Mission crew members unveiling a print-out of the Mariner 2 flyby of Venus
On 14 December 1962, the Mariner 2 became the first spacecraft to perform a successful planetary flyby of Venus.
It passed the planet at about 34,773 kilometers.
The NASA Mariner program
Mariner 2 was the second spacecraft in the NASA Mariner program, sometimes also called the Mariner R missions. The first launch of the program, Mariner 1, malfunctioned shortly after launch and wasn't able to clear Earth's atmosphere.
The Mariner 2 was launched on 27 August 1961.
Launch of the Mariner 1 - Image: NASA
It was planned to launch with a Atlas-Centaur stage, but because of delays with the launch vehicle, the less powerful Atlas-Agena B rocket was used.
That meant less equipment aka experiments could be hauled up into space.
The Mariner 2 Probe
The Mariner 2 probe weighted about 202 kilograms and measured 3.35 meters in width with it's solar panels deployed.
The fact that the Mariner 2 was the first the first probe to ever reach another planet makes it a true milestone.
But luckily the Mariner 2 mission also had other goals!
Mission objectives were to study the surface and atmosphere of Venus and while it was making it's way over to the planet, also measure the solar wind, the high-energy particles flowing out from the Sun.
The experiments reveelaed the atmosphere to be very hot, 500 degrees Celsius (900 degrees Fahrenheit).
It also confirmed some of the findings about the solar wind that were first done by the Soviet Luna 1 mission in 1959.
After the Venus flyby, the Mariner 2 continued in a heliocentric orbit. The last communication was received on 3 January 1963, officially ending the mission 129 days after launch.