It has been fifty years since a human spacecraft flew past low Earth orbit, and NASA is set to end the streak with a mission that is as much of a test of engineering as it is a milestone flight. Artemis II, which launches as soon as February 5, will carry four astronauts on a ten-day lunar flyby aboard the Orion spacecraft, atop the rocket most powerful ever constructed the Space Launch System.
The course of the mission will be a “free-return” path, taking the crew more than 5,000 nautical miles past the Moon before gravity pulls them back toward Earth. This distance is further than was reached by Apollo missions, providing a perspective from which, as Jeff Radigan, the chief Artemis II flight director, said, “the moon’s going to look a little bit smaller.” The astronauts Reid Wiseman, Victor Glover, Christina Koch, and Canadian astronaut Jeremy Hansen won’t be going down to the lunar surface, but their trip will be the first crewed test of the SLS-Orion system, clearing the way for future lunar landings.
The SLS rocket, which is 98 meters tall, combines Boeing-manufactured core stages with Northrop Grumman solid rocket boosters. The boosters will give the vehicle the initial boost, separating two minutes after takeoff. After reaching Earth orbit, Orion’s service module, built in Europe, will perform the Translunar Injection burn, sending the spacecraft on its four-day trip away from Earth. Engineers have also perfected the fueling process to avoid the liquid hydrogen leaks that caused a delay for Artemis I, and changes at the launch pad are intended to provide stable pressures and flow rates during tanking.
Within Orion, the astronauts will be dependent upon sophisticated life support systems to control cabin atmosphere, recycle water, and dispose of waste for prolonged periods. Navigation will be provided by a hybrid of star trackers, inertial measurement units, and GPS, allowing for accurate course adjustments throughout the mission. Twenty-three hours following launch, all systems will be checked out in final preparations before the crucial TLI maneuver.
Artemis II will also act as a biological laboratory. Scientists will cultivate organoids miniature, lab-grown tissue samples derived from the astronauts’ blood both before and after the mission. By comparing these samples, researchers aim to isolate the effects of microgravity and deep-space radiation on human cellular function. “I’m certainly not going to dissect an astronaut! But I can dissect these little organoid samples and really look at the difference,” said NASA’s head of science, Dr. Nicky Fox. This method provides thorough molecular analysis without having to do surgery on the crew.
The return phase will start once Orion swings around the Moon and deploys for a four-day inbound trajectory. As the spacecraft approaches Earth, the service module will detach, leaving the crew module to endure the intense heat of atmospheric reentry. Lessons from Artemis I’s unexpectedly severe heat shield char have driven changes to the reentry trajectory, reducing thermal stress and minimizing gas generation rates within the ablative material. Rick Henfling, the entry flight director, pointed out that the updated profile “is not going to replicate that temperature environment” of the earlier mission.
Although Artemis II is a milestone in its own right, it is also a step toward Artemis III, which will land astronauts on the Moon no earlier than mid-2027. That mission depends on the availability of SpaceX’s Starship Human Landing System, a variant of the system intended for lunar surface transportation. But NASA’s Aerospace Safety Advisory Panel has cautioned that the HLS timeline is “significantly challenged” because of remaining engineering challenges, among them cryogenic propellant transfer in microgravity. Without this function, Starship is unable to refuel on orbit for the transit from lunar orbit to the lunar surface. NASA safety analyst Paul Hill warned that the system “could be years late for a 2027 Artemis III Moon landing.”
These delays carry geopolitical weight. China’s own lunar program, centered on its Lanyue lander, targets a crewed Moon landing by 2030, and U.S. officials have voiced determination to beat that timeline. Acting NASA Administrator Sean Duffy underscored the urgency, saying, “could be years late for a 2027 Artemis III Moon landing.”
For the time being, the success of Artemis II will not be measured by how it plants a flag, but as to whether it can safely deliver humans into deep space and return them back home, something not demonstrated since Apollo 17 in 1972. All the subsystems, from propulsion to life support, will be scrutinized, with the data collected informing the engineering course to the next giant leap.
