The Hubble Space Telescope, after a shaky two months in orbit, has produced its second set of test pictures. The sharp images, taken by the Faint Object Camera, show that controllers at Goddard Space Flight Center in Greenbelt have significantly improved the focus of the telescope's mirror since the "first light" pictures from its other imaging system, the Wide Field and Planetary Camera, were produced May 20.
The new, sharper Hubble picture, below right, shows two stars in a cluster known as NGC 188 that is 5,000 light-years away. The best ground-based telescopes show the same stars as fuzzy blurs, as indicated by the image on the left.
The Hubble still has several weeks to go in its complicated focusing process. And although its pointing control is improving, it is still short of its advertised goal of pinpointing a dime as far away as New York City is from Washington. NASA scientist Ed Weiler said so far it can target "a large chocolate chip cookie."
The Hubble's most serious problem is a wobble caused by changes in temperature as it passes between day and night on every orbit.
Engineers say they hope to have reprogrammed the onboard computer by late August to compensate for the wobble by adjusting the telescope's line of sight.