Astronauts Sunita Williams, who grew up in Needham, and Butch Wilmore have been living on the space station since June after the Boeing Starliner capsule they arrived on experienced issues while docking.

Takeoff was slated for Wednesday evening from Kennedy Space Center in Florida, but the company called off the launch attempt because of an issue with the launchpad’s ground system. The problem stemmed from a hydraulics system used to control one of two clamps that hold on to the upper portion of the rocket as it sits vertically on the ground pad before launch.

NASA astronauts Butch Wilmore and Sunita Williams face potential long-term health issues after a nine-month space mission. They may experience irreversible physical damage due to microgravity, such as bone density loss and muscle atrophy,