Mariner 2

Mariner 2 was a NASA robotic probe that flew past Venus in December 1962, becoming the first spacecraft to successfully encounter another planet.

Venus flyby: A spacecraft passage near Venus that gathers data without entering orbit or landing. Mariner 2’s closest approach enabled measurements of Venus from space.
NASA: The United States government agency responsible for civilian spaceflight and aeronautics research. NASA designed and operated the Mariner program that produced the probe.
Venus: The second planet from the Sun, with a dense carbon-dioxide atmosphere and a surface hot enough to melt lead. It was Mariner 2’s target and the first planet examined by a successful flyby.
Interplanetary spaceflight: Spaceflight between planets, using spacecraft trajectories that cross the space between their orbits. Mariner 2 demonstrated a successful American mission across interplanetary space.
Deep Space Network: NASA’s worldwide system of antennas for communicating with spacecraft beyond Earth orbit. Its stations tracked Mariner 2 and received the probe’s faint signals.
Jet Propulsion Laboratory: A NASA center in California that develops and operates robotic space missions. JPL managed Mariner 2’s construction, launch operations, and flight.
Venusian atmosphere: The thick gaseous envelope surrounding Venus, composed chiefly of carbon dioxide with clouds of sulfuric acid. Mariner 2’s radio and infrared measurements constrained its structure and temperature.
Planetary science: The scientific study of planets, moons, and other bodies in planetary systems. Its measurements helped establish spacecraft flybys as a way to study planets directly.
Microwave radiometer: An instrument that measures microwave emission to infer the temperature of an emitting surface or atmosphere. Mariner 2 used one to estimate Venus’s surface temperature through its clouds.
Mariner program: A series of American robotic missions to explore the inner planets, conducted from 1962 to 1973. Mariner 2 was the program’s first successful planetary encounter.

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