In the half-century since Neil Armstrong’s first steps on the moon, spaceflight has seen dwindling attention. The Voyager probes were an exciting new leap into deep space, and the space shuttle system looked to bring down the cost of spaceflight.
With the end of the shuttle program, American spaceflight slipped into a limbo. NASA did not have a way to send astronauts to space on their own for nearly a decade, and their science missions were limited in scope.
The Artemis program is America’s newest attempt to truly advance the field of space exploration, through a return to the moon, permanently this time. NASA is taking the next step of this program later this year, sending astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen around the moon on a mission dubbed Artemis II.
This mission, currently set to launch from Florida as early as Friday, Feb. 6, will be not only the first mission to fly a crew in the vicinity of the moon since 1972, but it has several notable firsts with it.
Artemis II is set to be the first mission to carry people of new demographics to the moon. These demographics include the first person of color, the first woman, and the first non-American to fly beyond low earth orbit.
This next step in America’s exploration of the moon will follow a path similar to that of the Apollo 8 mission in 1968, flying freely around the moon, paving the way for the next phase of the program.
The mission stands as the first crewed spaceflight to fly in the vicinity of the moon since Apollo 17 in 1972, and hopes to clear a path forward for humanity to return to the lunar surface. If the tests of the mission are successful, then the next step, Artemis III, will launch in mid-2027 to put humanity firmly back on the moon.
The Artemis II mission will be proving the technology and methods to get back to the moon over roughly 10 days, including demonstrations of the life support and maneuverability of the spacecraft. If all goes well, the Artemis program will take its next giant leap forward and send humans down to the lunar surface.
How does the Artemis program work?
Although the program is relatively young, the hardware of Artemis has been around for several years, with some articles dating back to the early days of the shuttle program.
The rocket at the heart of Artemis, the Space Launch System (or SLS), has been around in concept since the late 2000s, when it existed as a concept called Ares-V.
Orion, the capsule that will carry the crew, was called the Crew Exploration Vehicle (CEV) and was a part of this same program. Ares-V and the Crew Exploration Vehicle (CEV) were a part of the Constellation program, which had the goal of expanding humanity’s reach although it has been canceled since then.
The broad strokes of Ares-V and the CEV have survived through other programs, and now are tied to the Artemis program as SLS and Orion.
Once the Constellation program was canceled, key components were kept alive, such as Orion and SLS. These systems stayed alive through the 2010s, with Orion getting one test flight in 2014.
The components of SLS continued development over the next several years, with the goal of launching in 2020.
In 2017, the Artemis program was officially launched, realizing America’s goal of returning to the moon. Artemis adopted the SLS and Orion programs, and continued toward a 2020 launch. Delays and complications came up, and the inaugural launch of SLS and Orion slipped into 2022.
Artemis I was the first launch of SLS, and went around the far side of the moon, demonstrating the technologies and methods that will be used in the future. It launched on Nov. 16, 2022, with no crew on board.
The lack of a crew allowed the mission to last much longer, and test as many things as possible. The mission spent over a month in space, proving the reliability of both the Orion spacecraft and the methods the program relies on.
Overall, the mission was a resounding success, surpassing nearly every standard of performance that had been set out.
How do the SLS and Orion spacecraft work?
SLS is a rocket that leans heavily on past hardware, designs, and partnerships. This lowers the cost, as all the foundations are already established. The majority of SLS hardware has its beginnings in the space shuttle program of the late 20th century, and this connection is visually obvious.
SLS uses the same tank structure, solid rocket boosters, and main engines, as the space shuttle, and all of those components heavily contributed to the iconic look of the space shuttle.
The new parts of SLS, such as the upper stage and Orion capsule, are results of the requirements of lunar missions, and have their own interesting origins.
The most recognizable portion of SLS is the core stage. This portion of the rocket draws its heritage from the shuttle program, as the tank section of SLS is made from the same diameter tanks as the space shuttle external tank, and even uses a very similar type of insulation, which gives both of them their iconic orange colors.
The core stage carries over another key aspect of the shuttle program: its engines.
The space shuttle was built around the RS-25 engine, which uses a combination of liquid hydrogen and liquid oxygen, often called hydrolox. Hydrolox is one of the most common fuel combinations, which has seen use since the early days of spaceflight.
The RS-25 is a marvel of engineering, balancing power and efficiency, with a fuel as difficult to work with as hydrogen. For this reason, it was selected to power the SLS launch vehicle.
With the Artemis program, old RS-25 engines are seeing new use, with some specific engines having a career dating back into the 1980s. SLS uses four of these engines on the core stage, generating nearly two million pounds of thrust to get into the air.
At the top of the core stage is the launch vehicle stage adapter, which holds the second stage of the system in place until it is ready to fire.
Attached to either side of the core stage are the solid rocket boosters, or SRBs. These boosters also date back to the shuttle program, with the oldest segments having debuted on the STS-8 mission all the way back in 1983.
The main difference in the shuttle boosters and SLS boosters is the size. Shuttle’s boosters consisted of four segments each, while the new SLS boosters use 5 segments each, with upgrades to the system, including insulation, nozzles, and flight control computers.
The solid rocket boosters provide the overwhelming majority of the thrust of the system while they are firing, totaling about seven million pounds of thrust between the two boosters. The solid rocket boosters burn for the first two minutes of the flight, before they fizzle out and separate.
SRBs are released by separation bolts, which have small explosive charges in them to break the bolt and allow the boosters to move away. In order to separate the boosters and prevent collisions, smaller solid motors fire at the top and bottom of each of the boosters to push them away from the core stage.
After separation, the boosters fall down to the ocean over the next three and a half minutes, before they crash into the ocean and sink to the bottom.
Above the core stage is the second stage, which is called the interim cryogenic propulsion stage, or ICPS. This gets its name from the fact that it is a fill-in until the real upper stage, called the exploration upper stage, is finished.
The ICPS is a four-story-tall stage that pushes the Orion spacecraft into the necessary orbits. It runs on the same hydrolox fuel as the core stage, fed through an RL-10B-2 engine, from the same line of engines that were the first to use these hydrolox fuels.
This engine is unique among upper-stage engines because it includes an extendable nozzle to maximize efficiency in the low-pressure environment of space. The ICPS uses a single RL-10, but the exploration upper stage will use four of these engines to push even more mass around in orbit.
The second stage begins its own leg of the mission after separating from the core stage, and is completing burns on and off for the next two hours. The last burn that the ICPS completes is a short one, intended to put the trajectories of itself and the Orion capsule safely above the atmosphere in what is called a parking orbit.
After this burn, the ICPS separates from the Orion capsule and its European service module, which go on their own way to the rest of the mission. The ICPS has a pair of secondary missions, which are completed after the separation of Orion.
The first is a demonstration of Orion’s maneuverability, which is done using the ICPS as a target. Orion will separate, then turn back towards ICPS and move around relative to it, treating it as a target spacecraft to simulate docking procedures for later missions.
Once this demonstration, which is set to last around 70 minutes, has concluded, Orion will go on with its mission to the moon, and the ICPS stage completes its final task before returning to burn up in earth’s atmosphere.
The ICPS has a handful of small satellites, each around the size of a shoebox, stored in the adapter that holds Orion to the stage. These satellites are built by various organizations and countries, and allow these groups to conduct their own research on deep space conditions.
The organizations involved have included university researchers such as the University of Tokyo, but also national space agencies, such as the Korean AeroSpace Administration and the German Aerospace Center. These satellites will deploy in the hours following Orion’s separation, and conduct their research over the next few days or weeks.
At the top of the SLS stack is the Orion capsule and its associated hardware. This includes three main parts: the capsule itself, the European service module, and the launch abort system.
The launch abort system is the easiest to explain, because it has one purpose: protect the crew if everything else fails. It sits at the top of the stack, and has a tower to separate the highly flammable solid motors from the fragile crew.
These solid motors stand at the ready for the event that the core stage or boosters have an issue, when they will light and pull the capsule away within seconds.
The next part of the Orion system is the European service module, which, as the name suggests, is designed by the European Space Agency and built by Airbus Defence and Space.
This module is where all the necessary components of the spacecraft lie, including life support, power, and propulsion. It connects to the ICPS stage, and will stay connected to Orion until shortly before the vehicle reenters the atmosphere.
The last and most important part of the system is the Orion capsule, which is where the crew will spend their time. Orion is the new generation of crew vehicle, which is wildly more capable than the Apollo capsule.
Apollo was able to sustain a crew of three for around two weeks, while Orion is capable of sustaining a crew of four for three weeks.
This comes partially from the upgrades to the service module, notably the addition of solar panels to allow for continuous power generation, but also a considerably larger pressurized volume, which is space that astronauts can use and access easily.
Orion has nearly sixty percent more pressurized volume than Apollo, which lends itself to not only reaching the moon easier, but also to reaching beyond the moon as an ultimate goal.
The Orion capsule is the only part of SLS that is designed to return to earth, and it does this through what is called an ablative heat shield. This means that the material of the shield is physically burned away, absorbing the energy of the reentry. The heat of reentry burns the heat shield, creating a layer of charred material, and this char layer can then chip away, taking away massive amounts of energy over the course of the reentry.
Ultimately, Orion will be flying for a long time, because it is the heart of the Artemis program, and has the foundation present to possibly fly to destinations beyond the moon.
How does the Artemis II mission work?
The rocket that will fly this next mission is on the launch pad going through some pre-flight testing, including a full fueling run called a wet dress rehearsal.
If all goes well with these tests and the weather cooperates, the earliest date to launch is in the late night hours of Feb. 6th. If there are minor issues or weather is not quite ideal, then there are opportunities every day for the next week or so, but after that week the launch slips to March.
Each day, the launch windows are around 2 hours long, so if the conditions aren’t perfect at the opening time there is a bit of fallback.
When the rocket does launch, it will spend around a day in a parking orbit, before completing translunar injection, or TLI. This burn will send the Orion spacecraft on its way to complete the rest of the mission.
It will fly out toward the moon, and then around it in such a way that the spacecraft will naturally return to earth and splash down in the ocean. The full trajectory will look something like a figure eight centered around the earth and moon.
The technical name for this type of path is a free return trajectory, and the name explains exactly what it is: a trajectory that freely returns the spacecraft. This type of path is the same one used in the Apollo missions, and it is popular with crewed lunar missions because they are safer by their very nature.
In the event that there is a failure that would prevent an engine burn, the spacecraft, and crew with it, will be heading back to earth.
While the end goals of the programs are different, Artemis’ early flights will look fairly similar to those of Apollo. Artemis I served a similar purpose to Apollo 4, in that it tested the rocket itself and put the spacecraft through its paces.
Artemis II will be similar to Apollo 8, taking a crew around the moon to test it through everything except for the orbit and landing segments.
After this mission, the programs will diverge, with Artemis focusing more on long-term stays and research. Artemis will be focusing all of its landings on studying the south pole of the moon and truly understanding everything there, as opposed to the wide-spread approach Apollo took.
The Artemis program has been described by some as “Apollo 2.0” or something similar, but it is far different. Artemis is humanity’s next step into space, and this time it is to stay. Instead of going to the moon for national pride, this time is for science and science alone.
This makes it much more exciting and worthwhile, because there is so much to learn from extended stays on the moon, which is exactly what the plan is.
Artemis II is the next exciting step of this ultimate plan and there is so much to learn about the program and its technologies. There are several resources available from NASA itself that give some incredible information about Artemis as a whole, Orion, SLS, and all of their associated programs, for anybody interested in learning more.
