Exploration of Mars
The Viking program launched "Viking 1" and "Viking 2" spacecraft to Mars in 1975; The program consisted of two orbiters and two landers – these were the first two spacecraft to successfully land and operate on Mars.
The primary scientific objectives of the lander mission were to search for biosignatures and observe meteorologic, seismic and magnetic properties of Mars. The results of the biological experiments on board the Viking landers remain inconclusive, with a reanalysis of the Viking data published in 2012 suggesting signs of microbial life on Mars.
The Viking orbiters revealed that large floods of water carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. Areas of branched streams, in the southern hemisphere, suggest that rain once fell.
2012 in spaceflight
The year 2012 saw a number of significant events in spaceflight. In May and October, the first Commercial Orbital Transportation Services resupply missions took place, during which the SpaceX Dragon became the first private spacecraft to dock with the International Space Station (ISS). In June, China launched the manned Shenzhou 9 orbital mission, and North Korea achieved its first successful orbital launch in December. 2012 also saw China's first successful asteroid exploration mission, and the landing of NASA's "Curiosity" rover on Mars. The Vega and Unha-3 rockets made their maiden flights in 2012, while the Proton-K made its last.