol: 4.44 trillion (far away, tiny SOI that's hard to hit, and no atmosphere!)

Edited September 29, 2014 by Yakky

[Himynameisjake]

Some representative point totals possible for various interplanetary landings:

Eve: 376 million (big SOI and handy atmosphere)

Duna: 1.25 billion

Eeloo: 54.2 billion

Laythe: 125 billion (far away, small SOI, but has atmosphere that makes the landing easier than other Jool moons)

Pol: 4.44 trillion (far away, tiny SOI that's hard to hit, and no atmosphere!)

This is, again, a simple matter of timing your launch, it doesn't really require super intelligent design, just moar rockets. Kind of annoyed to be bumped on the point system by that but it's your challenge.

The obvious winner (as the other options are too difficult for any but the self loathing to attempt), will be a Laythe return mission.

I got frustrated with testing the ship, so someone else can figure it out, but it can be done mathematically speaking. You just need to land flat and then have about a thousand quicksave tries to perfectly nail the timing of your orbital adjustment.

Edited September 29, 2014 by Himynameisjake
Minor adjustment to ship design

[metaphor]

I have to agree, getting periapsis at Minmus's orbit in the Kerbin system without gravity assists is more impressive than landing on Eve.

[gm537]

Hey I have question for landing on Mun how is Kerbin Periapsis counted? I am trying a mission which just lands on the Mun but pointing and thrusting. But once you land of course your periapsis is effectively the Mun's. Is that how the scoring would work?

Edited October 5, 2014 by gm537

[Yakky]

This is, again, a simple matter of timing your launch, it doesn't really require super intelligent design, just moar rockets. Kind of annoyed to be bumped on the point system by that but it's your challenge.

The obvious winner (as the other options are too difficult for any but the self loathing to attempt), will be a Laythe return mission.

I got frustrated with testing the ship, so someone else can figure it out, but it can be done mathematically speaking. You just need to land flat and then have about a thousand quicksave tries to perfectly nail the timing of your orbital adjustment.

Both accomplishments (Himynakeisjake's trans-Minmus orbit and Metaphor's Eve landing) are quite impressive and both rely on clever innovations that seem obvious after the fact, but hadn't been thought of before you and Metaphor came up with them. Which is "more impressive" is definitely a judgment call and is totally at the whim of the challenge's imperfect scoring system, not denying that. I'm impressed with both efforts. Frankly it's tough to come up with a single scoring system that can properly quantify all the different achievements that are possible.

Here's an argument why I think it's very subjective which is "more impressive": Having now had the benefit of seeing and benefitting from Himynameisjake's design, I would say it has now become pretty easy to get a Kerbin periapsis well past Minmus. If you just burn straight up to (just under) 85 million km, Kerbin's gravity becomes so weak that you'll have several days of hang time out in the 75-85 million km range before you really start falling back to Kerbin again. In fact, the majority of your time on the ballistic trajectory will be spent out there. All you need is a very slow sideways burn (in any perpendicular direction, doesn't matter which one) over the course of those several days to impart about 200 m/s of sideways delta-v and you will have a near-circular orbit well past Minmus. Is that more or less tricky than getting to Eve? Hard to say, and very open to opinion.

Edited October 5, 2014 by Yakky

[Yakky]

Hey I have question for landing on Mun how is Kerbin Periapsis counted? I am trying a mission which just lands on the Mun but pointing and thrusting. But once you land of course your periapsis is effectively the Mun's. Is that how the scoring would work?

Yes, your periapsis would be the Mun's periapsis, but your score would be tripled because the landing would earn you the 3x multiplier. I would absolutely love to see someone accomplish that BTW. And I'll say again that the scoring system definitely isn't perfect. Given the massive challenge of landing hands-free on a body with no atmosphere, the multiplier for doing so should probably be higher than 3x, but at this point I'm hesitant to change the existing scoring system any further, since others (e.g. Himynameisjake above) have spent a lot of time optimizing their entries under the existing rules.

However, to encourage the pursuit of no-atmosphere landings, I've set up a special separate category to recognize (and encourage) that achievement. Best of luck in pulling it off!

[gm537]

Yes, your periapsis would be the Mun's periapsis, but your score would be tripled because the landing would earn you the 3x multiplier. I would absolutely love to see someone accomplish that BTW. And I'll say again that the scoring system definitely isn't perfect. Given the massive challenge of landing hands-free on a body with no atmosphere, the multiplier for doing so should probably be higher than 3x, but at this point I'm hesitant to change the existing scoring system any further, since others (e.g. Himynameisjake above) have spent a lot of time optimizing their entries under the existing rules.

However, to encourage the pursuit of no-atmosphere landings, I've set up a special separate category to recognize (and encourage) that achievement. Best of luck in pulling it off!

Thanks for the rules clarification and encouragement. I've definitely gotten far enough to say "I think it's possible" but also that "It's freakishly hard and quite possibly up to a bit of luck"... Probably gonna let it go for today but will keep trying tomorrow after work.

[Himynameisjake]

Both accomplishments (Himynakeisjake's trans-Minmus orbit and Metaphor's Eve landing) are quite impressive and both rely on clever innovations that seem obvious after the fact, but hadn't been thought of before you and Metaphor came up with them. Which is "more impressive" is definitely a judgment call and is totally at the whim of the challenge's imperfect scoring system, not denying that. I'm impressed with both efforts. Frankly it's tough to come up with a single scoring system that can properly quantify all the different achievements that are possible.

Here's an argument why I think it's very subjective which is "more impressive": Having now had the benefit of seeing and benefitting from Himynameisjake's design, I would say it has now become pretty easy to get a Kerbin periapsis well past Minmus. If you just burn straight up to (just under) 85 million km, Kerbin's gravity becomes so weak that you'll have several days of hang time out in the 75-85 million km range before you really start falling back to Kerbin again. In fact, the majority of your time on the ballistic trajectory will be spent out there. All you need is a very slow sideways burn (in any perpendicular direction, doesn't matter which one) over the course of those several days to impart about 200 m/s of sideways delta-v and you will have a near-circular orbit well past Minmus. Is that more or less tricky than getting to Eve? Hard to say, and very open to opinion.

That is implying that you can impart that d-v at apoapsis. You have to design your craft to burn for (at least at my TWR) 3/4ths of the total ballistic flight. And you have to account for drift, and about a thousand other things. But, that's just my experience.