Space Exploration Milestone - Mariner 2 50 Years Later
December 13, 2012

50th Anniversary Of First Step Of Planetary Exploration

[ Watch the Video: The 50th Anniversary of Planetary Exploration ]

Lee Rannals for - Your Universe Online

Fifty years ago this Friday, America's space exploration ushered in a new era when NASA's Mariner 2 spacecraft became the first ever to study a planet other than our own.

On December 14, 1962, Mariner 2 became the first spacecraft to successfully make a close-up study of another planet. The event took place about 36 million miles away from Earth.

To celebrate the occasion, NASA's Jet Propulsion Laboratory, which built the spacecraft, released an interactive presentation highlighting 50 years of planetary exploration.

JPL said the first Mariners were built on a demanding schedule, and had three probes in less than a year.

The Soviet Union first tried to get a spacecraft to Venus, but failed in their attempts in 1961. The rocket carrying NASA's first attempt, Mariner 1, was self-destructed four minutes and 53 seconds into flight.

Mariner 2 launched August 27, 1962 from Cape Canaveral, but the lift off was not at all smooth. During its launch, the rocket began to roll, and it was unable to accept guidance commands. The electrical short causing the issue was mysteriously fixed after about a minute and all was okay.

While Mariner 2 was on its way towards Venus, NASA said it encountered many problems that nearly ended the mission.

"Among these were a solar panel that twice stopped working, a balky sensor designed to locate Earth and gyros that mysteriously misbehaved," NASA said in a press statement remembering the spacecraft. "Most troubling of all, temperatures on the spacecraft climbed to alarming levels as Mariner 2 drew closer to Venus. Mission controllers worried the spacecraft might cook itself before reaching its destination."

After traveling for a few months in the abyss, Mariner 2 glided within just 21,564 miles of Venus, during which the spacecraft produced the first close-up measurements of Venus' scorching surface temperature.

This science mission helped confirm scientists' hypothesis of a "greenhouse" effect that trapped heat from the sun under an atmospheric blanket. The spacecraft's tracking also enabled navigators to use radio signals to measure the effect of Venus' gravity on the spacecraft and calculate the most precise figure ever of the planet's mass.

During Mariner 2's cruise phase, it was the first to confirm the existence of the solar wind, which is the steam of charged particles flowing outward from the sun.

Data from the mission also enabled scientists to refine the value for the average distance between Earth and the sun. Mariner 2 also showed that micrometeorites and the radiation environment were not significant threats in that part of the solar system.

"There will be other missions to Venus, but there will never be another first mission to Venus," Mariner 2's project manager Jack James of JPL reflected before his death in 2001.

Mariner 2 was the stepping stone for NASA's exploration beyond our own planet, including rovers on Mars, probes around Saturn, and the Viking twin spacecraft, which are in the process of leaving our Solar System, 37 years later.