NASA’s oft-delayed James Webb Space Telescope has suffered yet another setback. While it was most recently scheduled to lift off on December 18th, it now won’t launch until December 22nd at the earliest. The delay is due to an incident that occurred while technicians were preparing to attach the telescope to the Ariane 5 rocket that will ferry it into space.

“A sudden, unplanned release of a clamp band — which secures Webb to the launch vehicle adapter — caused a vibration throughout the observatory,” according to NASA. It’s now conducting additional testing to ensure the telescope wasn’t damaged during the incident. NASA says it will provide an update on the situation by the end of the week.

The successor to the Hubble Space Telescope has been plagued by delays. When development started in 1996, NASA expected to deploy the JWST in 2007. However, by 2005, it went back to the drawing board. The telescope was then deemed complete in 2016 but then delayed again due to its complex construction. It was only fully assembled in 2019 and then the pandemic caused yet another round of setbacks. Given the history of the JWST, you can understand why NASA wants to play it safe.