History of the telescope a wider field of view than a classic Cassegrain. During the period 1850–1900, reflectors suffered from problems with speculum metal mirrors, and a considerable number of "Great Refractors" were built from 60 cm to 1 metre aperture, culminating in the Yerkes Observatory refractor in 1897; however, starting from the early 1900s a series of ever-larger reflectors with glass mirrors were built, including the Mount Wilson 60-inch (1.5 metre), the 100-inch (2.5 metre) Hooker Telescope (1917) and the 200-inch (5 metre) Hale telescope (1948); essentially all major research telescopes since 1900 have been reflectors. A number of 4-metre class (160 inch)
Lovell Telescope up by a household radio, the Lovell Telescope was the only telescope capable of tracking Sputnik's booster rocket by radar; it first located it just before midnight on 12 October 1957. It also located Sputnik 2's carrier rocket at just after midnight on 16 November 1957. The telescope also took part in some of the early work on satellite communication. In February and March 1963, the telescope transmitted signals via the moon and Echo II, a NASA balloon satellite at 750 km (466 mi) altitude, to the Zimenki Observatory in the USSR. Some signals were also relayed from the USA