Jool aerocapture altitude?

[Soda Popinski]

I'm doing my first mission to Jool, arriving at about 5000 m/s (year 1 day 282 launch from Kerbin, arrival year 2 day 222). I want to slow to about 2000 m/s for orbit. I tried the KSP Aerobraking Calculator, but it's designed to pop you out at the same orbital velocity (not really what I want).

I am using DRE (ballute heat shields), so I can't go super extreme. If needed, I can do an aerocapture, and dip back into the atmosphere to circularize a few times.

So, what altitude should I shoot for to get me from 5000 m/s to 2000 m/s (and/or aerocapture)?

Edited December 30, 2013 by Soda Popinski

[MrPopcup]

Hello!

I used Aero-braking to get captured into Jools orbit, Laythe and Tylo.

so far I only put my periapsis when I arrived between 124 - 130 km to get captured into either jool's orbit or tylo.

and To get captured by laythe I simply put 118-120 km.

I can't tell you the altitude to slow down from 5000m/s to 2000m/s.

You should explain more. do you want to LAND on jool or just to get captured?

or maybe land/orbit other moon?

[BlackBicycle]

I have just set my sights on Jool - sent a mighty ship there. 5 docked modules, hope they arrive in one piece.

How I did it on Duna though, was:

1. Quicksave before apoapsis.

2. Burn to a certain periapsis at the apoapsis

3. Check what that periapsis does to you

4. Quickload and repeat with a different periapsis till you hit the ballpark

Cheating? Well, I CBA to calculate it beforehand (that would be one hell of a bunch of calculations too). So I do the Kerbal way - by trial and error (and quickload : )

[Taki117]

anything less than about 130km and you run the risk of burning up as soon as you hit atmo. (especially with DRE) you might also want to start burning retrograde as you come in because that 5000m/s will become well over 10km/s as you hit atmo. if you are going for capture your best bet is to get mechjeb and use its landing guidance to show you your orbit after aerobrake.

[regex]

anything less than about 130km and you run the risk of burning up as soon as you hit atmo. (especially with DRE)

You will only burn up if using DRE.

If you're coming in for Jool itself you could do worse than about 117km, but that really depends on your incoming speed.

There's this site for help with estimates:

http://alterbaron.github.io/ksp_aerocalc/

[Soda Popinski]

Thanks! I'll shoot for 120km with quicksaves just in case.

My plan is to get into Jool's orbit eccentric out to at least Laythe. I plan to launch my 4 ion powered probes to Vall, Tylo, Bop, and Pol to search for Kethane. Meanwhile, orbit Laythe, and put my science lander on it, science around a bit, and return to orbit. Head to whichever moon looks good for Kethane (equatorial deposit), drop off my Kethane rig to refuel, and land my science lander. Rinse and repeat for the other 3 moons. Refuel and head home (leaving the kethane rig and lander to save mass).

[BlackBicycle]

Good luck Soda, I bet all that equipment weighs a lot : ) I am doing something similar in the coming days, I'll be watching your progress with great interest. Maybe you should start a thread somewhere.. (where do we keep our current reports at?). I'll probably make a parallel one. See each others designs, brag a bit, find some solutions to impossible situations : ? In other words, talk to ya soon : )

[Soda Popinski]

Good luck Soda, I bet all that equipment weighs a lot : ) I am doing something similar in the coming days, I'll be watching your progress with great interest. Maybe you should start a thread somewhere.. (where do we keep our current reports at?). I'll probably make a parallel one. See each others designs, brag a bit, find some solutions to impossible situations : ? In other words, talk to ya soon : )

Yeah, I'll be putting something in the Mission Reports sub forum. I've been taking screen shots along the way. Just waiting to do something worthwhile. My ship is vaguely based on the Discovery from 2001. This thing should have taken 5 launches (cockpit/science lab/hitchhiker [need 6 guys for RT2 commands to work] + truss, NERVA powered drive section + Jumbo fuel tank, science lander [integrated into the spine], 2 halves of my kethane rig, 4 ion probes). Unfortunately, mistakes were made involving docking ports being put on wrong, or not at all, requiring relaunches of the cockpit section and probes. Plus, I couldn't get the kethane rigs launched together, and had to launch them separately. 2 more launches to refuel and send up the crew on my SSTO. Waiting for 8 days until launch window.

[Soda Popinski]

BlackBicycle. I've posted a thread on the mission thus far. Just orbital assembly and crewing / refueling. Launching in a little while.

[SSSPutnik]

I used 118km a couple of times. Gets me into a Laythe orbit intersect pretty closely.