SOLAR SYSTEM

Detailed explanation-1: -The first spacecraft to visit Mercury was NASA’s Mariner 10, which imaged about 45% of the surface. NASA’s MESSENGER spacecraft flew by Mercury three times and orbited the planet for four years before crashing on its surface at the end of its mission.

Detailed explanation-2: -Using a gravity assist from this planet, Mariner 10 first crossed the orbit of Mercury on March 29, 1974 and did so a second time on September 21, 1974. A third and last Mercury encounter took place on March 16, 1975. It measured the environments of both Venus and Mercury.

Detailed explanation-3: -MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) was the seventh Discovery-class mission, and the first spacecraft to orbit Mercury. Its primary goal was to study the geology, magnetic field, and chemical composition of the planet.

Detailed explanation-4: -Also the first spacecraft to visit Mercury, a feat that wouldn’t happen again for more than 30 years, Mariner 10 data revealed a surprising magnetic field and a metallic core comprising about 80 percent of Mercury’s mass.

Detailed explanation-5: -Only one NASA spacecraft has visited Mercury and that was Mariner 10 in 1974 and 1975.