Laythe Delta V

[SpaceDirt]

I was wondering about the delta v to Laythe and back with gravity assists. Would 4,143 m/s delta be adequate to get to Laythe with gravity assists?

[Aegolius13]

You mean from LKO to Laythe orbit, and back to Kerbin?  And with no Laythe landing?  If so, then yeah, that should be enough. 

• It's around 2,000 m/s to move your apoapsis out to Jool with no assists.   I think a Juno-style Kerbin-Kerbin assist can save a few hundred m/s.  Very fancy Eve assists can probably get the cost down closer to 1,000 m/s.
• If you get assists around the Joolian moons and aerobrake to capture around Laythe, you should have no braking burn. So you're looking at whatever it costs to maneuver into the right assists.  I'd say a few hundred here. 
• It's about 1,000 m/s to get from Laythe back to a Kerbin intercept (again, without any assists on the way)
• And it should be pretty much free to capture back at Kerbin, if you have the heat tolerance to aerobrake.

So 4,000 m/s should be enough for a round trip, without needing to get too terribly fancy with your maneuvers.  

[Foxster]

I'd say it was marginal without some luck. Sure, it is do-able but risky. It would almost certainly mean aerobraking back at Kerbin, which for me usually means just a capule and heatshield (20% ablator is good for almost any re-entry). 

There are some variables that are hard to predict, particularly your gravity brake at one of Jool's inner moons. So I'd build in a bigger a margin. 

 

Edited March 27, 2018 by Foxster