At time of writing, Artemis 1 is scheduled to be launched on the 2nd of October. (fingers crossed for no further delays). The rocket will carry the Orion spacecraft into space where it will spend six weeks, traveling to the Moon, putting itself in a stable orbit, then returning to Earth. The craft will be unmanned, but it will carry instruments meant to measure the radiation conditions a human crew would be exposed to. The goal is to be a dress rehearsal for the first manned missions to the Moon in fifty years. Since I rarely get to talk about unambiguously optimistic things, I thought it would be fun to talk about the Artemis program, what it plans to do, how it compares to the Apollo program, and the value of these missions to scientific research.
Basics of Rocketry
NASA’s Space Launch System (SLS) is currently the most powerful rocket ever built. It has to be to do what it was designed for. There’s a concept in rocketry called the Tyranny of the Rocket Equation; the heavier a rocket is, the more propellant* it needs to get up to speed, but the more propellant a rocket has, the heavier it is, so the more propellant it needs. Just to get to low earth orbit where the ISS is, a rocket can have 85% of its mass being just propellant, compared to 40% for cargo planes or 4% for cars. And getting to the Moon requires much more propellant, which then requires more propellant to carry that propellant. To get the 23 metric ton (~50,000 pound) Orion spacecraft to lunar orbit, the Artemis 1 rocket will require 2,600 metric tons (5.7 million pounds) of propellant. All of this fuel is needed to get the Orion vehicle to 10.4 km/s (~30 times the speed of sound) needed to reach the moon.
I’ve talked about basic orbital mechanics before, but this video from Con Hathy provides a good recap. I would also recommend this series of three videos by Jared Owen, which explains the mechanics and maneuvers of the original Apollo flights.
Artemis
The Orion capsule used by Artemis has the benefit of research and design built for the space shuttle program and for the ISS. The habitable space of Orion is about 50% larger than that of Apollo, allowing for four crew members instead of three. Onboard power, controls, radiation shielding, waste recycling, and heat shields will all benefit from the past 50 years of NASA research. While each Apollo capsule had less computing power than modern pocket calculators, Orion’s computers are comparable in speed and processing power to the computers on modern commercial airplanes. Orion capsules will be able to be flown unmanned, which it will for the upcoming Artemis 1 mission. Both the Orion spacecraft and the SLS meant to carry it into orbit were designed to be used for potential missions beyond Earth’s orbit, possibly even to Mars, so this is a well-designed craft.
Artemis’ goal is to eventually create a long-term human presence on the Moon, which will require rockets with a greater cargo capacity than Apollo had. The SLS has a maximum payload capacity of 45 metric tons (99,000 pounds), three times that of Saturn V. The plan is to use this extra cargo capacity to construct the Lunar Gateway, a space station in orbit around the Moon which will serve as a staging ground for lunar surface missions. Like the ISS, the Gateway will be built in modules sent to lunar orbit with either manned Orion missions or by unmanned rockets launched by NASA partners. This additional crew facilities will allow for missions up to 30 days in length and will allow for experiments to be conducted in deep space. The station will orbit the Moon in a highly elliptical orbit, its low point being only 3,000 km (1,900 mi) over the lunar north pole and its high point being 70,000 km (43,000 mi) over the lunar south pole. The Apollo capsules orbited in a circular orbit around the Moon’s equator at roughly 110 kms, which was the easiest orbit to get to, but also meant they couldn’t land anywhere other than near the Moon’s equator and would lose communication with Earth whenever the craft went behind the Moon. Since an object in an elliptical orbit moves fastest when it is closest to what it’s orbiting, the Gateway will only go behind the Moon for at most a few hours every seven days, maintaining constant communication with Earth the rest of the time. For the same reason, the station can maintain near constant communication with the Moon’s south pole, the proposed landing site for most missions.
Note; the solid green orbit labeled ‘South L2’ is the orbit of the Lunar Gateway. https://blog.maxar.com/space-infrastructure/2019/what-is-cislunar-space-and-a-near-rectilinear-halo-orbit
Unlike Apollo, Artemis will not be solely a NASA program. The space agencies of Canada, Europe, and Japan are partnered with NASA and will provide modules for the Lunar Gateway, crew, and logistical support. NASA is also working closely with private aerospace companies to provide logistical support via unmanned launches. One such support element will be the development of new reusable lunar landers. The first of these landers, to be used in the first few landings, is currently being developed by SpaceX under a NASA contract. Planned to be launched in 2025, the Starship Human Landing System (HLS) will first be launched into low earth orbit where it will be refueled in orbit by a series of additional launches. Once fully fueled, Starship will travel to lunar orbit where it will stay until it eventually docks with an Artemis capsule to transport its crew to the lunar surface. If this is successful, this will be the first such refueling in orbit in history, greatly expanding the payload capacity of future missions since rockets won’t have to carry all of their own fuel. The Starship system is an extremely innovative design that will soon have a larger payload capacity than NASA’s Space Launch System (SLS) while also being fully reusable. That said, it is still very much in its testing stage and hasn’t yet flown with a human crew. This is why the more tried and tested SLS design will be flying crewed missions for the foreseeable future while Starship and other private rockets test their mettle running unmanned logistics. What this will look like in a decade’s time will be seen.
Long-Term Goals
Whenever discussions of space travel come up, a common question is “Why should we be spending money on this? What are the practical applications?” The answer I tend to give comes from history; the first scientific work published about electricity was De Magnete, written by William Gilbert in 1600.** The first widely-used technology built upon electricity was the telegraph, invented in 1837. It took over 200 years of research and study for electricity to be understood well enough for humans to use it, and I doubt Gilbert envisioned the telegraph when he wrote De Magnete. While it is sensible to want scientific research to lead to practical outcomes, if we only research what will have immediate practical applications, we won’t ever understand the world well enough to find those applications. My ranting aside, Artemis has some very real applications, both for further scientific exploration and for general use.
Several experimental modules have already been designed for use on the Lunar Gateway. The Gateway’s vantage point in deep space, far away from Earth’s light and magnetosphere, make it a good spot to observe the sun and solar wind. The sun inconsistently emits plasma and radiation that can impact electronics on Earth and expose future astronauts to deadly radiation, so understanding this better will be useful. Being able to observe the Earth from far away could have applications for climatology and earth sciences and the station could be a good platform to launch cubesats carrying experiments into high orbit around Earth. Tests on humans and other organisms living long-term in deep space will have applications for future manned space travel and easy access to the lunar surface will open up experiments in everything from the history of the solar system to the development of new technologies.
Having infrastructure on and around the Moon will also make future space missions easier. Launching spacecraft to other parts of the solar system will be far easier from the Moon than from Earth, due to the Moon only having one-sixth Earth’s gravity and being closer to the edge of Earth’s gravitational field. A future mission to Mars could be done more efficiently by constructing a modular spacecraft in lunar orbit and launching it from there.
Lastly, there is the reason why so many corporate partners are attached to this mission; lunar resources. The Moon is rich in iron, titanium, aluminum, and silicon. Rare earth elements that are critical to modern computers, batteries, and electronics are likely to be present in lunar meteor craters at minable concentrations. Lunar regolith (moon dust) contains trace amounts of Helium-3, an isotope of helium that some have proposed could be used as a fuel for fusion reactors (a topic for future posts). Solar power would be far more efficient on the Moon due to the lack of an atmosphere and two week long days, so some have proposed building solar farms on the Moon from local materials and beaming their power to Earth with lasers. Now, all of this is at least decades away; getting mining and construction equipment to the Moon and getting mined material back to Earth will remain prohibitively expensive compared to resources on Earth for the foreseeable future. Much of the Artemis program will be to determine how much ore there actually is, is it in quantities that can be mined efficiently, and can it be transported back to Earth in a remotely cost-effective manner. But for the foreseeable future, the only lunar resources that will be exploited will be those with practical uses by astronauts on the Moon itself. This is why the lunar south pole is a site for landings; the craters there contain a large amount of frozen water. Not only can this water be used by future lunar colonists, but water can be split into hydrogen and oxygen by electrolysis to create rocket propellant. I’ve already mentioned launching a future Mars mission from the Moon, and this could mean we wouldn’t need to transport any propellant for said mission from Earth, which is again the vast majority of any rocket’s mass. If future lunar missions could find water, oxygen, and rocket propellant on the Moon, it would radically extend the length and scope of future missions.
All of this is still in the planning stage. Artemis 1 will only be a test of the SLS rocket, Orion craft, and maneuvers needed to execute future missions. Artemis 2 is planned for 2024 and will carry crew to lunar orbit for the first time since 1972. Artemis 3 is planned for 2025 and will land humans on the Moon for the first time in 50 years. Artemis 4 is planned for 2027 and will see the first use of the Lunar Gateway by a human crew. The goal of Artemis is to establish a long-term human presence on the Moon which could open up the rest of the solar system for exploration. As meaningful as the Apollo program was, it was only intended as a short-term project to maintain international prestige. This time, we intend to stay.
For More Details
*To be pedantic, it’s technically not correct to call it rocket fuel. In chemistry, ‘fuel’ refers to a substance that releases energy in a chemical reaction. For combustion reactions, fuel would be the wood, gasoline, methane, etc. that reacts with oxygen to produce heat. But since there’s no air in space, rockets have to take oxygen with them. A rocket’s propellant consists of two separate chemicals, a fuel (often liquid hydrogen or methane) and an oxidizer (liquid oxygen). Rocket fuel is a term that’s used, but it’s only half of a rocket’s propellant.
** Electricity has been known to exist since antiquity from shocks delivered by eclectic eels and rays to static electricity making objects magnetically attractive. De Magnete was simply the first historical record of experiments being performed to understand the properties of electricity.
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