NASA's giant Webb telescope succeeds in key pre-launch test, here's all you need to know

The world’s largest and most powerful space science telescope, James Webb Space Telescope, opened its iconic primary mirror for the last time it is on earth. The event marked a key milestone in preparing the observatory for launch later this year. As a part of the final test, the 6.5 meter mirror was commanded to fully expand and lock itself into place. After this test, all of the telescope’s movable parts will have confirmed in testing that they can perform their intended operations after being exposed to the expected launch environment.

(The process of deploying, moving, expanding and unfurling all of Webb’s many movable pieces after they have been exposed to a simulated launch is the best way to ensure they will perform as intended once in space. Image Credits: NASA.gov)

All that you need to know 

In order to observe objects which are in distant cosmos, and to do science that has never been done before, Webb’s mirror needs to be so large. Webb consists of many movable parts that have been specifically designed to fold themselves. This makes a compact formation that is considerably smaller than when the observatory is fully deployed. Also, this allows it to just barely fit inside a 5 meter rocket fairing, with little room to spare.

Lee Feinberg, optical telescope element manager for Webb at NASA's Goddard Space Flight Center in Greenbelt, Maryland said, “The primary mirror is a technological marvel. The lightweight mirrors, coatings, actuators and mechanisms, electronics and thermal blankets when fully deployed form a single precise mirror that is truly remarkable”. He added, “This is not just the final deployment test sequence that the team has pulled off to prepare Webb for a life in space, but it means when we finish, that the primary mirror will be locked in place for launch. It’s humbling to think about the hundreds of dedicated people across the entire country who worked so hard to design and build the primary mirror, and now to know launch is so close”.

To deploy, operate and bring its golden mirrors into focus, the telescope requires 132 individual actuators and motors. A proper deployment in space is considered critically important to the process of fine-tuning Webb’s individual mirrors into one functional and massive reflector. Once the wings are fully extended and are in place, extremely precise actuators on the backside of the mirrors position and bend or flex each mirror into a specific prescription. The testing of each actuator and their expected movements was completed in a final functional test earlier this year.

 Ritva Keski-Kuha, deputy optical telescope element manager for Webb at Goddard said, “Pioneering space observatories like Webb only come to fruition when dedicated individuals work together to surmount the challenge of building something that has never been done before. I am especially proud of our teams that built Webb’s mirrors, and the complex back-end electronics and software that will empower it to see deep into space with extreme precision. It has been very interesting, and extremely rewarding to see it all come together. The completion of this last test on its mirrors is especially exciting because of how close we are to launch later this year”.

(Image Credits: NASA.gov)