On This Day in History: NASA's Viking 2 Makes a Second Landing on Mars

The Viking 2 mission that sought to find life on Mars landed on the red planet 46 years ago today.

NASA's Viking Project was a historic US mission that sought to land spacecraft safely on the surface of the Earth's neighboring Red Planet: Mars. It sought to collect data on Mars and transmit it back to Earth for scientists' research on Mars.

A pair of identical spacecraft made up of a lander and orbiter were built and sent off to Mars, NASA said. Viking 1 was launched on August 20, 1975 and landed on Mars on July 20, 1976 at Chryse Planitia or the "Golden Plain," while Viking 2 launched on September 9, 1975 and landed on September 3, 1976, exactly 46 years ago today. The price tag for the entire Viking program hardware was $1 billion in 1970s dollars, which is equal to $4 billion to $6 billion in today's money.

NASA's Viking 2 Mission

The purpose of NASA's Viking mission to Mars was not only to look for signs of life but to study the Red Planet's soil and atmosphere and take photos to transmit back to Earth. The mission was composed of the launches of Viking 1 and 2 aboard Titan-Centaur rockets. The two spacecraft arrived on Mars six weeks apart in 1976.

However, it was NASA's Viking 2 landing on September 3, 1976 that was more eventful and was even described as "dramatic" by Wired. This is because when the lander separated and began its descent on Mars, the orbiter's stabilization system unexpectedly blacked out for up to an hour. The Viking 2 craft also moved in such a way that its main antenna pointed away from Earth.

Scientists said that there was a short communications problem that caused the landing to occur some 31 seconds later than planned, but confirmed that there were no adverse effects to the mission. Viking 2 successfully landed in what is called Utopia Planitia, the largest impact crater on Mars. Scientists chose this landing spot because satellite images showed it had more moisture than the Golden Plain, where Viking 1 landed. Scientists also noted that Viking 2 appeared to touch down on a rock, as images of it showed that it was tilted, Space.com reported.

What to Know About the Viking Landers for NASA's Mars Mission

Each of the Viking landers for NASA's mission toMars stood seven feet tall and measured 10 feet wide and weighed about 1,270 pounds without fuel. Both Viking 1 and Viking 2 were made up of the lander body, which was a platform upon which scientific experiments were conducted, a bioshield, an aeroshell, a parachute system, a base cover, lander subsystems used for communicating back to Earth, power subsystems, and descent engines among others.

The Viking 2 was also equipped with an onboard computer with memory that stored instructions to guide the lander's first 22 days on Mars without any contact from NASA back on Earth. Its instructions were embedded in "two general-purpose computer channels with plated-wire memories (.pdf)," with each having an 18,000-word storage capacity. One was dedicated for the operation, while the other one served as a reserve.

While on Mars, Viking 2 performed an array of experiments involving Mars' soil, atmosphere, biology, meteorology, seismology, and more. In total, NASA's Viking mission successfully mapped most of Mars' surface and enabled scientists to understand the Red Planet's seasonal changes.