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On Christmas Day 2021, the most powerful telescope ever built was launched into space atop an Ariane 5 rocket – the beginning of a new era in astronomy and planetary science. In the months insured, this $10 billion telescope has made its way to a distance of about a million miles from Earth; unfolded its huge, origami-esque sunshade; and began to use his instruments. And when it returns its first scientific images later this summer, it will 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 6 meters wide, the telescope is equipped with instruments that can see in the near to mid-infrared – a particular part of the electromagnetic spectrum that allows the telescope to see extremely distant and faint objects that would otherwise be invisible. with existing telescopes. JWST should be able to look back more than 13.5 billion years, to the era when the very first galaxies, and even the first stars, started forming.

The telescope’s planning dates back to the 1990s, with major construction beginning in the mid-2000s. Despite the promise, the actual construction of JWST was not smooth sailing: several problems arose during testing, numerous management issues delayed the project further, and eventually a telescope intended for launch in 2007 and costing only $500 million flew 14 years late and cost a whopping $9.7 billion.

Part of the huge cost of this project was its groundbreaking design: To see ultra-weak objects back near the beginning of the universe required a giant mirror, far too big to fit into the nose cone of an existing rocket. And to see such faint objects, you need a telescope that is extremely cold, requiring a huge sunshade to protect the telescope’s sensors from sunlight. The mirror and sunshield (the latter about the size of a tennis court) together led NASA engineers to a design in which the telescope folds tightly for launch, then slowly, gently slide a complex set of arms, pulleys and motors on its way to its permanent position. abode in space – a location called “L2” where the gravitational forces of the Earth and the sun are in balance and where JWST can easily stay in place. This design contained nearly 400 so-called “single points of failure”, where a problem deploying even one element would spell disaster for the telescope. But thankfully, remarkably — and a testament to NASA engineering — the telescope finished deploying its myriad pulleys, tensioners, arms, mirror segments and sunshade layers two weeks after launch with no problem.

Among its scientific objectives, JWST will measure the composition of atmospheres of rocky planets orbiting other stars, looking for evidence of, say, liquid water or even oxygen, to gauge whether those worlds could be considered habitable or even inhabited.

Paul Byrne

In the months that followed, JWST was allowed to passively cool, allowing the sensors to reach the ultra-cold temperatures necessary for the science campaign to begin. And that campaign will answer 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 does their death litter surrounding space with the materials needed to form the next generation of stars and planets? JWST will address these and many more questions underlying the beginning of the universe itself.

But there’s an angle to JWST that really excites me. I am a planetary scientist and I am driven to understand why planets are the way they do – including what makes a world habitable (Earth) or uninhabitable (almost everywhere else). Among its scientific objectives, JWST will measure the composition of atmospheres of rocky planets orbiting other stars, looking for evidence of, say, liquid water or even oxygen, to gauge whether those worlds could be considered habitable or even inhabited.

There are plenty of reasons to be impressed with the JWST mission thus far, despite the project’s arduous and horribly expensive history. But the value of the discovery, however slim the possibility that JWST detects life on a planet orbiting another star? Priceless.

Paul Byrne is an associate professor of Earth and Planetary Sciences in Arts & Sciences.

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