What do astronomers eat for breakfast on the day that their $10 billion telescope launches into space? Their fingernails-Dennis Overbye.
Very much true.
The launch of the single greatest and most important mission is due this Christmas morning. Physicist and astronomers from all over the world have eyes on this and are expecting…let’s say “not failure”
With 344 failure points on the James Webb Telescope that can occur while unfurling the telescope, if there is even a single mistake. That would mean mission failed.
But here we are to take it from the start, not the end (not like end-end though, that would be terrible).
Table of Contents
What is James Webb Telescope?
James Webb Space Telescope started off 20 years from now. With the previous experience of Hubble Telescope and everything that Hubble taught us. It has been named after the former Administrator, James Edwin Webb. He was a prominent figure in the history of Space Exploratory mission, including the Apollos.
James Webb Telescope Mission
James Webb Telescope is the most important mission for NASA and every other astronomer and engineer who poured their heart-with precision-in this mission.
James Webb Space Telescope is built to see beyond the dust clouds that block our vision when we attempt to see farthest galaxies. It is impossible to see distance beyond what Hubble has already captured in visible light. The visible light wavelength from those galaxies has further stretched as the universe has expanded. It can’t be captured. This is why James Webb will be capturing the photons of infrared light which can still produce an image.
Precisely, we will be looking 13 billion years back in time; when those stars are in their infantry. Images from those stars will unveil the history of universe starting from the Big Bang. The unravelling mysteries will begin just after 13-day process of full deployment of James Webb Space Telescope.
James Webb Telescope Anatomy
This telescope is the most mesmerizing as telescope could ever be. 21 feet span of the Reflective sheets spreading, protecting the 18 Gold-plated mirrors that project those infrared photons onto the primary mirror that then project the photons into the Cassegrain focus-the black head in the middle of the hexagonal telescope. The aft optics subsystem (the middle one) itself has two mirrors inside that focus the light and make it clearer to be photographed.
How to Keep James Webb Space Telescope Cool?
James Webb Space Telescope has to function in an extremely cold temperature. The sun doesn’t allow that, so, there are different actions taken to have the telescope functioning in extremely cold temperature-negative 380 Fahrenheit to be precise. James Webb’s MIRI instrument takes way lower than that; -447-degree Fahrenheit (7 Kelvin). Closest the to the coldest, 0 Kelvins. This is how they’ll achieve it.
The Sun Shield
The Sun shield of the James Webb spans 21 feet in size, which is roughly the size of a tennis court. The sheet has five layers to dissipate the radiation and the heat with it in each layer. This wouldn’t have been possible without a very unique plastic, Kapton.
Although Kapton is very efficient in reflecting radiation back and is light weight, it was translucent. This problem was solved by putting a sheet of aluminum with Kapton to reflect light and radiation off of the Telescope.
The first two layers are of silicon which gives them the pinkish color. The sheets are kept at a distance to lessen the reflecting radiation on each layer coming closer to the mirror.
James Webb’s MIRI needs a temperature of 7 Kelvin to work. A cryocooler will be used to achieve those temperature. To come up with something like that, it took quit a bit of funds and wasted experiments. Until they came up with a simple physical phenomenon that would solve the problem. The pressure. Using the pressure to cool down and then using it to cool the MIRI.
The Positioning of James Webb Telescope
The position where the James Webb Space Telescope will be standing is Lagrange-2. Lagrange are the celestial positions near two heavy bodies with unbalanced gravity that, at that point, balances. And keeps the object steadily moving with the star. There are five Lagrange points near Earth and Moon.
Lagrange-2 is behind the Moon away from the Earth. Lagrange-2 is chosen for the James Webb to stay in the cold Shadow of the Earth and Moon. The Telescope needs absolute darkness to operate and any light or heat from the sun would depreciate the imaging process.
The Beautiful Hexagon Mirrors
The mirrors of James Webb Space Telescope are the most mesmerizing of all. These mighty mirrors are 6.5 meters each, in size. These huge mirrors are made with the metal called beryllium. Beryllium is a light weight metal and is also expensive.
Why not use steel? Although steel is stronger than beryllium; beryllium tends to deform after taking much more pressure than steel and is also lighter than steel. This is how this expensive metal qualifies for the mission.
But there’s a problem. Beryllium isn’t reflective at all. To tackle this problem; scientists used gold. Gold is very highly reflective to infrared. The size of a golf ball amount of gold is used for gold-plating on each mirror. This is a very thin layer of gold on each of its mirrors.
The hexagons are built to configure the direction they are point to adjust to the primary mirror. This is a solution of a problem that occurred on board with the Hubble Telescope. The mirrors can adjust to the 1/10000 size of the human hair-precise electromagnetic movement. Moreover, the mirrors can also adjust the curvature through cables and motors in the back of these mirrors.
The Spacecraft Bus
The James Webb Space Telescope is built on the Spacecraft bus that keeps track of all the operation so the mirrors can take care of the observations of the sky. The Spacecraft Bus has six jobs to perform onboard.
- Electrical Power Subsystem
- Attitude Control Subsystem
- Communication Subsystem
- Command and Data Handling Subsystem
- Propulsion Subsystem
- Thermal Control Subsystem
Electrical Power Subsystem
The main job of the Electrical Power Subsystem is to turn the sunlight into electricity through the solar panels for the payload and the system to use. The Telescope depends on this crucial system to stay on mission with observations and transmission of captured data.
Attitude Control Subsystem
The Attitude Control Subsystem has a job to detect movements of the observatory in the space and reassure on the course of the observatory. It also to directs it to the part of the sky it wants to observe.
The Operation Control System needs this crucial part to work in order communicate with the Operations Control System. Which ultimately controls the observations and receives them.
Command and Data Handling Subsystem
This is the brain of James Webb telescope. The system has a computer; Command Telemetry Processor which receives commands and process them their respective instruments of the spacecraft. The Solid-State Recorder is also used to record the observations and commands.
The system comprising of rocket thrusters that use the fuel from the fuel tanks in Spacecraft Bus. There are two kinds of thrusters on board. There are eight MRE-1, which control the attitude of the Webb. They are small and mono-propellant rocket engines; meaning, that they only use one of two fuels on board; Hydrazine.
The other type of thrusters is bi-propellant; Secondary Augmented Combustion Thrusters. They are used for maneuvering in orbit. To correcting the path and stay stationary. They are bi-propellant because they use Hydrazine and Dinitrogen tetroxide. One of them fuel and another oxidizer.
Thermal Control Subsystem
This system is used to maintain the temperature on the spacecraft to keep the observatory functioning. Since temperature is one of the key necessities of this observatory, they need a precisely built system to maintain that.
James Webb Telescope VSHubble
James Webb is on a very long and very different mission than the Hubble. Although both have the job to look in to the space and both will be used for the space exploration, their missions are different because of the amount of work have been put in them.
There were spacewalks that were deployed when Hubble was in trouble, there can be no rescue if there’s a problem with the James Webb. Hubble can only view the visible light spectrum and the James Webb will be operational for the infrared vision.
There is a huge difference in James Webb and Hubble Telescope although they both are a huge investment in the field of space exploration.
How Far Can The James Webb Telescope See
James Webb is made to see 13.4 billion years back in time and that would allow us to see the infant galaxies still forming. It will precisely be able to look at 100 million years after the Big Bang into the galaxies and starts still emerging from the start dust from clusters of dust.
The infrared photons are so minute that this huge machine will take quite bit of the space and time to capture the image, though it would be successful in doing so, hopefully!
When is James Webb Space Telescope Launch?
The launch of James Webb Space Telescope is something we have all been waiting for. Today is 25th December 25, 2021, 5:45 PM Islamabad Time, I am writing this as I am watching the James Webb Telescope Separation from the Spacecraft! Super Cool! This is the last time we will be looking at Webb. So, you can watch it recorded live on NASA’s YouTube Channel.