Repaired Hubble telescope back in action

NASA scientists showed off spectacular new pictures from the Hubble Space Telescope Wednesday, a stunning gallery of remote galaxies, a stellar nursery, an enormous globular cluster packed with countless pinpoint stars, and a dying sun blowing off its outer atmosphere in butterfly-like wings of debris.

The pictures clearly show the fabled telescope is back in action, ready to resume its role as one of the most productive observatories on or off the planet, thanks to a dramatic five-spacewalk shuttle repair mission last May.

"Every field of astrophysics, whether it's our local neighborhood of planets, nearby stars and their attendant planets, galaxies, clusters of galaxies, out to the edge of the universe, every field has questions that are awaiting the power of Hubble," said Heidi Hammel, senior research scientist at the Space Science Institute in Boulder, Colo. "You're only getting the tiniest taste of what the astronomers are planning to do with Hubble over as many years as it can last.

"We're giddy with the quality of the data that we have with this new telescope," she said. "We're especially excited to have the spectrographic data restored to Hubble. ... We are entering a new era of astronomy. Hubble's new beginning is just setting the stage for what's going to be coming."

The shuttle Atlantis roared into orbit May 11 on a fifth and final mission to service and upgrade the space telescope. The flight was canceled by former Administrator Sean O'Keefe in the wake of the 2003 Columbia disaster because heat shield repair techniques were not available and because a Hubble crew, operating in a different orbit, could not seek safe haven aboard the space station if a major problem prevented a safe re-entry.

Michael Griffin, O'Keefe's successor, reinstated the repair mission after spacewalking astronauts demonstrated heat shield repair techniques. He also ordered engineers to process a second shuttle in parallel to serve as an emergency rescue vehicle if needed.

During Atlantis' mission, four spacewalkers, working in two-man teams, carried out five back-to-back spacewalks to install six new stabilizing gyroscopes, six new nickel-hydrogen battery packs, a replacement data computer, and two new instruments, the $132 million Wide Field Camera 3 and the $88 million Cosmic Origins Spectrograph. Like all modern Hubble instruments, both were equipped with corrective optics to counteract the spherical aberration that prevents Hubble's 94.5-inch mirror from achieving a sharp focus.

The Atlantis astronauts also repaired two other instruments: the Space Telescope Imaging Spectrograph, which suffered a power supply failure in 2004, and the Advanced Camera for Surveys, which broke down in 2007. Neither instrument was designed to be serviced in orbit, but engineers devised custom tools and an ingenious plan that allowed the spacewalkers to bypass the failed electronics.

The repair crew installed an upgraded fine guidance sensor, new insulation, and a grapple fixture that will permit a future spacecraft to lock on and drive Hubble out of orbit when it is no longer able to do science.

"Bottom line, these professionals left Hubble as a new state-of-the-art telescope," said Ed Weiler, NASA's associate administrator for space science. "This is the fifth time we've had a new telescope up there, capable of continuing its historic scientific journey for at least five more years and, I would bet, a long time after that."

While enormous ground-based telescopes currently on the drawing boards will dwarf Hubble's relatively modest mirror, Weiler said its position above the atmosphere guarantees it will remain at the forefront of astronomy for years to come.

Along with unparalleled wide-field views of the cosmos, "the other thing Hubble can do that can never, ever be done from the ground is imaging in the ultraviolet and imaging in some of the near infrared wavelengths of light," Hammel said. "Because our Earth's atmosphere absorbs the photons before they get to the surface of the Earth.

"So you could make a football field-sized telescope and never collect a photon because they aren't there. Hubble is absolutely unique, we must have a telescope in space to complement the very large telescopes on the ground. Hubble is absolutely unique at those wavelengths. Nothing else can do it."

Asked to predict how Hubble will be remembered a century from now, senior Project Scientist David Leckrone said "we need to be humble. But in all humility, I truly believe that Hubble has fundamentally changed the course of modern astronomy and astrophysics. And it's taken it in new directions."

"I think we have basically shoved aside the old textbooks and the old concepts of the universe we live in that were based entirely on this distorted view we have through the Earth's atmosphere. And we have laid a foundation of clear vision that is the starting point from which all future UV/optical and near-infrared astronomy will proceed."

NASA spent some $887 million on the final Hubble servicing mission, pushing the total cost of the project to around $10 billion since its inception in the late 1970s.