Resurfacing Fattens up Big Lens

A team of astronomers at the University of Arizona had a second try at creating the world's largest one-piece telescope mirror June 10. In April, it was discovered that 2 tons of glass had leaked out from the 8.4-m mirror and in certain places the mirror's top surface diminished to less than 20 mm thick, instead of the planned 36 mm. To remedy the problem, astronomers laid several hundred 5-kg chunks of new glass on the mirror and reheated its surface, spreading the molten glass to the outer rim where the surface was too thin. The mirror will be the centerpiece of the Large Binocular Telescope under construction on Mount Graham in Arizona. The telescope is slated for completion by the year 2002.