Summary Reader Response Draft 1

 

Griggs, in “Why stars look spiky in images from the James Webb Space Telescope” (Griggs,2022) explains the technology behind the James Webb Space Telescope (JWST) and how it compares to its predecessor, the Hubble Space Telescope with regards to the number of diffraction spikes. The article was published in the American technology news website known as The Verge on the 16^th of July 2022.

The JWST is the latest, most powerful telescope, cruising millions of miles away from earth, developed by NASA. It observes our galaxy by using infrared light and hopes to see the past and give information about how the galaxy has changed from billions of years ago until today. It was launched on the 25^th of December 2021 in Guiana Space Center, Europe.

The article begins by giving a very brief explanation on the working principal of a telescope. It then discusses the differences between the Hubble Telescope and the JWST. The reason why the JWST is becoming popular is because of its improved design and technology. The JWST is a revolutionary telescope because it utilizes hexagonal mirrors and multiple camera instruments which is able to gather and study new information about our solar system that other telescopes are not capable of doing so due to their lack of technology.

There are several mentioned examples in the article explaining the engineering and technology used by the JWST.

Because JWST’s main aim is to see far into the galaxy, a bigger mirror setup is used for the mission. The JWST uses hexagonal mirrors primarily instead of a single round mirror used in the Hubble Telescope. The purpose of primary mirrors in a reflective telescope is to guide the light into the secondary mirror. Griggs states that “The shape of the primary mirror, in particular the number of edges it has, determines the mirror’s diffraction pattern” (Griggs, 2022). This results in an image with six diffractions.  The use of a hexagonal shape mirror eliminates gaps between each mirror, obtaining a high filing factor. A high filing factor indicates that there are no gaps in between each mirror. A hexagonal outline also makes the design additionally symmetrical, making it easier to launch into outer space as the whole telescope would need to be compact during takeoff. The mirrors are also engineered specifically to withstand the conditions in outer space, specifically its temperature. The mirrors must be kept cold to see far into the galaxy because stars give off infrared light which is studied by astronomers and any warmth present would also produce infrared light, affecting the images shown. NASA explains “Because warm objects give off infrared light, or heat, if Webb’s mirror was the same temperature as the Hubble Space telescope‘s, the faint infrared light from distant galaxies would be lost in the infrared glow of the mirror” (NASA, 2022). The mirrors need to be maintained at around -220 degrees Celsius and it does that by incorporating sunshields.

The JWST utilizes multiple camera instruments to view the solar system. The NIRCam (near-infrared light) is the telescope’s main imager. It shows more prominent diffraction spikes because stars are very bright at those wavelengths (0.6 to 5 microns). “NIRCam will detect light from: the earliest stars and galaxies, in the process of formation, the population of stars in nearby galaxies, as well as young stars in the Milky Way and Kuiper Belt objects” (NASA, 2021). The NIRSpec (Near InfraRed Spectograph) is used to distribute the amount light from a certain target into a spectrum. “Analyzing the spectrum of an object can tell us about its physical properties, including temperature, mass and chemical composition” (NASA, 2021). There is also a Mid-Infrared Instrument (MIRI) that consists a camera and a spectrograph. Its main role is to view the light in the mid-infrared area of the electromagnetic spectrum. The wavelength of the MIRI has a range of 5 to 28 microns. In this range, it gives us a visual of the solar system longer than our eyes can ever see.

The reason behind the making of the JWST is for astronomers to discover further into the galaxies than ever before. The aim is to discover what lies after the Big Bang. Scientist have spent over 30 years developing the JWST, costing approximately $10 billion USD. Compared to Hubble, the JWST is bigger and better and can see much further into the universe. For example, the JWST can look further because the mirrors collect much more light energy due to its 6.5-meter diameter mirror while the Hubble’s primary mirror is only 2.5 meters in diameter (CNET, 2022). The new and improved mirror and camera instruments allows scientists and astronomers to discover new galaxies and learn about the beginnings of time.

 

1)      Griggs, M. (2022). Why stars look spiky in images from the James Webb Space Telescope. Retrieved 17 September 2022, from https://www.theverge.com/23220109/james-webb-space-telescope-stars-diffraction-spike

 

2)      Key Facts - Webb/NASA. (2022). Retrieved 17 September 2022, from https://jwst.nasa.gov/content/about/faqs/facts.html

 

 

3)      Reilly, C. (2022). James Webb Space Telescope: NASA's First Images Explained. Retrieved 24 September 2022, from https://www.youtube.com/watch?v=XvfuxtVr7JY&t=1s

 

4)      Mirrors Webb/NASA. (2022). Retrieved 28 September 2022, from https://webb.nasa.gov/content/observatory/ote/mirrors/index.html#:~:text=The%20Webb%20Telescope%20team%20also,in%20diameter%2C%20flat%20to%20flat.