Researched by: Sara Varghese and Ankita Ghosh 

Here are the basic deets

• The JWST took 25 years and $10 billion to build—and will be the most expensive telescope ever to be launched into space.
• It is the product of a collaboration between three space agencies: NASA, the Canadian Space Agency and the European Space Agency.
• The telescope will be loaded onto an Ariane 5 rocket on the morning of December 25—and will take off from Kourou, French Guiana, on the northeastern coast of South America.
• It will travel for 29 days and a million miles to an orbital spot beyond the moon—and park itself there, looking out into the universe and eternity. 
• The Webb mission is expected to continue for five to 10 years—and it will produce its first scientific photo this summer. 

Point to note: The name of the telescope has been controversial as it is a tribute to a NASA administrator who oversaw the Apollo program—and supported policies that discriminated against gay and lesbian employees.

This is the very tricky (scary) bit… 

The JWST is way too large to fit on to any existing rocket. So scientists had to fold it down—and the telescope will have to unfurl itself, stage by stage, as it hurtles through space toward its resting spot. As The Atlantic puts it, “[the] new observatory is one of the most complicated pieces of engineering in history. It makes a Mars rover look like a toy car.”

The unfurling: will take place over 29 days. It will be the most complicated series of movements ever attempted in space—and look something like this:

As USA Today summarises it:

“The roughly $10 billion telescope has to be folded and stowed to exact specifications in Ariane 5's payload fairing, survive the vibrations of launch, then spend 29 days unfurling into a sunflower-like telescope with a massive 72-foot sunshield below.”

344 ‘single points of failure’: That’s the number of things that could possibly go wrong—and forever doom the telescope—and 80% of them are during that period of unfolding from its launch configuration. Hundreds of parts are responsible for the unfurling—and each one has to work perfectly in sequence and with great precision—as this video titled ‘29 Days on the Edge’ lays out. 

No ‘do overs’ this time: When the last big telescope—Hubble—was sent into space in 1990, it had a defective mirror, which made its lenses blurry. So astronauts were sent out to fix it. But unlike Hubble—which orbits only 340 miles above Earth—we don’t have the space technology to reach JWST, which will be a million miles away. So if something goes wrong with the telescope, there is no way to fix it—and a $10 billion marvel of engineering could become a piece of space junk in seconds. 

Why JWST is a big deal

Everyone is excited about this NASA project for two very good reasons:

One: Hubble taught us a lot—including the age of the universe, about what happens when stars explode, about black holes. But JWST will be “100 times more powerful.” For starters, there’s its sheer size: “Hubble was about the size of a school bus, whereas Webb is more like the size of a tennis court.” And its “mirrors” (lens) are also far bigger—spanning a diameter of 21.3 feet compared to Hubble’s 7.8 feet. See the size difference below:

Ergo, it can quite simply ‘see’ more of our universe:

“While Hubble’s ‘deep field,’ the famous shot featuring thousands of galaxies, could fit on a standard sheet of paper, Webb’s equivalent would be so expansive, one astronomer told me, that it would need to be printed on wallpaper. This time, the shot would reveal one million galaxies, including some of the earliest.”

Two: Space telescopes essentially look back into time—across millions of light years. But Hubble could only capture light visible to the human eye—which represents a tiny fraction of the spectrum. JWST is designed to detect infra-red light—and that allows it to see further into the past. 

Here’s why infra-red matters: The earliest stars and galaxies are rushing away from us (because space is expanding all the time). So what began as blue light 13 billion years ago has turned into invisible infrared wavelengths by the time it reaches us today: “as light travels through space from those distant galaxies, the light is literally stretched by the expansion of space.” And when light stretches, it turns red. 

Hubble was able to see light dating to about 400 million years after the Big Bang—which took about 13.3 billion years to reach us. JWST can do far more:

“But Webb has the capability to take us to 250 million years after the Big Bang. It might not sound like a big difference. What’s a few hundred million years between friends? Actually, it’s the difference between seeing the first stars that ever turned on [and] arriving a bit too late after the funeral.”

The bottomline: We may not be able to witness the beginning of creation, but we will get a bit closer to it. How marvelous is that?

Reading list

We highly recommend The Atlantic’s big picture take on why the Webb telescope matters. Also very good: Vox’s explainer that compares JWST to Hubble. USA Today has more on all the things that could go wrong. Nature takes a more critical look at this staggeringly expensive telescope that “ate astronomy.” Space.com has more on the differences between Hubble and potential Webb images. NPR explains the controversy over its name.