Mars is the fifth planet from the Sun, often termed the "red planet," due to that fact that it gives of a reddish appearance that comes from iron oxide in the surface. Mars has two moons: Deimos, and Phobos. An average day on the planet Mars is 24 hours and 36 minutes (in terrestrial terms), while the planet taken 587 terrestrial days to revolve around the sun. The planet has been known to mankind since its earliest days. Many early civilizations often referred to it as the "red one", as it looked like a red star with the naked eye. Mars is one of only three Worlds inhabited by Humans (the others being Earth and the Moon) with a population as of 2014 of 112.
Mars-1, launched on November 1, 1962, was the first man-made object or spacecraft of any kind to reach the planet Mars. Launched by the Soviets in order to gain information about Mars the spacecraft flew by in May 1963 at an altitude of 100,000 km but was unable to return any information about the Planet.
In 1964, NASA's Jet Propulsion Laboratory made two attempts at reaching Mars. Mariner 3 and Mariner 4 were identical spacecraft designed to carry out the first flybys of Mars. Mariner 3 was launched on November 5, 1964, but the shroud encasing the spacecraft atop its rocket failed to open properly, dooming the mission. Three weeks later, on November 28, 1964, Mariner 4 was launched successfully on a 7½-month voyage to the red planet.
Mariner 4 flew past Mars on July 14, 1965, providing the first close-up photographs of another planet. The pictures, gradually played back to Earth from a small tape recorder on the probe, showed impact craters. It provided radically more accurate data about the planet; a surface atmospheric pressure of about 1% of Earth's and daytime temperatures of −100 °C (−148 °F) were estimated. No magnetic field or Martian radiation belts were detected. The new data meant redesigns for then planned Martian landers, and showed life would have a more difficult time surviving there than previously anticipated
NASA continued the Mariner program with another pair of Mars flyby probes, Mariner 6 and 7. They were sent at the next launch window, and reached the planet in 1969. During the following launch window in 1971 the Mariner program again suffered the loss of one of a pair of probes. Mariner 9 successfully entered orbit about Mars, the first spacecraft ever to do so, after the launch time failure of its sister ship, Mariner 8. That same year Mars-2 and Mars-3 also entered orbit around Mars and dropped two landers Mars-2 and Mars-3 (each with their own mini-rover).
NASA launched the famous Viking 1 & 2 landers the following opportunity in 1973. These Orbiter/Lander system provided the basis for all future unmanned Mars Missions rather than the outdated Mariner system. The Viking 1 & 2 orbiters mapped the entire planet in unprecedented high resolution and continued to provide data for four years (losing contact in 1978) while the Viking 1 & 2 orbiters explored the surface of Mars for four to six years (losing contact in 1978 and 1980). All the evidence pointed to at least the existence of past-life, rivers, lakes and oceans and remnants of that life either living or fossilized.
Viking 3 & 4 along with a Mars Explorer Orbiter were subsequently launched in 1975. By the time they arrived the original Viking Orbiters and Landers were still operating allowing cooperation and communication between the various robotic outposts in orbit and on the surface.
Viking 5 & 6 followed in 1977 but with one notable difference from all the previous Viking spacecraft. These landers were themselves modified into mobile laboratories or "Rover" that could traverse km of the Martian sand. Mars also received a High Data Rate Orbiter and another Mars Explorer Orbiter. By now there were six Viking landers (of which two were rovers), six Viking orbiters, two Mars Explorer Orbiters and one high data rate orbiter.
In 1978 the Viking 1 & 2 orbiters were deliberately crashed into Mars's moon Phobos to prevent contamination of the Martian environment with Earth microbes.
In 1979 a single spacecraft named Viking 7 was launched as a partial replacement. This Orbiter/Lander combo also deployed the third Viking Mars Rover. This event was captured live in the 1979 PBS Television Documentary Series "Cosmos: A Personal Voyage" hosted by Carl Sagan.
In 1981 as preparation for NASA's then upcoming Manned Expedition to Mars planned for the following year three separate spacecraft were dispatched to help update and partially replace the aging 1970s fleet. One Mars High Data Rate Orbiter, One Mars Explorer Orbiter and a single Orbiter/Rover combo named Viking 8 (the final in the Viking series).
On November 12, 1981 the first Manned Expedition to Mars launched from the 50-Person Space Base in Low Earth Orbit after a full year of assembly in Space. Each Mars expeditionary Vehicle (MEV) required three NERVA shuttles, one Space Station Module and one Mars Excursion Module. The two Nuclear spacecraft in convoy each with a crew of six arrived in a highly elliptical Mars orbit on August 9, 1982 and after a few weeks the eight survey crew members arrived at the desired landing site (previously scouted by Viking Rovers) while the four Orbital "skeleton" crews remained in Mars Orbit maintaining the MEVs.
After a full 60 days on the Martian surface exploring hundreds of square miles in lond duration Rover traverses the crews returned to Mars Orbit and departed for Earth on 28 October 1982. The next crew arrived just one year later in 1983 having already launched while the first Manned Expedition was still ongoing. In 1986 a third Manned Mars Expedition established a temporary 12-person outpost on the surface before the fourth mission in 1988 established a permanent 48 person surface base and 24 person orbital base (leading to 72 people in the Mars System in 1988).In August 2012 SpaceX became the first private company to deliver commercial crew and cargo to the surface of Mars. Tickets are currently being sold for $20 million for a round-trip stay. The second such mission scheduled to arrive in September 2014.