Atmospheric mapping and aerobraking

[Kosmic Debris]

Is there a way to land a probe on a planet with an atmosphere and map the barometric pressure on the way down to get a profile of the density curve?

If so, how (with maths) do you apply that to aerobraking altitudes?

I'm interested in how KSP would determine an aerobraking profile "in the real world" vs. going to the wiki or here and looking it up

Thanks!

[GJames]

I believe that the Telemachus plugin does that very well, although I haven't used it myself.

And you'll have to get someone else much more knowledgeable than me to figure out the aerobraking profiles...

[MennoLente]

If you wanna do it like a kerbal, use the graphotron, downloadable on spaceport. I use it quite often, especially to gather data for the wiki and discover it is already there. When dropping probes, I recommend to use a lightweight probe, say <3t, parachute, 3 lightweight legs, instruments, graphotron. Change the graphotron's settings to have a larger resolution, adjust to taste. Than quicksave in case you forgot to change a setting. Than enter the atmosphere, angle not too steep, the idea is that you survive the drop, and when you touch the ground, save the graphotron's data, et voilà!

And for the math, mechjeb calculates a lot of it. Perhaps r4mon, the mechjeb fellow. Nice guy, very helpful. If he doesn't know, than he knows at least who knows, or where to find the equations. link to mechjeb topic *click!*

EDIT: Well, I know a part of the math... The drag equation of course! Why didn't I think of that before! the only unknown is the drag coefficient. I know how to calculate it for shapes, but I guess ksp uses different values. Would that be the those drag numbers in parts their cfg files? Hmmm... That would explain a lot.

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Edited May 22, 2013 by MennoLente

[GJames]

the only unknown is the drag coefficient.

The drag coefficient for nearly all the parts in KSP is 0.2, apart from a few parts. I think rover wheels may be 0.15 or something... Either way, a drag coefficient of 0.2 should give you enough accuracy for aerobraking.

[Specialist290]

Funnily enough, someone posted a topic on the subject in the General Discussion forum last night that might prove as enlightening to you as it was to me. The math for calculating aerobraking is in one of the posts further down the thread. To summarize, though, you're basically calculating the change in your orbit's angular momentum brought about by the effects of drag for the duration of your time in atmosphere.

Hope this helps

Edited May 22, 2013 by Specialist290