James Webb vs. Hubble Telescope Mirror (IMAGE) NASA/Goddard Space Flight Center Caption JWST will have a 6.6-meter (21.65 feet) diameter primary mirror, which would give it a significant larger collecting area than the mirrors available on the current generation of space telescopes. Hubble Space Telescope's mirror is a much smaller 2.4 meters (7.8 feet) in diameter. Credit NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.