PDA

View Full Version : How did Apollo get to the moon?


ryank614
Feb10-08, 03:05 PM
Q: What kind of trajectory was used? And why was it used over the Hohmann transfer?

The time of flight to the moon on Apollo 11 was 100 hours, 39 minutes 53 seconds. The time of flight for a Hohmann transfer would have been 119 hours from my calculations.

I've done some research and found a translunar injection was used. But I couldn't find ANY INFO on WHY it was used. Was it to reduce launch window? For safety reasons?

D H
Feb10-08, 03:40 PM
A Hohmann transfer implicitly assumes a system with one and only one massive body. Strictly speaking, you can't do a Hohmann transfer from the Earth to the Moon, or the Moon to the Earth.

The term translunar injection just means the burn that transfers the vehicle from LEO to a trajectory to the Moon. What they used was a patched conic (http://en.wikipedia.org/wiki/Astrodynamics#The_patched_conic_approximation).