NASA updates list of Artemis 3 landing sites

WASHINGTON — NASA has updated a list of candidate landing sites near the south pole of the moon for the Artemis 3 mission, taking into account surface conditions and capabilities of SpaceX’s Starship lander.

NASA announced Oct. 28 that it had updated the locations in the lunar south pole region it was considering for the Artemis 3 mission. The agency had released a list of 13 candidate landing locations there in August 2022.

The nine locations include some of the same regions of the earlier list as well as new locations. All are clustered near the lunar south pole, a region of science and exploration interest because of the potential of water ice deposits in permanently shadowed craters.

The analysis required a “multi-variable” analysis, said Tamra George of NASA’s Johnson Space Center during an Oct. 28 presentation about the landing sites at the annual meeting of the Lunar Exploration Analysis Group (LEAG). “Our number one priority is that safe landing and safe return of our astronauts, and with doing that, getting some amazing science,” she said.

That required accounting for a wide range of factors. They include surface conditions at the landing site within the capabilities of Starship as well as lighting conditions and visibility of the Earth for direct-to-Earth communications. That can be “tricky,” she said, particularly during winter, when it can be difficult to find both acceptable lighting and Earth visibility conditions for the projected six-day surface stay.

Those factors mean that each location is available for only part of the time. “We’re going to stay pretty constrained” for Artemis 3, she said, “as we wait for more infrastructure to come for future missions.” That would include relay satellites that would alleviate the direct-to-Earth communications constraints.

“We wanted to maintain flexibility in that mission availability in any potential schedule changes, so we wanted to keep it open longer instead of really narrowing down tight right now,” she said later at the meeting when asked why NASA selected nine sites.

Science is also a factor in the selection of the sites. “Artemis 3 is still a test flight, but it is an opportunity to do amazing science,” said Sarah Noble, Artemis lunar science lead at NASA Headquarters, at the LEAG meeting. “We can do good science anywhere but some sites are better than other sites.”

Future Artemis landing sites will not be limited to the list compiled for Artemis 3. “Science is going to help us drive the landing site selection” for Artemis 4, she said. That would include the earlier list of 13 sites as well as other potential locations that may be of scientific interest.

That could, in theory, lead to landings outside the south polar region to meet broader scientific objectives. “We’re opening up the entire lunar surface for [Artemis] 4 and 5,” said Jacob Bleacher, NASA chief exploration scientist, at LEAG. “We recognize 100% that we cannot meet all objectives at any one location. We also recognize that some objectives require data collected from elsewhere on the moon.”

He added, though, that it was unlikely that early Artemis landings would go outside the south polar region, citing the interest in volatiles like water ice as well as an architecture that includes the use of the near-rectilinear halo orbit that is optimized for polar landings. “These first handful of missions, in my opinion, will be going to the south polar region,” he said.