Why a Rask and Rusk Infinite Cycler without thrusting would not work (explained using LOGIC!)

[Akagi]

So, to get one of those hypothetical Rask-Rusk infinite cyclers, you have to be going just barely fast enough to escape 1, then get a gravity assist off the other to return to the first one, right?

Well, the little bit of speed you would gain with each pass would eventually kick you out of the SOIs, right?

So, you would have to occasionally retroburn to stay in orbit. You still with me?

Did I get something wrong? If I did, please tell me.

[Bej Kerman]

15 minutes ago, Akagi said:

So, to get one of those hypothetical Rask-Rusk infinite cyclers, you have to be going just barely fast enough to escape 1, then get a gravity assist off the other to return to the first one, right?

Well, the little bit of speed you would gain with each pass would eventually kick you out of the SOIs, right?

So, you would have to occasionally retroburn to stay in orbit. You still with me?

Did I get something wrong? If I did, please tell me.

It's an unstable system. The most stable orbits either wrap tightly around either Rask or Rusk, or orbit at a distance where Rask and Rusk act like one body.

[Akagi]

2 minutes ago, Bej Kerman said:

It's an unstable system. The most stable orbits either wrap tightly around either Rask or Rusk, or orbit at a distance where Rask and Rusk act like one body.

*facepalms*

Just now, Akagi said:

*facepalms*

waiiit

This is the kind of orbit that has issues with avoiding large colonies

[Bej Kerman]

6 minutes ago, Akagi said:

8 minutes ago, Bej Kerman said:

It's an unstable system. The most stable orbits either wrap tightly around either Rask or Rusk, or orbit at a distance where Rask and Rusk act like one body.

*facepalms*

What did I do wrong?

[Akagi]

5 minutes ago, Bej Kerman said:

What did I do wrong?

No, I realized I screwed up.

[Bej Kerman]

8 minutes ago, Akagi said:

13 minutes ago, Bej Kerman said:

What did I do wrong?

No, I realized I screwed up.

How?

[Akagi]

1 minute ago, Bej Kerman said:

How?

Orbit would be highly unstable. If Rask and Rusk aren't tidally locked to their star, I might -- key word being might, I don't know -- hit the planets as their positions change.

I'm bad at math ;-;

[Pthigrivi]

11 minutes ago, Akagi said:

Orbit would be highly unstable. If Rask and Rusk aren't tidally locked to their star, I might -- key word being might, I don't know -- hit the planets as their positions change.

I'm bad at math ;-;

Don't worry, I think this pair is going to be a little counterintuitive and treacherous for all of us.  

[Guest]

18 minutes ago, Pthigrivi said:

Don't worry, I think this pair is going to be a little counterintuitive and treacherous for all of us.  

a little?

[Bej Kerman]

1 hour ago, Akagi said:

If Rask and Rusk aren't tidally locked to their star

What changes if they're tidally locked? They will be tidally locked to each other, not that their rotational periods would have much relevance to the orbits of spacecraft elsewhere.

[t_v]

46 minutes ago, Bej Kerman said:

What changes if they're tidally locked? They will be tidally locked to each other, not that their rotational periods would have much relevance to the orbits of spacecraft elsewhere.

If the two planets were stationary from an inertial reference frame, it would be possible to get a stable orbit around them. But, since they are moving, orbits will be unstable. 

Edited April 20, 2022 by t_v

[Nazalassa]

I tried to simulate a 2-planet-system on my calculator once. Yes, on my calculator. Worked perfectly.

I then tried to simulate Risk and Rusk, explain me why the pair is slowly drifting leftwards on my screen?

I noticed a bug, patched it, and relaunched the simulation.

So I had 2 bodies orbiting each other. I thought it was stable until they collided and disappeared from the screen.

Conclusion? Such a system won't work because of drag, even minimal, due to the void not being completely empty.

Or, because of technical limitations. Since there's no drag implementation on my simulator, I'll say that physical limitations would render the whole thing unstable if the celestial bodies' orbits were not burnt into memory.

[shdwlrd]

11 minutes ago, Nazalassa said:

I tried to simulate a 2-planet-system on my calculator once. Yes, on my calculator. Worked perfectly.

I then tried to simulate Risk and Rusk, explain me why the pair is slowly drifting leftwards on my screen?

I noticed a bug, patched it, and relaunched the simulation.

So I had 2 bodies orbiting each other. I thought it was stable until they collided and disappeared from the screen.

Conclusion? Such a system won't work because of drag, even minimal, due to the void not being completely empty.

Or, because of technical limitations. Since there's no drag implementation on my simulator, I'll say that physical limitations would render the whole thing unstable if the celestial bodies' orbits were not burnt into memory.

It's already understood that Rask & Rusk will collide at some point. It's just being created as a stable system for game play reasons. 

[Nazalassa]

5 minutes ago, shdwlrd said:

It's just being created as a stable system for game play reasons. 

I thought KSP2 was meant to be realistic.

[Bej Kerman]

2 minutes ago, Nazalassa said:

8 minutes ago, shdwlrd said:

It's just being created as a stable system for game play reasons. 

I thought KSP2 was meant to be realistic.

Yes - strike a balance between realism, simplification for gameplay and realistic dev goals.

[Nazalassa]

But Rask and Rusk are not realistic.

[Bej Kerman]

20 minutes ago, Nazalassa said:

But Rask and Rusk are not realistic.

Why not?

[shdwlrd]

2 hours ago, Nazalassa said:

I thought KSP2 was meant to be realistic.

If Rask & Rusk was truly realistic, how would the player see it? You will have to account for the time it will take players to find and travel to the dancing duel. Not everyone will find it at the same point in the game. Player 1 can take 50 yrs to find and travel there. Player 2 takes 150 yrs, player 3 takes 300 yrs. So you will have to make it stable to account that players will visit the system at different times during their individual play through.

That makes KSP a game, not a simulator. The little annoyances and not quite right things in reality can be ignored for a better experience. 

[Maria Sirona]

17 hours ago, t_v said:

If the two planets were stationary from an inertial reference frame, it would be possible to get a stable orbit around them. But, since they are moving, orbits will be unstable. 

So by your logic getting into Earth oebit is impossible?

[Pthigrivi]

For folks that have a more intuitive grasp of limited n-body, if I put myself in what looks like a lowish circular equatorial orbit arounds rask, what is going to happen as rusk pulls on my vessel over time?

[Maria Sirona]

7 minutes ago, Pthigrivi said:

For folks that have a more intuitive grasp of limited n-body, if I put myself in what looks like a lowish circular equatorial orbit arounds rask, what is going to happen as rusk pulls on my vessel over time?

I think the orbit will eventually ellipsize (is that even a word) until crashing into Rask

[Pthigrivi]

Yeah like, your Ap is going to lift perpendicular to the angle to rusk as you’re headed directly away from rusk, and your Pe is going to fall on the opposite side of rask as you’re headed directly toward rusk until eventually you crash—right?

[Maria Sirona]

19 minutes ago, Pthigrivi said:

Yeah like, your Ap is going to lift perpendicular to the angle to rusk as you’re headed directly away from rusk, and your Pe is going to fall on the opposite side of rask as you’re headed directly toward rusk until eventually you crash—right?

Yeah if my logic is sound

[Pthigrivi]

...And the Akagi and t_v are right that a cycler doing a figure 8 around them wouldn't work because rask and rusk are proceeding around each other and your incoming vector is going to shift on each orbit. 

[t_v]

1 hour ago, Maria Sirona said:

So by your logic getting into Earth oebit is impossible?

Yes, earth orbit is actually unstable - in real life, satellites and space stations have to deal with stuff like orbital decay and fluctuations which, if you are in a bad orbit or are really unlucky, can push you into denser atmosphere. Similarly, nothing left in low lunar orbit is thought to survive because the fluctuations caused by Earth’s tug causes orbit altitudes to fluctuate a lot.