ISS altitude in KSP terms

[Olvirm]

What altitude is the ISS orbiting in in terms of KSP altitudes (ie if it was orbiting at the very edge of earth's atmosphere it would be at 70km)

[JSD]

I know ISS is orbitting 407 KM above us. I just don't know the scale used in the Kerbal system..

[Wjolcz]

everything in ksp is 11 times smaller

at least kerbin and its moon

[iBotz]

So using 100km as the end of the Earth's atmosphere that is useful for aerodynamic lift (the Kármán Line) and using some basic math (370-400km and 70km for the end of Kerbin's atom) for ISS, the ISS would be about 259km in orbit. It may look different because Kerbin is smaller than Earth.

[Schweehog]

37 Kilometers?

[TwoHedWlf]

What altitude is the ISS orbiting in in terms of KSP altitudes (ie if it was orbiting at the very edge of earth's atmosphere it would be at 70km)

I believe the "official" edge of the atmosphere, or at least what is considered the beginning of space is 100 km. If that's the case and the ISS is at 407 that would put its orbit at roughly 284km.

Coincidentally I tend to put my stations at about 250km.

[Schweehog]

Notice the Earth in Pictures of the ISS: http://scienceblogs.com/startswithabang/files/2010/09/iss_sts119_big.jpeg

See how close the ISS is to the Earth? If the Earth was a Classroom globe, the ISS wouldn't be far from the lacquer on that Globe. Though 284 KM might be the correct altitude in some ways, to get the same view as the ISS, you need to be MUCH lower.

[TwoHedWlf]

Notice the Earth in Pictures of the ISS: http://scienceblogs.com/startswithabang/files/2010/09/iss_sts119_big.jpeg

See how close the ISS is to the Earth? If the Earth was a Classroom globe, the ISS wouldn't be far from the lacquer on that Globe. Though 284 KM might be the correct altitude in some ways, to get the same view as the ISS, you need to be MUCH lower.

True, to get the earth to cover the same relative arc as kerbin it would be much closer. Someone do the trig? I'm at work...Pretending to work so don't have time.

[Sᴄɪɴᴛɪʟʟᴀᴛᴏʀ]

Kerbin is 64% the size of Earth, is that not the agreed upon scaling factor??

[skendzie]

This is a cool image showing the altitude and the effects of orbital decay on the International Space Station. Interesting!

[Gaux]

<Accidental Post>

I don't see a delete button anywhere

Edited June 6, 2013 by Gaux

[NeoMorph]

34km? But that's suborbital..

370km/11 = KABOOOOOOOM

[NeoMorph]

I know ISS is orbitting 407 KM above us. I just don't know the scale used in the Kerbal system..

Well what you know seems to be wrong... ISS is orbiting at a mean of 370km (between 330 and 410). I do know it gets a boost every know and then from the visiting resupply rockets like the ATV.

[Spatzimaus]

There's no easy answer for this, because KSP works on absolutes. If you're within the atmosphere, there's drag; if you're outside the magic line, there's no drag. If you're within the SOI there's gravity; if you're outside, there's none. This is all done to keep the phyiscs manageable, and works fine when discussing short-term behaviors, but it's just not realistic for the sort of long-term things we're dealing with here.

The ISS is at an altitude where atmospheric drag is very slight, but it's still there. The timescale for the orbital decay would be years, so we have to do minor adjustments periodically, but it's not the sort of constant decay you'd get if you put an object below the 70km line in KSP (where you'd hit the ground within a matter of minutes). If KSP wanted to provide a comparable amount of drag to things above 70km, the per-second force would be so slight that it'd be below the level of precision used by the internal math, which means it'd require a whole other layer of accounting. It's just not worth it, so they simply say that above the magic line, drag is zero and you can stay in a circular orbit forever.

[Gaux]

Brand new to the forums, all because of this

The ISS orbits Earth at a periapsis of 330km, and apoapsis 435km (According to Wikipedia). To get the same 'distance to the horizon' from a satellite orbiting Kerbin, (Using the formula d = √(2Rh + h^2)) you need heights at 157.9km, and 169.5Km respectively. But this would not give the same look.

If you were to scale the distance to the horizon to match the scale of Kerbin (One tenth of the distance to the horizon? As in 2077/10 and 2394/10), it would then give the same look as the ISS does. This would be at 50.0km periapsis and 53.6km apoapsis, but this wouldn't work because of atmosphere.

I'm not 100% sure if this is correct, so, here are my workings, check them please!

Radius of the Earth is around 6371km, Kerbin is 600Km.

ISS:

√(2*6371*330 + 330^2) = 2077km (To the horizon, at periapsis).

√(2*6371*435 + 435^2) = 2394km (To the horizon, at apoapsis).

Kerbin ISS:

√(2*600*X + X^2) = 2077km

√(2*600*Y + Y^2) = 2394km

Rearrange the equation..

√(2*600*2077) = X

√(2*600*2394) = Y

X = 157.9km

Y = 169.5Km

Kerbin ISS relative distance to the horizon:

√(2*600*X + X^2) = 2077km

√(2*600*Y + Y^2) = 2394km

(Divide answer by 10)

Rearrange the equation..

√(2*600*208) = X

√(2*600*239) = Y

X = 50.0km

Y = 53.6km

Edited June 6, 2013 by Gaux