Learn the delta-v, gravity turn, apoapsis target and circularisation burn needed to reach Kerbin orbit, with fixes for common launch failures.
To reach orbit around Kerbin in Kerbal Space Program, launch east, make a gradual gravity turn, and stop accelerating when your apoapsis is about 75–85 km. Coast near apoapsis, then burn prograde until the periapsis rises above Kerbin’s 70 km atmosphere. Both markers above 70 km mean a stable orbit.
The method works in the original Kerbal Space Program and Kerbal Space Program 2, although their interfaces and manoeuvre-node controls differ. Related game-wide topics appear among our other Kerbal Space Program answers.
How much delta-v do I need for Kerbin orbit?
A well-flown stock launch normally requires roughly 3,400 m/s of delta-v to enter low Kerbin orbit. For a first attempt, build for about 3,800–4,000 m/s so an imperfect gravity turn or delayed staging does not end the flight.
- Aim for a launch thrust-to-weight ratio of about 1.3–1.5 on Kerbin.
- Use an engine with good sea-level thrust on the lower stage and an efficient vacuum engine above it.
- Give the upper stage enough thrust to complete its circularisation burn before passing far beyond apoapsis. A very low upper-stage TWR makes the timing harder.
- Carry a separate reserve if the craft must deorbit and land.
More fuel is not always the cure: extra tanks add mass, which may require larger engines and stronger staging. If thrust, oxidiser or vacuum performance is unclear, our explanation of how rocket engines turn propellant into thrust covers the underlying terms.
What launch profile reaches orbit around Kerbin?
A reliable ascent first clears the dense lower atmosphere, then converts most of the rocket’s thrust into horizontal velocity.
- Prepare the stages. Use a controllable capsule or probe, a powerful launch stage and a lighter upper stage. Add fins near the base if the rocket is aerodynamically unstable. Include electrical power for an uncrewed probe and recovery equipment if the crew must return.
- Launch east. Set full throttle, engage stability assistance if available and lift off vertically. East is heading 90° on the navball and takes advantage of Kerbin’s rotation.
- Begin a gentle gravity turn. At roughly 50–100 m/s, tip only 5–10° east. Keep the nose close to the prograde marker rather than forcing a sharp turn. Being near 45° around 10 km and almost horizontal by 30–40 km is a useful guide, not a rigid timetable.
- Set the apoapsis. Watch
Apin map view. Continue pitching towards the horizon and cut the engine when apoapsis reaches roughly 75–85 km. Orbit requires sideways speed, so climbing far higher does not compensate for a vertical ascent. - Coast towards apoapsis. Point prograde and confirm that the velocity reference is orbital rather than surface-relative if your edition offers that choice. Do not time-warp past the burn point.
- Circularise the orbit. Burn prograde near apoapsis. If a manoeuvre node is available, place it at
Apand add prograde velocity untilPerises above 70 km. Start approximately half the estimated burn duration before apoapsis; a 40-second burn, for example, should begin about 20 seconds beforehand. - Verify the result. Stop when periapsis is safely above the atmosphere, preferably 75 km or higher for some margin. The orbit can be elliptical; it does not need matching apoapsis and periapsis values.
Why does my Kerbin launch keep failing?
Most failed first orbits result from flying too vertically, turning too sharply or reaching the circularisation burn without enough useful upper-stage delta-v.
| Symptom | Likely cause | Fix |
|---|---|---|
| The rocket flips during the gravity turn | The turn is too abrupt, the craft is unstable or its nose is far from prograde | Make a smaller initial pitch, keep heavy parts forward and place fins near the bottom of the launch stage |
| Apoapsis is high but periapsis remains inside Kerbin | Too much fuel was spent climbing vertically | Turn east earlier and build horizontal speed instead of continuing upwards |
| Fuel runs out during circularisation | Insufficient delta-v, dead lower-stage mass or an inefficient upper-stage engine | Stage empty tanks promptly and give the upper stage more vacuum delta-v |
| The craft passes apoapsis before completing the burn | The burn began too late or the upper stage has too little thrust | Start half a burn duration before apoapsis or use a higher-thrust upper stage |
| The rocket barely leaves the pad | Launch TWR is near or below 1, or the active engine performs poorly at sea level | Check staging and throttle, then use less mass or more suitable launch thrust |
| The map shows an orbit, but the craft re-enters | Periapsis is below 70 km or only marginally above it | Burn prograde near apoapsis until periapsis reaches at least 75 km |
How do I return safely from Kerbin orbit?
A typical capsule returns by burning retrograde until its periapsis falls to roughly 30–40 km. This sends it decisively into the atmosphere without aiming directly at the surface.
Keep the heat shield facing into the airflow, hold retrograde while control remains available and deploy parachutes only when their indicator shows safe conditions. Spaceplanes and unusually heavy craft need a shallower, more carefully managed descent than a basic capsule.