when did exploration to the inner solar system begin
Discovery and exploration of the Solar System The first successful probe to fly by another Solar System body was Luna 1, which sped past the Moon in 1959. Originally meant to impact with the Moon, it instead missed its target and became the first artificial object to orbit the Sun. Mariner 2 was the first probe to fly by another planet, Venus, in 1962. The first successful flyby of Mars was made by Mariner 4 in 1965. Mariner 10 first passed Mercury in 1974.
Moons of Jupiter By the time that the Voyager space probes reached Jupiter, around 1979, 13 moons had been discovered, not including Themisto, which had been observed in 1975,[21] but was lost until 2000 due to insufficient initial observation data. The Voyager spacecraft discovered an additional three inner moons in 1979: Metis; Adrastea; and Thebe.[22]