Jan 23, 2000

Hubble Opens for Business

HST image of the Eskimo Nebula
January 24, 2000 -- NASA announced today that the Hubble Space Telescope (HST) is back in business and working better than ever. To show off the capabilities of the newly refurbished telescope, the Space Telescope Science Institute released two new pictures of remote galaxies and a colorful dying star.

The images were taken January 10 - 13, 2000, to recommission the HST following the recent shuttle servicing mission. In December, 1999, astronauts refitted Hubble with improved electronics, a new computer, and critically needed replacement gyroscopes.

Above: In its first glimpse of the heavens following the successful December 1999 servicing mission, NASA's Hubble Space Telescope captured this spectacular view of planetary nebula NGC 2392.

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"After a two-month hiatus, it is a tremendous boost to all of astronomy to see Hubble back in action," said Steven Beckwith, director of the Space Telescope Science Institute, the Hubble science operations center in Baltimore, MD. "NASA has restored the observatory to a condition that was better than it was even before the fourth gyroscope failed,"

Astronomers resumed operations this month by aiming the telescope at two scientifically intriguing and photogenic celestial targets. One object is an intricate structure of shells and streamers of gas around a dying sun-like star 5,000 light-years away.

Designated NGC 2392, it is dubbed the "Eskimo Nebula" because, as seen through ground-based telescopes, it resembles a face inside a furry parka. In Hubble's sharp view, the "furry" features resemble giant comets all pointing away from the central star, like the spokes of a wheel. "The clumps that form the comet heads all seem to be located at a similar distance from the star. This fact will be important in developing a theory of why the clumps formed in the first place," said planetary nebula expert J. Patrick Harrington of the University of Maryland, College Park, MD. He adds, "Of all the planetary nebulae imaged by the Hubble Space Telescope, this new image is unsurpassed in subtle beauty."

A second target is a massive cluster of galaxies called Abell 2218. The cluster is so massive that its enormous gravitational field deflects light rays passing through it, much as an optical lens bends light to form an image. This phenomenon, called gravitational lensing, magnifies, brightens, and distorts images from faraway objects. The cluster's magnifying powers provides a powerful "zoom lens" for viewing distant galaxies that could not normally be observed with the largest telescopes.

HST image of Abell 2218

Above: Hubble Space Telescope image of Abell 2218. This massive cluster of galaxies resides in the constellation Draco, some 2 billion light-years from Earth. The arcs are images of very distant galaxies far behind the cluster that have been distorted by the effect of gravitational lensing.

This useful phenomenon has produced the arc-shaped patterns found throughout the Hubble picture. These "arcs" are the distorted images of very distant galaxies and quasars, which lie 5 to 10 times farther than the lensing cluster. This distant population existed when the universe was just a quarter of its present age. Through gravitational lensing these remote objects are magnified, enabling scientists to study them in more detail.

Below: The original black and white HST image of Abell 2218, captured in 1994.

he original black and white HST image of Abell 2218, captured in 1994.
The Hubble telescope first viewed this cluster in 1994, producing one of the most spectacular demonstrations of gravitational lensing up to that time. Scientists who analyzed that black-and-white picture discovered more than 50 remote, young galaxies. Hubble's latest multicolor image of the cluster will allow astronomers to probe in greater detail the internal structure of these early galaxies. The color picture already reveals several arc-shaped features that are embedded in the cluster and cannot be easily seen in the black-and-white image.

The colors in this picture yield clues to the ages, distances, and temperatures of stars, the stuff of galaxies. Blue pinpoints hot young stars. The yellow-white color of several of the galaxies represents the combined light of many stars. Red identifies cool stars, old stars, and the glow of stars in distant galaxies. This view is only possible by combining Hubble's unique image quality with the rare lensing effect provided by the magnifying cluster.

"For the first time we can view the internal color structure of some very distant galaxies. This gives us new insight into details of what young galaxies are like," says Richard Ellis at the California Institute of Technology, Pasadena, and University of Cambridge, England and a co-investigator on an earlier (black- and-white) Hubble image of Abell 2218 taken in 1994. "The color of a distant source is preserved by gravitational lensing. By matching images of the same color, families of multiple images produced by the lensing process can be identified."

Spacecraft operators report that all the new equipment installed on the telescope in December is working perfectly, including the new computer, solid state recorder, and fine guidance sensor. In particular the new gyroscopes are allowing Hubble to reliably point with exquisite precision at celestial objects.

The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. for NASA, under contract with NASA's Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.Web Links

Space Telescope Science Institute -home page

Hubble Servicing Mission -information from the NASA/Goddard Space Flight Center