BASIC Stuff: How to go into Solar Orbit?

[DavidRocket]

Hey Folks

 

Newbie question:

What is the best process for going into Solar Orbit?

Apologies if this is a REALLY BASIC question.

 

Thanks

 

David

[Gargamel]

Moved to Gameplay Questions. 

[Kerbalsaurus]

Have quite a bit of delta-v with you in Kerbin orbit, and then burn prograde from there, until you’re on an escape trajector. If you want a low solar orbit, god have mercy on your soul for the numbers of your craft’s delta-v will be high enough a man would die from looking at them.

[Streetwind]

Burning straight ahead for long enough in any direction should eventually get you into solar orbit, barring collisions with Kerbin, Mun, or Minmus. Expect to spend about 1000 m/s worth of dV (or a bit less, depending on your starting orbit around Kerbin).

However, your resulting solar orbit is shaped by the direction you chose.

If you chose to fire your engines in the direction of Kerbin's orbit around the Sun (prograde escape, nightside burn), then your solar orbit will have a raised apoapsis on the other side of the sun. You use this maneuver if you wish to go to the outer planets.

If you chose to fire your engines opposite the direction of Kerbin's orbit around the Sun (retrograde escape, dayside burn), then your solar orbit will have a lowered periapsis on the other side of the Sun. You use this maneuver if you wish to go to the inner planets.

If you pointed neither directly Kerbin-prograde nor Kerbin retrograde, but still within the equatorial plane, you will get less of a raising or lowering effect, depending on how far off you were. The energy will get put into a radial shift instead, but those are subtle; your solar orbit is is incredibly high energy compared to anything you do around Kerbin, and thus, spending a few hundred m/s in radial will hardly move it. You can use such an escape burn in niche situations. For example, if you use a transfer planning tool/mod to compute transfers to other planets, they will sometimes give you a burn that goes partially radial in order to correct for being somewhat out-of-window. And personally, I like to use a burn 45 degrees off Kerbin-prograde towards the Sun for my very first dip into solar orbit for science collection, where I just want to spend a minute or two there before getting recaptured by Kerbin. It is easier to get that quick recapture if you're not immediately starting to climb towards Duna the moment you exit the SoI.

Finally, if you pointed up or down with respect to the equatorial plane (normal/antinormal), your solar orbit is going to be inclined. Not as much as you think, though. Your inclination will be that of the point where you exited Kerbin's SoI. So the highest inclination solar orbit that you can possibly achieve with a full 90 degree up or down burn is the inclination of the northern or southern tip of Kerbin's SoI, which is... uh, I forget. A few degrees. You can use escape burns like this to help you hit an inclined target orbit, but only if (in addition to the transfer window being open) Kerbin is reasonably close to an ascending or descending node of the target orbit. Most of the time, you'll only use an inclined escape burn because a transfer planner tool/mod told you to.

 

Edited November 25, 2022 by Streetwind

[DavidRocket]

16 hours ago, Gargamel said:

Moved to Gameplay Questions. 

Thanks for the Help!

[DavidRocket]

12 hours ago, Streetwind said:

Burning straight ahead for long enough in any direction should eventually get you into solar orbit, barring collisions with Kerbin, Mun, or Minmus. Expect to spend about 1000 m/s worth of dV (or a bit less, depending on your starting orbit around Kerbin).

However, your resulting solar orbit is shaped by the direction you chose.

If you chose to fire your engines in the direction of Kerbin's orbit around the Sun (prograde escape, nightside burn), then your solar orbit will have a raised apoapsis on the other side of the sun. You use this maneuver if you wish to go to the outer planets.

If you chose to fire your engines opposite the direction of Kerbin's orbit around the Sun (retrograde escape, dayside burn), then your solar orbit will have a lowered periapsis on the other side of the Sun. You use this maneuver if you wish to go to the inner planets.

If you pointed neither directly Kerbin-prograde nor Kerbin retrograde, but still within the equatorial plane, you will get less of a raising or lowering effect, depending on how far off you were. The energy will get put into a radial shift instead, but those are subtle; your solar orbit is is incredibly high energy compared to anything you do around Kerbin, and thus, spending a few hundred m/s in radial will hardly move it. You can use such an escape burn in niche situations. For example, if you use a transfer planning tool/mod to compute transfers to other planets, they will sometimes give you a burn that goes partially radial in order to correct for being somewhat out-of-window. And personally, I like to use a burn 45 degrees off Kerbin-prograde towards the Sun for my very first dip into solar orbit for science collection, where I just want to spend a minute or two there before getting recaptured by Kerbin. It is easier to get that quick recapture if you're not immediately starting to climb towards Duna the moment you exit the SoI.

Finally, if you pointed up or down with respect to the equatorial plane (normal/antinormal), your solar orbit is going to be inclined. Not as much as you think, though. Your inclination will be that of the point where you exited Kerbin's SoI. So the highest inclination solar orbit that you can possibly achieve with a full 90 degree up or down burn is the inclination of the northern or southern tip of Kerbin's SoI, which is... uh, I forget. A few degrees. You can use escape burns like this to help you hit an inclined target orbit, but only if (in addition to the transfer window being open) Kerbin is reasonably close to an ascending or descending node of the target orbit. Most of the time, you'll only use an inclined escape burn because a transfer planner tool/mod told you to.

 

Thank you Steetwind

This exactly the informative answer I was looking for.