Help with heavy math about the atmosphere of Jool.

[Brainlord Mesomorph]

I’m not a physicist. And have absolutely no idea how do the following maths.

My goal is to recover low-atmosphere science from Jool. The wiki says low-atmosphere starts at 120 km. Aerobraking altitude is 138 km. So the questions are, assuming you start in low Jool orbit, and aerobreak down to 120 km:

1. What is your speed and trajectory? (are you going straight down?, With wings could you be going sideways? are you ablating at that altitude?)

2. What’s you’re delta V requirement for getting back to orbit?

Like I said I have no idea how to do this math, and if you respond with a bunch of equations I probably still won’t.

[Snarfster]

Hmm, I'm not entirely sure, but I think I aerobraked at 106 km coming in from Kerbin. That ought to do the trick for you. However, that's with a rather excessive amount of speed.

Lifting the periapsis out of the atmosphere after the aerobrake wasn't bad, something like 100 m/s I think.

[Brainlord Mesomorph]

I think the the Pe has to inside the planet.

Edited January 29, 2015 by Brainlord Mesomorph

[SkyRex94]

look at my Jool-5 Log in my Signature. I've done exactly what you are planning, and I've taken pics

[Levelord]

Part of the fun is discovering where exactly that is on your own. I used to attach small drones to my ships and launch them into Jool where I would record the different atmospheric layers and biomes on where to measure science before letting the drone destroy itself. It's a bit like the Galileo spacecraft mission to Jupiter.

Most of the time, I consider a manned mission into Jool a suicide mission. I'm not sure if I can design a ship powerful enough to get back into orbit, but hey, that's what unmanned drones are meant to find out eh?

[Brainlord Mesomorph]

Skyrex:

Looking at the screenshots:

You are still ablating. You are going sideways.

Trying to read your velocity:

You start at about 6800 m/s, and slow down to 5200? (is that what that says)

1600 m/s to get back out? (edit: plus drag, makes it 3200? right?)

This looks much easier than I thought.

Edited January 29, 2015 by Brainlord Mesomorph

[magnemoe]

Yes, I have done science while flying at Jool during aerobrake multiple times.

Note that you have be in "orbit around the body before you can do atmospheric science, that is your Ap has to be inside the SOI before this you are in space near the body.

This is mostly an issue for Duna and perhaps Laythe.

[Brainlord Mesomorph]

Yes, I have done science while flying at Jool during aerobrake multiple times.

Note that you have be in "orbit around the body before you can do atmospheric science, that is your Ap has to be inside the SOI before this you are in space near the body.

This is mostly an issue for Duna and perhaps Laythe.

The wiki says for "Low-Atmosphere" your Pe has to inside the planet.

[Laie]

I think the the Pe has to inside the planet.

No. On Jool, you don't need to be suborbital to get a "flying at" result. You can explore Jools lower atmosphere while aerobraking. I've done that in v0.24 and 0.90. Orbit may not be hyperbolic, however: no results while you're still on an escape trajectory.

I usually plan for two rounds of aerobraking: the first leaves me with an AP somewhere in the neighborhood of Pol, the second is still deep enough to enter the lower atmosphere (for science!) and leaves we with an AP near Laythe.

[NASAHireMe]

Like what snarfter said above, your best bet to getting low-altitude Jool data is to do it while aerobraking from Kerbin. Unless, you're doing a Jool-5 missions in which you're hitting all 6 bodies in one go, you're probably sending multiple crafts to the Jool system throughout your game play. I ended up sending 10 ships to Jool (two Tylo landers, three Laythe spaceplanes, 1 Bop/Pol/Vall lander, 4 refueling/labs) over the course of gameplay, each one with all the science instruments. Since they all need to be aerocaptured, that's 10 sets of low-altitude data-- more than enough to get max science.

Another thing you can do if you really want to milk Jool's low-altitude science is to use Laythe or Tylo as a gravity-assist to sling you into an orbit with an Ap just inside Jool's SOI. With an Ap that high, you're going to have more than enough velocity to safely dip below 120km and emerge again. I've used this to Jool-dive as far down as 105km and still make it out. Since Tylo is so large, near to Jool, and has a periodic orbit that can be predicted (see the orbital resonance sheet in my signature), it makes a very attractive gravity-assist target.

[Brainlord Mesomorph]

No. On Jool, you don't need to be suborbital to get a "flying at" result. You can explore Jools lower atmosphere while aerobraking. I've done that in v0.24 and 0.90. Orbit may not be hyperbolic, however: no results while you're still on an escape trajectory.

I usually plan for two rounds of aerobraking: the first leaves me with an AP somewhere in the neighborhood of Pol, the second is still deep enough to enter the lower atmosphere (for science!) and leaves we with an AP near Laythe.

!@#$%^&@#$%^#$ !!!!!

I’ve spent hours in the VAB designing this massive two stage spaceplane/rocket thingy with some 10km/s of delta V because I thought that’s what I needed to do this.

Now it turns out I can do it by sticking my head out the window as I drive by!

LOL!

Well that will save me a million dollars.

Edited January 29, 2015 by Brainlord Mesomorph