Design Considerations for an Earth–Mars Cycler Spacecraft Using the S1L1 Cycler

Abstract

This paper discusses the design considerations for an Earth–Mars cycler spacecraft using the ballistic S1L1 cycler trajectory. The primary objective is to estimate the mass of a cycler spacecraft designed to transfer a crew of six from Earth to Mars on a nominal 154-day trajectory, with sufficient consumables and life-support capabilities to accommodate the crew on a 1032-day contingency mission, in case the transfer from the cycler to Mars is not possible. The paper develops the functional system requirements from the concept of operations and discusses the bottom-up mass and power estimates for the individual subsystems. The cycler spacecraft design includes system capabilities that are not needed for spacecraft designed for point-to-point interplanetary transfers, such as a 30-year design life and the capability to be robotically maintained, repaired, and replenished during an uncrewed Earth–Earth resupply loop. The resulting spacecraft design is similar in size, mass, and operational complexity to deep space transfer vehicles for point-to-point mission architectures. However, as a minimum number of two cyclers are needed for round-trip missions with acceptable duration, a cycler-based architecture is less suitable for initial Mars exploration than for a sustained, continuous Mars exploration campaign.