Multiple space agencies plan to send astronauts, cosmonauts and cosmonauts to the Moon in the coming years, with the long-term goal of establishing a permanent human presence there. This includes NASA Artemis program, which aims to establish a “sustainable lunar exploration and development program” by the end of the decade. There is also a Chinese Russo competitor International Lunar Research Station (ILRS) to create a series of facilities “on the surface and/or in orbit of the Moon” that will enable profitable research.
Other than these programs led by government agencies, there are many companies and non-governmental organizations that hope to undertake regular trips to the moon, either for “lunar tourism” and mining, or for construction.Moon International VillageThis would serve as a spiritual successor to International Space Station (ISS). These plans will require moving a lot of cargo and freight between Earth and the Moon through the next decade, which is no easy task. To address this, a team of US/UK researchers recently released research paper On optimal trajectories for travel between Earth and the Moon.
The team consisted of Professor Emeritus Thomas Carter from Eastern Connecticut State University and Professor of Mathematical Sciences Meyer Homey from Worcester Polytechnic Institute. For their study, the prepress Of which are available online, Carter and Homey examined how a shuttle could ferry supplies to a lunar outpost and carry resources mined from the surface. Based on their calculations, they concluded that a trajectory that puts the shuttle in an elliptical orbit and reduces thrust requirements would be optimal.
During the space race, both NASA and the Soviet space program rely on free return trajectories to send missions to the moon. This consisted of using lunar gravity to perform a figure-eight maneuver resulting in the spacecraft returning home with minimal orbit modifications (reducing the amount of fuel required). The Artemis missions’ orbits will be similar to those of their Apollo predecessors in that they will also perform figure-eight flights ending in a “splashdown” into the ocean.
In other words, these missions will be one-way trips. But other than returning astronauts to the Moon, assembling the Lunar Gateway, and setting up Artemis Basecamp on the surface, the long-term goal is to use the Artemis infrastructure to establish a permanent human presence on the Moon. There’s also a need to keep things cost-effective, which makes launching heavy payloads from the surface to the moon ineffective. As co-author Professor Homey explained to Universe Today via email, their proposal envisions a shuttle orbiting the Earth and Moon:
“one of [the ISS’] The “functions” are to avoid sending large payloads to low Earth orbit. Instead, we send “capsules” with supplies and replacements to the astronauts. to accomplish [lunar settlements] At the lowest cost, we need something similar to the International Space Station but orbiting the Earth and the Moon. This shuttle will never land on Earth or the Moon. Capsules from the Earth will stick to it when it is near the Earth, and similarly, capsules from the Moon will stick to it when it is near the Moon. This will avoid the need to lift large loads from the Earth or the Moon, and this will save a lot of money and resources.”
However, the shuttle will need engines and propellants to keep that shuttle in orbit because it is subject to gravitational perturbations (from the Earth, Moon, and Sun). While a shuttle would not require the massive thrusters and fuel tanks needed to break free from Earth’s gravity, the engines and fuel add large amounts of mass to the mission, driving up costs. To address this, Homey and Carter considered maneuvers that would reduce fuel consumption while still allowing the shuttle to orbit the Earth-Moon system in a reasonable amount of time.
“The process we used to obtain our results was to develop appropriate mathematical models based on the gravitational forces of the Earth and the Moon (and the Sun) affecting the orbit of the shuttle,” said Homey. With this in mind, they decided that a circular, elliptical orbit with a perihelion near Earth and aphelion beyond the Moon would be the optimal path. Only minimal thrust would be required for course corrections, eliminating the out-of-plane solar gravitational effects, which could be further reduced by ensuring that the orbital eccentricity remains near zero.
This type of shuttle and trajectory, Homey said, is necessary for any plans to establish a permanent human
on the Moon, but could also lead to a thriving Earth-Moon economy:
At present, there are plans to establish a permanent “outpost” on the surface of the moon. This outpost will need supplies from Earth to function properly (food, medical computers, parts for robots, etc.) and a mechanism to replace the astronauts). At the same time, it will return to Earth the elements that are so deficient on Earth (for example, helium-3) and which, according to all theoretical calculations, are the fuel for the fusion reactor.
with a signature US Commercial Space Launch Competitiveness Act in 2015 and US Commercial Space Launch Competitiveness Act For 2020, the US government has made it clear that commercial activities on the moon will include resource extraction. In addition to securing mineral resources (such as rare-earth metals that are vital to electronics and digital devices), scientists have been dreaming of a day when lunar sources of helium-3 would come in handy because it would allow the widespread use of fusion reactors to meet our energy needs. Homey and Carter included a caveat in their study, saying their results would require further testing and validation. As noted in conclusions:
“It should be possible to devise a control system that will return the spacecraft to the specified orbit in order to compensate for perturbations that are not taken into account in the analysis. It might be said that one might guess that the circular orbit of the shuttle provides the optimal orbit in terms of thrust. But this orbit has path with a maximum length. It follows that the result obtained in this paper although it may be ‘intuitively obvious’ is not necessarily obvious”.
Further reading: arXiv
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