What makes the James Webb telescope so special?

One would have to ask what is not particularly about the James Webb telescope.

It is one of the riskiest, most complex, most expensive missions of all time.

In short, it is a technical miracle.

But let’s start with the predecessor.

The Hubble Telescope has done an incredible job, revolutionizing astronomy over the past 20 years.

(see Hubble Ultra Deep Field)

Hubble Ultra Deep Field – Wikipedia

Although Hubble has been serviced and modernized three times in Earth’s orbit, time is running out for this telescope.

In order for the telescope to continue to take these fantastic images, it must be extremely precisely aligned by gyroscopes/bearings/wheels over days.

These benefits decrease over time. So NASA was looking for a successor.

She turned to the astrophysicist and Nobel laureate John C. Mather.

(Nobel Prize for COBE satellite that captured the background radiation for the first time)

The team led by project leader J. Mather developed a space telescope that dwarfs everything that has happened.

Because the diameter of the payload cladding of rockets is limited, it is not appropriate to design wide satellites. (e.g. with the Ariane 5 max 5m width is allowed)

Therefore, the James Webb telescope was not built as a single mirror like Hubble, but as segments in honeycomb form.

The yellow color comes from a gold coating.

The mirror itself is made of beryllium (beryllium does not warp at extreme temperatures) and was extremely difficult to manufacture.

Each segment can be controlled separately.

Similar to a facet eye of a fly.

Here is a comparison of the Hubble and JWST mirrors.

Unlike Hubble, the mirror will not work in the visible spectrum.

Because the further you look into the past, the more the light shifts into the infrared.

Gold best reflects infrared radiation.

With this mirror, humanity will be able to, except for 13.5 billion!

(in memory of the Urnkall was 13.8 billion years ago) Years into the past and watch how the first galaxies, stars and even planets were formed.

In order to look back to the past, the mirror must be cooled to the almost absolute zero point.

This is achieved by two methods: on the one hand, a very complex sun/heat shield has been developed, which is the size of a tennis court.

Between the individual layers is the vacuum of space, which is very well insulated.

Secondly, a limited supply of coolant is taken and the telescope is actively cooled down.

Here you can see how the heat is shielded between the heat shield and the telescope.

To be as far away from the disturbing sun as possible, James Webb will not fly around Earth like Hubble in orbit, but will be at Lagrange Point 2, 1.5 million km from Earth.

Lagrange Points – Wikipedia

If something of this highly complex telescope doesn’t work, no one can fix it.

Everything has to work perfectly right away, otherwise it is 9 billion dollars, that’s how much the project has lost so far.

The heat shield is far too big to be transported in a rocket, so it is built up like an origami and unfolded in space.

Here is an animation that takes two minutes, will take over a month.

ESA is also involved in this telescope, which, in addition to new instruments, will also provide the Ariane 5 rocket.

This telescope has integrated 10 brand new technologies.

Particularly interesting, Nirspec (ESA/Airbus) is a very complex instrument with microshutter (small windows 100x 200 microns x 62000 pieces).

Through these shutters, the JWST is able to analyze thousands of objects/exoplanets simultaneously.

This makes it possible for the first time to search exoplanets for extraterrestrial life on a large scale.

What the Kepler telescope used to need a day for, the JWST manages in half an hour.

This video shows how the light is guided through a series of complex mirrors into the NirSpec.

In addition, the JWST has the most advanced infrared detectors (MIRI), making it 100 times more sensitive than the Hubble telescope.

Originally the start was planned for 2018, unfortunately the development has been delayed several times, the earliest start date is March 2021.

There were doubts about the reliability of the heat shield.

The cost will be about 10 billion dollars at launch.

The telescope itself is finished, but it is being tested tirelessly to make sure everything is running perfectly, because there will probably be no second telescope of this kind.

At the start, many people will hold their breath, because so much can go wrong.

The rocket could explode at launch, the JWST could not reach L2, the antenna or solar panel could not extend, the heat shield could not unfold properly, the optics of the telescope could not align properly, etc.

Many scientists find the project too risky.

The service life is only designed for 10 years.

When it goes into operation, we will better understand how the Sun and Earth were created, and see unique images from the earliest years of the universe.

Interesting fact: If the telescope were 21 light years away from Earth, it would still be able to see the Earth.

If all goes well, it will be the first time to take highly detailed shots of Proxima Centauri.

Image of the finished telescope without heat shield in a special cooling chamber (-250掳C) to test the optics.

Originally built for the Apollo program.

Leave a Reply