By Jamie Carter
In precisely one year—on Tuesday, March 30, 2021—the almost US$10 billion James Webb Space Telescope (JWST or “Webb” for short) will launch on a European Ariane 5 rocket from the Guiana Space Centre to the northwest of Kourou in French Guiana.
The successor to the Hubble Space Telescope, “Webb” will study the solar system, directly image exoplanets, photograph the first galaxies, and explore the mysteries of the origins of the Universe. By detecting infrared light, Webb will be able to look further back in time than any other telescope thus far (all telescopes look back in time; when it takes images of a galaxy 13 billion light years away, it’s capturing light from 13 billion years ago).
Webb is the most ambitious and complex space science telescope ever constructed, and tantalisingly soon it will be the plaything of scientists … or, at least, that’s the plan.
What is Webb?
A joint venture between NASA, the European Space Agency (ESA), the Canadian Space Agency (CSA) and Space Telescope Science Institute (STScI), Webb is a massive space telescope with a near-infrared camera and spectrograph for collecting light from the early Universe. It’s named after James E. Webb, NASA’s administrator during (some of) the Apollo era.
How does Webb compare to Hubble?
For starters, Webb can collect a lot more light than Hubble, so it will be able to peer deeper into the Universe—essentially, further back in time.
Launched on April 24, 1990 and now in its 30th year, the US$2.5 billion, 11-ton Hubble has a primary mirror with a diameter of 8 feet/2.4 meters. The US$9.7 billion, 6-ton Webb has a primary mirror with a diameter of 21 feet/6.5 meters. It’s made up from 18 gold-plated beryllium hexagonal mirror segments and will have vastly improved infrared resolution and sensitivity compared to Hubble.
Where will Webb go?
There’s also a very different physical side to Webb and Hubble. While the latter orbits Earth from 550 km, Webb will observe the Universe from the second Lagrange point (L2) around a million miles/1.5 million kilometers from Earth. It will send its images back to Earth via NASA’s Deep Space Network.
Why do we need Webb?
“Hubble and Webb are designed to complement each other—it’s a blending of different wavelengths to give us a better understanding of what’s out there,” said Dr Maggie Aderin-Pocock, a space scientist who has worked on the Webb’s instruments, during a recent lecture in London. “Webb will look even further back in time to give us a better understanding of how our Universe began.”
Webb will be able to “see” the cosmos as it was when just a few hundred million years old, capturing images of the first-ever stars and galaxies. As well as “cosmic dawn” images, expect never-before-seen images of planets, comets, Kuiper Belt objects and—most excitingly—exoplanets. Armed with an instrument that can block the light of a star, Webb will detect exoplanets using its infrared skills, and even study their atmospheres.
What comes after Webb?
The Wide Field Infrared Survey Telescope (WFIRST). At 8 ft./2.4 meters, its mirror will be the same size as Hubble’s but WFIRST is all about the big picture; its wide-angle lens on a 288 megapixel camera will give it 100x the field of view of Hubble, essentially enabling it to map the Milky Way and other galaxies in super-quick time. It’s designed to research three key areas: exoplanets, dark matter/dark energy, and the formation of stars and planets. Positioned in a very similar place to Webb, WFIRST is scheduled to launch in 2025.
Wishing you clear skies and wide eyes.