What's inside Mariner 2?

Mariner 2 (“Mariner-Venus 1962”), an American space probe to Venus, the second planet from the Sun, orbiting it every 224.7 Earth days, was the first robotic space probe, a scientific space exploration mission in which a spacecraft leaves Earth and explores space, to conduct a successful planetary encounter.

The first successful spacecraft/spaceship, a vehicle, vessel or machine designed to fly in outer space, in the Mariner program, which launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1962 to 1973, a program conducted by the American space agency NASA (“National Aeronautics and Space Administration”) who is responsible for the nation's civilian space program and for aeronautics and aerospace research, in conjunction with Jet Propulsion Laboratory, it was a simplified version of the Block I spacecraft of the Ranger program, a series of unmanned space mission by the United States in the 1960s whose objectives was to obtain the first close-up images of the surface of the Moon; and an exact copy of Mariner 1, the first spacecraft of the American Mariner program. The missions of Mariner 1 and 2 spacecraft are together sometimes known as the Mariner R missions. Mariner 2 passed within 35,000 kilometers (22,000 mi) of
Venus on December 14, 1962.

The Mariner probe consisted of a 100 cm (39.4 in) diameter hexagonal bus, to which solar panels (also “solar modules,” “photovoltaic module,” or “photovoltaic panel”), a packaged, connected assembly of photovoltaic cells, instrument booms, and antennas (“aerial”), an electrical device which converts electric power into radio waves, and vice versa, were attached The scientific instruments on board the Mariner spacecraft were: two radiometers (one of each for the microwave--radio waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz--and infrared light (“IR”) portions--electromagnetic radiation with longer wavelengths than those of visible light extending from the nominal red edge of the visible spectrum at 0.74 micrometres to 300 micrometers--of the electromagnetic spectrum, the range of all possible frequencies of electromagnetic radiation), devices for measuring the radiant flux (power) of electromagnetic radiation; a micrometeorite (a tiny meteor: a small particle of rock in  space, usually weighing less than a gram) sensor; a solar plasma (in physics and chemistry, is a state of matter similar to gas in which a certain portion of the particles is ionized) sensor; a charged particle sensor; and a magnetometer, a measuring instrument used to measure the strength and perhaps the direction of magnetic fields.

These instruments were designed to measure the temperature distribution on the surface of Venus, as well as making basic measurements of Venus’ atmosphere, a layer of gases that surrounds Venus and that is held in place by the gravity of the planet. Due to the planet’s thick, featureless cloud cover, no camera, or a device that records images that can be stored directly, transmitted to another location, or both, were included in the Mariner unit. Mariner 10, an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus, later discovered that extensive cloud detail was visible in ultraviolet (UV) light, electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, that is, in the range 10 nm to 400 nm, corresponding to photon energies from 3 ev to 12 eV.

See: SpaceX CRS-1's Mission Plan: Flight Day 1 and 2 (October 8-9)