Mars exploration has been a serious priority of the world's larger space programs ever since 1960, when the Soviet Union attempted to launch the space probes Korabl 4 and Korabl 5 to the Red Planet as part of the Marsnik program. The rockets propelling these probes failed to provide sufficient thrust, and both fell back and burned up in the atmosphere after barely making it into outer space. This would the first in a long line of failed and half-failed Mars missions.
Between 1960 and 1964, the Soviets failed to get probes to Mars on seven additional occasions, with the probes either failing on launch or ceasing communications prior to reaching the planet. The first successful probe to Mars was Mars 2, which arrived in orbit around the Red Planet on 27 November 1971. Its lander, which was supposed to land and take measurements, crashed on the surface of Mars at 6 km/s (13,421 mph) when the descent system on the module malfunctioned. Still, this was the first man-made object to reach the surface of Mars, and therefore a milestone in Mars exploration.
NASA launched several probes to Mars in the 1960s, including Mariner 4, which flew past Mars on 14 July 1965, providing the first close-up pictures of another planet. Upon arrival in the orbit of Mars, another NASA probe, Mariner 9, observed a planet-wide dust storm, the first and only example of this phenomenon currently known. Planet-wide dust storms are impossible on Earth because of the oceans and the small percentage of the Earth's surface covered by desert. In contrast, Mars is covered in 100% desert.
The Golden Age of Mars surface exploration by space probes was in the late 1970s, when the Viking 1 and Viking 2 landers reached Mars, providing the first close-up shots from the surface of another planet. These probes also tested the soil for organic molecules, which they did not find, disappointing many who were hoping for signs of microbial life on Mars. The missions also contributed to Mars exploration by including orbiters that stayed in orbit for many months, sending back information about the planet to Earth.
The most highly anticipated facet of Mars exploration is that of landing a man on Mars. However, the 50% success rate of previous Mars space probe missions gives cause for concern. If a spaceship to Mars were to suffer a technical malfunction, miss its target, or fail to leave the surface on the way back, then the astronauts would be stranded, and probably forced to consume cyanide capsules to avoid dying of dehydration. This would forever leave a blight on space exploration. Still, NASA is still tenatively making plans for manned Mars mission, likely to occur sometime after 2030.
Michael is a longtime WiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.