Notable Two-Synodic-Period Earth-Mars Cycler

Abstract

Earth-Mars cycler trajectories (cyclers) could play an important role in a future human transportation system to Mars. A particular cycler that repeats every two synodic periods and has one intermediate Earth encounter is very promising. In a circular-coplanar model it requires no propulsive maneuvers, has 153-day transfer times between Earth and Mars, and has arrival V ∞ magnitudes of 4.7 km/s at Earth and 5.0 km/s at Mars. A method to find an analog cycler in a more realistic model (i.e., using an accurate ephemeris for the states of Earth and Mars) is described. Two cost metrics are considered: total cycler ΔV and total cycler ΔV plus total taxi ΔV. Numerical solutions are presented for both metrics. The total required ΔV is very small, though not zero. If the Earth-Mars and Mars-Earth transit times are constrained, then the characteristics of the optimal cycler trajectory change. Tradeoffs between maximum transit time and other mission characteristics are analyzed for all possible launch periods. Nomenclature a = orbital elements vector g = vector of V ∞ constraints, km/s h = flyby altitude, km h = vector of flyby altitude constraints, km N = number of intermediate Earth flybys P = primer vector R = position vector of the cycler vehicle, AU S = Earth-Mars synodic period, year T = time for orbits of Earth and Mars to repeat inertially, year t = time since launch, year V ∞ = hyperbolic excess speed, km/s V = magnitude of change in velocity, km/s τ = duration of leg 1, 2.8276 years Subscripts i = Earth encounter index in = incoming out = outgoing

System Design of Large Space Structures Using Tailored Force Fields

“…• It is a long-duration mission, such as a mission to Mars. Further, it is likely to be a routine mission, such as a Cycler 16 that stays in orbit, or perhaps a military earth-observation station that requires human presence. • It is a tourist hotel with some staff stationed for long durations.…”

Guidance Strategy for Hyperbolic Rendezvous

“…Cycler and semi-cycler architectures are two promising options to sustain the human exploration of Mars. In a cycler architecture [1][2][3] the interplanetary transfer vehicle, which transfers the crew between Earth and Mars, expends no propellant at either planet; instead, this vehicle receives periodic gravity assists at Earth and Mars that allow it to cycle between the planets. In a semi-cycler scenario, the transfer vehicle receives a gravity assist at either Earth or Mars, and expends propellant to capture into or depart from a parking orbit at the other planet.…”