Image: Drew Noel
A gold-coated segment of the engineering design unit’s primary mirror at the Ball Aerospace and Technology Corp
What the JWST will actually see as it peers back all those billions of years are traces of infrared light from distant galaxies. Infrared light (IR) waves can’t be seen with the naked eye because IR light is not in the visible spectrum. However, when detected with instruments like the JWST, these light waves provide scientists with invaluable information about the way the universe works (and used to work, long before we were around to observe it).
Image: Northrop Grumman Aerospace Systems
A life-sized sunshield membrane being tested at ManTech, Huntsville
The telescope is made up of three parts: the Integrated Science Instrument Module, the Optical Telescope Element, and the Spacecraft Element. As mentioned, the mirror used to detect the infrared rays is covered with reflective gold – and this increases the mirror’s ability to reflect infrared light. And when you think about trying to get a mirror this size into space, why it’s made up of hexagonal segments might become apparent: to make it easier to fold up and fit into a rocket.
Image: Drew Noel
A segment of the telescope’s primary mirror
Besides size, another important aspect of the JWST is temperature. In order to measure the incoming infrared light accurately, the mirror will need to be “cryogenically” chilled – to an astounding -364° F (-220° C)! To achieve this, it will be shot deep into space, with attached sunshields used to protect it from the warmth of the Sun and the heat given off by the spacecraft bus (which houses six major subsystems: electrical power, attitude control, communications, command and data handling, propulsion, and thermal control).