The most complicated science project in NASA’s history is nearly operational. Last week, the James Webb Space Telescope (JWST) completed its delicate unfolding process while cruising to its final destination in space.

The US$ 10bn successor to the Hubble Space Telescope will see further into the cosmos than any device ever devised by humans, allowing scientists to see light that has taken 13.8 billion years to reach us. Observing distant light effectively means observing ancient light, and the JWST will see back to a mere 100 million years after the Big Bang, perhaps allowing scientists to image the earliest star formations and first light in the universe.

The telescope’s mirror is actually 18 separate hexagonal panes, made of lightweight beryllium and spanning over 6.5m, compared to the 2.4m mirror of Hubble. This allows for much more light to be gathered. The JWST also operates best in the infrared end of the spectrum, which is superior for detecting old light.

This design means that any local heat would disrupt telescope operations, so the JWST is bound for Lagrange Point 2 (L2), a point in space 1.5 million kilometres from Earth, or three times further our than the moon. The telescope will also be protected by an immense heat shield, lowering the temperature from 50°C on the sunward side to below -200°C on the operational side.

The great distance from Earth means that, if anything goes wrong, it is infeasible for astronauts to travel to the telescope to undertake maintenance. This is why although construction finished in 2016, it took until 25 December 2021 before there was confidence to launch.

In the final approach to L2 the JWST will delicately position its mirrors to perform as one, tiny actuators aligning the plates at a rate slower than the speed of growing grass.

For more information on the James Webb Space Telescope, click here