Scheduled to launch in 2018, the James Webb Space Telescope (JWST) will orbit about 930,000 miles (1.5 million kilometers) away from Earth. The JWST is estimated to cost a total of $8.8 billion. JWST will keep its mirror at a temperature of minus 388 degrees Fahrenheit (minus 233 degrees Celsius).
The cold and the telescope’s distance from the Earth will give JWST the precision to observe red-shifted light from the early universe. The James Webb Space Telescope will detect infrared light that is 400 times fainter than current space-based telescopes can see.
The telescope's segmented primary mirror is 21 feet (6.4 m) in diameter and consists of 18 hexagonal segments made from gold-plated beryllium. A secondary mirror reflects light from the primary mirror into the science instruments.
The JWST's mirror dwarfs that of the Hubble Space Telescope, but has one-tenth the mass of the Hubble's mirror. Each of the 18 beryllium mirror segments weighs 46 pounds (20 kilograms).
JWST will travel through space for roughly 30 days to reach the L2 point, a gravitationally stable point about four times further from Earth than the moon.
NASA has no plans at present to service the JWST as the Hubble telescope was serviced by space shuttle missions, as the Soyuz spacecraft does not have the range or cargo capacity to reach JWST. However a docking ring was attached to JWST anyway, in the event that a future manned spacecraft could make the journey.