The James Webb Space Telescope is in work for about 30 years. This massive machine has involved thousands of scientists and engineers all over the globe. Let’s learn all about the James Webb Space Telescope.
Before the Hubble Space Telescope launched in 1990, we didn’t know how old the universe was. We had never seen a planet outside of our solar system. We didn’t even know about dark energy. Hubble taught us a lot, but it can only see so far and in so much detail. To see farther, all the way back to the formation of the very first stars and galaxies (what’s known as the universe’s first light) we are going to need a bigger telescope. And that is exactly what started the largest, most expensive, and most challenging space engineering project humans have ever attempted, the James Webb Space Telescope. It’s been over 30 years since work on this massive machine began, so when will it be ready? And how close are we to use it to see the universe’s first light?
Since its beginning, the James Webb Space Telescope has involved thousands of scientists and engineers all over the globe. But all this work raises the question, what’s so important about creating a telescope that’s able to see the universe’s first galaxies?
“The Hubble Space Telescope has been absolutely revolutionary in changing the way that we understand the universe. But we are really missing a key piece of the puzzle. We are missing the very start of how galaxies got started,” says Amber Straughn, Deputy Project Scientist at Nasa Goddard Space Flight Centre.
Also Read: Race to See the Edge of the Universe
“When you know how they formed when you understand the situation that this galaxy arises from, you understand the evolution, the forces at work, and a better picture of what the universe was like back then. It will help us do things like predicting what will happen to the stars and galaxies in our universe further on. What’s going to happen at the end of everything?” says Amy Lo, Alignments Lead at Northrop Grumman Aerospace System.
And if finding out how the world ends isn’t enough for you, Webb will be able to do a whole lot more.
“The search for life is one of the big things that we are doing at NASA right now. And it’s really exciting. And Webb is going to make, I think, really ground-breaking discoveries in exoplanet science. Really Webb is a multi-purpose observatory. It will observe everything from the planets in our own solar system out to the most distant objects we can see, and everything in-between” says Dr. Amber Straughn.
“One never knows. We could get lucky. Now, personally, Do I hope we find signs of life with the Webb Telescope? Yes, of course. It would be awesome” says Amy Lo.
So how do we engineer to see back in time?
Well, it has to see in infrared. Dr. Straughn explains. “So, if you think about, for example, the Hubble Ultra Deep Field. In this deepest image of the universe that we have ever had, we are able to see very very distant galaxies. If you pick out what the most distant ones are you will see that they are these little tiny red blips. They are so far away that the expansion of the universe has caused the light from those galaxies to literally be stretched into longer wavelengths. And longer wavelengths mean redder light.”
“That’s why we built the James Webb Space Telescope to be sensitive to the infrared. So that it can pick up where Hubble left off and really complete that very first picture to look at the very first stars and very first galaxies,” says Dr. Amy Lo.
And Webb’s ability to see in infrared really relies on 3 main things. Its mirror, its sun-shield, and its orbit. Let’s start with the mirror. That mirror is HUGE. 6 and 1/2 meters in diameter to be precise.
According to Dr. Amy Lo, “the reason why it’s so big is really that the very first stars and very first galaxies that were ever formed, they are very far away and they are very dim. We are trying to collect one photon approximately every second. We are counting individual photons. So, we need to be able to collect all of that light. “
Now, the reason the mirror is gold is that it reflects infrared light. Making it easier to focus that distant light down to the instruments. But there’s a problem, the sun also emits infrared. Which brings us to the sun-shield. This part is also huge, about the size of a tennis court.
Also Read: The First Ever Molecule Of The Universe
“So, part of the job of the sun shield is literally to block the light from the sun from reaching the telescope and messing up all of the good work that it’s going to do. It allows the telescope to operate at a temperature that is about 30 degrees kelvin. Room temperature is about 300-ish kelvin. So, we are going very, very cold” says Dr. Amy Lo.
And finally, the orbit. The James Webb Space Telescope is going far. Really far, about 1.5 million km away from earth, to a place called the second Lagrange point, or L2.
“When you go out to L2, you don’t have the Earth and the sun filling half your sky. That’s why we can use the sun shield to kind of cover them up so that all Webb sees is the dark of space and be able to do its mission” says Dr. Amber Straughn.
So, we need to launch all of this enormous, sensitive equipment on a rocket into space, over a million kilometers away. Which complicates things further because rocket launches are basically well-controlled explosions.
According to Dr. Amy Lo, “In order to survive that explosion, it has to be designed to be very robust and strong. That coupled with the fact that JWST is also fairly large means we have to design it very carefully to fit inside the rocket, then deploy it.”
“It has to be right when we launch it. We have to test everything to make sure that it works correctly once it’s in space because we can’t go fix it” says Dr. Amber Straughn.
That’s what makes this project so unique. They won’t get a second chance unlike Hubble, which was serviced by astronauts 5 separate times. Webb has to be perfect on the first try, so understandably, that’s taken some time to achieve.
The James Webb Space Telescope was first scheduled to be launched in 2007 and was budgeted at 500 million dollars. But as construction progressed and testing began, that launch date and budget have changed a lot.
According to Dr. Amber Straughn, “This really is engineering at the extreme. It’s pushing the edge of what’s possible. As a scientist that’s going to depend on this telescope for my future research, to hear of another delay was sad, it was disappointing. But that’s the reason we test because we don’t want these things to happen once we’re in space.”
And that brings us to where we are today. With construction mostly complete, all that’s left are the final testing stages leading up to the launch.
The sun shield and the spacecraft element are currently undergoing thermal vacuum testing. And then after that, they will undergo some more tests. Then they will ship the whole observatory down to South America in French Guiana to prep it for launch.
“Once the telescope launches and is on its way to L2, it will start to unfold in space. The entire process will take about two to three weeks. I don’t expect any of us are going to be getting much sleep for that time” says Dr. Amy Lo.
According to Dr. Straughn “The thing for me that is maybe the scariest is the deployment of sun-shield. There are 100s of different individual sort of movable parts that have to happen during that deployment.”
“Between it deploying and being fully tensioned up, the position requires that it has to hold on orbit in space is very little. My job is to make sure that this thing, through its manufacturing, through installation, through all the testing, and whatever happens to it on orbit” says Dr. Amy Lo.
After the telescope is fully deployed there are still a few key things they have to do. They are going to tweak the mirror in order to make it perfect. And then they have science instruments, cameras, and spectrographs that they turn on one at a time and bring those up to working order. This whole process takes a few months after launch to get ready.
Only then, after testing, launch, and deployment, can we discover the mysteries of our beginnings.
So, how close are we to seeing the universe’s first light?
“Well, JWST will be launching in the spring of 2021. So, about the summer to fall of 2021 is when we’ll start getting those very first pictures back, first light” says Dr. Amy Lo.
According to Dr. Straughn “Our current theories in astrophysics tell us that we should be able to see those first galaxies with Webb. Of course, we don’t know yet, we won’t know until we look. But if the theories are right, then I think we should see the very first galaxies something like a couple years from now after Webb is launched and starts taking its first data. Astronomy really gets to the heart of what it means to be human. It’s asking these big questions that humans have always asked, you know, “Where do we come from? How did we get here? And are we alone?” I think we will answer questions that we haven’t even thought to ask yet. That is one of the most exciting things about any big telescope like this.”
We are creatures of curiosity and of wonder. This is an expression of it, I think, the highest level that we can achieve.