James Webb Space Telescope – Cosmic Observer or Time Machine?
Some scientists have described the James Webb Space Telescope as a powerful time machine. It is equipped with infrared vision technology capable of gazing back in time, over 13.5 billion years in fact.
It’s main purpose? Capture a glimpse of the first stars and galaxies that came into existence around the time of the early universe.
It was launched into space on the 25th of December 2021 and is expected to operate for 5–10 years.
The Early Universe
After the Big Bang, the Universe was like a hot soup of particles (i.e. protons, neutrons, and electrons).
Eventually after millions of years, the Universe began to cool, enough to allow the protons and neutrons to begin the process of combining into ionized atoms of hydrogen and eventually, some helium.
These ionized atoms of hydrogen and helium then began to attract electrons, turning them into neutral atoms. It was this process which finally allowed light to travel freely for the first time ending the dark stage of the Universe.
Scientists are on a mission to uncover exactly when this ‘first light’ (i.e. first stars) began to form and what this process may have looked like.
This is what the James Webb Space Telescope was designed for, it is hoped it can help answer the many questions scientists have about the origins of our Universe.
The Webb’s Infrared Technology
In order to understand why the Webb uses infrared technology we refer to Einstein’s Theory on General Relativity.
This theory tells us that the expansion of the Universe is actually the space between objects stretching, this causes objects (i.e. galaxies) to move away from each other.
But it’s not just the space that stretches, any light in that space will also stretch. Light travels in wavelengths, as the space stretches, so too does the light wavelengths.
Imagine drawing a wavelength on an elastic band and stretching it, you will see visual evidence of the distance between the wavelengths increasing the further the elastic is stretched.
As a result, distant objects (i.e. galaxies) appear very faint or may actually be invisible, the stretching of the light wavelengths now means that the light reaches us as infrared light.
This is why the Webb uses infrared technology.
The Incredible Engineering Involved to Create the Webb
In order to detect infrared light, the dark side of the telescope needs to operate at -233 degrees Celsius or -387.4 degrees Fahrenheit.
To accomplish this, scientists and engineers designed a massive ‘Sun Shield’ (the size of a Tennis Court) to block out the heat of the Sun.
It consists of 5 separate thin layers which reflect the rays of the sun. Any heat that gets through the first one or two layers can escape through the gaps between layers.
The temperature on the hot side of the Webb can reach up to 83 degrees Celsius or 181.4 degrees Fahrenheit.
It really emphasises what a monumental challenge it was to design and build such a shield fit for purpose.
Webb also has a 6-meter solar array attached to the main observatory. Referred to as the “powerhouse” of the telescope. It supplies energy to all of the telescope’s scientific instruments, as well as it’s communication and propulsion systems.
Webb’s gold coated hexagonal mirror is made up of 18 separate hexagonal pieces, it measures 6.5 meters in width.
One of the most difficult challenges scientists and engineers faced was designing the Webb to fold up for launch and to unfold in space without damaging the extremely fragile sun shield or mirror.
After numerous tests and adjustments as a result of issues during testing, scientists and engineers were finally satisfied that the Webb was ready for launch.
Early Discoveries Made by Webb
One of the first major discoveries by Webb has some scientists questioning everything we know about the Big Bang.
Scientists believed that it took over 1 billion years after the Big Bang for the formation of the first galaxies to begin.
In this period, the Universe completed its cooling process. This allowed the billions of stars that make up a galaxy to form, as well as the billions of planets that orbit those stars (a process that takes quite a long time).
But Webb has discovered 6 massive ancient galaxies that scientists believe may have formed between 500 and 700 million years after the Big Bang.
Although this discovery may have forced scientists to rethink the Big Bang and come up with an explanation, this is exactly what the James Webb Space Telescope was built for.
There is no doubt that there will be future discoveries by Webb that will both amaze scientists and test some of their existing theories.
