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. Personally, it
has always been an interest learning about outer space. After reading the
above-mentioned article, I was astonished at the advancement of the technology
used to study the galaxy. From multiple camera instruments to highly engineered
mirrors, I feel that the JWST will be a game changing telescope in the air and
space industry. 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 25th 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 are
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.
The JWST uses hexagonal mirrors primarily instead of a single round
mirror used in the Hubble Telescope. Because JWST’s main aim is to see far into
the galaxy, approximately 13 billion light years away (Kluger, 2022), a bigger
mirror setup is used for the mission. The purpose of primary mirrors in a
reflective telescope is to guide the light into the secondary mirror. “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, indicating minimal
gaps between mirrors. (NASA, 2021) 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. (NASA, 2021)
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 (NASA, 2021).
However, the JWST does pose an obvious weakness. Being millions of miles
away from earth, it would be nearly impossible to carry out repairs if
something were to go wrong. Unfortunately, the JWST was hit by a meteoroid
sometime in May of 2022. The meteor strike damaged one of the mirrors and has
caused an uncorrectable damage to the telescope. Thankfully, the effect of the
damage is insignificant and the telescope is still functioning above
expectations (Howell, 2022). Even so, the idea of the telescope running into
complications and not being able to correct it directly is concerning.
From where I stand, I did not think it was possible to view what the
galaxy looks like about 13 billion years ago. Nonetheless, the articles
explaining the technology behind the JWST refutes my opinion.
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, making it a revolutionary
telescope with its improved mirror and camera technology. 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). Therefore, with JWST’s breakthrough, it allows
scientists and astronomers to discover new galaxies and learn about the
beginnings of time.
References:
Griggs, M.B. (2022,
July 16). Why stars look spiky in images from the James Webb Space Telescope.
The Verge. https://www.theverge.com/23220109/james-webb-space-telescope-stars-diffraction-spike
Howell, E. (2022, July
18). James Webb Space Telescope picture shows noticeable damage from
micrometeoroid strike. Space.com. https://www.space.com/james-webb-space-telescope-micrometeoroid-damage
Kluger, J.
(2022, July 13). What the 5 Mind-Blowing Webb Telescope Pictures Tell Us.
Time.com. https://time.com/6196675/five-james-webb-telescope-images-explained/
Reilly, C. (2022, July
13). James Webb Space Telescope: NASA's First Images Explained. Youtube: CNET. https://www.youtube.com/watch?v=XvfuxtVr7JY&t=1s
Webb Key Facts - Webb/NASA. (n.d). jwst.nasa.gov. https://jwst.nasa.gov/content/about/faqs/facts.html
Webb’s Mirrors. (n.d).
webb.nasa.gov. https://webb.nasa.gov/content/observatory/ote/mirrors/index.html#:~:text=The%20Webb%20Telescope%20team%20also,in%20diameter%2C%20flat%20to%20flat
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