In 1960, when Eisenhower's administration began planning and funding for the famous Apollo program that would land the first men on the Moon in 1969, the Soviet Union was already thinking further ahead, literally. In one of the worst kept secrets of the Space Race, the Soviet Union launched two probes, Korabl 4 and Korabl 5, toward Mars in October 1960. Meanwhile, throughout the 1960s, NASA would spend tens of billions on missions to the Moon, the most expensive peacetime program in American history to that point, and Apollo was only made possible by the tests conducted through earlier missions, including the historic Ranger Program.
When the Soviet Union attempted to launch probes to Mars in 1960, the goals were considerably less ambitious than saying hello to little green men. Those first two probes were intended merely to fly by Mars and transmit photos of the planet. In addition to getting closer looks at the Red Planet than ever before, the true value of those 1960 missions was the propaganda victory the Soviets hoped to score, obtaining yet another notch in their Space Race belt. The descent module aboard Mars 2 crash landed on Mars' surface on November 27, but less than a week later, Mars 3's descent module began its historic descent down to the surface. On December 2, 1971, after a few hours of descending, it successfully completed its "soft landing." Mars 3's lander was poised to become the first functional probe on Mars' surface, but within seconds of landing on Mars, all communications ceased. The reason for this sudden failure is still uncertain today, with the likeliest explanation being that the lander had landed in the middle of a powerful dust storm that quickly knocked it over.
While Mars 3's descent module failed, Mariner 9 spent hundreds of days orbiting around Mars, taking pictures and mapping the Red Planet's surface. In addition to giving NASA a much better understanding of the geography and topography of the Martian surface, it determined potential landing sites for the upcoming Viking missions.
Several years before Mariner 9's successful orbiting mission, NASA had begun designing missions for unmanned landings on Mars that would use a spacecraft consisting of an orbiter module and a landing module. The design of the modular spacecraft came from NASA's successful use of a similar spacecraft delivery system for the Apollo program's manned missions to the Moon.
The Viking 1 landing on Mars had originally been scheduled to coincide with the nation's bicentennial on July 4, 1976, but the dual celebration did not work out as planned because the original landing site was found to be unfit due to the number of large boulders that would be able to upend the craft upon landing. By then, Viking 1 had been heading to Mars for nearly a year, and Viking 2 was on its way as well. Viking 1's lander would successfully land on the Red Planet on July 20, 1976.
Both Viking landers were huge successes just for landing on Mars and transmitting data, but they would end up exceeding NASA's wildest expectations. NASA hoped the Viking missions would provide better images of Mars' surface and the ability to determine the chemistry and biology of the soil, which might indicate signs of life. The Viking missions ended up providing an extremely comprehensive overview of the Martian surface and atmosphere.
The Viking orbiters successfully orbited around Mars thousands of times, and the Viking landers were even more successful. Both Viking landers functioned on Mars' surface for several years, successfully analyzing Martian soil, analyzing Mars' weather and atmosphere, searching for life, and taking pictures from the surface. After nearly four years, Viking 2's battery failed, but Viking 1's lander continued transmitting data. In fact, Viking 1's lander only stopped functioning after a human error at NASA inadvertently shut down the lander's antenna, over six years after it had landed on Ma...
