Artificial gravity and abort scenarios via tethers for human missions to Mars

Minimum-mass tether designs are developed for a spinning human transport that not only provides artificial gravity, but also the potential for free-return aborts. The investigation reveals that severing the tether can provide a propellant-free boost to return astronauts to Earth in the event of an aborted landing on Mars. Earth-Mars-Earth, Earth-Mars-Venus-Earth, and Earth-Venus-Mars-Earth trajectories requiring little, or no, velocity change after departure from Earth, are examined. The investigation covers trajectories with launch opportunities between 2014 and 2030, launch hyperbolic excess speeds of up to 4.5 km/s and total flight times of less than 1000 days. We identify propellant-free abort scenarios in every Earth-Mars synodic period (2.14 years) with mission configurations that closely match NASA's design reference mission.