Patrick Rei-po Chai | Engineering Papers

NASA NTRS2024

Round-Trip Mars Mission Mass Challenges

As noted in the 2022 Architecture Concept Review Mars Transportation, white paper, the distance between Earth and Mars changes constantly as the two planets revolve around the Sun. Regardless of their relative position, traveling to Mars requires significantly more energy than lunar missions. However, the distance between the planets is only part of the story. This white paper explains how gravity wells, combined with the distance and desired transit duration between them, serve as a mass, and potentially cost, multiplier for a round-trip human Mars mission.

Moon↗

NASA NTRS2024

Mars Communications Disruption and Delay

The communications disruption and delay profile for a Mars mission will depend on the trajectory profile of the mission, though some generalizations can be made. While several factors can contribute to communications disruption and delay, this paper addresses the unique physical characteristics of Mars transit and Mars-vicinity operations.

Michael B Chappell↗

NASA NTRS2024

Mars Mission Abort Considerations

Throughout the history of human spaceflight, astronauts have never been more than and rarely more than a few hours) from Earth. Aborts for missions to low-Earth orbit or the International Space Station are relatively short. Aborts for lunar missions may be longer than aborts from Earth vicinity but are still measured in days.

Patrick Rei-po Chai↗

NASA NTRSDate not supplied

Integrated Trajectory, Habitat, and Logistics Analysis and Trade Study for Human Mars Missions

Environmental Control and Life Support System (ECLSS) architecture selection has profound implications for mission cost and mass extending far beyond the ECLSS itself. Similarly, other mission architecture decisions – particularly involving transportation systems – can influence optimal ECLSS architectures. Loop closure influences requirements for water, oxygen, and other consumables. System maintainability and reliability influences spares mass and risk. System, consumables, and spares mass interact with transportation system architectures, including propellant demands and propulsion element sizing. All these interactions with other systems must be considered when evaluating ECLSS options. Analyses that focus only on maximizing ECLSS loop closure – or minimizing ECLSS mass, or minimizing ECLSS life cycle cost – may lead to sub-optimal or even counterproductive system architecture and investment decisions at the mission level. For example, an ECLSS architecture that minimizes ECLSS life cycle cost but results in excessively high logistics mass could lead to significantly increased transportation system costs or make interplanetary transportation infeasible. Increased loop closure could result in higher development costs and higher mass if system/spares mass increases outweigh consumables reduction. In addition, systems mass and consumables mass are not directly comparable and have different impacts on propellant requirements, as consumables mass changes over the course of the mission. This paper presents an integrated analysis examining the overall impact of different ECLSS and transportation architectures on Earth departure mass for a crewed Mars mission, including the habitat and transportation systems as well as consumables, spares, and propellant. Key observations are discussed, along with opportunities for further sensitivity analysis and model development. Overall, ECLSS development activities must consider their impacts at the mission level, as part of an integrated system, rather than in isolation.

Mars↗