The Launch of the James Webb Space Telescope

 The Launch of the James Webb Space Telescope

Zach Locher

February 27, 2022

Links:

• https://astrobites.org/guides/guide-to-major-telescopes/the-james-webb-space-telescope/#:~:text=The%206.5%20meter%20James%20Webb,Earth%2DSun%20L2%20Lagrange%20point.

• https://webb.nasa.gov/content/observatory/ote/mirrors/index.html

• https://solarsystem.nasa.gov/missions/james-webb-space-telescope/in-depth/#:~:text=The%20James%20Webb%20Space%20Telescope%20is%20an%20infrared%20observatory%20orbiting,see%20stars%20forming%20planetary%20systems.

Purpose:

The James Webb Space Telescope (JWST), named after Apollo-Era Administrator James Webb, is an infrared light telescope designed to replace the Hubble Telescope, after it moved out of our range of communication. The telescope was made in a collaboration between NASA, ESA (European Space Agency), and CSA (Canadian Space Agency). The purpose of the James Webb Telescope is to expand upon the knowledge found by the Hubble Telescope with longer wavelength coverage and better sensitivity, up to 100 times more powerful than the Hubble Telescope. The main things that the Webb Telescope is proposed to look for are to look for the the first galaxies to form in the early universe, to see stars forming planetary systems, and to look for interstellar objects passing through our solar system, something that the Hubble Telescope was able to catch images of.

The Primary Mirror:

A significant amount of the required time to build the James Webb Space Telescope was dedicated to creating the mirrors. The telescope’s primary mirror is split up into 18 hexagonal mirrors, each 1.32 meters in diameter, creating a total diameter of 6.5 meters. The choice to make the mirror segments be hexagonal was because hexagons were roughly circularly shaped, had high filling factor (could fit together without gaps), and the symmetry allowed for there to be 18 segments in a roughly circular shape, which is desirable because it centers the light into the most compact regions of the detector, for example, if the mirror were oval instead of circular, the image produced would be elongated in one direction and a square mirror would send a lot of the light out of the central region. The telescope’s primary mirror is made out of beryllium, a good choice for a multitude of reasons, first, beryllium is a light metal that is very strong when considering its weight, secondly beryllium is good at holding its shape at a range of temperatures, so there would be less risk of the mirror segments deforming on launch, and finally, while Beryllium is a good conductor of electricity and heat, it is not magnetic, which is good for the electronics on the telescope. After the mirror segments were shaped and polished, a thin layer of gold was added to the surface of the mirror in order to increase reflectivity. 

Figure 1: Image of the primary mirror on the JWST, shows the 18 hexagonal mirrors. The 3 mirrors on right and left side fold back for launch and have to be deployed when in orbit around the Earth

Timeline:

The James Webb Telescope launched on December 25, 2021 on an Ariane 5 rocket from Europe’s Spaceport in French New Guiana. On January 8, 2022, the James Webb Telescope’s mirrors were fully deployed, and on January 24, 2022 the mission team used the thrusters to insert the telescope into orbit around the Sun, approximately 1 million miles away from Earth. The JWST, originally called the Next Generation Space Telescope, was slated to be launched in 2007, but was delayed due to engineering issues and political hesitancy. U.S. politicians almost pulled funding from the project in 2011, but ended up letting it continue. Then slated for launch in 2018, the JWST was delayed again due to technical issues with the telescope, then in 2020, the project was delayed due to the coronavirus, and it was finally launched in December 2021.