Hohmann Transfer (Changing Orbits)
Move a spacecraft from a low orbit to a higher one with two engine burns — see the half-ellipse it coasts along, read both speed changes, and find out why the cheap route is also the slow one.
Preview — sign up free to change the numbers yourself
What you can adjust
- Central body
- 0 – 3
- Starting orbit radius (multiple of body radius)
- 1.05 – 3 × body radius
- Target orbit radius (multiple of starting radius)
- 1.2 – 8 × starting radius
- Animation duration
- 4 – 8 s
What you're orbiting. A heavier body pulls harder, so the same maneuver costs more speed change around it.
How far out the starting circular orbit is, as a multiple of the body's own radius — e.g. 1.063 around Earth is about a 400 km altitude, a real low orbit.
How much higher the final circular orbit is than the starting one. 6.6 around Earth lands close to a geostationary orbit.
How long the clip runs — long enough to watch the starting orbit, both engine burns, and the coast up to the new orbit.
About this simulation
What it shows
A spacecraft moves from a low circular orbit to a higher one using two engine burns, coasting along a half-ellipse in between. Both speed changes and the transfer time are read out.
The key idea
The first burn raises the far point of the orbit and the second circularises it at the new height. This is the cheapest way to change orbit in speed change, but it takes the longest, because the craft coasts half an ellipse.
Try this
Lower Target orbit radius (multiple of starting radius) from 6.6 to 3: both the total speed change and the coasting time get smaller.