The orbiting space telescope that just won't quit collecting gobs of celestial data well beyond its expected twilight is set for a major tune-up and upgrade, NASA scientists said Tuesday at a meeting of the American Astronomical Society.
This servicing mission will be the Hubble Space Telescope's fifth and last.
The latest word is that the space shuttle Atlantis could lift off in August with a crew of seven astronauts and a cargo of equipment, tools and new instruments for Hubble. But that launch date could change. "That's dependent upon the shuttle flights between now and the servicing mission," said Alan Stern, associate administrator for NASA's Science Mission Directorate in Washington. He added that safety always comes first.
Orbiting at about 350 miles (563 kilometers) above Earth, Hubble is above the atmosphere and doesn't have to contend with shifting pockets of air that distort images made by ground-based telescopes. This atmospheric distortion is the reason stars appear to twinkle.
Hubble's clear view has meant, for one, that over its 16-plus years in orbit, the telescope has sent back a spectacular photo album of sci-fi-like jets from black holes, galaxies in all stages of evolution and snapshots of planets in our own solar system.
"Hubble is, without exaggeration, a national treasure," Stern said, "and all of NASA is looking forward to seeing it receive this tune-up and upgrade."
The public's love for Hubble, along with political pressure, has played a role in NASA's decision to service the observatory, a mission deemed risky compared to other shuttle ventures.
During the 11-day Hubble service mission, which will include five spacewalks, shuttle astronauts will install two new science instruments plus a set of gyroscopes to help stabilize the telescope, as well as batteries and thermal blankets to keep the observatory operating until at least 2013.
Astronauts will also install a soft capture mechanism that will allow a future unmanned spacecraft to dock with Hubble in about 2020 and deorbit it for a controlled plunge and disposal in the ocean.
Leading the spacewalks will be self-labeled "Hubble Hugger," astronaut John Grunsfeld, who had told Space.com last year he wanted to be on the mission.
"As both an astronaut and an astronomer, the opportunity to go back to Hubble is more than a dream come true," said Grunsfeld. "When we left Hubble in 2002, I was convinced it would be the last time I would see my friend Hubble Telescope," said Grunsfeld, wearing a NASA flight suit and space gloves.
However, he noted, "this mission promises to be quite challenging."
For instance, astronauts will attempt the first-ever on-orbit repair of two existing instruments, the Space Telescope Imaging Spectrograph, or STIS, and the Advanced Camera for Surveys, which failed a year ago this month.
Installed on Hubble in February 1997, the STIS separates incoming light into its constituent colors, giving astronomers a chemical map of distant objects. Since its deployment, STIS has been critical in the confirmation of black holes at the centers of galaxies, made the first discovery of an atmosphere around an exoplanet and helped confirm the age of the universe.
Two additions to Hubble's science cargo will include the Wide Field Camera 3, a panchromatic camera that is expected to provide sharp images over a wide range of colors; and the Cosmic Origins Spectrograph.
The Cosmic Origins Spectrograph will probe the large-scale structure of the universe, the so-called cosmic web, in which strands of galaxies transect seemingly empty space like a gargantuan 3-D spider web. The universe's invisible "glue," called dark matter and thought to make up about 85 percent of all matter in the universe, gives the web its structure, astronomers say.
Astronomers infer the existence of the cosmic web just as a child might know a Christmas tree exists by looking at the colorful lights that outline its branches. Instead of little bulbs, the stars and galaxies trace out the cosmic web.
In the end, scientists expect to breathe new and improved life into Hubble.
"Our goal for this mission is to leave Hubble at the apex of its scientific capabilities," said David Leckrone, Hubble senior project scientist at NASA's Goddard Space Flight Center in Maryland. The addition of new instruments along with repairs of others should give astronomers a full "toolbox" for resolving many cosmic conundrums, Leckrone said.