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 the two-burn, fuel-optimal way to move between two coplanar circular orbits. You start with a burn at the first orbit to place the spacecraft on an elliptical transfer orbit whose periapsis is at the initial orbit and whose apoapsis reaches the final orbit. Then, when you reach the final orbit, you perform a second burn at the apoapsis of that transfer ellipse to circularize into the target orbit. This geometry makes the total delta-v minimal for an impulsive transfer between two circular, coplanar paths, because the transfer orbit is the ellipse that just touches both orbits. It’s the go-to method when you want to minimize fuel for moving between two circular orbits in the same plane, such as a typical Earth orbital transfer from a low parking orbit toward a higher one. It’s not the fastest in time, and if you allow more complex schemes or non-circular orbits, other transfers might be more favorable for different constraints.

A Hohmann transfer is the two-burn, fuel-optimal way to move between two coplanar circular orbits. You start with a burn at the first orbit to place the spacecraft on an elliptical transfer orbit whose periapsis is at the initial orbit and whose apoapsis reaches the final orbit. Then, when you reach the final orbit, you perform a second burn at the apoapsis of that transfer ellipse to circularize into the target orbit.

This geometry makes the total delta-v minimal for an impulsive transfer between two circular, coplanar paths, because the transfer orbit is the ellipse that just touches both orbits. It’s the go-to method when you want to minimize fuel for moving between two circular orbits in the same plane, such as a typical Earth orbital transfer from a low parking orbit toward a higher one. It’s not the fastest in time, and if you allow more complex schemes or non-circular orbits, other transfers might be more favorable for different constraints.