This website is dedicated to studies of Mars and Moon technology and mission analysis. I am open to add work of others as well – Donald Rapp
KEY WORDS: Mars, Moon, space mission, propulsion, ISRU, system engineering
My credentials can be viewed here
Click on any link to see papers
Editorial:
Any plan to send a human crew to explore Moon or Mars requires (among many other things) tons of propellant to blast off from Moon or Mars for return to Earth. The highest energy propellants are stored cryogenically. Two propellants are needed: (1) a fuel, either methane or hydrogen, and (2) oxygen. Oxygen represents the greatest mass of propellant.
An important question is whether one can economically and safely produce these propellants on the Moon or Mars and thus avoid the difficult task of bringing them from Earth? We call this process In Situ Propellant Production from indigenous resources (ISPP). More generally, ISPP is a branch of in situ resource utilization (ISRU).
Martian ISPP has a much greater mission impact than lunar ISPP because it has much greater leverage. If ISPP were to replace all the oxygen ascent propellants on one liftoff from each planet, the mass saving in LEO per liftoff form the Moon would be about 10 to 13 tons, and about 240 to 300 tons per liftoff from Mars. The inherent value of Martian ISPP per liftoff far exceeds that for the lunar ISPP. Therefore, use of ISPP has a much greater impact on reducing mass on a Mars mission than it does on a lunar mission.
In addition to leverage, there is a great disparity between the challenges and complexity of lunar ISPP vs. Mars ISPP. Mars ISPP based on atmosphere only is relatively simple with high payoff. However, lunar ISPP is so challenging it might not even be technically feasible, and if it can be made feasible, the cost will be so high that the payoff may be nil compared to the cost, and the risk is high.
NASA is now embarked on a major initiative to return humans to the Moon whereas a human expedition to Mars is likely to be relegated to at least several decades in the future. As a result, NASA is heavily focused on unattractive lunar ISPP and has diminished interest in attractive Martian ISPP despite an extremely successful demonstration on Mars by MOXIE. Since the NASA Administrator outvoted the NASA system engineers and selected a "short stay" (without ISPP) concept as the current baseline for a human mission to Mars, Martian ISPP is not regarded as important by NASA. Yet, the short stay concept (aka "plant the flag and run") has almost all the risks of a long stay mission but almost none of the accomplishments. The short stay mission depends on nuclear propulsion which introduces a number of problems, some technical and some political. link
The NASA Administrator is a giant fan that blows a strong wind. The NASA system engineers are like weather vanes that align with the prevailing wind, despite their private doubts.
NASA also has some misconceptions about what they call the "Gateway" – a concept to use lunar produced propellants to send spacecraft throughout the solar system. But when the numbers are crunched, it doesn't work.
A great foundation was laid for Mars ISPP by the MOXIE Project. The field of solid-oxide electrolysis is active and burgeoning for terrestrial applications to climate control. NASA can leverage technology advances in that field at relatively moderate investment levels to further advance Mars ISPP. Yet NASA does not seem to have the intellect to appreciate this and continues to pursue a seriously problematic lunar ISPP program.
Editorial: The ultimate tautology
Why is NASA returning to the Moon?
To produce propellants
Why is NASA producing propellants on the Moon?
So it can return to the Moon
General Papers on Mars and Lunar ISRU
Papers related to the MOXIE Mars Project
Recent papers pertaining to Moon and Mars
Lunar-Derived Propellants for Fueling Mars-Bound Spacecraft in Cis-Lunar Space by Donald Rapp
Mars Ascent Propellants and Life Support Resources - Take it or Make it? by Donald Rapp
The Value of Utilization of Extraterrestrial Resources for Propellant Production for Space Exploration - A Perspective
by Donald Rapp