NASA has set a luanch date for their newest, most powerful telescope. The James Webb Space Telescope (JWST) will be launched into space on December 18 aboard a European Space Agency (ESA) Ariane 5 rocket, reports Abigail Beall for New Scientist.
The orbiting infrared observatory will be the largest telescope ever launched into space. As the Hubble Space Telescope's successor, JWST is designed to complement and expand Hubble's discoveries with its extended wavelength coverage and improved light sensitivity, NPR's Nell Greenfieldboyce. Once launched into space, the observatory will travel to a location one million miles from Earth. From there, it will help astronomers understand how young galaxies form, peer through clouds to examine how stars take shape, study exoplanets, and observe nearby celestial objects, including planets within our own solar system, reports New Scientist.
"Webb will be able to see galaxies as they looked a couple hundred million years after the Big Bang," NASA astrophysicist Jane Rigby tells NPR.
First envisioned in 1996, construction of the enormous space observatory has cost a total of $10 billion. A team of 1,200 scientists, technicians, and engineers from 14 countries and more than 28 U.S. states have worked on the telescope in the past 25 years.
To observe the far reaches of space, JWST will use four cameras and several sensor systems to collect data, writes Marcia Rieke, a JWST astronomer who worked on the Near Infrared Camera aboard the telescope, for The Conversation.
The observatory will also use a colossal mirror consisting of 18 hexagonal mirrors assembled into a honeycomb shape that spans just over 21 feet across, New Scientist reports. Scientists decided the mirror needed to be this long because a telescope's sensitivity, or how much it can see, is related to the size of the mirror. The larger the mirror's area, the more light it can collect and the more it can see—sort of like increasing a camera's aperture. The mirrors are also lined with a microscopically thin layer of gold which helps reflect infrared light. In total, JWST's mirrors can collect more than six times more light than the Hubble telescope can, according to The Conversation.
The telescope will work similarly to a satellite dish. Light from either a galaxy or a star will enter the telescope and bounce off its four cameras and sensors. The JWST will observe infrared light, whereas the Hubble telescope primarily observes ultraviolet light and visual elements of the electromagnetic spectrum.
Creating a giant mirror that is not only large enough to peer deep into the mysteries of space but also light and cold enough to launch into orbit took a lot of planning and engineering. To achieve this, researchers built the hexagon-shaped mirrors out of beryllium, a light metal that will not warp at various temperatures. The segmented mirrors that weigh 46 pounds each also needed to fold origami-style so that they could fit inside the rocket and later bloom open once it reaches its destination, per NPR.
Engineers need to keep the mirrors at negative 364 degrees Fahrenheit to see galaxies in infrared. If it's not at this temperature, the telescope will detect its own heat with the infrared sensors and blur out other galaxies. To keep the mirrors cold, the team will send the telescope into deep space fitted with sun shields to protect its mirrors from the sun's heat.
Once in space, the telescope will wait 35 days after launch before aligning its mirrors to focus on faraway galaxies. This waiting period gives the telescope's parts time to cool after launch, The Conversation explains.
"Aligning the primary mirror segments as though they are a single large mirror means each mirror is aligned to 1/10,000th the thickness of a human hair. What's even more amazing is that the engineers and scientists working on the Webb telescope literally had to invent how to do this," explains Lee Feinberg, a Webb Optical Telescope Element Manager at NASA Goddard, on the JWST website. The alignment will take a total of six months to complete.
According to The Conversation, the James Webb Space Telescope will be 4,500 times farther than where the International Space Station orbits, making missions to service the telescope nearly impossible. Various teams have rigorously tested all its components to make sure commands sent by a radio link will be received and control the telescope successfully, per The Conversation.
If the launch goes as planned in early December, the first images taken by the Webb telescope will arrive on Earth by next summer, per NPR.
"James Webb Space Telescope is a bigger telescope than both Spitzer or Hubble, and it's going to take magnificent images in the infrared," says Lisa Storrie-Lombardi, the director of the Las Cumbres Observatory and former project manager of the Spitzer Space Telescope, to NPR. "They will be beautiful."