SCIENCE NEWS SPOTLIGHT
The James Webb Space Telescope is finally here! Well, it’s actually 1.5 million km away from us
NASA engineer Ernie Wright looks on as the James Webb Space Telescope's primary mirror segments are prepped to begin final cryogenic testing at NASA's Marshall Space Flight Centre.
Astronomy was given the best Christmas present this year: the successful launch of the James Webb Space Telescope (JWST). From the birth of such a concept in 1996, the project suffered multiple technical problems and delays, with its budget soaring from $500 million to a whopping $10 billion. Criticisms aside, there is no doubt its highly-anticipated launch on 25th December came as a relief to those at NASA, ESA and the Canadian Space Agency who collaborated on the project. In 1996, the Hubble Space Telescope, predecessor of JWST, viewed a seemingly empty region of the sky. Upon closer inspection, the Hubble Deep Field image showed the opposite. Turns out, that region housed 3000 galaxies,
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some of which were the oldest ever observed. The astronomers subsequently worked on building the Next Generation Space Telescope to probe this further, which later evolved into the JWST. The idea was revolutionary, but was met with several obstacles. Technical problems with the sun shield and thrusters meant its planned launch in 2018 was pushed back. When COVID-19 hit, pandemic protocols delayed the launch date even further, from March 2021 to December 25th, the day JWST finally took its leap into the cosmos. Launched on the ESA’s Ariane 5 rocket from French Guiana, JWST reached the moon’s orbit in 3 days. On 4th January, JWST unfolded and tensioned its sunshield, a meticulous manoeuvre comprising a total of over 140 release mechanisms. Once this was
deployed successfully between the telescope and the Sun, Earth and moon, its secondary and primary mirrors were unfolded. 27 days after its launch, JWST then reached the second Lagrange point (L2), 1.5 million km from Earth (in the direction opposite to the Sun). L2 is one of the five Lagrange points established in the 18th century. It is the point where the gravitational forces of the Earth and the Sun are equal, meaning JWST would orbit steadily around the Sun along with the Earth, only needing rocket thrust every three weeks to keep it in orbit. At L2, it would not be precisely stationary; instead, it would orbit around L2 in a “halo orbit”. The instruments were then turned on and astronomers began calibrating them, a key step to ensure images captured by the observatory were
perfectly aligned. JWST took its first picture of its mirrors (a “mirror selfie”, some may even call it), and astronomers have proceeded to align the 18 hexagonal mirrors. After all of this, JWST will be ready to capture images of everything from exoplanets and stars, to the most distant galaxies. (Update: as of April 2022, JWST has sent back an image of a star - our highest resolution yet! The alignment process is nearly completed, and its instruments and mirrors are nearly fullycooled.) The advanced design of the JWST caters to the primary function of the observatory: to look at infrared radiation. As our universe continues to expand, light travelling from distant galaxies to us stretches in wavelength towards the infrared side of the electromagnetic spectrum, resulting in a phenomenon termed “red shift”.
