Seven Surprises From the First Flybys of Each Planet in the Solar System

As the New Horizons probe approaches Pluto, find out what wonders were uncovered by the first spacecraft to zip past other worlds

This artist's rendering shows New Horizons encountering Pluto and its largest moon, Charon. (JHUAPL/SwRI)

In the early hours of July 14, a NASA spacecraft will make a historic first encounter with Pluto, the beloved dwarf planet that currently sits about 2.9 billion miles from Earth. The New Horizons spacecraft will take the first close-range photos and scientific readings of the Pluto system, helping to clear up many mysteries of the dark, icy world and its strange flock of moons.

New Horizons won't orbit or land on Pluto, but will instead fly past and continue studying objects in a zone known as the Kuiper Belt—a vast area filled with the frozen remnants of the solar system’s building blocks. While that may seem like a brief visit, many space agencies and scientists know that a flyby can confirm truths and reveal hidden wonders about the planets and other objects that make up our celestial neighborhood.

Here are just a few of the accomplishments of the first probes to visit the other members of the solar system's planetary family:

Venus: Mariner 2, 1962

As the closest planet to Earth, Venus was the logical first target for a flyby mission. Launched on August 27, 1962, the Mariner 2 mission to Venus was the first spacecraft to successfully conduct a planetary encounter. It flew within 21,600 miles of Venus on December 14. Mariner 2 didn’t have a camera, but it did carry microwave and infrared instruments that revealed the surface of Venus is about 930 degrees Fahrenheit, hot enough to melt lead, and its atmosphere contains mostly carbon dioxide. The findings quashed any hopes that Venus might harbor surface life, but they did pave the way for more detailed planetary studies. In the late 1970s and early '80s, the Soviet Union sent a series of landers to Venus designed to function for a short time before succumbing to the incredibly hostile environment. The Venera probes completed the first-ever soft landing on another planet, made the first broadcast from the surface of another world, and took the first color pictures of the Venusian surface.


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