The moon is one of the best place to move rocket gas
When astronauts return to the moon in the next few years, the plan is for them to stay forever while establishing a permanent outpost on Earth’s nearest celestial neighbor. Like all space missions, a lunar outpost requires fuel for long-term sustainability, but would it be better to mine fuel on the moon or replenish fuel from Earth? That’s what a team of researchers led by Bocconi University in Italy is hoping to address as they looked at the best option for getting fuel from either the Earth or the Moon.
Mattia Pianorsi, a junior researcher at the Space Economy Laboratory at the SDA Boccini School of Management and a doctoral student at the University of St. Gallen, recently told Universe Today that the study’s main objective is to establish the economic and technical feasibility of using fuel from the moon’s water-ice deposits, or to extract from the earth. Both options would use an orbiting depot (OD), which Pianorsi said would be used “as a distribution channel for satellites as well as rockets in space.” The OD, which is separate from NASA’s proposed Lunar Gateway and also not mentioned in the study, would have a maximum fuel capacity of 25 tons and be located at the Earth-Moon Lagrange point L1, about three-quarters of the distance between the OD is earth and moon.
Artist’s impression of an orbiting depot at the Earth-Moon Lagrange point L1. (Source: Sommariva et al. (2023))
For the study, the researchers performed a Monte Carlo analysis to assess the risks associated with both options. For their scenario, the researchers used hypothetical variables such as a lunar mining company, a transport company/distribution company, and end users. The hypothetical lunar mining company charges fuel at $500 per kilogram, while for the terrestrial refueling option, a transporter purchases fuel from Earth at a negligible cost. Both options considered fixed costs, including design, development, testing and evaluation (DDT&E), manufacturing and transportation, while recurring costs included fueling and operation.
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Researchers determined that the ground refueling option would involve approximately 1.5 launches of a Falcon Heavy (FH) Expendable Plus fuel tank with a payload of 17.5 tons to refuel the spacecraft. While the OD has a capacity of 25 tons, the FH would need to bring a total of 26.69 tons, as the remaining 1.69 tons of fuel would be used to “transfer the refill tank with its subsystems,” according to the study. As noted, fuel costs are negligible, but launch costs are estimated at $150 million per launch, resulting in a total fueling price of $227.9 million, which includes launch and fuel costs. Estimated start-up costs also totaled $6511.4 per kilogram for a total cost of ownership of $42.38 million per year.
For the lunar refueling option, researchers used a hypothetical lunar shuttle built by Cislunar Space Development Company (CSDC) with a 25-ton payload, which launches from the Moon, docks the OD and refuels to its maximum 25-ton capacity, and then returns to lunar surface, assuming no fuel is lost throughout the process. As previously mentioned, the hypothetical lunar mining company put fuel costs at $500 per kilogram, and the study put the total price for refueling at $37.51 million, including launch and fuel costs, for a total cost of ownership of $35 million per year results.
Depiction of the Cislunar Space Development Company’s lunar shuttle. (Source: Sommariva et al. (2023))
Based on these results, the researchers concluded that refueling the OD from the Moon is cheaper than from Earth.
“So if you want to give this project real substance, it should be able to understand and analyze data from a project funding perspective,” Pianorsi recently told Universe Today. “So, it’s the same logic that you use to fund infrastructure here on Earth, you have to understand how to incentivize your investors to jump in, based on the risk mitigation that you put through contracts, for example. So this is very important if you want to develop an infrastructure that involves not only public money and maybe corporate money, but even financial investor money. And I’m not talking about venture capital or private equity, I’m talking about institutional investors.” Pianorsi told Universe Today that he believes these factors should be the next steps in terms of research.
Regarding the upcoming Artemis missions, Pianorsi stressed to Universe Today the importance of “creating an economic cycle between the Earth and the Moon”, but also emphasized the importance that not only space agencies and space companies conduct lunar and Mars activities, but also non- also aerospace companies.
“Companies need to understand that economic sustainability is the new prerogative of the new space economy,” Pianorsi told Universe Today. “They are no longer NASA cost-plus contracts. Times are changing right now, and even space agencies, especially in times of tight budgets, must rely on private companies to innovate and improve efficiencies. And not just from a cost perspective, but also from a market perspective.”
Could a future orbital depot help with manned missions to the moon, and will it prove cheaper to refuel from the moon than from Earth? Only time will tell, and that’s why we know science!
As always, keep doing science and keep looking up!