We’re being followed
The need to keep Spitzer extremely cold also affects its location. Unlike other space telescopes, Spitzer doesn’t orbit the warm Earth. Instead, it trails behind the Earth as the Earth orbits the Sun, in a place where the temperature is only 35° Kelvin. This helps the telescope to stay cold naturally, and means it doesn’t need to carry a lot of coolant. The telescope’s solar shield helps further protect it from the heat of the Sun. The telescope operates at about 5.5° Kelvin. Eventually, the liquid helium will be consumed, and the telescope’s mission will end.
Spitzer is a basic reflecting telescope. It has a 33.5-inch (.85-meter) mirror made of beryllium, a lightweight metal that stands up well to cold. Solar panels and batteries provide power. The telescope has three science instruments on board. One is a camera that records a range of infrared radiation. Another is a spectrograph that studies the makeup of cosmic objects such as stars and black holes. The third instrument gathers pictures and information suitable for studying the distribution of dust, an important ingredient of future planet and star formation, throughout our galaxy, the Milky Way.
