Difference between revisions of "Orbital rendezvous"

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(Tutorials: added summary of tutorial. should be sufficient for the purpose of this article. not very in-depth though)
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In general, an orbital rendezvous involves two steps - '''encounter''' and '''velocity matching'''.
 
In general, an orbital rendezvous involves two steps - '''encounter''' and '''velocity matching'''.
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== Usages ==
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Possible usages of orbital rendezvous include:
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* [[Docking]] two craft together
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** Assembling a [[space station]]
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** Interplanetary craft
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** In-orbit refuelling
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** Transfering a more experienced [[Scientist]] to an orbital [[Mobile Processing Lab MPL-LG-2]]
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* Grabbing an [[asteroid]] with the [[Advanced Grabbing Unit]]
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* Rescuing [[Kerbonaut|kerbonauts]] on [[EVA]] stranded in orbit
  
 
====[[Encounter]]====
 
====[[Encounter]]====
  
The process of creating an encounter with a target object requires the player to meet two conditions.  The first is that the orbit of the craft must intersect the orbit of the target (this is usually tangential for efficiency).  The second is that both craft and target must be at the intersection at the same time.
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The process of creating an encounter with a target object requires the player to meet two conditions.  The first is that the orbit of the craft must intersect the orbit of the target (this is usually tangential for efficiency).  This can be from a lower orbit where you will be travelling at a slower velocity, or from a higher and faster orbit.  The second is that both craft and target must be at the intersection at the same time.   
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Often only one craft does the orbital maneuvers and the other object is passive and does not change its orbit.
  
 
====Velocity Matching====
 
====Velocity Matching====
  
Once the craft is in close proximity to the target, a maneuver is made to match velocity with target, thus matching orbits.  When relative velocity is null, a more or less stable situation exists.  The player can then EVA to the target, dock with the target (if craft and/or target are properly equipped), or perform any task which requires the craft to remain in close proximity to the target.
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Once the craft is in close proximity to the target you must now bring your craft into the same orbital plane in a maneuver that also matches velocity with the target.  When relative velocity is null, a more or less stable situation exists.  The player can then EVA to the target, dock with the target (if craft and/or target are properly equipped), or perform any task which requires the craft to remain in close proximity to the target.  Some situations make it simpler to match orbital planes first, then either play catchup or slow down till proximity is reached (2.2k or less for EVA from or to target, or to switch control between vessels using [ or]).
  
 
====[[Tutorials#Orbital Rendezvous|Tutorials]]====
 
====[[Tutorials#Orbital Rendezvous|Tutorials]]====
  
Several tutorials exist which can help the player learn the process of orbital rendezvous.
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For low planetary orbits, it is easier to approach the target from a higher more elliptical orbit where you are initially in front of the target and your orbit slows your craft.  For higher planetary orbits it is faster to approach from a lower orbit from behind.  Your velocity will be slower but your orbital period will be shorter.  Low planetary orbits take little time and allow many trial and error attempts.  High orbits, especially solar orbits, mean days, months or years between passes, so planning is important.  With practice, your craft can come from an oblique orbit at a vastly different velocity to intercept the target, changing plane and velocity in a single manoeuvre for a spectacular rendezvous!!  Chasing asteroids, for example, or crash diving into a moon's SOI for ship to ship docking.
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Several tutorials exist which can help the player learn the process of orbital rendezvous. As of version [[1.0]], there is also an ingame tutorial.
 
* [[Tutorial:Orbital Rendezvous|Orbital Rendezvous]]
 
* [[Tutorial:Orbital Rendezvous|Orbital Rendezvous]]
 
* [[Tutorial: Orbital Docking with the Kergena Target Vehicle|Orbital Docking with the Kergena Target Vehicle]]
 
* [[Tutorial: Orbital Docking with the Kergena Target Vehicle|Orbital Docking with the Kergena Target Vehicle]]
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* [[Tutorial: Orbital Rendezvous|In depth tutorial for an orbital rendezvous and docking]] by It's Just Rocket Science
 
* [[Tutorial: Orbital Rendezvous|In depth tutorial for an orbital rendezvous and docking]] by It's Just Rocket Science
  
A summary of how to do a rendezvous:
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== Gallery ==
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<gallery>
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File:Kerbal Space Program Enhanced Edition 20220117205015.jpg|A small docking craft rendezvouing with a satellite.
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</gallery>
  
# Go to the [[map view]] and use the maneuver tool.
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[[Category:Maneuvers]]
# Begin by [[#Match Orbital Inclination|matching your orbital inclination]] as described above. During the procedure below occasionally check to ensure that the inclination is exactly zeroed and make correction burns as necessary.
 
# Bring one point on your orbit (ideally an [[Terminology#Orbital Terms|apsis]]) tangent to the target orbit. You will see an orange/purple pair of arrows. Each colored arrow corresponds to the relative position of you and your target. The orange is the nearest encounter, and the purple is the next encounter after that.
 
# At the point of nearest encounter maneuver to make:
 
##your orbits as close as possible to each other.
 
##the next encounter (probably right back here) to within 0.5&nbsp;km or so.
 
# On reaching that encounter, burn to match velocity. To do this, go back to the staging or docking screen. Click on the "point of reference" on the [[navball]] until it displays the relative target velocity. Rotate the "Level indicator" [[File:Level indicator.svg|24x24px|frameless|default]] (which indicates the direction your vehicle is pointing) until it is aligned with "Retrograde" marker [[File:Retrograde.svg|24x24px|frameless|default]] and burn until you bring the relative target velocity (displayed at the top of the [[navball]]) close to zero (ideally less than 1–2&nbsp;m/s). At this point you have brought your vehicle close to the target and almost stationary relative to the target - your orbits and velocities should now be nearly identical, and position separated only by a fraction of a kilometer.
 
# Now, rotate so that the "Level indicator" is aligned with the "Target Prograde" marker [[File:Target prograde.svg|24x24px|frameless|default]]. This points the nose of your vehicle towards the target. You should keep these markers aligned as you approach the target until you are within a few metres and ready to make the final docking maneuvers. Using the SAS may help with this.
 
# Activate your RCS system, this gives you the finest control of your approach.
 
# Press the "H" key to start moving towards the target (using RCS thrusters to thrust forward). You should keep the relative velocity low as you approach (less than 10&nbsp;m/s when more than 500m away, slower as you approach). You should see the "Prograde" [[File:Prograde.svg|24x24px|frameless|default]] marker line up with the "Target Prograde" marker [[File:Target prograde.svg|24x24px|frameless|default]](check that you navball is still has the "Target" as its "Point of Reference"). Use the lateral thrust keys ("I","J","K" and "L") to adjust the "Prograde" marker as you approach, and keep it lined up with the "Target Prograde" marker.
 
# As you get closer, use the "N" key to slow your approach. Slow down gradually to ~1&nbsp;m/s by the time you are within 50 meters or so. Eventually come to a stop (0&nbsp;m/s relative velocity) close to the target.
 

Latest revision as of 12:48, 10 May 2022

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An Orbital Rendezvous is a series of maneuvers which result in a craft achieving a stable condition of close proximity to a target object orbiting the same parent body.

In general, an orbital rendezvous involves two steps - encounter and velocity matching.

Usages

Possible usages of orbital rendezvous include:

Encounter

The process of creating an encounter with a target object requires the player to meet two conditions. The first is that the orbit of the craft must intersect the orbit of the target (this is usually tangential for efficiency). This can be from a lower orbit where you will be travelling at a slower velocity, or from a higher and faster orbit. The second is that both craft and target must be at the intersection at the same time.

Often only one craft does the orbital maneuvers and the other object is passive and does not change its orbit.

Velocity Matching

Once the craft is in close proximity to the target you must now bring your craft into the same orbital plane in a maneuver that also matches velocity with the target. When relative velocity is null, a more or less stable situation exists. The player can then EVA to the target, dock with the target (if craft and/or target are properly equipped), or perform any task which requires the craft to remain in close proximity to the target. Some situations make it simpler to match orbital planes first, then either play catchup or slow down till proximity is reached (2.2k or less for EVA from or to target, or to switch control between vessels using [ or]).

Tutorials

For low planetary orbits, it is easier to approach the target from a higher more elliptical orbit where you are initially in front of the target and your orbit slows your craft. For higher planetary orbits it is faster to approach from a lower orbit from behind. Your velocity will be slower but your orbital period will be shorter. Low planetary orbits take little time and allow many trial and error attempts. High orbits, especially solar orbits, mean days, months or years between passes, so planning is important. With practice, your craft can come from an oblique orbit at a vastly different velocity to intercept the target, changing plane and velocity in a single manoeuvre for a spectacular rendezvous!! Chasing asteroids, for example, or crash diving into a moon's SOI for ship to ship docking.

Several tutorials exist which can help the player learn the process of orbital rendezvous. As of version 1.0, there is also an ingame tutorial.

Gallery