A tiny spacecraft bound for the Moon will wait at least a few more days for launch.
Liftoff for the CAPSTONE mission, short for “Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment,” has been pushed back four days to May 31, NASA announced this week.
“We will continually evaluate the date of the first target launch attempt within the launch period, which runs through June 22,” agency officials wrote Wednesday (May 11) on their blog for the Artemis lunar program. The post did not specify why the release was slightly delayed.
The microwave oven-sized CAPSTONE spacecraft will launch from New Zealand aboard a Rocket Lab Electron rocket with a Lunar Photon upper stage. Its mission is to verify the stability of a near-rectilinear halo orbit (NRHO) around the moon, modeling what Gateway, the small lunar-orbiting space station that is a key part of the Artemis plan, will need to follow with the astronauts on board.
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The planned orbit will bring CAPSTONE within 1,600 kilometers (1,000 miles) of a lunar pole at its closest point, providing access to the south pole. That’s the main goal of the manned Artemis missions, given the likely presence of water ice in the permanently shadowed polar craters.
At its highest altitude, CAPSTONE will spin 43 times as high at 43,500 miles (70,000 km). The advantage of such an orbit is that future spacecraft arriving and leaving the lunar surface at the south pole will not need to fly as high to meet Gateway, but the halo orbit has yet to be tested by other spacecraft.
To complicate matters, the moon has known mascons (concentrations of mass) that can perturb orbits. So NASA is looking for an inexpensive test run before sending the much more expensive Gateway into orbit.
CAPSTONE’s secondary mission is to assess spacecraft-to-spacecraft communication and navigation systems with NASA’s Lunar Reconnaissance Orbiter, which has been circling the moon since 2009. CAPSTONE was initially supposed to fly in 2021, but the mission has since been delayed due to COVID-related issues.