Looking back to the future
There’s something exciting happening if you look up. No, not at your ceiling. Set your sights on the stars. The biggest telescope ever launched into space, James Webb Space Telescope (JWST) is soon going to be able to send its first images back to Earth. A lot of engineering ‘firsts’ had to happen before this even became possible.
This telescope has 18 separate hexagonal gold plated mirrors, creating an area of 26 m2. To set all the mirrors in the right position to achieve and retain the optimal focus, there are 132 motors which can adjust these mirrors with 10 nanometers (nm) precision. To appreciate this, a human hair is approximately 80,000 to 100,000 nm in diameter. A single water molecule is about 1.5 nm.
The telescope is designed primarily for near-infrared astronomy and can detect objects up to 100 times fainter than the famous Hubble telescope can. Unlike Hubble, which orbits 550 km (340 mi) above the Earth's surface, JWST is now orbiting around the sun at a distance of nearly 1.5 million km (1 million miles) from Earth. Why that far? It has been positioned in a unique place: the L2 Lagrange point. That position near the Sun-Earth L2 keeps all three bodies on the same side of the spacecraft at all times.
JWST must be kept under 50 K (−223.2 °C; −369.7 °F); otherwise, infrared radiation from the telescope itself would overwhelm its instruments. It therefore uses a large sunshield to block light and heat from the Sun, Earth, and Moon. (Interestingly enough, 50 K is still hot for quantum computers, which have to operate near 0 K.)
You might recall that the Hubble telescope had 5 servicing missions thanks to its proximity to Earth and the Space shuttle. In contrast, the distance of the JWST from Earth also means that there will be no possibility for fixing or upgrades for the telescope. The JWST just has to work. There’s no help coming from 1.5 million km away.
When did the first discussion about JWST start? That was back in the 1980s, but it was more of a “sure, it would be nice if we could do this” kind of brainstorming. The actual planning started in the early 1990s. It took 30 years of planning, building and testing to get to launch in December 2021. Now that the JWST is in position and almost all the setup and configuration is done, we can expect the first images at the end of June 2022.
What are the goals for JWST? The mission has four main objectives, to:
search for light from the first stars and galaxies that formed in the universe after the Big Bang.
study galaxy formation and evolution.
understand star formation and planet formation.
study planetary systems and the origins of life.
Just reading about all the engineering and science which went into getting the project to this point makes you stop and marvel how far humans got. Now, imagine all the things we will learn in the next 20 years. Think about how many new patterns we will discover.