Trade space evaluation of ascent and return architectures for a Mars Sample Return mission

The concept of Mars Sample Return (MSR) has been considered since the 1960s and is still a top priority for the planetary science community. [1] Although a plan on the number and types of samples to be collected for MSR has been outlined, as articulated in the Mars 2020 Science Definition Team report [2], the trade space of options to return this sample from the surface of Mars to the surface of the Earth is still being explored. One of the main challenges with MSR is that it is inherently a multi-vehicle system where each vehicle's design impacts that of the others. Defining the trade space must therefore be treated as a System of Systems (SoS) problem. The work presented puts forward a framework to rapidly explore such spatially and temporally distributed systems. It investigates the possible vehicle and technology options for MSR, assuming that a packaged sample has been left on the surface of Mars. It also evaluates how launch sequencing choices affect the expected return on investment of different architectures. The paper explores eight key trades, including different types of landing and propulsion systems, as well as low-cost direct return options. A large set of architectures are compared to the baseline proposed in the Planetary Science Decadal Survey [1] for MSR, which consists of a stationary lander, a small fetch rover, a Mars Ascent Vehicle (MAV), and a return orbiter with chemical propulsion. Overall, the baseline is found to be well optimized, although a few options, including the use of solar electric propulsion and of a roving vehicle carrying the MAV to the sample, are shown to offer a better return on investment. Furthermore, when considering only the goals of MSR, an approach where the lander is sent to Mars at least one launch window ahead of the return orbiter is demonstrated to be preferable.