NASA has plotted Gateway’s path with special considerations in mind.
The orbit is a highly elongated ellipse, swooping to within 1,000 miles of the moon’s southern polar region and then flinging to a far distance of 43,500 miles, circling the moon every seven days. The orbit takes advantage of the point of balance between the gravity of Earth and the moon, which means it’s a very stable orbit that requires minimal fuel for a spacecraft to maintain over time.
Gateway’s orbit will make it easier for spacecraft flying to and from the moon’s surface — particularly the south polar region that NASA is interested in exploring — to rendezvous with the station. And at the far end of the loop, away from the moon, spacecraft departing for Earth (and future destinations like Mars) won’t need to burn as much fuel to break free of the moon’s gravity.
Illustration of the near rectilinear orbit that NASA’s CAPSTONE will test in preparation for the building of the Gateway space station. (Courtesy of NASA)
Another advantage of Gateway’s orbit is that it keeps an almost constant line of sight with Earth, allowing near continuous communication between the station and controllers at home. The orbit also provides coverage to the moon’s far side, where the body of the moon blocks radio signals from Earth. For future missions that will land on the far side of the moon, Gateway will serve as a Wi-Fi connection in the sky.
Untethering (a little) from Mission Control
Another of CAPSTONE’s goals is to test new navigational technologies that will help future moon-bound spacecraft to operate with less dependence on controllers back on Earth.
As part of this test, CAPSTONE will communicate directly with the Lunar Reconnaissance Orbiter, which has been circling the moon for over a decade now, making a high-resolution image survey of the lunar surface.
CAPSTONE will use this orbiter as a form of lunar GPS, a navigational reference to determine its own location and orbital trajectory.
Coming up: astronauts aboard Artemis
Named for the Greek moon goddess and twin sister of the sun god Apollo, the Artemis missions mark not only the first human-crewed expeditions to the moon since Apollo 17, five decades ago, but also the first time humans have ventured farther than 300 miles from Earth’s surface since that time.
Diagram illustrating the planned flight of the uncrewed Artemis 1 mission, which will launch as early as April 2022. (Courtesy of NASA)
Artemis 2, planned to launch in May 2024, will carry human astronauts around the moon, then back home again.
Artemis 3 will land astronauts on the lunar surface as early as 2025. NASA has announced that the spacecraft will carry the first woman and first person of color to the moon’s surface. The plan is to send the two astronauts to a site in the moon’s southern polar region, where they will explore for about a week. A third astronaut will remain aloft in Gateway.
Why are we going to the moon?
Good question. The moon is a valuable resource, not only as a place for humans to explore, or a repository of natural resources to fuel missions on the moon and destinations beyond, such as Mars, but also as a unique platform for scientific observation of the universe.
An ‘illumination map’ composite image of the moon’s south pole, created from images collected by NASA’s Lunar Reconnaissance Orbiter over about four weeks — one full lunar day. The brightness at any spot represents the percentage of a lunar day that spot was in sunlight. Black reveals locations that are in permanent shadow, where no sunlight ever reaches — deep crater floors where water ice may have built up over millennia. (Courtesy of NASA/GSFC/Arizona State University)
The far side of the moon, which always faces away from Earth, is protected from the radio noise that human civilization generates and spews into space, a natural shelter where sensitive radio observatories may probe the cosmos.
