Two engineers in white body coveralls, gloves, and masks are seen framing the image, with one engineer facing towards the camera on the left and one facing away from the camera on the right. They are seen holding a black, two-foot-wide circular reaction wheel, which is in the center of the image. The engineers are installing the reaction wheel to the main body of the spacecraft, which is visible looming above the engineers and the reaction wheel. To the back right of the reaction wheel that is being installed, another reaction wheel that has already been installed is visible.
Source: NASA/JPL-Caltech
Published: November 21, 2022

Engineers install 2-foot-wide reaction wheels onto the main body of NASA’s Europa Clipper spacecraft at the agency’s Jet Propulsion Laboratory in Southern California. In all, four wheels were integrated onto the spacecraft, which is being assembled for its launch to Jupiter’s moon Europa in October 2024.

When the spacecraft heads through deep space, slips into orbit around Jupiter, and collects science observations while flying dozens of times by Europa, the wheels rotate the orbiter so that its antennas can communicate with Earth and so its science instruments, including cameras, can stay oriented. Two feet wide and made of steel, aluminum, and titanium, the wheels spin rapidly to create a force that causes the orbiter to rotate in the opposite direction. The wheels will run on electricity provided by the spacecraft’s vast solar arrays.

Scientists believe the icy moon Europa has a vast internal ocean that may have conditions suitable for supporting life. Europa Clipper will fly by the moon about 50 times while its suite of science instruments gathers data on the moon’s atmosphere, surface, and interior – information that will help scientists learn more about the ocean, the ice crust, and potential plumes that may be venting subsurface water into space.