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Why the James Webb Space Telescope Matters

Jan 4, 2022 6:43 AM 5 min read

Omicron cases aren’t the only thing that have shot up to the sky of late…

25 years in development, repeated delays, ballooning budgets, and sky-high expectations: On December 25th, the James Webb Space Telescope (JWST) was finally launched from Earth to its orbit, a million miles away, which it will reach in about 29 days.

The scientific community is all agog in excitement. This proverbial Christmas miracle is comparable to the detection of gravitational waves in 2016 (H/T Albert Einstein) or the black hole "photograph" two years ago. Only this time, the cause for celebration isn't a discovery per se, but rather the anticipation that more momentous discoveries are on the horizon.

Back to Basics

Space telescopes aka space observatories are basically telescopes for and in space that are used to identify, observe, and track astronomical objects. They are the source of those awe-inspiring images of the universe you see online, but they are also critical in satellite imaging and weather analysis applications. The most popular space telescope in history is probably the Hubble Space Telescope, which has been in operation since 1990.

The James Webb telescope - named after a former NASA administrator - was envisioned as a successor to Hubble. It is the largest and most powerful space telescope ever built. The project, which involved 1,200 scientists and engineers, is a brainchild of NASA, but also includes contributions from 13 other space agencies, most notably the European Space Agency (ESA) and the Canadian Space Agency (CSA).


A Peek Into the Past

JWST is an undertaking of historic proportions - literally. A high-capability space observatory, it was built to help scientists study star formation and galaxy evolution, dating back to the very first stars and planetary systems in the history of the universe.

Wait, “history” as in “the past”?

Yes! And no, it doesn't involve time travel. (Well, not as we understand time travel anyway…)

You see, a telescope is essentially a time machine. That's because when you look into space, you're literally looking back in time, because light from such faraway distances takes time to reach you. That's why the unit of astronomical distance is a light year (which is equivalent to the distance travelled by light in one year = approximately 6 million million miles).

So, say you're spotting a star 10 light years away. What you're actually seeing is the star 10 light years ago, because the light emanating from the star takes that much time to reach you. To put it in more relatable terms, the Sun shines over Earth, but our nearest star is also quite far from us, so sunlight itself takes a little over eight minutes to reach us.

The universe is huge, so it takes more than a dollop of disbelief and awe for us mere mortals to comprehend its size and magnitude. Also, if you think space telescopes are a concept hard to wrap your head around, wait till you go through the Wikipedia page for the Timeline of the Far Future. (Especially the jaw-dropping bit about "an astroengineering project to alter the Earth's orbit, compensating for the Sun's rising brightness and outward migration of the habitable zone, accomplished by repeated asteroid gravity assists"!)

Anyway, coming back to James Webb…


A Class Apart

JWST is three stories tall and “as broad as a tennis court”. The telescope's mirror consists of 18 gold-plated segments that make it six times larger than Hubble and 100 times more powerful.

Webb’s uniqueness lies in its sensitivity. In fact, it’s so sensitive, it could detect the heat signature of a bumblebee at the distance of the Moon (from Earth), and can see details the size of a US penny at the distance of about 25 miles.

Then there’s the fact that JWST is designed for near-infrared astronomy…



All objects in the universe emit electromagnetic radiation. The larger the object, the more substantial the waves emanated. And as these waves travel longer distances, they naturally lose energy = their wavelength increases.

Hubble was designed primarily for ultraviolet radiation. But if you want to study really faraway galaxies and systems that are often shrouded by gas clouds, you need a telescope that can detect infrared waves, which can penetrate these shrouds and travel longer distances.

For context, here’s a comparison of the Carina Nebula in visible light (left) and infrared (right), both images taken by Hubble. In the infrared image, we can see more stars that weren't visible before. (Credit: NASA/ESA/M.)

Why the James Webb Space Telescope Matters

Webb of Delights

JWST’s gargantuan primary mirror will give the telescope a view into older and colder things.

The first category includes photons from as much as 13.5 billion years ago - or, just 300 million years after the Big Bang and during the time the first stars and galaxies are expected to have emerged. The "cold" objects refer to new planets, exoplanets, or nebulae that emit electromagnetic waves in the infrared spectrum.

As such, JWST is expected to answer some of the biggest questions in astronomy today. Questions like how did the universe begin? How did the first stars and galaxies evolve? What are exoplanets made up of? What is the composition of possibly habitable planets?

The crux of how the space telescope functions lies in its infrared camera, which will take photographs of distant objects, and spectrometers that will break the incoming infrared light into different colours for scientists back on Earth to analyze.

FYI: For more insights, here’s an easy-to-digest explainer and here’s a more detailed one.


Into the Abyss

Besides the fact that it’s larger and more powerful, Webb is also unique in that it wasn’t designed with future repair missions in mind. Hubble is less than 600 km from Earth, and astronauts have visited it four times till now to make fixes. Webb will be too much farther away for such undertakings. Which is what makes the mission all the more nail-biting.

The mission was also a notoriously delayed one. It was first mooted in the 1990s and work began in earnest in 2001. Launch dates were consistently pushed as the project suffered unexpected delays. Meanwhile, the price tag expanded from $500m in 1996 to nearly $10bn today.

However, for the hundreds who worked round the clock to make the project a reality, the wait and the bill were worth it.

The James Webb space telescope has now been successfully launched, but it will take a few more weeks before it reaches its place in orbit for the next 10 years. In the meantime, it would have to maneuver 344 “single points of failure” to unwind its gigantic golden mirror in the piercing darkness of outer space. For astronomers back on Earth, it will be a nail-biting time. But once in place and operational, James Webb looks set to answer some of the biggest questions of our time.

To quote Dr. Marcia Rieke, who worked on the telescope’s infrared imaging device: “When the camera turns on we’ll have another party.”


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