NASA’s Artemis II mission has yet to return to Earth—it will do so on Friday evening, splashing down into the Pacific Ocean off the coast of San Diego—but the agency is already nearing some key decisions on the next Artemis mission.
The US space agency announced six weeks ago that it was modifying its Artemis timeline to insert a mission before beginning planned lunar landings. This new mission, designated Artemis III and intended to fly in Earth orbit rather than to the Moon, would attempt to “buy down” risk to give the lunar landing mission (now Artemis IV) a higher chance of success.
NASA Administrator Jared Isaacman said Tuesday afternoon that the space agency is debating about which orbit to fly Artemis III in before locking in a blueprint, noting that the first “senior level” Artemis III mission design discussion had taken place earlier in the day.
Where will it occur?
“One of the questions is what the initial orbit will be for Artemis III,” Isaacman said during a news conference. “Is it going to be LEO or HEO? There are pros and cons for each of them, for sure.”
Low-Earth orbit, or LEO, is designated as a distance of about 160 km to 2,000 km above the Earth’s surface. High-Earth orbit is considered to be greater than 36,000 km from the Earth’s surface, above geosynchronous orbit.
During Artemis III, the Orion spacecraft will launch (presumably with four astronauts) on a Space Launch System rocket from Florida. In Earth orbit, they will rendezvous with one or both of NASA’s Human Landing Systems. These are the Starship vehicle’s upper stage under development by SpaceX and a modified Blue Moon lander being built by Blue Origin.
A rendezvous in low-Earth orbit would potentially allow NASA to fly the SLS rocket without using an Interim Cryogenic Propulsion Stage, or ICPS. This is valuable because it could then save this final remaining ICPS stage for the Artemis IV mission (for future SLS missions, NASA would use a Centaur V upper stage, also provided by United Launch Alliance). For an Artemis III mission in a higher orbit, however, NASA would need the ICPS to push Orion there.