1. Skip to content
  2. Skip to main menu
  3. Skip to more DW sites
ScienceGlobal issues

New telescope set to peer into space's secrets

December 22, 2021

With the launch of the James Webb Space Telescope, we might be getting closer to answering many questions. "What did the early universe look like?" is just one of them.

The James Webb Space Telescope
The James Webb Space Telescope promises to give us new insights into the origins of the universeImage: NASA/abaca/picture alliance

Imagine you are flipping through the pages of your old family photo album. You start from the back — that is, at the newest photos. You arrive to the time of the planet pinata-party photos from your fourth birthday, and even get to see some of yourself as a toddler. 

But at that point you realize there are no baby pictures. Your life has been captured only from the time you were already out of babyhood.

Then someone comes and offers to reveal some earlier pictures of you as a baby. You'd probably want to see them.

Now imagine you were offered the chance to see such pictures for the whole universe. That's exactly what the new and impressive James Webb Space Telescope, finally (re)scheduled for launch on December 25, 2021, promises just that. It's likely to drastically change our understanding of the cosmos.

Space-based clarity

Telescopes allow us to see faraway objects. Most use mirrors to gather and focus light. And the bigger the mirror, the more powerful the telescope is.

Telescopes can be found on hills and in deserts, but also mounted onto satellites

Being in space means losing the distortion from the Earth's atmosphere. This results in sharper and higher-resolution images.

But why are space telescopes important, and why should we care?

The accomplishments of the Hubble Space Telescope provide some convincing reasons.

The legacy of the Hubble

For many of us, the emblematic Hubble Space Telescope (HST) was our window into space. It showed us how incredibly huge, dazzling and sometimes weird and even scary the universe can be.

It provided stunning and colorful images of gas clouds that reminded us of animals, and of galaxies of all sorts.

But the Hubble gave us much more than pictures: It enabled us to establish a better estimate of the age of the universe — about 13.8 billion years.

The Hubble was also crucial for confirming that, contrary to what many scientists previously believed, the universe is expanding at an accelerated rate.

Although the Hubble is still working, far beyond its life expectancy, the James Webb Space Telescope is expected to add to its viewing range.

The Hubble Space Telescope

Back to our photo album. The Hubble's deep field images provided an unprecedented look at the oldest and remotest objects known so far in the universe, billions of light years away.

Because light takes time to travel, we see very distant objects as they were billions of years ago. So with the Hubble, we could go only as far back as the "toddler pictures" of the universe, around 400 million years after the Big Bang.

If this is what we accomplished with the Hubble, what wonderful new things may be revealed with the new James Webb Telescope, the biggest and most complex space telescope ever built?

'Baby pictures' of the universe

It has been almost 20 years since the James Webb's original planned launch date. Many technological advances and even new inventions were needed for the telescope's completion. 

The Webb has the largest primary mirror that will ever have been sent into space. Consisting of 18 gold-plated hexagonal smaller mirrors, it's more than six times the size of the Hubble's.

But it also has improved sensitivity and observes in infrared light, while the Hubble observes mainly in visible light; that is, the sort you and I can see with the naked eye.

Hexagonal mirrors of the James Webb Space Telescope seen at the Goddard Space Flight Center/NASA
The launch of the telescope has been delayed many timesImage: picture-alliance/dpa/NASA

All warm bodies emit infrared radiation, even you and I. Being able to observe in infrared light means that the Webb can see much more distant and older objects. That is because, thanks in part to the Hubble, we know that the farther these objects are from us, the more their light shifts towards the infrared side of the spectrum. If we want to look at the very earliest stars and galaxies, we thus need to observe them in infrared light.

The Webb will be the first telescope to see the most distant galaxies and get a glimpse of what the universe looked like around 250 to 100 million years after the Big Bang — the first "baby pictures" of the universe, perhaps even first galaxies.

Seeing through clouds

But looking in infrared light has another benefit: It enables the viewer to see through dust clouds.

The tiny particles in these clouds are very good at blocking visible light. We can't see through them with our eyes, just as we can't see any stars on a very cloudy night on Earth. And neither could the Hubble.

But infrared light is much less affected, so the James Webb Telescope will be able to see past these dust clouds not only to what is behind them, but also gain a better picture at the formation of stars and planets.

A cataclysmic cosmic collision takes centre stage in this Hubble photo
Images captured by the Hubble Space Telescope revolutionized our understanding of the universeImage: R. Chandar/ESA/Hubble & NASA

Space telescope launch: A unique challenge

The Webb's gigantic size presents a huge challenge. It is no simple task to send a telescope with a 6.5-meter-wide (21-foot-wide) mirror into space, especially when the rocket that will carry it up, an Ariane 5, can't carry anything broader than 5 meters wide.

This is why the telescope had to be designed to be able to fold like a gigantic, high-tech, billion-dollar piece of origami so it would fit into the rocket.

Additionally, because the telescope can function only at near absolute zero temperatures (-223° C), it required a tennis-court-sized, five-layered sunshield to cover it from sunlight and insulate it from solar heat. And that sunshield must also be able to fold and then unfold once in position — another convoluted engineering problem.

James Webb Space Telescope orbit

Shortly after launch, the complex and subtle tango of the telescope's unfolding will begin — a tango that will take three weeks to compelte. During this time, the control team on Earth will have to remotely unfurl the first parts of the Webb, an operation that must be carried out with great precision and timing.

There is no room for error: Because the telescope's final destination is 1.5 million kilometers (932,000 miles) from Earth, if something doesn't work or breaks down, there will be no chance for repair missions.

Unprecedented new view

Despite a controversy around the name of the James Webb Space Telescope, such telescopes will give us access to unseen parts of the universe, hidden stars and planets and new worlds, and provide us with the chance to make new discoveries.

With the promise of observing the formation of galaxies, the birth of stars and planets and the appearance of the very early universe, the Webb mission seems likely to come up with intriguing and fascinating insights.

The Webb will definitely deepen and perhaps even change our understanding of the universe, its origin and early days. What new astonishing pictures will inspire the next generation of astronomers and science enthusiasts?

So cross your fingers that all goes well, as our view of the universe could change forever.

This article was updated to reflect the postponed launch date. 

Editor: Fabian Schmidt