The Artemis mission will send astronauts into a stable orbit around the Moon — one that NASA is calling the "Gateway" orbit.

In a live presentation titled Artemis: Back to the Moon, a Tech Briefs attendee had a question for Nujoud Fahoum Merancy, Chief of the Exploration Mission Planning Office in the Houston-headquartered NASA Johnson Space Center.

Nujoud Fahoum Merancy
Nujoud Fahoum Merancy

"What is the Gateway orbit?"

Read Merancy's edited answer below.

Nujoud Fahoum Merancy: The orbit that we're going to use is what we've been calling the "Gateway" orbit. It's a near-rectilinear halo orbit (NRHO), which is a big mouthful, but in practice, the orbit is an Earth/Moon gravity-balanced orbit, which means we're using both the Earth's gravity and the Moon's gravity, so we can get in a really stable orbit that requires very little propulsion over time to maintain it.

We don't have to do a lot of burns for stability, and it looks like a highly elliptic orbit. We'll pass about 3,000 kilometers over the Moon's north pole, and then it's about a 7-day orbit period. It takes about six-and-a-half days to go one rev around the orbit, and at the furthest point from the Moon, below the south pole, the distance is about 70,000 kilometers.

What you get is this very stable orbit. It takes about a week per orbit, and when we dwell on the south pole, you have really good line-of-sight to the south pole. This orbit is very fascinating because it has continuous Earth coverage. The spacecraft can talk to the Earth for communication 100 percent of the time, and with these long passes over the south pole, we can have direct line0of-sight to the south pole for communication, for telerobotics, for other types of uses that last over 6 days at a time; then you just very quickly pass over the north pole and then dwell again.

We can use the gateway on the relay for communications between the astronauts on the surface to Earth as well as reach the astronauts between the habitats or the human landing system on the Moon to the Gateway.

It's a really fascinating orbit, because we don't need a lot of propulsion to stay in the orbit. This is a really balanced orbit for power and communications. That orbit also has near-100 percent coverage for power. We don't need to put a lot of batteries on Gateway and deal with a lot of passes through eclipsing. We just do short passing. It's very similar to the types of orbit we'd need on Mars where you park your transportation vehicle in a high Mars orbit and go down to the surface form there.

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