11 May 2009
Atlantis Launch Begins Final Repair Mission for Space Telescope
Fixes will extend life of 19-year-old Hubble space observatory through 2014
Washington — Space shuttle Atlantis and its seven-member crew began the fifth and final repair mission for the nearly 20-year-old Hubble Space Telescope May 11 with a midafternoon launch from NASA’s Kennedy Space Center in Florida.
During the 11-day STS-125 mission, which will extend Hubble operations through 2014, astronauts will install two new, cutting-edge instruments to enhance Hubble’s capabilities; replace gyros, batteries and other components; and attempt the first on-orbit repair of two instruments — the space telescope imaging spectrograph and the advanced cameras for surveys.
“… three, two, one and liftoff for space shuttle Atlantis,” the launch announcer said over the roar of the rocket engines, “the final mission to enhance the vision of Hubble into the deepest grandeur of our universe.”
The mission will include five spacewalks, called extravehicular activities (EVAs), each lasting up to seven hours. Traveling along with the astronauts is a basketball — deflated so it takes up less room — that astronomer Edwin Hubble, for whom the space telescope is named, used while on the University of Chicago basketball team in the early 1900s.
“This is a different mission for us than we’re used to. The back-to-back EVAs are a different activity. We typically have EVAs but they’re not back to back with five of them,” Bill Gerstenmaier, associate administrator for space operations at NASA headquarters in Washington, said in an April 30 NASA briefing.
“The tasks are also a little bit different [from tasks conducted at the] space station,” he added. “They’re much more integral, inside the space telescope. They’re pulling some cards out, they’re doing more detailed kind of work. Lots of new tool development for the Hubble [mission]. The station tasks are bigger, broader assembly tasks where we’re putting big pieces together, hooking things up that were meant to be serviced via EVA. The teams are using every minute of this mission.”
The final repair mission was originally planned for 2004 but was postponed after space shuttle Columbia disintegrated on re-entry in 2003, killing all seven crew members. The repair mission was then cancelled because of safety concerns. After the shuttle program resumed with the launch of Discovery on July 26, 2005, NASA managers re-examined the risks involved in repairing Hubble and approved a final servicing mission.
Veteran astronaut Scott Altman commands the final space shuttle mission to Hubble, and retired Navy Captain Gregory Johnson is serving as pilot. Mission specialists include veteran spacewalkers John Grunsfeld and Michael Massimino and first-time space fliers Andrew Feustel, Michael Good and K. Megan McArthur.
Previous repair missions took place in December 1993, February 1997, December 1999 and March 2002.
HUBBLE SCIENCE
The Hubble Space Telescope, launched in April 1990, is the only one of NASA’s four “Great Observatories” (Hubble, Compton Gamma Ray Observatory, Chandra X-ray Observatory and Spitzer Space Telescope) that was designed to be serviced by space shuttle astronauts.
Hubble’s precision optics, location above the atmosphere, advanced instrumentation and unprecedented pointing stability and control have provided the most detailed look at the farthest known galaxies in the universe.
During its time in space, Hubble has helped scientists figure out the age of the universe (13.7 billion years), determine that nearly all galaxies may have super massive black holes, understand how planets are born, detect the first organic molecule (methane) outside the solar system and detect a distant supernova that suggests the universe only recently began speeding up.
Hubble’s replacement, the James Webb Space Telescope, is a tennis-court-sized telescope that will orbit far beyond Earth's moon. Webb will launch in 2013 to detect infrared radiation that is vital to understanding the universe, unleashing new discoveries and opening the door to a part of the universe that has just begun to take shape through the lenses of space-based observatories.
TELESCOPE FIXES
STS-125 was originally planned for an October 14, 2008, launch. Atlantis was in final launch preparation when the “A” side of Hubble’s science instrument command and data-handling system permanently failed.
The system provides all the electronics to command Hubble’s science instruments from the ground and sends science and engineering data back to the ground. The mission was postponed to include this critical system in the servicing mission. Meanwhile, flight controllers switched operations to the system’s “B” side.
The cosmic origins spectrograph will be the most sensitive ultraviolet spectrograph ever flown on Hubble. It will probe something called the cosmic web — the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas.
The wide-field camera 3 will have a broad range of exploration, from early and distant galaxies beyond Hubble’s current reach to more nearby galaxies and planets in the solar system. The instrument’s key feature is its ability to span the electromagnetic spectrum from the near ultraviolet through the optical and into the near infrared.
The fine guidance sensor will extend the life of Hubble’s pointing control system. Two of three of these sensors are degrading and the new sensor will replace one of them, making for two healthy units — all that’s needed to point Hubble. The third sensor gives added target pointing efficiency and redundancy.
Subsystem components to be replaced include six new gyroscopes and two battery modules with three batteries each. Stainless-steel sheets will be installed on Hubble’s exterior to give added thermal protection to some equipment bays, replacing multilayer insulation that slowly degraded in the harsh environment of space.
The astronauts will try to repair the space telescope imaging spectrograph, Hubble’s most versatile spectrograph, whose power supply failed in 2004. They will also try to fix two of three observing channels of the advanced camera for surveys, which has produced many of Hubble’s most popular and dramatic images.
Space shuttle Endeavour is the backup vehicle for shuttle Atlantis in case something goes wrong during the mission. Endeavour will stay on launch pad 39B while Atlantis is in space. Once the shuttle is cleared to return to Earth, Endeavour will move to launch pad 39A for its next flight, STS-127 to the space station, scheduled to launch June 13.
More information about STS-125 and the Hubble Space Telescope is available on the NASA Web site.
