However, Apollo 13 had left its initial free return trajectory earlier in the mission, as required for the planned lunar landing at Fra Mauro.

Therefore, the first order of business was to re-establish the free return trajectory with a 30.7-sec.

Such free return trajectories add a margin of safety to human spaceflight missions, since the spacecraft will return to Earth "for free" after the initial TLI burn.

They are angling into a return trajectory.

Eve praises Shogo's basic goodness and announces that Megazone 23 is completing its return trajectory toward Earth.

Once the ERV is fuelled, the crew is launched to Mars on a free return trajectory.

Although in theory it is possible to execute a perfect free return trajectory, in practice small correction burns are often necessary during the flight.

Hughes had no ability to track the satellite at such a distance, and opted instead for an Apollo-style free return trajectory that required only a few days to complete.

A month later, Harman launches the New Prometheus and succeeds in making a free return trajectory around the Moon.

This engine was used on Apollo 13 to achieve free return trajectory and make a minor course correction after damage to the Service Module.