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In 1976, the Helios-B deep-space probe made (what was then) the closest controlled approach to the Sun at 27 million miles (43 million km) or within 0.3 AU. (1 Astronomical Unit (AU) = Earth-Sun distance = 93 million miles.) The purpose of the Helios-B mission was to make measurements and comparisons of the material found in space between Earth's orbit and a distance from the Sun of 0.3 A (AU). The vehicle carried a fluxgate magnetometer; electric and magnetic wave experiments; charged particle experiments; and a micrometeoroid experiment. This was one of two deep-space probes co-developed by NASA (US) and Germany. NASA launched Helios A on 10 Dec 1974, and Helios B on 16 Jan 1976.