Small foam-mirror telescope built.

Small foam-mirror telescope built

A standard 12-inch, f 5 reflector telescope might weigh 50 pounds and resemble a hot-water heater. A team of researchers at the University of Arizona in Tucson now has made a telescope with the same specifications but weighing only 10 pounds and standing just 1.5 feet high. The group accomplished this trick by developing metal mirrors with metal-foam cores that are lighter than glass mirrors. For instance, a normal 12-inch mirror would wiegh about 20 pounds, but the group's foam-core primary mirror weighs only 4.5 pounds, says team leader Van Vukobratovich. The lighter mirrors also mean the support system can be lighter, Vukobratovich says.

The foam-core mirrors allow shorter telescope design because the very nonspherical surfaces needed in short focal-length mirrors are difficult to grind into glass but can be engineered right into the metal mirrors, Vukobratovich says.

Vukobratovich thinks he will eventually be able to make lightweight mirror sfor about $125 a pound. Such small and relatively inexpensive telescopes are in tremendous demand, he says, not only for amateur awstronomy put also for military targeting systems, 35-millimeter telephoto photography, laser communications and other applications.