The James Webb Space Telescope, a unique and complex observatory

Artist's view of the James Webb Space Telescope
Credit: NASA
 Vue d’artiste du télescope spatial James Webb
  •  Vue d’artiste du télescope spatial James Webb
  • Le miroir principal du télescope spatial James Webb
The James Webb Space Telescope, a unique and complex observatory

The start of operations of the James Webb Space Telescope in 2022 will mark the birth of a new era in astronomy. This complex observatory will make it possible to explore the Universe as no other space telescope has done before now.

A long and arduous development

Development of this observatory began in the 1990s, with the aim of replacing the Hubble Space Telescope. It was supposed to be launched in 2008, but a succession of incidents and the telescope’s great complexity led to many delays in its design, as well as to soaring costs. After more than 25 years of development and planning and a final price tag of 10 billion dollars, this invaluable telescope will finally come into operation at some point in 2022.

The features of the James Webb telescope

The James Webb Space Telescope has a primary mirror 6.5 meters in diameter, compared to the Hubble telescope’s 2.4-meter mirror. It will capture seven times more light than its predecessor. The mirror is made up of 18 hexagonal segments of beryllium covered with a thin layer of gold. Its resolution will enable it to see objects 100 times weaker than what Hubble could.

The telescope will principally be observing in infrared light. This means that it will be highly sensitive to various undesirable sources of heat, and as a result will have to protect itself against sources of intense light such as the Sun, the Earth and the Moon. For that reason the observatory will be positioned 1.5 million kilometers from the Earth (a spot known as the L2 Lagrange point, which will allow the telescope to remain in gravitational equilibrium with the Sun and the Earth). An immense sunshield the size of a tennis court will permanently protect the telescope from different sources of heat and keep it at a temperature of -233° C.

Designed jointly by the American, European and Canadian space agencies, the Webb telescope will be equipped with four instruments. One of these was developed by Canadian researchers under the supervision of Professor René Doyon, director of the Institute for Research on Exoplanets at Université de Montréal. This contribution will entitle Canadian astronomers to guaranteed observation time on the Webb telescope.

What uses will the James Webb telescope be put to?

The objectives of the James Webb telescope’s mission are ambitious, and will be taking advantage of its sensitivity to infrared light to observe objects that are cold (like planets and the dust around stars) or very distant. When we talk about distant objects, that also means very old ones.

More specifically, the Webb telescope will be used to:

  • Search for the first stars and galaxies formed after the Big Bang more than 13 billion years ago;

  • Better understand the formation and evolution of planets, stars and galaxies;

  • Study the outer planets and objects at the far reaches of the solar system;

  • Study exoplanets orbiting other stars;

  • Look for biosignatures in the atmosphere of exoplanets to determine if there are forms of life.

A telescope for future generations

Scientific observations will start six months after the launch of the telescope, once calibration of all systems is completed. At that point the mission proper will begin, which should last 10 years or until the propellant keeping the observatory in position is exhausted.

Expectations are high, but it’s safe to anticipate that the James Webb Space Telescope will leave its mark on our collective imagination, just as the Hubble telescope did. It will above all permit a new generation of astronomers to make any number of discoveries and help us better understand the Universe in which we live.

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