Hohmann Transfer Time

ATRONOMY – ORBITAL MECHANIC (52) CALCULATOR Hohmann Transfer Time A precise tool.
πŸ“–
What is the Hohmann Transfer Time & How does it work?

A Hohmann transfer is the most fuel‑efficient two‑impulse maneuver to move a spacecraft between two coplanar circular orbits. It works by first raising (or lowering) the spacecraft onto an elliptical transfer orbit that tangentially touches the original orbit at periapsis and the target orbit at apoapsis.

The semi‑major axis of the transfer ellipse is simply the average of the radii of the two circular orbits, (a = frac{r_1 + r_2}{2}). Because the spacecraft travels half an orbit on this ellipse, the transfer time depends on the orbital period of the ellipse, which is governed by Kepler’s third law.

Using the standard gravitational parameter (mu = GM) of the central body, the transfer time can be expressed analytically. This allows quick estimation of mission duration without numerical integration.

t = pi sqrt{frac{left(frac{r_1+r_2}{2}right)^3}{mu}}
t = Hohmann transfer time (seconds)
βš™οΈ
Parameters
Result β€”
❓
Frequently Asked Questions
What is a Hohmann transfer?
A Hohmann transfer is an efficient way to move a spacecraft from one circular orbit to another by using two impulses, one to enter the elliptical transfer orbit and another to reach the target orbit.
How do I calculate the semi-major axis for the transfer orbit?
The semi-major axis of the transfer ellipse is calculated as the average of the radii of the two circular orbits: a = (r1 + r2) / 2.
What are the two impulses in a Hohmann transfer?
The first impulse raises the spacecraft from its initial orbit to the periapsis of the elliptical transfer orbit. The second impulse occurs at apoapsis, raising it to the target orbit.
Why is a Hohmann transfer considered fuel-efficient?
A Hohmann transfer requires only two impulses and uses the least amount of fuel compared to other orbital maneuvers for changing orbits.
Can this calculator be used for any type of orbits?
This calculator assumes coplanar circular orbits. For non-circular or inclined orbits, a different approach would be needed.
What is the significance of periapsis and apoapsis in a Hohmann transfer?
Periapsis is the point in the elliptical orbit closest to the central body, while apoapsis is the farthest. The impulses occur at these points to efficiently transition between orbits.
How does the time for a Hohmann transfer depend on the orbits' radii?
The transfer time depends on the semi-major axis of the elliptical orbit and the gravitational parameter of the central body. Generally, larger orbits require more time to transfer between.

Results are for informational purposes only and do not constitute professional advice.