Question: Stay faced to Kearth when in a low Kearth orbit

[Korbat]

Hey guys!

I\'ve got a question for you guys.

I\'m playing KSP for a several months now, and i\'m pretty good at it now 8)

But there\'s still something bothering me, and that is: Why does your spacecraft turn arround when orbitting and why doesn\'t it stay faced to earth like the ISS in real life. As an example the cupola module on the iss is always staying faced to earth. The only way i stay faced to Kearth is by adjusting my rotations and keeping my spacecraft horizontal by using thrusters.

If you still don\'t know what i\'m meaning look at the video in the spoiler below

I hope you guys can help me, because it can very useful to stay horizontal while docking with a spacestation or something like that ;D

Greets,

Korbat

[maltesh]

Your spacecraft doesn\'t turn when orbiting under SAS lock. Normal KSP SAS locks your spacecraft with respect to the fixed stars.

The ISS uses four Control Moment Gyroscopes to keep itself pointed in its desired directions, with assistance from gravity gradeint stabilization, atmospheric drag, and reaction thrusters.

[Korbat]

Oh wait i think i know the solution. I know the iss (in real life) uses gyroscopes (http://en.wikipedia.org/wiki/Gyroscope) to stay horizontal. And we don\'t have gyroscopes in kerbal spaceprogram. So i think that\'s the solution of my question but i\'m not sure about it.

So if anybody here can correct me i\'d appreciate your help!

[Korbat]

Your spacecraft doesn\'t turn when orbiting under SAS lock. Normal KSP SAS locks your spacecraft with respect to the fixed stars.

The ISS uses four Control Moment Gyroscopes to keep itself pointed in its desired directions, with assistance from gravity gradeint stabilization, atmospheric drag, and reaction thrusters.

When you wrote your reply on my topic a was writing a reply on my own topic because i figured it out myself already

[Korbat]

Your spacecraft doesn\'t turn when orbiting under SAS lock. Normal KSP SAS locks your spacecraft with respect to the fixed stars.

The ISS uses four Control Moment Gyroscopes to keep itself pointed in its desired directions, with assistance from gravity gradeint stabilization, atmospheric drag, and reaction thrusters.

Hey, thanks for your post!

But i think i don\'t understand what you\'re saying with orbiting under SAS lock. because i\'ve got my SAS on while i\'m orbiting but i\'m still turning arround. (and what do you mean with: Normal KSP SAS locks your spacecraft with respect to the fixed stars.)

[maltesh]

Relative to the Fixed stars is a way of saying 'Relative to the universe as a whole.'

When you turn on SAS, the ship points in a direction relative to the stars, not relative to Kerbin, or any object that it\'s currently orbiting. (Or, at least, that\'s what the spacecraft would be doing in the universe KSP is simulating.)

In the video, however, the camera is locked to keep Kerbin centered, so it looks like the spacecraft is spinning, when it\'s really keeping itself pointed in the same direction.

[Nibb31]

The spacecraft isn\'t actually 'turning around'. In fact, the ASAS is keeping a stable absolute attitude (relative to the universe) while it rotates around Kerbin, which gives the illusion that the spacecraft is rotating along its orbit.

What you want is to keep a relative attitude (relative to Kerbin), which means that the spacecraft would actually be rotating in sync with the orbit in the same way that the Moon rotates on itself around the Earth in sync with its orbit, so as to always present the same side.

If you use KSP 0.14, you can use the MechJeb plugin, which acts as a vastly improved ASAS and is capable of holding attitudes at relative attitudes.

[DonLorenzo]

While the effect is the same, under time acceleration it\'s not so much the ASAS as the rails system

[Tiberion]

As an aside;

Kearth ----> Kerbin

[Korbat]

The spacecraft isn\'t actually 'turning around'. In fact, the ASAS is keeping a stable absolute attitude (relative to the universe) while it rotates around Kerbin, which gives the illusion that the spacecraft is rotating along its orbit.

What you want is to keep a relative attitude (relative to Kerbin), which means that the spacecraft would actually be rotating in sync with the orbit in the same way that the Moon rotates on itself around the Earth in sync with its orbit, so as to always present the same side.

If you use KSP 0.14, you can use the MechJeb plugin, which acts as a vastly improved ASAS and is capable of holding attitudes at relative attitudes.

do you guys think it\'s also possible without using the MechJeb plugin?

[Korbat]

As an aside;

Kearth ----> Kerbin

I know that Kearth means Kerbin

[Nibb31]

do you guys think it\'s also possible without using the MechJeb plugin?

You would have to switch off the SAS and manually input the correct rotation with the RCS and correct it manually. Very hard to do.

[Korbat]

Okay thanks for the info guys!

I\'m going to lock this topic for now.

Later,