Nasa’s Webb telescope clears test
Washington, May 12: The world’s largest and most powerful space telescope unfolded its giant golden mirror for the last time on Earth on Tuesday, a key milestone before the $10 billion observatory is launched later this year.
The James Webb Space Telescope’s 21 feet 4 inch (6.5 meter) mirror was commanded to fully expand and lock itself into place, Nasa said a final test to ensure it will survive its millionmile (1.6 million kilometer) journey and is ready to discover the origins of the Universe.
“It’s like building a Swiss watch at 40-feet-tall... and getting it ready for this journey that we take into the vacuum at minus 400 degrees Fahrenheit (-240 Celsius), four times further than the Moon,” said Scott Willoughby of lead contractor Northrop Grumman.
He was speaking at the company’s spaceport in Redondo Beach, California, from where the telescope will be shipped to French Guiana to be launched on an Ariane 5 rocket, with Nasa targeting October 31 for liftoff.
Webb’s primary mirror is made of 18 hexagonal segments coated with an ultrathin layer of gold to improve its reflection of infrared light. It will fly to space folded like a piece of origami artwork, which allows it to fit inside a 16-foot (5-meter) rocket fairing, and will then use 132 individual actuators and motors to bend each mirror into a specific position.
Together, the mirrors will function as one massive reflector, to enable the telescope to peer deeper into the cosmos than ever before.
Scientists want to use the telescope to look back in time over 13.5 billion years ago and see for the first time the first stars and galaxies that formed, a few hundred million years after the Big Bang.
To do this, they need to detect infrared. The current premier space telescope, Hubble, only has limited infrared capacity.
This is key because by the time the light from the first objects reaches our telescopes, it has been shifted towards the red end of the electromagnetic spectrum as a result of the Universe extending the space between objects as it expands.