Built at a cost of $8.7 billion, the Webb will be launched by an Ariane 5 rocket from French Guiana in October 2018. It is considered as the successor to the agency’s 26-year-old Hubble Space Telescope.
“Today, we’re celebrating the fact that our telescope is finished and we’re about to prove that it works,” said John Mather, Webb’s senior project scientist.
“We will see things we have not seen before because this telescope is much more powerful than even the great Hubble telescope. To give you some perspective about what we can do with it. If you were a bumblebee at a distance of the moon, we will be able to see you, both by your reflective sunlight and by thermal radiation and heat you emitted,” he added.
Top Ten Facts about the James Webb Space Telescope: 2va56gxOLu
— NASA Goddard (@NASAGoddard) November 2, 2016
With a diameter of 6.5 meters, the Webb telescope’s primary mirror consists of 18 hexagonal segments that are made of ultra-lightweight beryllium. These hexagonal segments will adjust and unfold during the telescope’s launch.
The telescope’s most significant feature is its five-layer sunshield – as large as a tennis court – that protects its infrared sensors from the background heat from the sun. Each layer is made of kapton (a heat-resistant polyimide film), and is as thick as a human hair. Working together, the five layers reduce the temperatures of the observatory by approximately 570 degrees Fahrenheit.
Wonderfully designed. Excited to see NASA complete the James Webb Space Telescope JWST
— Daniel Sandoval (@d3sandoval) November 3, 2016
“All five layers are beautifully executed and exceed their requirements. This is another big milestone for the Webb telescope project,” said James Cooper, Webb telescope sunshield manager at NASA Goddard Space Flight Center in Greenbelt, Maryland.
On Wednesday, NASA said its engineers and technicians have successfully completed the first crucial optical measurement of the telescope’s fully assembled primary mirror known as the Center of Curvature test.
Several stages of rigorous mechanical testing will follow. These tests will simulate the violent atmosphere that the telescope will have to deal with inside the rocket while it travels into the space. This is a crucial period that could alter the primary mirror’s shape and alignment and ruin the Webb’s performance.
Since the telescope is built to survive its launch environment, the space agency is making sure that the Webb has the same optical measurements both before and after the testing in order for it to work in space.
“This is the only test of the entire mirror where we can use the same equipment during a before and after test,” said Ritva Keski-Kuha, the test lead and NASA’s Deputy Telescope Manager for Webb at NASA’s Goddard Space Flight Center.
“This test will show if there are any changes or damages to the optical system.”
The Webb telescope, whose construction is being supported by the European Space Agency and the Canadian Space Agency, will be used to observe distant objects in the universe.
