What is a Hohmann transfer and when is it used?

What is a Hohmann transfer and when is it used?

• A. A single-burn transfer
• B. A circularization burn at apoapsis
• C. A two-burn transfer between coplanar circular orbits with minimum delta-v
• D. A rapid re-entry maneuver

Answer: (C)

A Hohmann transfer is a two-impulse, minimum-energy way to move between two circular orbits that lie in the same plane. The idea is to pick an elliptical transfer path that just touches both orbits (tangent to each). The first burn at the initial orbit speeds you up enough to enter that transfer ellipse. You then coast along the ellipse until you reach the radius of the destination orbit, where a second burn corrects your speed to match the target orbit, effectively circularizing there.

Why this is the best fit for the concept: because, among two-impulse transfers between coplanar circular orbits, the Hohmann path requires the smallest total velocity change. The transfer ellipse being tangent to both initial and final orbits minimizes the energy needed for the two burns. The second burn occurs at the transfer ellipse’s apoapsis, which is why you might hear it described as a circularization burn at that point, but the key idea is the two-burn, minimum-delta-v transfer between those two circular, coplanar orbits.

This method isn’t a single-burn transfer, it isn’t used for rapid re-entry maneuvers, and it assumes no plane change. It’s the go-to efficient planar transfer when changing radii of circular orbits.