Scientists show off Hubble New photographs show Pluto's moon, Saturn's rings

October 05, 1990|By Frank D. Roylance | Frank D. Roylance,Evening Sun Staff

Scientists working to make the most out of the flawed Hubble Space Telescope have offered a series of striking photographs as proof that Hubble is still working well enough to produce "frontier science."

The images -- all of them improved by computer enhancement -- include the sharpest picture ever of the planet Pluto and its moon; a beautiful color image of Saturn, and unequaled pictures of galactic cores, gas jets and globular star clusters.

"To convey the joy of seeing what we are seeing is difficult," said Riccardo Giacconi, director of the Space Telescope Science Institute in Baltimore. "These pictures to me already demonstrate enormous potential for discovery with the Space Telescope as it is now."

Even so, Giacconi said, "If the Space Telescope only did what it can do now, I think it would be a disappointment to us."

Giacconi said he has appointed a "strategy panel" of European and American astronomers and optics experts to conduct an "exhaustive study of all the potential optical fixes" that might help correct for Hubble's flawed mirror.

A NASA inquiry into the mirror flaw found that the $400 million mirror was ground to the wrong shape more than a decade ago because of a single error in the placement of a spacer in a testing device used to guide grinding machinery.

As a result, the telescope is unable to focus as sharply as it was designed to do, especially on the very faint and distant objects that most intrigue some astronomers.

NASA is already planning to replace the telescope's Wide Field/Planetary Camera with one that will compensate for the flaw in the main mirror. Other schemes for improving the performance of the telescope's other instruments are also being explored.

In the meantime, astronomers are busy now rethinking and rescheduling observations on the telescope, trying to make the most of its remaining capabilities.

The telescope itself continues to operate 24 hours a day and, with the exception of a persistent shiver when it crosses from night into day and back, is "working flawlessly," said Duccio Machetto, principal investigator on the telescope's Faint Object Camera.

The images released yesterday are among many produced during the telescope's ongoing "scientific assessment." They are designed to test Hubble's remaining capabilities and computer enhancement techniques, rather than to seek "astounding" new discoveries, Machetto said.

L Hubble is scheduled to begin full-time astronomy next month.

One of the most striking pictures sent back from Hubble so far shows the ninth planet from the sun, Pluto, and its moon, Charon.

Discovered just 12 years ago, Charon -- no bigger than a big asteroid -- has appeared to ground astronomers as no more than a fuzzy wart on Pluto's disk.

In a photo taken last month, Hubble's Faint Object Camera was able to separate the sunlight reflected from Pluto and Charon, revealing them as two clearly distinct objects.

Rudolph Albrecht, of the European Southern Observatory, said the pictures show that Pluto is smaller (about 1,400 miles across) and brighter than previously thought, and that Charon's orbit is lower than predicted. As Charon orbits in front of Pluto, &r astronomers hope to use the eclipses to learn more about the two objects' surface features.

A sharp and beautiful picture of the sixth planet, Saturn, was clear enough to reveal details of the planet's atmosphere.

William Baum, of the University of Washington, said the picture proved Hubble's Planetary Camera will be able to conduct long-term studies of weather changes on the outer planets. One such study may start very soon.

"A white oval, a white spot, has showed up on Saturn very recently -- days ago," said Baum. "We'd like to observe the growth and development of that spot. It's the brightest and largest since 1933."

Giacconi later told Baum he is scheduling the observations, and if the spot persists, they will be made "as soon as we can."

In one of Hubble's most impressive observations to date, astronomers used the Faint Object Camera to peer deep into a "globular" star cluster called M14, about 70,000 light years away in our own galaxy.

Bruce Margon, of the University of Washington, said the target of the observation was a "nova," a star that exploded in a brief but brilliant display noted by astronomers in 1938. It was only the second nova ever observed in a globular cluster.

Such periodic novas are believed to be thermonuclear explosions touched off by the interactions of two stars in a close, double star system. The explosions do not destroy the stars, so astronomers have tried for years to find the 1938 star again in its "quiet" state.

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