The Cosmic Background Explorer, COBE, was launched in 1989 to study the faint infrared and microwave radiation from the early universe called cosmic background radiation. Scientists believe this radiation is left over from the Big Bang — the chain reaction that formed the universe.
COBE was sent into an orbit high above Earth’s atmosphere, where it could view this radiation. It had three instruments on board: one to observe infrared radiation, one to map microwave radiation, and one to measure the cosmic background radiation’s spectrum.
COBE used solar panels to collect light from the Sun for energy, and a funnel-shaped sunshade to keep the light from shining on and heating the cold parts of the satellite. In addition, liquid hydrogen helped keep the telescope cool. COBE had to stay extremely cold because it was studying infrared light, or heat. Unless the satellite and its detector could be kept cool, it would give off infrared signals of its own that would interfere with the infrared signals it was trying to detect.

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| Year launched: | 1989 |
| Telescope type: | Detector |
| Light collector: | Microwave receivers |
| Light observed: | Microwave, infrared |