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.
Mercury-P
"Mercury-P" would be the first lander on Mercury. A proposed flight scenario for the mission included a flyby of Venus, the insertion of the spacecraft into the orbit around Mercury and the delivery of a lander on its surface. The Institute of Space Research studied the possibility of "recycling" hardware developed for the Phobos-Grunt, Mars-NET, Mars-96, and Solar Sail spacecraft, with proposed upgrades of the hardware. As of 2012, Russian scientists have conducted a preliminary concept study of the project, and compiled a list of the required scientific payload.