What Was NASA’s First Successful Planetary Probe Launch and What Planets Did the Mariner Space Probes Visit?

Mariner 2, the first successful planetary probe launch, was sent into Earth’s orbit on August 27, 1962.

From there a rocket fired it on a 4-month journey to Venus.

On November 28, 1965, Mariner 4 came within 540 miles (870 km) of Mars and sent back the first pictures of the planet’s surface.

Mariner 6 and Mariner 7 (1969) both took detailed pictures of approximately 10 percent of the Martian surface, but missed some of the most interesting geological features later discovered by Mariner 9.

Mariner 9 (1971) was the first satellite to enter into orbit around Mars.

After waiting out a Martian dust storm, Mariner 9 sent back pictures of the entire planet.

Mariner 10, the final Mariner probe, had a dual mission. On February 5, 1974, it flew by Venus and transmitted more than 3,000 pictures of the planet’s surface.

It then went on to Mercury.

Mariner 10 photographed approximately 40 percent of Mercury’s surface before entering into orbit around the Sun.

In this orbit, the probe was able to pass by Mercury twice more: over the south pole and over the dark side of the planet.

The Mariner program was hailed as a great success.