The James Webb Space Telescope

Mission Objectives

The James Webb Space Telescope (sometimes called JWST or Webb) will be a large infrared telescope with a 6.5-meter primary mirror. NASA’s James Webb Space Telescope now is planning to launch between March and June 2019 from French Guiana, following a schedule assessment of the remaining integration and test activities. Previously Webb was targeted to launch in October 2018.

“The change in launch timing is not indicative of hardware or technical performance concerns,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington. “Rather, the integration of the various spacecraft elements is taking longer than expected.”

As part of an international agreement with the ESA (European Space Agency) to provide a desired launch window one year prior to launch, NASA recently performed a routine schedule assessment to ensure launch preparedness and determined a launch schedule change was necessary. The careful analysis took into account the remaining tasks that needed to be completed, the lessons learned from unique environmental testing of the telescope and science instruments at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the current performance rates of integrating the spacecraft element.

JWST will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.

JWST was formerly known as the "Next Generation Space Telescope" (NGST); it was renamed in Sept. 2002 after a former NASA administrator, James Webb. JWST is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center is managing the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate JWST after launch.

What will it see?


COBE, WMAP, and Planck all saw further back than JWST, though it's true that JWST will see farther back than Hubble. JWST was designed not to see the beginnings of the universe, but to see a period of the universe's history that we have not seen yet before. Specifically we want to see the first objects that formed as the universe cooled down after the Big Bang.

That time period is perhaps hundreds of millions of years later than the one COBE, WMAP, and Planck were built to see. We think that the tiny ripples of temperature they observed were the seeds that eventually grew into galaxies. We don't know exactly when the universe made the first stars and galaxies - or how for that matter. That is what we are building JWST to help answer.

JWST Facts