NASA Astrophysicist Explains The James Webb Space Telescope And It's Fascinating
On December 25th NASA finally launched perhaps the most anticipated mission of the entire year (or longer), the James Webb Space Telescope. The process leading up to the launch took two and half decades and an estimated $10 billion dollars to complete. That means that NASA began developing JWST when Bill Clinton was president, and not too long after its predecessor the Hubble telescope launched into space. Therefore it is no surprise that some people have spent their entire career on nothing else other than JWST. If you are one of those that have seen the design of JWST and wondered why it looks the way it does, NASA astrophysicist Amber Straughn and Vox's Joss Fong have provided a YouTube video that answers that question and a few more.
In the video, the two sit down and build a much smaller model of JWST. As they go along, Amber Straughn discusses a few things about why each piece of the space telescope looks the way it does and answers a few other key questions Fong. Straughn explains that the reason JWST began development so shortly after Hubble was launched was because Hubble can only see so far before you come up to an edge that cannot be seen past. Beyond that edge lies more galaxies that astronomers are certain exist and it is there where they believe we may be able to see the first epoch of galaxies that were born after the big bang. In order to see that far, Straughn says infrared would need to be utilized and that is where JWST comes in to play.
As light travels across the universe it takes time to reach wherever it is being looked at. Straughn explains that it takes eight minutes for the light from our Sun to reach Earth. So when we are thinking about distant galaxies and stars, that light takes billions of years to reach the telescopes that we use to view them. When that light from those distant galaxies does reach us we are essentially seeing what they looked like billions of years in the past. This provides a window into the past where NASA and others are hoping we can reach back into and gather new and exciting information about how galaxies were first created and evolved over time.
The design of the James Webb Telescope had to be well thought out in order to ensure it would work as planned and be protected from the heat of the sun. In older telescopes, such as Hubble, the tube design is what protected the inner workings from the Sun. With JWST and because it will be so far from the Sun NASA decided that a tube was not needed to protect it. One of the reasons for placing the telescope so far into deep space is because the telescope will be using infrared to look at those distant galaxies. If it were too close to the Sun the light from it would cause the telescope to heat up and essentially see itself. With that in mind, a five layer shield was designed to protect the massive telescope. The backside of the shields will be around 200 degrees Faranheit, while the cold side where the instrumentation is will be approximately -388 degrees Faranheit (-233 degrees Celsius).
When it comes to the mirror of JWST, it will be about 100 times more powerful than Hubble. The reason gold was used in the mirror is because it is a tremendous reflector of infrared light. And the reason the individual mirrors were designed into hexagon shapes was because the telescope had to be folded in order to be placed in the cargo area of the rocket that launched it into space. The three outer mirrors on each side of the telescope folded backward to be packed into the cargo area, and now that it is in space it will have to unfold back into place. The entire process of unfolding the telescope will take about two weeks.
If anything does happen to go wrong during the unfolding process, the teams back on Earth can pause the process and try and figure out if there is anything that can be done to correct it. But if for any reason there is nothing that can be done from Earth, there is no way for anyone or anything to reach JWST to fix it. So it is imperative that everything works as planned and is one of the main reasons it took two and a half decades for the telescope to reach space. During those two and a half decades of development, the teams who worked on JWST spent many days and nights trying to ensure every mechanism of the telescope would work flawlessly.
There is only enough fuel for the telescope to operate for about ten years. So when someone thinks about the cost and the time the telescope will be able to be utilized, some may wonder if the cost is worth it. Straughn explains that if you view it in terms of cost per U.S. citizen and the total time between the start of development and the end of life of the telescope, the cost is equivalent to a cheap cup of coffee. That would mean that each U.S. citizen will have spent about .90 cents per year on JWST over a 35 year period.
When we think of the potential of the James Webb Space Telescope and what questions it may be able to answer it is worth a cup of coffee each year. There is the possibility that something could go wrong and the entire mission will have to be aborted. But there is always a great risk that is included with something of this magnitude. Hopefully JWST will be able to take its place in orbit around the Sun and begin to send back the images of distant galaxies as it was designed to do.
