Orbit Input Panel
Example Data Table
| Body | μ m³/s² | Radius m | Rotation s | Expected Use |
|---|---|---|---|---|
| Kerbin | 3.5316e12 | 600,000 | 21,549.425 | Classic keostationary relay planning. |
| Duna | 3.0136321e11 | 320,000 | 65,517.859 | Interplanetary relay and station design. |
| Jool | 2.82528e14 | 6,000,000 | 36,000 | Large system communications planning. |
Formula Used
altitude = r − R
v = √( μ / r )
Here, r is orbital radius from the body center. μ is gravitational parameter. T is sidereal rotation period in seconds. R is body radius. v is circular orbital speed. The calculator also estimates Hohmann transfer delta-v from the chosen parking orbit.
How to Use This Calculator
- Select Kerbin or another preset body.
- Edit the body name when using a custom world.
- Enter μ, radius, and sidereal rotation period.
- Add sphere of influence when you want a feasibility warning.
- Enter parking altitude for transfer delta-v estimates.
- Set relay satellite count to calculate spacing.
- Press the calculate button. The result appears above the form.
- Download the CSV or print the page when needed.
Understanding KSP Geostationary Orbit
A geostationary orbit keeps a satellite above one longitude. In KSP, players often call it a keostationary orbit around Kerbin. The idea is simple. The craft must orbit once during one planet rotation. When both periods match, the ground track stops drifting. This calculator turns that idea into exact mission numbers.
Why The Orbit Needs A Period Match
Every circular orbit has a period. A low orbit moves fast and finishes quickly. A high orbit moves slowly and takes longer. The correct altitude is the height where orbital period equals the body day. For Kerbin, that height is far above normal low orbit. The satellite also needs zero inclination. Otherwise, it draws a north south path in the sky.
Useful KSP Planning Details
The main result is altitude above sea level. The radius from the center is also shown. Velocity helps you judge final circularization. The circumference and spacing values help with relay networks. Three satellites usually need one hundred twenty degrees of separation. Four satellites need ninety degrees. Extra satellites can reduce blind spots.
Custom Bodies And Mods
Many players use planet packs. These worlds may have different radius, gravity, and rotation period. Enter the gravitational parameter when it is known. It gives the cleanest result. When you only know mass, multiply it by the gravity constant. The calculator also checks the sphere of influence when you provide it. A synchronous orbit outside that limit is not practical.
Transfer Thinking
The optional parking orbit estimate is a planning aid. It treats the move as a simple Hohmann transfer. It does not replace a navigation tool. It still gives useful delta-v guidance. Launch into an equatorial parking orbit first. Then raise apoapsis to the target radius. At apoapsis, circularize carefully. Small errors can create slow longitude drift.
Reading The Result
A positive altitude means the target is above the surface. A negative value means the body rotates too fast for a surface clearing orbit with those values. A warning appears when the target radius passes the sphere of influence. Use the result as a starting point. Then fine tune period in flight. Match the period closely for stable relay coverage.
Common Setup Mistakes
Do not use a solar day when a sidereal day is needed. The orbit follows the rotating body, not the sun. Do not mix kilometers and meters inside the same formula. Keep radius and gravitational parameter in matching metric units. Also remember that geostationary means more than synchronous. The orbit must be circular and equatorial. An inclined synchronous craft still has the right period, but it will move north and south each day.
Network Design Tip
Build one accurate satellite first. Note its period after circularization. Copy the target orbit for the next craft. Use the spacing angle shown here. This keeps relay patterns neat and predictable. This saves fuel during later corrections.
FAQs
What does geostationary mean in KSP?
It means the satellite stays above the same longitude. The orbit period must match the body rotation period. The orbit should also be circular and equatorial.
Is geostationary the same as synchronous?
Not exactly. A synchronous orbit only matches the rotation period. A geostationary orbit also needs zero inclination and very low eccentricity.
Which input is most important?
The sidereal rotation period is critical. The gravitational parameter and body radius are also required. A wrong unit can move the final altitude far away.
Why use gravitational parameter μ?
It combines the gravity constant and body mass. Orbital equations use μ directly. That makes the calculation cleaner and less error prone.
Can I use this for modded planets?
Yes. Choose custom values. Enter the planet radius, rotation period, gravitational parameter, and sphere of influence from your mod data.
Why does the calculator show a warning?
A warning appears when the altitude is below the surface or outside the sphere of influence. Such orbits are not practical with those inputs.
Does atmosphere affect the result?
The equation assumes a clean circular orbit. If the target altitude enters atmosphere, drag will ruin the orbit. Use a higher safe body or revised values.
How many relay satellites should I use?
Three satellites give broad coverage when spaced evenly. More satellites can improve redundancy. Use the spacing angle result for clean placement.
What is the parking orbit estimate?
It is a simple Hohmann transfer estimate. It helps plan rough delta-v. It does not include launch losses, plane changes, or steering errors.
Why is inclination important?
An inclined satellite will drift north and south on the map. Keep inclination near zero for a true fixed point over the equator.
Can I download the calculation?
Yes. After a calculation, use the CSV button. You can also print the page or save it as a PDF from your browser.