Named after NASA's second administrator, the James Webb Space Telescope is the successor to Hubble, and is planned to launch in 2018. The Los Angeles Review of Books has a fascinating exploration of its development and future challenges, comparing and contrasting with its predecessor. Hubble had a rocky start, launching at six times over budget with a distorted mirror that blurred its first images, but after a series of repairs it has orbited the Earth for more than two decades and given rise to several landmark developments in astronomy.
Meanwhile, Webb is similarly over budget and delayed (it was supposed to launch last year), but the stakes are much higher this time. Webb is an infrared telescope designed to sit over one million miles away from us, using the combined gravity of the Earth and the Moon to stay in place, shadowed from the Sun. While this positioning will allow it to operate at temperatures near zero and be more sensitive to infrared light, the remote positioning means that manned repair will be impossible. Webb has lofty goals, from tracing light back to the Big Bang to searching for signs of life on other planets, but the high risk factor means NASA can't afford to make any of the mistakes it made with Hubble.