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Late on Monday night, Nasa's James Webb Space Telescope (JWST) finally arrived at its final destination, about 1 million miles, or 1.5 million kilometers, from Earth. For its entire mission, Webb will orbit at what’s called the Lagrange point 2 (L2), a point in space that balances the gravitational pull of Earth and the Sun. Orbiting the Sun in line with Earth at L2 keeps the telescope's instruments super cold and allows it to observe the sky at any moment.
The $10 billion ( ₹760 billion) space telescope, which was years in the making as part of an international collaboration between Nasa, the European and Canadian space agencies, was launched after multiple delays on Christmas Day last year on an Ariane 5 rocket.
At around 2:00 pm Eastern Time (1900 GMT) on 24 January, the space observatory fired its thrusters for five minutes to reach the so-called second Lagrange point. The delicate burn added 3.6 miles per hour (1.6 meters per second) to Webb's overall speed, just enough to bring it into a "halo" orbit around L2, an AFP report explains. The other previous missions to L2 include the European Space Agency's Herschel and Planck observatories, and Nasa's Wilkinson Microwave Anisotropy Probe, the AFP report adds.
Earlier this month, US space agency Nasa also completed the process of unfolding Webb's massive golden mirror that will collect infrared signals from the first stars and galaxies that formed a few hundred million years after the Universe began expanding, the AFP report explains.
While this location gives JWST an effective way to communicate continuously with Earth, it has also has a delicate downside. It will be almost impossible to make any physical repairs on Webb, given its distance from Earth. In contrast, the Hubble had its fifth and final servicing mission in 2009. That’s because the Hubble Space Telescope orbits Earth at an altitude of 570km above it.
According to the AFP report, Webb will begin its science mission by summer, which includes using its high resolution infrared instruments to peer back in time 13.5 billion years to the first generation of galaxies that formed after the Big Bang.
Visible and ultraviolet light emitted by the very first luminous objects has been stretched by the Universe's expansion, and arrives today in the form of infrared, which Webb is equipped to detect with unprecedented clarity. A big reason for this is the remarkable technologies it carries. This includes a big primary mirror, 6.5m across and made of 18 hexagonal segments. The focus of the mirror can be calibrated by shifting the various segments.
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Its mission also includes the study of distant planets, known as exoplanets, to determine their origin, evolution and habitability. The next steps in the telescope's journey include aligning the telescope's optics and calibrating its scientific instruments. It is expected to transmit its first images back in June or July, the AFP report adds.
There was, nonetheless, genuine excitement given this huge development. Nasa administrator Bill Nelson tweeted: “.@NASAWebb, welcome home! And congratulations to the team for all of their hard work ensuring Webb’s safe arrival at L2!".
Nasa's official Instagram handle also shared a detailed post explaining how engineers will begin the sophisticated three-month process of aligning the telescope’s optics to nearly microscopic precision, with some movements as small as 10 nanometers — only one-ten thousandth the width of a human hair. “From now until about June 2022, Webb will calibrate its instruments and continue to cool down so it can #UnfoldTheUniverse," the post adds.