Stockholm university

The James Webb Telescope has reached its orbit

After 25 years of planning, the world's largest space telescope to date, James Webb, is finally out in space. The telescope uses infrared light to measure objects in space. It will examine the atmosphere on planets in other solar systems and look further back into the history of the universe than has previously been possible. The instrument on the telescope designed to capture faint infrared light has been developed by scientists from Stockholm University, together with other Swedish researchers.

On Christmas Day 2021, the James Webb Telescope was sent into space from the European space centre Kourou in French Guiana. On 24 January the telescope reached its orbit – but only after six months will scientists know if everything works and the observations can then begin.

“With the help of the James Webb telescope, we will be able to see parts of the universe and other things we have not been able to see before. And what we have already been able to see, we will be able to see better,” says astronomer Jens Melinder at the Department of Astronomy at Stockholm University, whose project will hopefully receive its first measurement data in January 2023.

James Webb-teleskopet
The James Webb Telescope. Illustration: NASA GSFC/CIL/Adriana Manrique Gutierrez.
 

Measuring infrared light

The James Webb telescope makes observations mainly in infrared light, i.e. light with a longer wavelength than the human eye can perceive. As the universe expands, light becomes redder, wavelengths become longer, the farther away from us the light originates. Therefore, the James Webb Telescope can see farther than the 30-year-old Hubble Telescope, whose observations are mainly made in visible and ultraviolet light. The ability to observe farther into space than ever before also means that it is possible to look further back in time. The infrared light that reaches us has not only travelled a greater distance, it has also taken longer and can be several billion years old. This makes it possible to study what the universe looked like shortly after the Big Bang, and to follow the evolution of galaxies. Infrared light is also highly significant in relation to the search for planets around other stars, so-called exoplanets, which have similar properties to Earth and where life may be found. The telescope can also be used to study the atmospheres of the planets.

Galaxies and stars at the beginning of the universe

Jens Melinder
Jens Melinder. Image: Private.

Jens Melinder is one of the Swedish researchers in the consortium that has contributed to MIRI, Mid-Infrared Instrument, the instrument that will capture faint infrared light from the most distant and oldest celestial bodies in the universe. Together with Göran Östlin of Stockholm University and Kay Justtanont of Chalmers University of Technology, he will investigate the nearby galaxy IZw18, which is both irregular and low in metal.

“The galaxy consists almost exclusively of lighter substances such as hydrogen and helium and is therefore reminiscent of galaxies in the beginning of time. Heavier substances are thought to form gradually in stars. It will be like a lab where we can see what galaxies looked like and how stars were formed in the childhood of the universe,” says Jens Melinder.
Together with Göran Östlin and Arjan Bik, colleagues at the Department of Astronomy, Jens Melinder will also study dwarf galaxies that were formed 10-12 million years ago, to see how galaxies are built and why they look the way they do.

 

Fierce competition to make measurements

The competition to use the James Webb telescope is intensive. The research groups that have contributed to the development of the telescope have been given guaranteed opportunities to make measurements, and other researchers and research groups have been allowed to apply for slots. Among the lucky ones at Stockholm University, whose projects have been given the opportunity to make observations, are Angela Adamo, who will study nearby star-forming galaxies to find out how stars form, Thøger Rivera Thorsen, who will investigate how early galaxies evolved by examining light which has been amplified by the gravitational fields of other galaxies, and Alexis Brandeker who will study the atmosphere of a large lava planet which orbits extremely close to its star.

 

Impossible to repair

There have been many delays, but it is extra important that everything works as it should. In order to fit into the launch rocket, the James Webb telescope has been folded together; it must then be unfolded in the right way on the way to its orbit. The telescope will orbit 1.5 million kilometres from the earth, almost four times farther away than the moon, and will follow the earth's orbit around the sun.

 

The James Webb Telescope

The James Webb Telescope is the largest and most advanced space telescope ever built. The main mirror has a diameter of 6.5 meters and the total area is 25.4 square meters. The telescope weighs 6.5 tons and has a planned lifespan of 5-10 years or more.

The project is a collaboration between the European Space Agency (ESA), the American space agency NASA, and the Canadian space agency CSA.

Fourteen researchers from Stockholm University are involved in various projects that will use measurements from the James Webb telescope. Most of these researchers are at the Department of Astronomy, but researchers from the Department of Physics are also involved.

ESA's website about the James Webb Telescope