When Italian astronomer Galileo Galilei pointed the world's earliest telescope at the moon in 1610, he became the first person in history to see its craters and mountains. Four hundred years later, NASA is collaborating with the Canadian and European Space Agencies on the largest and most complex telescope ever constructed: the James Webb Space Telescope (JWST, or just "Webb" for short). Webb's primary mirror is 22 ft tall and 20 ft wide. Because of this extraordinary size, Webb was packed into the Ariane 5 rocket in its folded state for the launch from Kourou in French Guiana on 25 December 2021; it would unfold later on in space. The whole process of setting up the mirror in space, aligning and calibrating it, as well as the cooldown period, takes about six months! At the time of writing, Webb is in the fifth of six setup phases and will likely be fully operational by the time you read this article.
Mercifully for the hundreds of scientists and thousands of engineers involved in the project, everything has gone according to plan thus far. On 24 January 2022, the James Webb Space Telescope reached its intended orbit around the sun at the second (outer) Lagrange point (L2) – a special spot in the solar system where the telescope can keep a position relative to Earth with a minimum of energy, and where it is hidden from too much sunlight: it continuously faces the night side of Earth, and travels at the same speed as our world. Operating completely in the infrared spectrum, the JWST looks deeper into the past of the universe than any previous telescope was able to do. Its outstanding sensitivity makes it capable of picking up light from the early times of the universe, assumed to be 13.5 billion years ago. Webb can also “look” around in our neighborhood to advance planetary and exoplanet research, for example. So how did the James Webb Space Telescope come into being, and what was necessary to bring it all the way to where it is now?