A small microwave oven-sized spacecraft is on its way to the Moon, setting the stage for a sustained human presence on the lunar surface. NASA launched its CAPSTONE satellite on Tuesday, in a unique mission to test out a highly elliptical orbit around the Moon as part of the agency’s Artemis program.
CAPSTONE launched on board Rocket Lab’s Electron rocket at 5:55 a.m. ET from the private company’s Launch Complex 1 in Mahia, New Zealand. The launch was originally scheduled for Monday but suffered a slight delay when Rocket Lab decided to run final systems checks before liftoff. “Today’s launch was an important step in humanity’s return to the Moon,” Rocket Lab founder and CEO Peter Beck, said in a statement. “While CAPSTONE’s journey to the Moon has only just begun, we’re proud to have safely delivered CAPSTONE to space.”
Short for Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, CAPSTONE is headed for a near rectilinear halo orbit (NRHO) around the Moon. Once in NRHO, the 25-kilogram cubesat will require one full week to complete a full orbit around the Moon, travelling from a distance of about 76,000 km from the lunar north pole and coming to within 3,400 km of the opposite pole during its closest approach.
CAPSTONE is designed to test this unique orbit for NASA’s Lunar Gateway, which is expected to be built later this decade. As part of the Artemis program, Gateway will be a lunar space station for enabling longer duration missions to the Moon. Based on orbital models, NRHO should allow the Lunar Gateway to consume less fuel as it cruises its way around the Moon, the result of gravitational interactions between the Moon and Earth. The orbit would also allow the gateway to stay in contact with Earth at all times.
CAPSTONE is currently in a stable Earth orbit attached to Rocket Lab’s Photon Lunar spacecraft bus — a spacecraft designed to set the small satellite on its trajectory towards the Moon. Approximately a week from launch, CAPSTONE will separate from the Electron rocket’s upper stage and continue towards its lunar destination. The satellite will reach a distance of 1.55 million kilometres from Earth, which is more than three times the distance between Earth and the Moon, and then get pulled back towards the Earth-Moon system by the gravitational pull of the Sun. CAPSTONE will reach its intended orbit in about four months and then run tests in NRHO for another six months.