1960: The first launch opportunity to Mars in the "Space Age" occurred in 1960. The Soviet Union launched the world's first Mars probes. Little is known about the spacecraft, which were intended to complete a fly-by of Mars. The spacecraft never received names. The first was launched on October 10, 1960 and the second was launched on October 14, 1960. Due to launch vehicle failures, neither spacecraft reached Earth orbit and these attempts are still considered to be unofficial.
1962: During the Mars launch opportunity in 1962, the Soviet Union launched three spacecraft toward the Red Planet. All three were designed to complete a fly-by of Mars.
Sputnik 22 was launched on October 24, 1962. The final stage of the launch vehicle exploded while being accelerated to Earth-escape velocity, and the spacecraft was lost.
Mars 1 was launched on November 1, 1962 and was the first spacecraft placed on a successful course toward Mars. Contact with Mars 1 was lost on March 21, 1963 as the spacecraft was about 65.9 million miles from Earth. It had yet to complete a Mars fly-by when contact was lost, but could have passed between 620 and 6,700 miles of Mars on its course.
Sputnik 24 was launched on November 4, 1962. Like Sputnik 22, the final stage of the launch vehicle exploded while being accelerated to Earth-escape velocity and the spacecraft was lost.
1964: The United States entered the race to Mars with the launches of two spacecraft during the 1964 opportunity, both of which were designed to complete a fly-by of Mars. Mariner 3 was launched on November 5, 1964 but the shroud surrounding the spacecraft failed to separate and it could not be placed on a Mars trajectory.
Mariner 4 was launched on November 28, 1964. The spacecraft completed the first confirmed Mars fly-by on July 14, 1965 and transmitted 21 complete photos and one incomplete photo of Mars over the next ten days. These were mankind's first close-up photos of another planet. Mariner 4 was about 6,100 miles from Mars at its closest approach.
The Soviet Union launched one spacecraft to Mars in 1964. Zond 2 was launched on November 30, 1964 to complete a Mars fly-by. Like Mars 1, contact with Zond 2 was lost before it reached Mars, but the spacecraft could have passed within 930 miles of the planet on its course.
1969: The next two spacecraft were launched to Mars during an opportunity in 1969. The United States launched Mariner 6 on February 24, 1969 followed by Mariner 7 on March 27, 1969. Both spacecraft completed a successful Mars fly-by, returning a total of 201 television pictures of Mars back to Earth.
1971: Launch opportunities in 1971 produced the world's first landings on the Red Planet, with a total of five United States and Soviet spacecraft launched to Mars that year. United States missions were restricted to Mars orbital attempts, while the Soviet Union attempted three Mars landings.
The United States launched Mariner 8 on May 8, 1971 as the first spacecraft designed to orbit Mars. The second stage of the launch vehicle malfunctioned, and the spacecraft impacted the Atlantic Ocean about 900 miles downrange of Cape Canaveral.
Cosmos 419 was launched by the Soviet Union on May 10, 1971. This was the first attempt at sending both a Mars orbiter and Mars lander to the Red Planet. The payload failed to separate from the fourth stage of the launch vehicle, and Cosmos 419 reentered Earth's atmosphere two days after launch.
The Soviet Mars 2 was launched on May 19, 1971 and also included a Mars orbiter and Mars lander. The Mars 2 lander was supposed to make a soft landing on Mars. Although it crashed on Mars and was destroyed on November 27, 1971 it was credited with carrying the first national flag to the Martian surface. Orbit of the Mars 2 orbiter was successful.
This was followed by the Soviet launch of Mars 3 on May 28, 1971. The Mars 3 lander made a successful Martian soft landing on December 3, 1971. It was severely damaged during a raging dust storm and transmitted just 20 seconds of data, including the first hazy television images from the Martian surface. Orbit of the Mars 3 orbiter was successful.
The United States launched Mariner 9 on May 30, 1971. Although it was launched later than the Soviet spacecraft, it arrived at Mars earlier and achieved the first successful orbit of Mars on November 13, 1971. It remained operational in Martian orbit through October 27, 1972 and transmitted 7,329 photos plus a wealth of scientific data back to Earth.
1973: United States Mars efforts remained dormant during the 1973 launch opportunity, during which the Soviet Union launched four spacecraft to Mars. Mars 4, a Mars orbiter, was launched on July 21, 1973 but zipped past Mars when its retrorockets failed to fire.
Mars 5, also a Mars orbiter, was launched on July 25, 1973. Although it achieved an orbit of Mars, the spacecraft stopped transmitting data back to Earth after just a few days in orbit.
The Soviets also launched two Mars soft landers in 1973. On approach to Mars, these landers separated from a parent craft that was not designed to orbit Mars. Mars 6 was launched on August 5, 1973. The lander crashed on Mars, but did provide the first direct scientific measurements of the Martian atmosphere as it descended.
Mars 7 was launched on August 9, 1973. The Mars 7 lander separated from its parent craft prematurely, and never completed a landing. It flew a minimum distance of about 800 miles from Mars before passing the planet entirely.
1975: Although the United States had fallen behind the Soviet Union in landing spacecraft on Mars, this changed during the 1975 launch opportunity. The United States launched Viking 1 on August 20, 1975 and Viking 2 on September 9, 1975.
Both spacecraft included a Mars orbiter and a Mars lander. The attached Viking orbiter and lander first achieved an orbit of Mars, then the lander was separated to perform a soft landing. This differed from the Soviet approach, whereby the lander separated from its parent spacecraft prior to an orbit being achieved.
Viking 1 achieved an orbit of Mars on June 19, 1976. The Viking 1 lander successfully soft landed on July 20, 1976. Viking 2 achieved an orbit of Mars on August 7, 1976. The Viking 2 lander successfully soft landed on September 3, 1976.
The success of the Viking missions was unprecedented, although neither spacecraft was able to fulfill its ultimate mission, the search for life on Mars. Neither life nor traces of life were located. But, the Viking orbiters and landers transmitted over 50,000 photos of Mars and a treasure trove of scientific data that is still being analyzed.
1988: Mankind did not return to Mars until the 1988 launch opportunity, when the Soviet Union launched two spacecraft. Both were designed to orbit Mars and perform scientific research in particular regarding Phobos, one of the two Martian moons.
Phobos 1 was launched on July 7, 1988 but a ground control error caused communication with the spacecraft to be lost before it reached Mars. Launch of Phobos 2 followed on July 12, 1988, but communication with the spacecraft was lost as it attempted a fly-by of Phobos.
1992: Mars exploration in the 1990's has been dominated by the United States. The Mars Observer was launched on September 25, 1992. It was a huge, elaborate spacecraft intended to carry out a plethora of scientific observations during a four-year orbit of Mars.
Contact with the Mars Observer was lost on August 21, 1993 when it was just three days away from achieving orbit. The exact cause is unknown, but it is presumed that the spacecraft exploded when its fuel tanks were being pressurized in preparation for a Mars orbit attempt.
1996: Two United States and one Russian spacecraft were launched to Mars during the 1996 opportunity. The United States launched the Mars Global Surveyor on November 7, 1996. It achieved a Mars orbit on September 12, 1997 and began scientific observations, including an extensive mapping survey, in March, 1998. Its expected life span is through January, 2000.
Russia launched the Mars 96 spacecraft on November 16, 1996. It incorporated two Mars soft landers and two Mars penetrating probes, but unfortunately the spacecraft was lost due to a failure of the launch vehicle.
The Mars Pathfinder remains one of the most popular and successful Mars explorations, and was launched by the United States on December 4, 1996. It incorporated a Mars lander and encapsulated Mars rover, which completed a soft landing on July 4, 1997.
Landing of the Mars Pathfinder and deployment of the Mars rover captured the attention of the world, with many of the photographs presented to the public in real time via television and the Internet. The Mars Pathfinder transmitted pictures and data from the Martian surface through September 27, 1997.
1998: The nation of Japan launched its first spacecraft to Mars during the 1998-99 launch opportunity. The Japanese Nozomi (Planet-B) Mars orbiter was launched on July 4, 1998. Its scheduled Mars arrival date is October, 1999.
The United States launched two spacecraft to Mars in 1998-99. The Mars Climate Orbiter was launched on December 11, 1998 and was intended to be the first permanent Martian weather satellite.
The Mars Climate Orbiter was lost on September 23, 1999 due to a ground control calibration error which caused the spacecraft to fly too close to the planet. It is believed to have burned up in the Martian atmosphere.
But, another United States Mars lander presses on toward the Red Planet. The Mars Polar Lander/Deep Space-2, which includes a soft lander and two surface penetrating probes, was launched on January 3, 1999. It is expected to attempt a Mars landing in December, 1999.
These Mars explorations spanning four decades have been carried out in order to pave the way for a manned exploration of the Red Planet. However, no nation is currently pursuing a program in support of the manned exploration of Mars. Such a mission may be considered following completion of the International Space Station.
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