Today is the 30th anniversary of the closest approach to the Sun by a spacecraft (on purpose at least), On January 15, 1976, Helios 2, was sent to observe the Sun and the solar wind, it arrived n April 17, 1976. Constructed in West Germany and launched from Cape Canaveral, it was equipped with special systems to cope with the heat. From a distance of 28 million miles it is estimated the temperature was 370 C (700 F); yet the spacecraft managed to return useful data.

Helios 2 was the second such spacecraft to go to the Sun. Helios 1 was launched on December 10, 1974 and arrived at the sun a year earlier on March 15, 1975, it also returned data.

Helios 1 might have been first, but Helios 2 managed to be a little closer. Helios 2 was 0.29 A.U. from the Sun while Helios 1 was 0.30 A.U.

Source JPL