Artemis II vs Apollo 8: Moon Missions Compared

Artemis II and Apollo 8 are both crewed lunar missions, but they differ fundamentally in purpose, trajectory, and technology: Apollo 8 was the first crewed flight to leave Earth orbit and loop around the Moon in 1968, while Artemis II is the first crewed test of NASA’s Orion spacecraft and Space Launch System, scheduled to perform a similar free-return trajectory around the Moon in the 2020s. Both missions carry four astronauts, but Artemis II will not land, just as Apollo 8 did not land. The comparison reveals how much has changed in half a century—and how much of the original flight plan remains surprisingly similar.

Mission Objectives: Then and Now

Apollo 8 was a daring Cold War gambit. In December 1968, NASA sent Frank Borman, James Lovell, and William Anders to the Moon on a Saturn V rocket, partly to beat the Soviet Union and partly to test the hardware needed for a lunar landing. The crew orbited the Moon ten times, took the famous “Earthrise” photo, and returned after 6 days and 3 hours. The mission had no lunar module; the command service module was the entire spacecraft.

Artemis II is the first crewed flight of the Orion capsule atop the Space Launch System (SLS). It will carry four astronauts—Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen—on a free-return trajectory around the Moon, meaning the spacecraft will loop behind the Moon and use its gravity to slingshot back to Earth without firing a major engine burn. The mission is designed to test Orion’s life support, navigation, and heat shield at lunar distances, with a duration of about 10 days. Unlike Apollo 8, Artemis II will not enter lunar orbit; it will perform a single flyby and return.

Spacecraft and Technology

Apollo 8 used the command service module (CSM), a conical capsule about 3.9 meters wide at the base, with a service module that provided propulsion, power, and life support. The crew rode in a volume of about 6.2 cubic meters—roughly the size of a large van. The CSM’s computer had about 2 kilobytes of RAM and ran at 0.043 MHz. Navigation relied on ground tracking and star sightings with a sextant.

Orion is larger and more advanced. The crew module is about 5 meters wide and offers about 9 cubic meters of habitable volume. It uses modern avionics, a glass cockpit, and an automated docking system. The European Service Module (ESM) provides propulsion and power, using solar arrays instead of fuel cells. Orion’s heat shield uses an ablative material called AVCOAT, similar in concept to Apollo’s, but designed for higher reentry speeds from lunar return. The SLS is more powerful than the Saturn V, producing about 15% more thrust at liftoff.

Crew Composition and Training

Apollo 8’s crew were all military test pilots, veterans of the Gemini program. Borman and Lovell had flown Gemini missions; Anders was a rookie. The crew trained for about six months, with heavy emphasis on navigation, photography, and systems management. They had no realistic abort options once they left Earth orbit—if the service module engine failed, they would loop around the Moon and return on a free-return trajectory, but with no way to steer.

Artemis II’s crew includes three NASA astronauts and one Canadian Space Agency astronaut. Victor Glover will be the first person of color to fly to the Moon; Christina Koch holds the record for the longest single spaceflight by a woman (328 days). Jeremy Hansen is the first non-American to fly a lunar mission. Training is longer (over a year) and includes simulated launch and reentry, spacewalk practice for contingencies, and extensive work with the European Service Module. The crew will also test Orion’s manual flying capability, something Apollo 8 never needed because the CSM was fully automated for the lunar trajectory.

Trajectory and Duration

Apollo 8 followed a translunar injection burn that put it on a free-return trajectory, but once it reached the Moon, the crew fired the service module engine to enter a circular lunar orbit at about 110 km altitude. They stayed in orbit for 20 hours, then fired the engine again to return to Earth. Total mission duration: 6 days, 3 hours, 42 minutes.

Artemis II will not enter lunar orbit. It will fly past the Moon at a distance of about 10,000 km (6,200 miles) from the lunar surface—much farther than Apollo 8’s orbital altitude. This is intentional: it tests Orion’s navigation and life support on a trajectory that mimics the first part of an Artemis III landing mission, but without the risk of a lunar orbit insertion burn. The free-return trajectory ensures that if the main engine fails, the spacecraft will swing around the Moon and return to Earth without any additional burns. Mission duration is planned for about 10 days, roughly 4 days longer than Apollo 8.

Risks and Safety

Both missions carry inherent risks of deep space: radiation exposure, micrometeoroid impacts, and the impossibility of a quick return to Earth. Apollo 8 had no abort options after the translunar injection burn; the crew were committed to the trajectory. The service module engine was a single point of failure—if it didn’t ignite for the return burn, the crew would be stranded.

Artemis II has some improved safety features. Orion is equipped with a launch abort system that can pull the crew away from the SLS if something goes wrong during ascent—Apollo had a similar tower, but it was only usable in the first minutes of flight. Orion also has more redundant systems, including multiple flight computers and a backup guidance system. However, the free-return trajectory still requires a service module engine burn to fine-tune the return, and a failure of that engine would result in a longer, more stressful return but not a fatal one, because the free-return path alone brings the spacecraft back to Earth. The crew will also be exposed to higher radiation levels than Apollo 8 because of the longer duration and the lack of protective radiation shielding in the service module (the ESM is not designed as a storm shelter). NASA has set radiation exposure limits for the mission, but they are within acceptable risk for a single flight.

Scientific and Cultural Impact

Apollo 8’s Earthrise photo is often credited with inspiring the environmental movement. The mission also proved that humans could leave Earth orbit and return safely, paving the way for Apollo 11. The crew brought back photographs and measurements of the lunar surface, but no samples—they had no lander.

Artemis II will carry a suite of scientific experiments, including radiation detectors and cameras, but its primary goal is testing systems for Artemis III, which aims to land the first woman and the next man near the lunar south pole. The mission will also deploy small CubeSats during the journey, though these are secondary payloads. The cultural impact of Artemis II is likely to be different: it will be the first crewed lunar mission in the 21st century, and it will include the first non-American to fly to the Moon, symbolizing international partnership. The mission will also test the Orion spacecraft’s ability to support a crew for longer durations, which is essential for future Mars missions.

Cost and Political Context

Apollo 8 was part of the Apollo program, which cost roughly $25 billion in 1960s dollars (about $250 billion today). The mission itself was a fraction of that, but it was funded by a national commitment to beat the Soviets. The political stakes were enormous; the mission was moved up by several months because of intelligence reports that the Soviet Union was planning a similar circumlunar flight.

Artemis II is part of the Artemis program, with an estimated cost of $93 billion through 2025 (NASA’s Office of Inspector General). The SLS and Orion have faced years of delays and cost overruns. The program is international, with the European Space Agency providing the service module and Canada contributing the robotic arm for the Gateway station. The political context is different: no direct space race, but a renewed interest in lunar exploration for scientific and commercial purposes, including the Artemis Accords, a set of agreements for responsible lunar exploration. The mission is also a stepping stone for a planned lunar space station (Gateway) and eventual Mars missions.

Frequently Asked Questions

Will Artemis II land on the Moon?

No. Artemis II is a flyby mission, not a landing. It will travel around the Moon and return to Earth. The landing mission is Artemis III, currently planned for the mid-2020s, which will use a separate lander (the Starship HLS) to touch down near the lunar south pole.

How many people will be on Artemis II?

Four astronauts: three from NASA (Reid Wiseman, Victor Glover, Christina Koch) and one from the Canadian Space Agency (Jeremy Hansen). Apollo 8 had three astronauts.

How long will Artemis II take?

The mission is planned for about 10 days, from launch to splashdown. Apollo 8 took just over 6 days. The longer duration is due to the different trajectory—Artemis II will not enter lunar orbit, but it will travel farther out and take a slower return path.

What is the difference between a free-return trajectory and lunar orbit?

A free-return trajectory uses the Moon’s gravity to slingshot the spacecraft back to Earth without any engine burns. It’s like swinging a ball on a string around a post—it comes back automatically. Lunar orbit requires a braking burn to slow down and enter orbit; the spacecraft then orbits the Moon and must burn again to leave. Apollo 8 did the latter; Artemis II will do the former.

Why is Artemis II taking so much longer than Apollo 8?

Artemis II’s free-return trajectory is designed to be safer (no engine burn needed for the return) and to test Orion’s systems for longer durations. The mission profile also includes more time in deep space to collect data on radiation and life support. Apollo 8’s faster, more aggressive trajectory was a product of the Cold War urgency; Artemis II is more methodical.

What happens if Artemis II’s engine fails?

Because it’s on a free-return trajectory, the spacecraft would still loop around the Moon and return to Earth without any engine burns. However, the crew would need to manage the spacecraft manually and might have a longer, more uncomfortable return. The service module engine is only needed for small trajectory corrections, not for the main return path.

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