What Is The James Webb Space Telescope?
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The James Webb Space Telescope (JWST) is NASA's largest and most powerful space observatory, launched December 25, 2021. With a 6.5-meter mirror, it observes in infrared wavelengths and orbits the Sun 1 million miles from Earth. It can see the earliest galaxies that formed after the Big Bang.
The James Webb Space Telescope is the largest and most complex space telescope ever built. Launched on Christmas Day 2021 after decades of development, JWST is designed to see the earliest galaxies in the universe and to peer through dust clouds where stars and planets form. It works in infrared light, complementing Hubble's optical observations.
What is JWST?
NASA's successor to Hubble, with very different capabilities. According to NASA, JWST is a joint project of NASA, ESA, and the Canadian Space Agency. It launched December 25, 2021 aboard an Ariane 5 rocket from French Guiana. The primary mirror is 6.5 meters across (Hubble's is 2.4 meters), made of 18 gold-coated hexagonal segments. It orbits the Sun at the second Lagrange point (L2), about 1 million miles from Earth. The development cost about $10 billion.
How is JWST different from Hubble?
Several key ways. JWST observes in infrared light, while Hubble works in mostly visible and ultraviolet. JWST's larger mirror collects much more light, letting it see fainter, more distant objects. JWST is at L2 (cold and stable but unreachable by astronauts), while Hubble is in low Earth orbit (warmer but serviceable). JWST has a sunshield the size of a tennis court to keep its instruments at -370°F, cold enough to detect faint infrared signals. Both telescopes work together, with their different wavelengths revealing different aspects of cosmic objects.
What can JWST do?
See further back in time than any previous telescope. Because the universe is expanding, light from very distant galaxies is stretched into infrared wavelengths. JWST is optimized to detect this redshifted light, letting it observe galaxies as they appeared just 100-250 million years after the Big Bang. It can also study exoplanet atmospheres in unprecedented detail, peer through dust clouds where stars are forming, and observe cold objects in our own solar system. Since launch, JWST has made major discoveries about early galaxies, exoplanets, and supermassive black holes.
Why can't JWST be repaired?
Because L2 is too far. Hubble was designed for servicing by astronauts; JWST wasn't. The L2 orbit is about 1 million miles from Earth, far beyond where current crewed missions can travel. Any malfunction has to be addressed through software updates from Earth. The telescope was therefore designed and tested with extreme care to avoid problems. It carried enough fuel for about 20 years of operations after launch, so the expected mission lifetime extends into the 2040s. There's no current plan to extend or replace it.
The James Webb Space Telescope is NASA's most ambitious space observatory, launched in December 2021 to operate from a stable orbit 1 million miles from Earth. With a 6.5-meter mirror and infrared sensitivity, JWST can see the earliest galaxies in the universe and study exoplanet atmospheres in detail. It's expected to operate for about 20 years and is already revolutionizing astronomy.
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