Mars free returns via gravity assist from venus

The safety of the crew is the top priority for human exploration of Mars. If an unexpected emergency occurs, a free-return trajectory brings the spacecraft back to the Earth without a deterministic maneuver. We use an automated design tool to search for Mars free-return trajectories, which satisfy NASA's Design Reference Mission (DRM) constraints. While no cases exist for Mars alone, a Mars-Venus free return does meet the DRM requirements for a launch in 2014. This trajectory is remarkably fortuitous as it does not exist for many years prior to or after the 2014 date.