the cyclers [difficulty: inane]

[tuskiomi]

Your objective: make a cycler.

Reading can be done at

http://en.m.wikipedia.org/wiki/Aldrin_cycler

Note: this can be done with any celestial body. However, they have to be the same tier:

Eg

moon and moon: acceptable

Planet and planet: acceptable

Planet and moon: no!

Points:

1 point per ton (final cycler after last burn)

1 point per m/s in ÃŽâ€v

- 10 points per day before your final burn.

Full stock: 2000 points

Interplanetary cycle excludes kerbin: 1000 points

Manned: 100 points per kerbal (must survive)

Interplanetary cycle: 500 points

Inter-lunar cycle: 100

Cycle: one encounter to both planets / moons

Debris: -100 per piece

Probes:

Surface probes deployed:

50 points per surviving ton (must have 4 wheels and a radio controll module)

Orbital probes:

25 per ton deployed

Post flight log and any cool screenshots you get

As well as one at the start , before your final burn, and at each encounter.

[Synapse]

Is it possible? Have you tried?

[Pbhead]

Does it matter? It must be tried!

I know scott manley in one of his videos had a ship that started at kerbin, gravity assisted off of eve, and then gravity assisted off of kerbin... Which is about 1/2 of this challenge if you think about it.

The hard part is probably in the precision required to get it to stay stable for more than one loop...

[Peewee]

Did you read the challenge guidelines?

It does matter.

[sal_vager]

We really need to see your attempt, as it stands it's nearly certain that this cannot be done in KSP, the basic physics don't allow for it.

Please see the challenge submission guide and repost when you can show it's doable.

http://forum.kerbalspaceprogram.com/showthread.php/24898-Challenge-Submission-Guidelines

Update:

This may be possible after all, in a way, I'll let AncientGammoner explain

Edited September 14, 2013 by sal_vager

[AncientGammoner]

This is what I sent to sal_vager regarding this challenge and he asked me to post it here:

I believe the cycler challenge is possible, very hard but possible. I did some calculations and a lot of testing using precisenode and I managed to get an orbit like this:

It was just launched from the first crossing point with Kerbin on its orbit and notice that it encounters Duna then it encounters Kerbin again on the second crossing. The time until the Kerbin encounter is one synodic period, so when it encounters Kerbin again it will be lined up exactly how it was at launch, just like in a cycler orbit:

As you can see you have to do a burn/gravity assist on that second encounter to rotate the orbit, and playing around with Kerbin gravity assists (without Duna encounter so you can see it better) I managed to get this:

It shows a gravity assist that will alter the orbit exactly the right amount to restart the cycle. Approaching Kerbin looked like this:

Now the resulting trajectory wasn't as perfect as the prediction (probably because you need a small correction burn to make it work like IRL), but I'm certain it's possible to do a cycler in KSP.

Expanding on that, it looks the like 1 synodic period cycler (Aldrin Cycler) does require some burns in order to maintain (at least it does in real life for Earth-Mars). Here's an excerpt from a paper I was reading on a Mars transportation system:

The real world has more complicated alignments and in depth physics so maybe it can be done in KSP without a burn, or maybe not I think it would be really interesting to see what people can come up with.

[Captain Sierra]

We really need to see your attempt, as it stands it's nearly certain that this cannot be done in KSP, the basic physics don't allow for it.

Please see the challenge submission guide and repost when you can show it's doable.

http://forum.kerbalspaceprogram.com/showthread.php/24898-Challenge-Submission-Guidelines

Update:

This may be possible after all, in a way, I'll let AncientGammoner explain

HAHA! I too was about to criticize and say it could not be done without N-body physics but look here! Lesson learned, never be too quick do discount anything. Now how to do this. . . . . *grabs calculator*

[meyst]

This is my all stock 3 ton probe ballistic cycler attempt.

High energy burned for Duna.

Uploaded with ImageShack.com

On day 37 I did my last burn, onto a ballistic cycler trajectory.

Uploaded with ImageShack.com

I got a closest approach of 715 000 KM after a kerbin fly-by, only took 1401 days from the last burn... and should repeat about every 1438 days (4 years)... But is that close enough?

Uploaded with ImageShack.com

[metaphor]

This is totally possible in KSP between any 2 bodies. You only need patched conics for gravity assists, not n-body physics.

The reason you need extra burns on some of the orbits of an Earth-Mars Aldrin cycler is because Mars's orbit is eccentric. It travels from 1.4 to 1.7 AU away from the Sun. You would have the same problem in KSP.

But even in real life the cycler would need to do some small burns probably multiple times every orbit. All spacecraft need to do trajectory correction burns, usually about 2 or 3 correction burns between any 2 planets. So it would be a little hard to not do that at all in KSP.

AncientGammoner is pretty much as close to an Aldrin cycler as you can get.