Going back to the moon: Artemis II
- Kylie Sadsad
- 12 minutes ago
- 8 min read
At 5:35 p.m. EDT on April 1, the Artemis II launched from the Kennedy Space Center in Cape Canaveral, Florida. This was a 10-day journey and the first crewed mission to the Moon in over 50 years. At approximately 8:07 p.m. EDT last Friday, the spacecraft successfully splashed down in San Diego, California. As of right now, the four astronauts are home safely after breaking numerous records and being a symbol of hope towards space exploration: Victor Glover, the first African American ever to voyage to the Moon, Christina Koch, the first woman to do so, Jeremy Hansen, the first Canadian, and Reid Wiseman, the commander of the mission and the oldest person to leave Earth’s orbit.
Artemis mission
The Artemis program, led by the United States’ National Aeronautics and Space Administration (NASA), aims to send astronauts on lunar exploration missions to further build the foundation for our first crewed mission to Mars. NASA’s deep space exploration systems, the Orion space capsule and Space Launch System (SLS) rocket, are the backbone in exploring and learning more about our solar system. Orion is built to take humans farther than we’ve ever gone before, while the SLS rocket is record-breaking in being able to produce 13% more thrust at launch than the space shuttle, which has launched the Hubble Space Telescope, and 17% more than the Saturn V, which launched all nine crewed Apollo missions, during liftoff and ascent.
Launched in 2022, Artemis I was a 25.5-day uncrewed voyage that was the first integrated flight test of the SLS and the Orion spacecraft. Overall, the results were promising; however, the Orion’s heat shield sustained significant damage upon reentry. This was the first major spaceflight for NASA’s return to lunar exploration after the Apollo program, over half a century ago. It followed a distant retrograde orbit—a high orbit in the Moon’s sphere of influence—and was the first major spaceflight of the Artemis program. This mission marked the beginning of innovative technologies that will eventually establish a long-term presence on the Moon.
Now, building on the success of Artemis I, Artemis II is the first voyage with a crew on a lunar flyby. Beginning at Point A in Figure 1, the spacecraft followed an initial low-Earth orbit (Fig. 1: Point B), a small perigee-raise at Point C to raise the orbit up to Point D, then a translunar injection starting at Point E to a figure-eight loop around the Moon at Point F, and finally a “free return” flight back towards Earth. After launch, Artemis II is put in a high “parking” orbit about our Earth—a temporary, stationary destination at a high-Earth orbit. In this mission, NASA is heavily prioritizing safety and risk management, so at this “parked” point, systems can be tested at high altitude before reaching lunar orbit. If any issues are found that may interfere with the continuation of the mission, Orion, Artemis II’s spacecraft, could come back to Earth as soon as possible.
Eventually, around 2027, Artemis III will send astronauts to test future lunar landers and the docking capabilities of the Orion and the commercial spacecraft needed to land the crew back on the Moon. Then, after these monumental journeys, Artemis IV will be “one of the most complex undertakings of engineering and human integrity in the history of deep space exploration.” We’re set to explore the south pole of the Moon, where two crew members will spend approximately a week on the Moon, conducting research and new science before returning home. Finally, in late 2028, Artemis V will mark the beginning of building a long-term human presence on the Moon. This mission will focus on constructing a sustainable lunar base and potentially enable crewed missions to the Moon as frequently as every six months. So, perhaps in our lifetime, thanks to the Artemis program, normal people like us will be able to go to the moon as well.
“What is our legacy? I don’t want to look 5 years or 10 years into the future, I want to look 100 or 200 years into the future, and honestly… I hope we’re forgotten.” - Reid Wiseman, the commander of the Artemis II
Why did it take us so long to go back to the moon?
The short answer to this age-old question is funding. In 1965, the height of the space race, NASA’s budget was 4.31% of U.S. spending, while in 2026, it’s only 0.33%. After John F. Kennedy’s commitment to landing on the moon and eventually reaching that goal, President Lyndon B. Johnson began to prioritize funding towards the Vietnam War and domestic reforms, ultimately reducing space investment. Even before Apollo's success, the budget began to fall and consistently decline; planned missions were cancelled, and Apollo was forced to end in 1972. In that same year, President Richard Nixon directed NASA to shift their focus away from deep space exploration and instead towards operations in low-Earth orbit.
However, in 1989, President George H.W. Bush declared the Space Exploration Initiative (SEI). The SEI planned for a long-term commitment to permanently send astronauts to the Moon, and eventually aim towards Mars colonization. However, SEI required heavy funding, which led to its ultimate downfall. There was weak Congressional support, along with other factors that led to its cancellation under President Clinton’s administration. There began a repeated cycle of proposed space projects and then their cancellations, exposing the inherent limitations of the system for funding lunar exploration.
However, most people don’t even want to go back to the moon. After the Cold War, there has been no compelling justification for returning to human space missions. NASA argues that sending astronauts, instead of robotic exploration, to the Moon will allow scientists to learn “how to live and work on another world as we prepare for human missions to Mars.”
Fuel efficiency
The escape velocity—or the speed at which Artemis II will need to free itself from the orbital pull of the Earth—is 24,500 miles per hour, or about 40,000 km/h. In order to gain this much velocity, with maximum fuel efficiency, the Orion spacecraft relies on a maneuver known as translunar injection (TLI).
Before explaining TLI, the general terms for any orbit are periapsis, which is the lowest point in orbit, and apoapsis, which is the highest. However, when referring to objects orbiting Earth, we’ll use perigee and apogee. Now, to begin performing TLI, the spacecraft will begin burning its engines at perigee (Fig. 2: Point A). For Artemis II, they burned for five minutes and 50 seconds, and according to NASA’s Dr. Lori Glaze, the TLI went “flawlessly.” This burn allows the initial apogee (Fig. 2: Point B), which was previously within Earth’s orbit, to a highly eccentric orbit (Fig. 2: Point C). The next phase is letting the Orion spacecraft passively fly towards the moon under its own momentum and influenced by terrestrial and lunar gravity: translunar coast.
Perigee-propulsion (only burning at certain points of the trajectory), compared to continuous thrust systems, requires reduced energy to get to the same location. This trajectory compromises the mass ratio and time to reach the desired energy, ultimately meaning larger rockets can be propelled with lower thrust. For example, the optimum power for a 10,000-pound vehicle (Fig. 3) using continuous thrust is equivalent to the optimum power needed for a 100,000-pound spacecraft using perigee propulsion (Fig. 4). When considering interplanetary flight from an orbit around Earth, gravity loss has an overwhelming influence that dictates the initial thrust-to-weight ratio to be relatively high for continuous-thrust trajectories. Since low-acceleration continuous-thrust propulsion produces a long spiral trajectory, most of the energy is added while the spacecraft is moving at low velocity. However, adjusting the thrust schedule to intermittent can optimize the initial acceleration by minimizing gravity loss. Through TLI, we're able to utilize the force of gravity rather than going against it. Under perigee-propulsion, thrust is fragmented, being applied only in regions of highest velocity, which are near the perigee, as Artemis II did so (Fig. 4). Added energy at high velocity is appreciably efficient since, between thrust periods, the spacecraft can coast in an elliptic path until the desired location, apogee, is reached.
On April 2, Artemis II successfully completed this orbit, burning its engine to transform its initial, low-Earth orbit into a stable, high-Earth orbit in preparation for the lunar flyby. Eventually, when they reached apogee, on the south side of the Moon, the Orion only required a smaller burn to increase the total energy of the orbit since this is where the orbital velocity is at its lowest. After completing the lunar flyby, this will allow for a “free return” trajectory, further increasing their fuel efficiency.
Splashdown
Artemis II’s splashdown, or landing, marked more than the end of a successful mission; it represented the return of humanity’s ambition to explore beyond Earth. The voyage surpassed the record for the farthest humans have ever traveled from Earth. The capsule was about 4,068 miles above the lunar surface and reached the mission’s maximum distance from Earth at 252,756 miles—4,111 more miles than the Apollo 13.
After the Artemis II crew has gotten back to Earth, they’ve immediately been put to work. One of the first things the crew had to do was an obstacle course and simulated lunar space walks; these tests were to observe their maneuvering and navigation capabilities before the astronauts adapted back to Earth's gravity. This allows scientists to understand the difficulties when future Artemis crews will land back on the Moon. Now, their job is to relax, reunite with their families, and admire the beginning of Artemis’ legacy in space exploration: Artemis II was not an ending, but the start of a much larger journey.
I think one of the most beautiful things about this mission is how the Artemis program, and interstellar travel in general, has become a symbol of humanity’s greatness. Being able to leave our planet, explore our solar system, and learn even just a little bit more about the infinite being that is our universe is exhilarating. Though thinking about this may make you feel small in our tiny blue dot, be sure to remind yourself that you are a part of something vast and extraordinary, capable of reaching beyond it. It is also proof that our curiosity can carry us farther than our fears.
“One thing I will say is trust us, you look amazing. You look beautiful, and from up here, you also look like one thing. You know, homo-sapiens are all of us; no matter where you’re from, or what you look like - we’re all one people.” - Victor Glover, the pilot of the Artemis II
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