mission. These plans were later canceled, the robotic mission being described as "not feasible".[146] In late 2004, several Congressional members, led by Sen. Barbara Mikulski (D-MD), held public hearings and carried on a fight with much public support (including thousands of letters from school children across the country) to get the Bush Administration and NASA to reconsider the decision to drop plans for a Hubble rescue mission.[147]The arrival in April 2005 of the new NASA Administrator, Michael D. Griffin, changed the status of the proposed shuttle rescue mission. At the time, Griffin stated he would reconsider the possibility of a manned servicing mission. Soon after his appointment, he authorized Goddard Space Flight Center to proceed with preparations for a manned Hubble maintenance flight, saying he would make the final decision on this flight after the next two shuttle missions. In October 2006 Griffin gave the final go-ahead for the mission. The 11-day STS-125 mission by Atlantis was scheduled for launch in October 2008.[148][149] However, the main data-handling unit failed in late September 2008, halting all reporting of scientific data. This unit has a backup, and on October 25, 2008 Hubble was successfully rebooted and was reported to be functioning normally.[150] However, since a failure in the backup unit would now leave the HST helpless, the service mission was postponed to allow astronauts to repair this problem. This mission got underway on May 11, 2009[151] and completed all the long planned replacements as well as additional repairs, including replacing the main data-handling unit.[edit] SuccessorsMain article: James Webb Space TelescopeSome JWST mirror segments are testedM1 area: 4.5 m2 (HST) and 25 m2 (JWST)There is no direct successor to the Hubble as an ultraviolet and visible-light space telescope, as near term space telescopes do not duplicate Hubble's wavelength coverage (near ultra-violet to near infrared wavelength), instead concentrating on the farther infrared bands. These bands are preferred for studying high Z and low temperature objects, objects generally farther away and older in the universe. These wavelengths are also difficult or impossible to study from the ground, justifying the expense of a space-based telescope. Alternatively, large ground based telescopes include many of the same wavelengths as Hubble, sometimes challenge HST in terms of resolution (via adaptive optics), have much larger light gathering power, and can be upgraded more easily. However, they cannot yet match the Hubble's excellent resolution over a wide field of view, and the very dark background of space.Plans for a Hubble successor materialized as the Next Generation Space Telescope (NGST) project, which culminated in the James Webb Space Telescope (JWST), the formally planned successor of Hubble.[152] Very different from a scaled up Hubble, it is designed to operate colder and farther away from the Earth at the L2 Lagrangian point, where thermal and optical interference from the Earth and Moon are lessened. It is not engineered to be fully serviceable (such as replaceable instruments), but the design includes a docking ring to enable visitation by other spacecraft.[153] A main scientific goal of the telescope is to observe the most distant objects in the universe,