\<COLOUR 1> CLOSEST APPROACH: \<COLOUR 0> Venus - 5,768 km, February 5, 1974 Mercury - 703 km, March 29, 1974 48,070 km, September 21, 1974 327 km, March 16, 1975
\<COLOUR 1> COUNTRY: \<COLOUR 0> USA
\<COLOUR 1> COMMENTS: \<COLOUR 0> The first probe to visit more than one planet; the first to use the gravity-assist principle, using one planet's gravity to direct it to another; the first and
as yet only probe to visit Mercury, showing it to have a lunar-like landscape.