How low can you go?

[painless42]

In support of continued operations and preparation for docking support, KASA has decided to launch 3 space stations.

One into Low Kerbal Orbit,

One into Low Mun Orbit

and then some Kerbals in Black Suits showed up and 'asked' us to put 'classified payload' into geosynchronous orbit over the People\'s Republic of Kerbalastan.

I know that geosynchronous orbit is at 2.87 MM or so, but what are the minimum altitudes

for Kerbal and the Mun? I want to get just above the atmospheric drag.

[Sunlis]

Kerbin\'s atmosphere ends at about 70k (69,100 m according to the wiki). The Mun has no atmosphere, so you can get as low as you like, as long as you don\'t hit the ground anywhere. There isn\'t any solid data that I know of in terms of what the highest ground altitude is on the Mun, though.

[Millst0ne MK II]

Actually, If you orbit really low on the Mun, The game will eventually crash becuase of the engine not being able to render the terrain tiles fast enough at high detail.

[painless42]

Kerbin\'s atmosphere ends at about 70k (69,100 m according to the wiki). The Mun has no atmosphere, so you can get as low as you like, as long as you don\'t hit the ground anywhere. There isn\'t any solid data that I know of in terms of what the highest ground altitude is on the Mun, though.

So I can send a $1Billion dollar piece of space hardware hurtling around the Mun at a ridiculously high rate of speed 50 Meters off the ground 'Dukes of Hazard' Style? What could possibly go wrong?

/Thanks Guys

[Cooly568]

Actually, If you orbit really low on the Mun, The game will eventually crash becuase of the engine not being able to render the terrain tiles fast enough at high detail.

Unless you have a computer which can only play KSP at 0% terrain detail. :-[

So I can send a $1Billion dollar piece of space hardware hurtling around the Mun at a ridiculously high rate of speed 50 Meters off the ground 'Dukes of Hazard' Style? What could possibly go wrong?

/Thanks Guys

The highest mountain on the mun is around 3000 meters off the ground.

[Candre]

According to a poster in the ISA Mun mapper thread the tallest point is barely under 3300 meters. I\'ll try to find it, brb

EDIT:

3284m is, so far, the highest discovered point on the mun.

http://kerbalspaceprogram.com/forum/index.php?topic=10324.180

^Reply #188^

[togfox]

There isn\'t any solid data that I know of in terms of what the highest ground altitude is on the Mun, though.

Actually, there is. Search the forum for ISA_RAM and you\'ll see the Mun has been mapped.

My topography records show just over 3000m high on the Mun. An orbit of 3100m is cutting it close but it should be fine. If you have an equatorial orbit you can go even lower. I should work out exactly how low that is ...

[Zephram Kerman]

Kerbin\'s atmosphere ends at about 70k (69,100 m according to the wiki)...

Although if you\'re just slightly in the atmosphere, drag is minimal so you can stay there quite a long time, or indefinitely with periodic boosts. (This is one way the real ISS is protected from debris.) Time warp limited to 2x though.

We\'ve all seen a case where our heroes run out of fuel with periapsis just inside 70km. Yes, they\'ll eventually get home, but the drag that high up is almost nil, so it takes dozens of passes. When they finally do arrive, they\'re all beardy and cranky. Yeesh.

So if you feel like really pushing the lower end of the envelope, go ahead and experiment with 68km... 65km... oh jeez 55 km? Bring some reboost fuel and make it awesome.

[hubbazoot]

Atmospheric edge is at about 69100m, I\'ve been down to 60k before it started getting really notable, it depends on how much you wanna babysit it.

Highest peak is 3285M on Mun, so as long as you\'re above that, you\'re good. You can 'Get away' with lower. The highest peak is at about the 45 deg north, so if you stay less than 45 deg away from the equator, you could squeal it down lower.

I\'d recommend 69200 for Kerbin and 3300 for Mun.

Kerbosynchronous orbit is at 2868.4km, 1008.9m/s.

http://184.154.141.114/~kerbalsp/wiki/index.php?title=Main_Page

Oh, and remember, anything you put up into orbit before docking clamps you won\'t technically be able to attach to.

[wired2thenet]

I\'d recommend 69200 for Kerbin and 3300 for Mun.

For the Mun, is that 100% accurate? I seem to remember being about 5k up, and crashing into a hill while in an equatorial orbit (as of 14.4). I\'ve been limiting my orbits to no less than 8k as a result (haven\'t tried 5 or 6k yet).

[hubbazoot]

For the Mun, is that 100% accurate? I seem to remember being about 5k up, and crashing into a hill while in an equatorial orbit (as of 14.4). I\'ve been limiting my orbits to no less than 8k as a result (haven\'t tried 5 or 6k yet).

Oh, I\'m not saying those altitudes I recommended are safe. I tend to hang out at about 8k for a munar orbit, unless I\'m landing and then I drop down to 4k for a brief stint.

For kerbin orbits, I tend to hang around 73k for my low points.

Allegedly, the highest point on the mun is 3285, and so the lowest I\'d recommend for a 'low-as-you-can-go' orbit would be 3300m. I did an orbital survey of the mun (lots of screenshots that I still don\'t know what to do with) at 8km, and even that high I felt like stuff was reaching up more than halfway to me.

[Sunlis]

We\'ve all seen a case where our heroes run out of fuel with periapsis just inside 70km. Yes, they\'ll eventually get home, but the drag that high up is almost nil, so it takes dozens of passes. When they finally do arrive, they\'re all beardy and cranky. Yeesh.

Have I ever been there before. While trying to de-orbit some debris (with a MechJeb module so I could pilot it back down) I didn\'t quite leave enough fuel and was only able to get my Periapsis down to about 68k after emptying my fuel and RCS tanks. Apoapsis was something ridiculous like 4 million. It was taking so long for the Ap to come down that I ended up just leaving it overnight at 2x and coming back to a successfully crash-landed stage.

[wired2thenet]

Oh, I\'m not saying those altitudes I recommended are safe. I tend to hang out at about 8k for a munar orbit, unless I\'m landing and then I drop down to 4k for a brief stint.

For kerbin orbits, I tend to hang around 73k for my low points.

Allegedly, the highest point on the mun is 3285, and so the lowest I\'d recommend for a 'low-as-you-can-go' orbit would be 3300m. I did an orbital survey of the mun (lots of screenshots that I still don\'t know what to do with) at 8km, and even that high I felt like stuff was reaching up more than halfway to me.

Ahh, thanks for the clarification. I was wondering if I wasn\'t being Kerbal enough

Have I ever been there before. While trying to de-orbit some debris (with a MechJeb module so I could pilot it back down) I didn\'t quite leave enough fuel and was only able to get my Periapsis down to about 68k after emptying my fuel and RCS tanks. Apoapsis was something ridiculous like 4 million. It was taking so long for the Ap to come down that I ended up just leaving it overnight at 2x and coming back to a successfully crash-landed stage.

lol ... I used aerobreaking last night, after successful delivery of a permanent settlement on the Mun. In my original return burn, I overshot Kerbin, and had to wait to retro burn, and ended up spending most of my fuel doing so. When I realized I didn\'t have enough fuel to make a better orbit, I burned until Peri was about 70k above Kerbin. Took a LOT of orbits, before I finally had a descent, and through a fortuitous set of circumstances, I landed just outside that little lake south of the KSP

[SteevyT]

500m was too low before the new terrain (way too low), and the new terrain made bigger mountains.

But somehow I managed this.

(Yes, that is my shadow sticking out over the navball)

[Zephram Kerman]

...Peri was about 70k above Kerbin. Took a LOT of orbits...

Wow, that must have taken all night! I once experimented with aerobraking at various PE. I quit trying at 60km after the at least a dozen orbits. Now I shoot for 35-40 km, or else I call them 'lost'.

[wired2thenet]

Wow, that must have taken all night! I once experimented with aerobraking at various PE. I quit trying at 60km after the at least a dozen orbits. Now I shoot for 35-40 km, or else I call them 'lost'.

Pretty much. It was about 5am local time before I finally splashed down. I think I started the maneuver around midnight local. I was cursing my luck the entire time I have a tendency to stay with a mission, even if it\'s a bad one, all the way through before ending it. Won\'t be doing that again though. KSP needs a big red ABORT button in the bottom corner of the screen

Jeb was piloting, btw. Bill and Bob were huddled in a corner of the capsule, like little school-girls (not that there\'s anything wrong with that!).

[vexx32]

Jeb\'s always piloting... The other two just sit there going 'Shoudl you really be fiddling with those controls?!'

[willitstimothy]

I Usually set up for landing at around 35k, I think the lowest I have ever set up from was around 8k or so. It would be killer to try and set up at only 4k and then crash because you couldn't slowdown fast enough.

Edited August 18, 2012 by willitstimothy

[vexx32]

Oh, I\'ve been in situations where I was unable to properly setup for landing at over 10k... just going too damn fast xD

[Zephram Kerman]

Yep, me too. Did a sub-orbital trip to put a cart at KSC2. Too fast, too low, too proud for parachutes... too many pieces to clean up.

[hubbazoot]

Yep, me too. Did a sub-orbital trip to put a cart at KSC2. Too fast, too low, too proud for parachutes... too many pieces to clean up.

Well said, sir.

Oh, in reply to the original post:

After I did a little more plunking around, I wouldn\'t recommend having the PE of the orbit closer than 69100 to Kerbin at all. I had some PE\'s that were just inside that, and I was losing a couple hundred meters every orbit. At that rate, it may not take long to actually have them get completely sucked in.

[willitstimothy]

Anything below 70000 meters will degrade eventually in this game. Give it time, it will 'get sucked in.'

[Dehouston]

I had a an orbit around the Mün with a periapsis of 2,507m and an apoapsis of 3,054m. There was a point on the dark side of the Mün where a mountain range was higher up than my craft and I was only halfway in between apoapsis and periapsis.

I later tried to land and ended up accidentally toggling on the auto-rotate on the camera and couldn\'t manage the RCS and crashed; I have my RCS remapped to the numpad. ???

[willitstimothy]

I later tried to land and ended up accidentally toggling on the auto-rotate on the camera and couldn't manage the RCS and crashed; I have my RCS remapped to the numpad.

When setting up for a landing on Mun there is nothing more annoying than having your pc's accessibility controls pop up, taking you away from your nicely controlled landing which is now doomed to be a crash.

The second most annoying thing is running out of RCS, hence I modded one of my RCS tank parts to have a capacity of 25000 volume units of 'fuel.' ;D

Edited August 18, 2012 by willitstimothy

[nerdboy64]

Because the Mun has no atmosphere, theoretically you can orbit at any altitude; you just have to make sure you clear the hills. I don\'t actually know what Kerbin\'s minimum orbital altitude is, but I usually aim for 75-100 km.