The James Webb Space Telescope (JWST) has been in some stage of development since the 1990s. A long string of setbacks and delays have made the project much more expensive than NASA initially intended, but we’re nearing launch of the successor to the Hubble Space Telescope. Before it can head into space, NASA needs to make sure all the components are working, including the critical deployable tower that NASA just finished testing.
The JWST will take over for the Hubble Telescope, which is currently on its last legs following a final servicing mission more than 10 years ago. While NASA was able to make periodic visits to repair and improve Hubble in orbit of Earth, the JWST will be out of reach. The sensitive instruments on NASA’s new telescope need to remain extremely cool, so it will operate at the Earth-Sun L2 Lagrangian point 1.5 million kilometers (about 932,000 miles) away. The need to keep infrared radiation at a minimum is also why the JWST has a motorized deployable tower.
NASA designed the JWST in two parts. There’s the upper observatory with its iconic gold-coated beryllium reflectors and the spacecraft bus below that. The observatory section has all the sensitive scientific instruments that will probe the universe, and the bus is home to propulsion, communications, and other electronic systems that produce heat. The tower moves the instruments away from the bus to ensure it remains frosty and effective. If the tower didn’t work in space, that could spell doom for the mission.
During the test, engineers instructed the JWST to deploy the tower exactly as it will in space. Over the course of several hours, the tower extended 48 inches (1.2 meters) upward to its final position. The team even managed to simulate the zero-gravity environment of space using a series of pulleys. NASA reported no issues with the tower, moving Webb one step closer to launch.
The deployable tower is also an important part of the agency’s launch plan. Sure, it would be easier to build the telescope with the necessary space between the electronics and science payload, but the entire contraption has to fold up and fit inside an Ariane 5 rocket. The launch is currently scheduled for March 2021.
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