On December 25, 2021, an Ariane 5 rocket took off from the Kourou space center in French Guiana. On board, "the mission of the century": the James-Webb space telescope, supposed to revolutionize astronomy...

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After a year, the James-Webb telescope keeps all its promises

The Tarantula Nebula is an area of star formation.

This snapshot reveals tens of thousands of them that would have remained invisible to us if not for Webb's ability to see in the infrared.

Text by: Simon Rozé Follow

9 mins

On December 25, 2021, an Ariane 5 rocket took off from the Kourou space center in French Guiana.

On board, “

the mission of the century

”: the James-Webb space telescope, supposed to revolutionize astronomy and the understanding of the Universe.

A year later, the promises are kept.

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It's in good condition, and generally performing better than expected

" Nancy Levenson has a smile in her voice.

The acting director of the Space Telescope Science Institute (STScI) in Baltimore has indeed cause for celebration: the James-Webb Space Telescope (JWST) is performing wonderfully.

In orbit at the Lagrange 2 point, 1.5 million kilometers from Earth, the most expensive machine ever sent into space – 10 billion dollars – keeps all its promises.

What a year it has been for Webb!

It feels like just yesterday we were getting ready to launch, and now Webb has hit the ground running in its mission to #UnfoldTheUniverse.

Break out your box of tissues and relive the magic with us.

Happy Birthday, Webb!

🎉 pic.twitter.com/yl3RD932LI

— NASA Webb Telescope (@NASAWebb) December 19, 2022

With its mirror 6.5 meters in diameter, its ability to see infrared light, it has been awaited for more than twenty years by the scientific community.

This last skill is indeed crucial: it allows you to see the oldest objects in the cosmos, and also has the particularity of showing what is hidden behind the clouds of space dust.

All this, because Webb must indeed make it possible to better understand the young Universe, the exoplanets, which revolve around stars other than the Sun, the life and death of stars, or even our solar system.

Six months were needed after its launch to set it up and adjust it.

Since then, his pictures have never ceased to impress.

“

Each time this telescope points towards a piece of the sky, I have the impression that

“, explains Éric Lagadec, from the observatory of the Côte d'Azur and president of the French society of astronomy and astrophysics.

“

In fact, it's a multifunction observatory: we have a great tool and, as an astronomer, as soon as we have an idea, we can request observation time and point it towards something to learn.
The first images revealed were also a good preview of what it can do

►Also read: The James-Webb telescope unveils its first shots

In mid-July, its first five sightings were presented to the world.

The oldest galaxies, the birth and death of stars, the cosmic ballet of galaxies, the atmosphere of an exoplanet… The main fields of research have in fact all been covered.

Six months later, these pictures still continue to provide information to scientists.

Presentation by Joe Biden

The first observation revealed is, in this respect, particularly revealing.

Presented by US President Joe Biden himself, we see in the center a galactic cluster, SMACS0723.

Around, a multitude of luminous points.

It is actually galaxies, countless, in a portion of the sky as big as a grain of sand held at arm's length.

SMACS0723 was targeted because it then acts as a gravitational lens: its mass deflects the rays of light that come from the galaxies located behind it.

They then become visible and enlarged, like the lens of a telescope.

This technique therefore makes it possible to observe very distant galaxies.

Since light has a finite speed and took some time to reach us, we therefore see them as

they were when the light was emitted.

SMACS0723, for example, is 4.6 billion light-years away from us.

We see it as it was 4.6 billion years ago.

The Pillars of Creation, in the Eagle Nebula, where new stars appear.

By taking advantage of the gravitational lensing effect, scientists therefore set out to find galaxies that emitted their light when the Universe was still very young.

We are not only able to observe these most distant galaxies, but we can also measure their distance and therefore the moment when they formed

", specifies Nancy Levenson.

“

We have observed some that formed a few hundred million years after the beginning of the Universe.
It's just amazing to be able to see them

These are indeed some of the very first galaxies that formed after the Big Bang, which occurred 13.8 billion years ago.

Since then, these observations have been enriched and clarified.

Webb has indeed suffered at the start of a "

race

" to find the oldest object in the Universe ever observed.

But since the first photograph, another Webb tool has begun to be used to clarify all of this: spectroscopy.

It allows by studying the light received by the telescope to determine the chemical composition of its source.

With this information, astrophysicists can then deduce the age of the object they are observing: the first generations of stars, for example, contained very few metallic elements,

opposite of the most recent.

These first galaxies, probably made up of the first stars, must have a different spectral signature

”, explains Pierre Ferruit, scientific manager of the mission for the European Space Agency (ESA).

“

The abundance in the stars of the different chemical elements is not the same: quite simply, because it is the first stars which will create the heaviest elements which will nourish the following generations

”, he continues.

►Also listen

:
Grand Reportage - The James-Webb telescope to discover the origins of the Universe

We are starting to have this spectroscopic data

", details Nancy Levenson, who continues: "

We had

'candidates'

for the oldest galaxy, but we really need spectroscopy to have a measurement.
We have some, although of course it will take time to specify all our “candidates”, but it is being done

”.

Already, the observations made by the JWST have shifted the lines: "

We see very old massive galaxies, which appeared very early in the life of the Universe, and we did not expect that they arrive so early.
We will have to adjust our models to take this into account

,” adds the director of the telescope's scientific institute.

Study exoplanets

The scientists are however probably not at the end of their surprises, because the observations to come are promising: "the more it goes, the deeper the observations will be", anticipates Pierre Ferruit.

“

We are going to push the machine further and further.
We couldn't do it at the start of the mission, we needed to fully understand how it behaves in space, its stability, its calibration... Now, scientists have a real understanding of the instrument, which is major. .
We're going to start pushing the limits

Another of Webb's fields of study illustrates the rise of the mission well, the study of exoplanets, planets that revolve around stars other than the Sun.

Here too, spectroscopy is essential, because it makes it possible to analyze the composition of the atmosphere of other worlds.

At the start of the mission, observations focused on the more massive of these other worlds, gas giants similar to Jupiter, which were easier to make.

“

For example, we have detected water vapor in the atmosphere of these planets

“recalls Nancy Levenson.

But now, harder observations have been made.

This is the case of the TRAPPIST-1 system, a star around which revolve at least seven rocky planets more or less the size of the Earth, three of which are located in the habitable zone of the star.

“

The observation has been made and the analyzes are in progress

”, explains Nancy Levenson.

The team behind this project has observed several planets, including at least one in the habitable zone, where the presence of liquid water is possible

", but it will be necessary to wait for the results, which are scheduled for publication in 2023.

A star in formation in the L1527 cloud from which it feeds on matter.

It also emits jets of matter that eject dust in the orange and blue areas in this shot.

But while waiting for Webb's future discoveries, his impact on the scientific community and the general public is already major.

“

What strikes me are the answers he is bringing to fundamental questions: how were the galaxies formed?
How did stars form, how do they die?
Every time this telescope points to a patch of sky, we learn something.
As an astronomer, I really feel like I'm living through an exceptional period

,” says Éric Lagadec.

With Webb, the astronomer from the Observatory of the Côte d'Azur has a dream instrument: "We have the largest observatory ever sent into space, which allows us to free ourselves from the disturbances caused by the earth's atmosphere.

It allows you to do things!

We have a huge bucket of light, capable of seeing details all over the Universe.

Together with colleagues, we obtained observing time of a dying star.

The name is not very sexy: NGC6302, but it will be spectacular.

Then, with other stars, we will try to observe stars in the process of forming stardust.

It is often said that humans are stardust.

What we are going to try to do is

is to understand how this dust forms around dying stars.

Webb has only been in orbit for a year, and operational for six months.

Yet it has already fulfilled all its promises and revolutionized the study of the Universe.

However, this is only the beginning: barring unforeseen problems, it should continue to operate for around twenty years.

At the same time, on the side of NASA, ESA, and the Canadian space agency, partners in this project, we are already thinking about the future, with even more powerful space telescope projects.

a start: barring unforeseen problems, it should continue to operate for about twenty years.

At the same time, on the side of NASA, ESA, and the Canadian space agency, partners in this project, we are already thinking about the future, with even more powerful space telescope projects.

a start: barring unforeseen problems, it should continue to operate for about twenty years.

At the same time, on the side of NASA, ESA, and the Canadian space agency, partners in this project, we are already thinking about the future, with even more powerful space telescope projects.

After a year, the James-Webb telescope keeps all its promises

After a year, the James-Webb telescope keeps all its promises

Presentation by Joe Biden

Study exoplanets

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