What Is a Hohmann Transfer?
A Hohmann transfer orbit is the most fuel-efficient two-impulse maneuver to move between two coplanar circular orbits. Developed by Walter Hohmann in 1925, it uses an elliptical transfer orbit that is tangent to both the initial and final circular orbits. Two engine burns are required: one to enter the transfer ellipse and one to circularize at the destination orbit.
The Hohmann transfer is widely used in space mission planning, particularly for satellite deployment to geostationary orbit and interplanetary missions. While it minimizes fuel usage, it is also the slowest two-burn transfer. Faster transfers require more delta-v.
Hohmann Transfer Equations
Common Transfers
| Transfer | Total Δv | Time |
|---|---|---|
| LEO to GEO | 3.94 km/s | 5.3 hours |
| Earth to Mars | 5.59 km/s | 259 days |
| Earth to Venus | 5.24 km/s | 146 days |
Frequently Asked Questions
Why is the Hohmann transfer most efficient?
The Hohmann transfer fires engines at the optimal points (perigee and apogee of the transfer ellipse) where the Oberth effect maximizes the energy gained per unit of fuel. Burns at these tangent points change only speed, not direction, minimizing wasted energy on direction changes.
When is a Hohmann transfer not optimal?
When the ratio of final to initial orbit radius exceeds about 11.94, a bi-elliptic transfer actually requires less delta-v despite taking longer. Also, when transfer time is critical (crewed missions), direct or fast transfers using more fuel may be preferred over the slow Hohmann trajectory.