The Kerman Line

[NecroBones]

Recently the topic of the "Karman Line" came up in a post I was making on Facebook, and I realized I kept wanting to call it the "Kerman Line" instead, because KSP has infected my brain.

I'm sure most of you know what the "Karman Line" is, but for those who don't, it's considered to be the international standard for the altitude at which space begins. It's based on the altitude at which the velocity an aircraft would need, in order to maintain deflection lift, reaches orbital velocities sufficient to maintain altitude via the centrifugal component of that trajectory. (Read the wikipedia page for a better explanation than that).

But that raised a question that I thought I'd bring to the community here. What would you consider to be your "Kerman Line"? That is, when do you consider yourself safely in space, launching from KSC? It's hard to remember the exact altitude at which the atmosphere ends, and the game considers you to be "in space" (69,078m, according to the wiki). Do you have some other number you use?

Personally, I've usually aimed to get my PE up to about 75km minimum over Kerbin, to consider it a "safe" orbit.

[Javster]

The Kerman line should be at 70 km.

[cantab]

70 km. The game's atmosphere ends precisely, unlike in real life, and though it actually ends at 69.something km 70 is easier to remember.

[skeevy]

70km, but I like to use 75km after a bad EVA had Jeb do a freefall back to the surface. I almost grabbed the capsule around 45km, but I came in too hot, smacked it hard, and never had a chance to catch it again. He didn't make it.

Oh, for some lulz, the other day I had a launch go very badly so I had Bill jump out around around 200m over the ground, the resulting explosion, Bill was about 20m over it/the ground when it happened, sent him up to about 40m where he fell down and had a bit of a tumble...but he survived a 200m free fall.

[Cirocco]

Others have said before me: my Kerman Line is 70 km, but I always aim for at least a 75 km orbit. Usually I go for an 80-85km orbit, just to leave me some room for orbital manouvering.

[Tw1]

If I'm going for orbit, I aim for 80. That's 10km worth of space to fall before atmospheric drag should something stuff up.

[Kizarvexis]

When the music starts. (70km) I usually shoot for 80 km orbits and am happy with anything between 70-100km.

[Norpo]

70km for bare minimum (if, say, I need to test if something can *barely* get into orbit), 75km for a safe orbit, 100km for space stations (so if i'm a bit behind, I can still lower my orbit a little bit to get ahead)

Those are generally my goals for orbits.

[biohazard15]

Below 100 km: Test flights

100 km: Safe orbit for in-system operations

120 km: So-called "Atlas orbit" (I have an Atlas replica that ends with its 1st stage at the orbit; since I don't want to add retroboosters and KSP don't have atmospheric drag to deorbit it, I just launch it at 120 km to ensure some safety. There is about 25 Atlas debris up there already)

150 km: Interplanetary transfer orbit

200-300 km: Space stations

[Zylark]

My bare minimum is 75km, anything below I wouldn't consider safe. Any little nudge if coasting at 70km might just very well throw the vessel under the magic border.

Though the actual altitude I aim for depends greatly on the mission at hand. Usually above 140km for two reasons. It allows greater time acceleration, and I got a Station zipping around Kerbin at 200km that I often visit for refueling or crew transfer purposes.

[Red Iron Crown]

70km is the line where I consider an object "in space".

I aim for 75-80km for most launches to make circularization TWR less critical, but that's just a preference. 70km is a perfectly safe orbit.

I know it's actually a bit less than that, but 70km is a round, easy to remember number.

[tg626]

70km is the Kerman line for me. As such, I tend to take real world altitude numbers and multiply them by 0.7 to get my in KSP targets.

For instance, I use RealChute so I have both drogue and main chutes on my Mk1-2 pods and using this:

I set the drogue to pop at 5000m (real 24,000ft or 7315m: 7315 * 0.7 = 5120.5)

Disreef at 3500m (cut at 2100m)

Mains pop at 2000m (real 10,000ft or 3048m: 3048 * 0.7 = 2133)

Disreef at 700m

Makes reenty "very Jeb"

[justidutch]

Yeah, 70 k is my Kerman line. And yeah, I aim for about 75 k to circularize my orbits before boosting them higher.

[montyben101]

Wow? people usually orbit around 75-85 km? My usual orbit is at 125 KM !

[NecroBones]

Wow? people usually orbit around 75-85 km? My usual orbit is at 125 KM !

It's actually pretty rare for me to orbit that low. Most of my parking orbits are around 100-120 km.

One thing I learned early on, is that when you're executing an escape burn, if you just point at the maneuver marker and execute a long burn, you may lower your altitude quite a bit during the burn. So I started aiming for 120-ish (sometimes 150), just to make sure I didn't hit atmosphere.

While orbiting right at 70km is perfectly feasible, I consider it dangerous, in that a very small nudge can make you hit atmosphere.

[timsfitz]

I put stuff I'm docking with above 240 so I can use x1000 time warp.

[Trentendegreth]

i keep my stations at 110km, most of my orbital stuff happens at 100k, interplanetary at 150k, i rarely deviate from that, nothing lower than80k, ssto's must circularize at 100k-150k 70k-80k is reserved for debris.

[merendel]

While I generaly call anything above 70 safeish 80 is where I aim for on launch. I've been known to send tugs down to 70 for very tight margian launches to pull a ship up to a fuel depot.

80km is my LKO transfer orbit. Non stop flights to mun or minmus also leave from here.

100km is my primary interplanetary transfer orbit. Any vessel that is expecting a 4min or higher burn to leave goes up at least this high so I dont run into atmo on the way out.

121 is my primary station orbit. Fuel depots are there. Some interplanetary vessles may leave from this orbit if they needed refueling. hight chosen for the 100x timewarp limit.

300 is my local comsat orbit for remote tech. covers the low orbits with omnies and mun/minmus with directionals.

interplanetary comsats end up out past mun somewhere

[Jas1126]

80k myself. I prefer to have a little leeway for rendezvous missions.

[problemecium]

My Kerman line is 69.1 km, but with floating point imprecision to deal with I try to shoot for about 70.5km so that in case something wobbles I won't find myself stuck with no timewarp.

[Slam_Jones]

70km to get to space.

I'll get my spaceplanes just barely beyond it, but for stations and such, I try to stay beyond 100km

[Thomas988]

For me, the atmosphere ends at 70 km. I like my orbit real low. Tend to orbit at about 72 km, and at most 80 km. It's easy to reach, and it doesn't take a massive rocket to get there.

[Bishop149]

70 km. The game's atmosphere ends precisely, unlike in real life, and though it actually ends at 69.something km 70 is easier to remember.

Well, this obviously.

However orbiting at 70km give you absolutely no room to speed-up your orbit should you need to catch up to something in a higher orbit . . . . for this reason around 100km is my minimum, although much of my orbital infrastructure is higher up, usually at 100km increments, topping out with the Antimatter collectors at 1,000km up.

Edited October 28, 2014 by Bishop149

[worir4]

You can get orbits pretty much above 60km. They will only seriously degrade if you play non time warp for quite a while. It's pretty fun to try build a station that low as you have to occasionally correct your orbit with RCS or something.

[Pecan]

75km 'temporary' launch and de-orbit.

150km low rendezvous and phasing.

250km station.

400km high rendezvous and phasing.

600km+ parking.