AUSTIN, Texas —

The Hubble Space Telescope, which

continues to



celestial data well beyond its expected twilight, is set for a major tune-up and upgrade, NASA scientists announced Jan. 8

here at a meeting of the American Astronomical Society.

This fifth servicing mission, tentatively scheduled for launch Aug. 7

aboard Space Shuttle Atlantis, will be



[The launch date is] dependent upon the shuttle flights between now and the servicing mission,” said

Alan Stern, associate administrator for

NASA’s Science Mission Directorate in Washington, adding

that safety always comes first.

At about

563 kilometers

above Earth, Hubble orbits

above the atmosphere and is unaffected by

shifting pockets of air that distort the images made by ground-based telescopes. This atmospheric distortion is the reason stars appear to twinkle.

With its clear view, Hubble 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 during its 16-plus years in orbit.

“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.

Hubble hugger

During the 11-day Hubble service mission, which will include five spacewalks, the crew of seven 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.


also will install a soft capture mechanism that around 2020 will allow a future unmanned spacecraft to dock with Hubble

and de

orbit it for a controlled plunge and disposal in the ocean.

Astronaut John Grunsfeld, a self-labeled “Hubble hugger,” will lead the spacewalks. Grunsfeld, who has flown on three Hubble servicing missions,

told Space News last year that he wanted to be on this


“As both an astronaut and an astronomer, the opportunity to go back to Hubble is more than a dream come true,”

Grunsfeld said. “When we left Hubble in 2002, I was convinced it would be the last time I would see my friend, Hubble telescope.

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 (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, providing

astronomers with a chemical map of distant objects. Since its deployment, STIS has been critical in


black holes at the centers of galaxies, has made the first discovery of an atmosphere around an exoplanet and has helped confirm the age of the universe.

Better science


two additions to Hubble’s science cargo will include the Wide Field Camera 3, a


camera, and the Cosmic Origins Spectrograph (COS).

The COS 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. Dark matter, known as the

universe’s invisible “glue

and thought to make up about 85 percent of all matter in the universe, gives the web its structure, astronomers say.

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, Greenbelt, Md.

The addition of new instruments along with repairs of others should give astronomers a full “tool box” for resolving many cosmic conundrums, Leckrone said.