The instrument was put through its paces in the thermal vacuum chamber at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The Webb will be the most powerful space telescope ever built. It is an international project led by NASA with its partners, the European Space Agency and the Canadian Space Agency. The telescope is designed to take images of the first galaxies forming 13.5 billion years ago and to look through interstellar dust clouds to capture stars and planets forming in our own galaxy.
But it will have to operate in an extreme environment, with temperatures as low as -233 degrees Celsius, or 40 degrees Kelvin. That is 127 degrees Celsius colder than any place on the Earth’s surface has ever been.
To create those conditions here, the NASA team used the massive thermal vacuum chamber, a 12-metre-tall and 8-metre-diameter cylindrical chamber that eliminates the tiniest trace of air with vacuum pumps and uses liquid nitrogen and even colder liquid helium to create the space-like temperatures.
“We complete these tests to make sure that when this telescope cools down, the four parts of the heart are still positioned meticulously so that when light enters the telescope we capture it the right way,” said Paul Geithner, Webb’s deputy project manger.
“The biggest stress for this telescope will be when it cools down. When the telescope structure goes from room temperature to its super cold operating temperature, it will see more stress from shrinkage than it will from violent vibration during launch.”
NASA photographer Desiree Stover captured the photo of ISIM as it was lowered into the chamber for testing. The heart of the telescope weighs about as much as an elephant. Inside its black composite frame the four science instruments are tightly packed and are specially designed to capture specific information about distant light in the universe.