Nearly a year after NASA's virtually flawless shuttle mission to correct the Hubble Space Telescope's nearsighted optics, the orbiting telescope has more than vindicated the high hopes scientists placed in its restored vision.
Since January, the Hubble has discovered a quasar in the nearby galaxy Cygnus A -- a mysterious object that can emit a trillion times the energy of the sun -- given scientists a glimpse of the interstellar gas from which the stars were formed, photographed the impact of a comet in Jupiter's atmosphere, uncovered the first conclusive evidence for the existence of black holes and forced astronomers to revise their most fundamental notions about the age and structure of the universe.
Not bad for one year's work.
Last year we predicted that the planning and execution of the complex telescope repair mission would rank as one of the Space Age's most spectacular successes. But hardly anyone could have guessed how bountiful a harvest of scientific knowledge the telescope would produce in the short time it has been operating since then. NASA initially hoped the corrective optics installed by the shuttle Endeavor's crew last December would let the Hubble telescope achieve 75 percent of its design potential. In fact, the refurbished instrument is operating at 90 percent or better.
This week, the Hubble produced the first pictures ever taken from Earth of the surface of Saturn's giant moon, Titan. Nearly the size of the Earth, Titan is the only moon in the solar system with a dense atmosphere like our own. Fly-bys from the Pioneer and Voyager spacecraft produced disappointing pictures, however, because thick clouds made it impossible to discern any detail on the satellite's surface.
The Hubble photos show a moon that looks as Earth might if Australia were the only continent. A bright spot about 2,500 miles wide lies just south of Titan's equator, surrounded by a sea of darkness. Astronomers have speculated that Titan might be covered by an ocean of liquid ethane or methane. The new images suggest that the dark areas of Titan are covered by tarry hydrocarbons that rain down from its methane-rich atmosphere, and that the bright, continent-like feature may be an elevated area where hydrocarbons have been etched away to expose the water ice thought to compose Titan's interior. These stunning photos are only the latest example of how the Hubble's refurbished eye is pushing back the frontiers of science.