James Webb: 13 Questions to Understand the Space Telescope Mission

The James Webb Space Telescope (JWST) is 1.5 million kilometers from Earth. In mid-July 2022, the first official images of the observatory were released. The results are fabulous. Hubble’s legacy is assured.

James Webb has finally shown what he is capable of. The space telescope, now located 1.5 million kilometers from Earth, received the first historic image of the universe’s bottom, released on July 11, 2022. The event was so historic that even the President of the United States, Joe Biden, attended the festivities. Even in France, Emmanuel Macron went there with his tweets.

Then on July 12, the observatory delighted astronomers, the public and journalists even more with the remnants of a dead star, a cosmic ballet between four galaxies, the mystery of a giant exoplanet and the cosmic cliff – where stars are born, in the giant nebula. These shots by James Webb are stunning.

The capacity of the telescope, built by the US space agency with the help of its European and Canadian counterparts, is enormous. Just do a simple comparison between James Webb and Hubble. Or to see how the area imaged by the observatory is only a tiny fraction of the entire universe. And yet, the details are incredibly precise.

Here’s everything you need to know about the very exciting JWST mission, which will provide spectacular observations of space to astronomers around the world.

What about the James Webb Telescope?

It’s done now: The James Webb Telescope is in space! The launch was successful on December 25, 2021. Then it was left to turn it on completely. In total, more than 300 critical points have been identified as potentially problematic during deployment; Apparently, they were closely scrutinized by NASA.

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What is the James Webb telescope used for?

This observatory was designed to advance research in four main areas:

  • identify The light of the first galaxywhich appeared shortly after the Big Bang,
  • Study Formation and evolution of galaxies,
  • You will understand well star born,
  • as well as Exoplanet.

For this, JWST observes in the infrared range (that is, the radiation between visible light and microwaves) and in space. In this way, the observatory is able to reach back into the universe’s past, see the first galaxies to form – “baby galaxies” – and inspect the interior of the dust cloud where stars and planets form.

What are the instruments of the James Webb Telescope?

The observatory has four scientific instruments:

  • A Near infrared cameraNIRCam (for “Near-Infrared Camera”), which will, among other things, detect stars formed after the Big Bang, search for supernovae, measure light distorted by dark matter,
  • A Near infrared spectrometerNIRSpec (“Near-Infrared Spectrometer”), which allows for example the study of chemical elements in distant galaxies or young star clusters,
  • A Mid-infrared instrumentMIRI (“Mid Infrared Instrument”), with which it is remarkably possible to observe the evolution of brown dwarfs, exoplanets and stellar and protoplanetary systems,
  • and one Near infrared imagers and slitless spectrographsNIRISS stands for (“Near Infrared Imager and Slitless Spectrograph”), which helps study exoplanets and distant galaxies.

Why does the James Webb telescope have a segmented mirror?

The James Webb Telescope’s magnificent primary mirror, with an estimated diameter of 6.5 meters, is not overlooked because of its golden color and its 18 segments arranged in a hexagonal shape. In astronomy, a mirror is called a fragment. This is not a technical choice, as it could have been made in a single block.

There is a logical motivation behind this choice: it was impossible to fit a mirror of this size made of a single block on the JWST space launch rocket. For the first time, it was therefore decided to launch a telescope with a segmented mirror in space.

Will the James Webb Telescope replace Hubble?

It would not be entirely accurate to say that the James Webb Space Telescope is intended to replace the Hubble. You should see more of him as a successor. Of course, JWST exceeds a limit of Hubble, which has proven unable to see beyond the near-infrared (so it goes back less into the past than JWST). It is bigger than Hubble in size.

But the day Hubble stops working, the James Webb Telescope won’t have the means to completely replace it. Currently, Hubble is the only telescope capable of observing in the ultraviolet and JWST is not equipped to do the same.

When was the James Webb telescope launched?

The James Webb Space Telescope was originally scheduled to launch on December 18, 2021 Finally, its launch took place on December 25, 2021, Christmas Day

Where was the James Webb telescope launched?

It took off from Kourou Space Center in French Guiana, aboard an Ariane 5 ECA rocket. The observatory had to reach its launch base by boat from California.

What is the price of the James Webb telescope?

The total cost of the telescope is estimated at 9.7 billion dollars or 8.2 billion euros. Since the project’s inception, this budget has been regularly revised upwards.

NASA noted that its share of the total cost of JWST was $7.998 billion. He estimates that the observatory’s first five years of operation, added to the two years needed to absorb its data, will cost an additional $8.835 billion—knowing that JWST must double its lifetime.

Why has the launch of the James Webb telescope been postponed?

JWST’s flight into space has been repeatedly postponed. In 2003, the planned date for its launch into space was 2011. However, that year, the schedule had to be rearranged due to regular problems and budget increases. Representatives of the American Congress even considered canceling the project, which had become too expensive. However, the launch was pushed back to 2018.

And since then, take off has been continuously postponed. The Covid-19 pandemic further disrupted the pace of work, forcing the launch date to be further postponed until late 2021.

Why is James Webb telescope’s name controversial?

At the beginning of the project, the telescope was given the temporary designation “Next Generation Space Telescope” (NGST, “for Next Generation Space Telescope”). It is named to symbolize the continuity of its operations compared to Hubble.

JWST received its official name on September 10, 2002, in reference to James Webb (1906–1992), the second administrator of NASA. He is known for leading Apollo. Nevertheless, this choice of name is questioned by many and many scientists, as James Webb advocated the policy of excluding LGBTQI+ people within the space agency. However, NASA does not want to change its name.

Why should the James Webb telescope be sent into space?

JWST needed to build a space telescope, and not a terrestrial one, because this observatory required very specific observing conditions. Earth’s atmosphere can obscure images obtained by telescopes, as it is nearly opaque and glows at infrared wavelengths where James Webb will be observing. Technologies currently used in terrestrial telescopes do not overcome this problem.

The need to send it into space further complicates the mission: all of JWST’s mechanisms must work perfectly.

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JWST, in stock position.  // Source: Northrop Grumman via Flickr (cropped image)

Where is the James Webb Telescope placed in space?

After the telescope was launched, it took about a month to reach its planned location: the Lagrange point L2, about 1.5 million kilometers from our planet. Keeping the JWST far away is essential, as it requires low temperatures (-223°C) to function properly. Its shield, consisting of 5 layers, helps keep it cool by blocking light emitted by the Sun, Earth, and Moon (which, by heating the telescope, can distort its observations).

But in addition to the shield, the position of the space telescope plays a role: it is placed behind the Earth relative to the Sun. JWST is thus roughly always aligned with our planet and the Sun.

At such a distance, no repairs in space like the maintenance missions carried out with Hubble can be imagined.

How long should the James Webb Telescope mission last?

From its launch, the telescope was designed to last at least 5.5 years (including the first six months of its commissioning). The intention is rather to exceed its lifespan of 10 years. Unlike the Hubble Telescope, it is not so much the operation of its various components that can become problematic over time. It is rather the amount of fuel absorbed by the observatory to maintain its orbit that will be decisive. The JWST therefore carries enough fuel to operate for about ten years.

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Final test of basic mirror wing folding.  // Source: Northrop Grumman via Flickr (cropped image)

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