Successor of Hubble - The James Webb Space Telescope

July 25, 2022

Partnered with European Space Agency and Canadian Space Agency, NASA has recently published a series of data and colored photos captured by the James Webb Space Telescope (or abbreviated as JWST) on Tuesday, July 12. The telescope, having just been launched on Christmas day last year, represents a new dawn of mankind’s space exploration. While the new discoveries sure excite scientists and space lovers alike, let’s find out what is the reason that the discoveries are exciting.

The JWST is a successor of the HST, Hubble Space Telescope. It is currently the largest space telescope in space and has a number of differences, or improvements, compared to the HST. The JWST had a launch mass of 6,164.4kg, or 13,584lbs, which is 55.4% of the launch mass of HST. This weight loss does not translate into ability loss for the JWST. In fact, JWST’s main telescope has a diameter and a focal length that is more than two times larger than HST’s one. (diameter: 6.5m, or 21ft. compared to 2.4m, or 7 ft. 10 in.; focal length: 131.4m, or 431ft. compared to 57.6m, or 189ft.) All this made the collecting area of JWST, which  is the area in which the telescope is able to pick up EMR(Electromagnetic radiation), 6.25 times greater than HST’s collecting area of 4.0 meters squared. In addition to all those heightened perception abilities, the position of JWST is also a special one. It is placed in a Sun-Earth Lagrange point. A Langrange point, named after the Italian mathematician and astronomer Joseph-Louis Lagrange, is a point between 2 celestial bodies where the net force is 0. This makes Lagrange points ideal for satellites and space telescopes as they will require less orbit corrections than those that are not on Lagrange points.

So, why do we need this brand new space telescope? Why can’t just let HST do the job since it is still in near-earth orbit? First, as listed in the previous paragraph, JWST is improved in many aspects compared to the HST, thus it would operate more efficiently than the HST. Also, the HST mainly observes in the infrared range of the electromagnetic waves. Though this do mean that it can only observe red and yellow light of the visible light range, the ability to be able to see in the infrared range is rather more valuable than the ability to see in visual light. According to NASA, many space structures are hidden behind dust clusters where visual light cannot penetrate but infrared can. Thus, JWST can observe more objects than HST can. Finally, since light takes time to travel, the farther the distance a telescope can look, the farther back in time it can look. Again, according to NASA, the HST can see up to when the first galaxies are formed, while the JWST can see up to when the first stars are formed, this makes the JWST to see what has happened 700 million years ahead the limit of HST.

Overall, JWST is a space telescope that is simply more advantageous than the HST in finding out the origin of the universe and stuff like that. However, this does not mean that JWST can outright replace HST or any other space observational devices. These devices are often built for various purposes, and they all are very capable in one field of space observation instead of being omnipotent. True, maybe one day humanity will develop the swiss knife equivalent of a spacecraft, but before that day happens in the distant future, we have to rely on a variety of specialized spacecraft for space exploration.

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