On Christmas Day 2021, the most powerful telescope ever built was blasted into space atop an Ariane 5 rocket – heralding the start of a new era in astronomy and planetary science. Over the next few months, this $10 billion telescope traveled to a distance of about a million miles from Earth; unfolded its enormous origami-shaped sun visor; and began to order his instruments. And, when it renders its first scientific images later this summer, it will begin to revolutionize our understanding of the cosmos.
The James Webb Space Telescope (JWST) – named after a former NASA administrator, and not without controversy – is designed to delve into the universe’s distant past. With a primary mirror over 21 feet wide, the telescope is equipped with instruments capable of seeing into the near to mid-infrared – a particular part of the electromagnetic spectrum that will allow the telescope to see extremely distant and faint objects otherwise invisible. with telescopes. JWST should be able to go back more than 13.5 billion years, to the time when the very first galaxies, and even the first stars, began to form.
Planning for the telescope dates back to the 1990s, with major construction beginning in the mid-2000s. further delayed the project, and eventually a telescope slated for launch in 2007 and costing just $500 million ended up flying 14 years late and costing a colossal $9.7 billion.
Part of the vast expense of this project was its revolutionary design: to see ultra-faint objects near the beginning of the universe required a giant mirror, far too large to fit in the nose cone of any rocket. existing. And to see such faint objects requires an extremely cold telescope, which requires a huge sunshade to shield the telescope’s sensors from sunlight. The mirror and sunshade (the latter the size of a tennis court) led NASA engineers to a design in which the telescope is folded tightly for launch, then slowly and carefully unfolds a complex array of arms, pulleys and motors on its way out to its permanent home in space – a place called “L2”, where the gravitational forces of Earth and the Sun balance each other and where JWST can stay in place easily. This design had nearly 400 so-called “single points of failure”, where a failure to deploy a single element would be catastrophic for the telescope. But, thankfully, remarkably – and a testament to NASA engineering – the telescope finished deploying its myriad pulleys, tensioners, arms, mirror segments and layers of sunshades two weeks after launch without any problems.
Over the months that followed, JWST was passively allowed to cool down, allowing its sensors to reach the ultra-cold temperatures needed to launch its science campaign. And this campaign will address some of our most fundamental questions: What was the early universe like? How and when did the first stars and galaxies form? How do stars die, and how do their deaths leave the surrounding space with the materials needed to form the next generation of stars and planets? JWST will address these and many other questions that underlie the beginnings of the universe itself.
But there is one angle with JWST that particularly excites me. I’m a planetary scientist and I’m driven to understand why planets look the way they do – including what makes a world habitable (Earth) or uninhabitable (almost everywhere else). Among its scientific goals, JWST will measure the compositions of the atmospheres of rocky planets orbiting other stars, looking for evidence of liquid water, for example, or even oxygen, to assess whether these worlds could be considered habitable… or even inhabited.
There are plenty of reasons to be impressed with the JWST mission so far, despite the project’s painstaking and terribly expensive history. But the value of the discovery, however remote the possibility, of JWST detecting life on a planet orbiting another star? Invaluable.
Paul Byrne is an Associate Professor of Earth and Planetary Sciences in Arts & Sciences.