Lunar Free Return Trajectory [Last saved 4/19/2006. Scenario originally created by Mike Loucks, SEE]

4-19. Original scenario:

This scenario is a Lunar Free Return trajectory.

The inner targeter (‘Target Moon’) is similar to many we have created in the past, with the standard sequence of profiles: RA-Dec and Bplane profiles getting us to a lunar encounter. In this scenario, the final profile targets a BdotR of zero (thus giving us the minimum inclination we can have on this encounter) duration, and a radius of periapsis. The outer targeter (‘Target Return’) takes advantage of the Nested Targeting capability introduced in 6.2. The duration (or time of flight) and the BdotR constraints of the inner targeter are varied in order to achieve an inclination and altitude of periapsis at the Earth encounter after the return. This setup allows us to insure that the lunar encounter will always take place at the same altitude (250 km) because the inner targeter is always forcing us to this condition.

Note that while this scenario targets an inclination of 28.5 degrees, not all other inclinations are possible at all times of the month. For example, you cannot get back to a equatorial inclination (0 deg) when your encounter of the Moon is at 23 degrees. Higher inclinations may be available, but not lower. If you want zero, you’ll have to get to the Moon when it’s near the equatorial plane.