James Webb Space Telescope

The James Webb Space Telescope (JWST), previously known as Next Generation Space Telescope (NGST), is a planned space telescope optimized for observations in the infrared, and a scientific successor to the Hubble Space Telescope and the Spitzer Space Telescope. The main technical features are a large and very cold 6.5-meter (21 ft) diameter mirror, an observing position far from Earth, orbiting the Earth–Sun L₂ point, and four specialized instruments. The combination of these features will give JWST unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, enabling its two main scientific goals — studying the birth and evolution of galaxies, and the formation of stars and planets.

In planning since 1996, the project represents an international collaboration of about 17 countries led by NASA, and with significant contributions from the European Space Agency and the Canadian Space Agency. It is named after James E. Webb, the second administrator of NASA, who played an integral role in the Apollo program.

JWST's capabilities will enable a broad range of investigations across many subfields of astronomy. One particular goal involves observing some of the most distant objects in the Universe, beyond the reach of current ground and space based instruments. This includes the very first stars, the epoch of reionization, and the formation of the first galaxies. Another goal is understanding the formation of stars and planets. This will include imaging molecular clouds and star-forming clusters, studying the debris disks around stars, direct imaging of planets, and spectroscopic examination of planetary transits.

The mission was under review for cancellation by the United States Congress in 2011 after about $3 billion had been spent, and more than 75 percent of its hardware was either in production or undergoing testing. In November 2011, Congress reversed plans to cancel the JWST and instead capped additional funding to complete the project at $8 billion.