One of the most exciting endeavors in modern space exploration is extended human exploration of the Moon and Mars. We have entered a new phase in the human venture where we seek to expand our "...presence deeper into space and to the Moon for sustainable long-term exploration and utilization" [1]. With this endeavor come new challenges. Among them is the requirement for In Situ Resource Utilization (ISRU) methods to supplement or replace materials transported from Earth. The energy required to leave Earth's gravity well is immense, as is well illustrated by the nearly 3000 metric ton Saturn V required to deliver a payload of less than 50 metric tons to the Moon during the Apollo era [2]. Much of this mass is propellant. Launch vehicles from Earth into space are generally 85 to 95% propellant (oxidizer + fuel) by mass [3].

Potential ascent vehicles from Mars would also need to be approximately 80% propellant by mass to return to Earth [3, 4]. ISRU of fuel reactants could exchange delivered fuel mass directly for payload mass on the order of several metric tons. Devices like MOXIE [5] are being designed to address the oxidizer component. However, 30% of the propellant mass in an ascent vehicle can be fuel reactant, and ISRU of this component has not been addressed for Mars or the Moon.

Toward addressing this need, we have begun to develop and optimize methods to generate and recover fuel components, including H2, from Lunar and Martian relevant materials as potential in situ resources for future extended human missions. Hydrogen is an ideal resource to target. Not only can H2 be used directly as part of a propellant, it can also be used as a component in other fuels, such as methane. It is useful agriculturally for fixing nitrogen and can be oxidized to produce heat and water.

Link To LPSC 51 Abstract

References

[1] NASA (2018), NASA 2018 Strategic Plan, Washington, D.C.

[2] Orloff, R.W., (2000) Apollo by the numbers: a statistical reference: NASA

[3] Holt, J. and T. Monk. (2009), AIAA SPACE 2009 Conference & Exposition. #6655

[4] Drake, B.G. and D. Watts Kevin (2014), Human exploration of Mars design reference architecture 5.0, addendum# 2. NASA

[5] Hartvigsen, J., et al., (2017), ECS Trans., 78(1)