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Past Missions

For nearly 50 years, our civilization has been attempting to send spacecraft to Mars. By the beginning of the 21st century, only 10 missions out of 33 tries had been a complete success. Journey with us down the rocky road of Mars exploration.


Mars 1969A: March 27, 1969
Mars 1969B: April 2, 1969

By the Spring of 1969, the Soviet Union was losing the race for the Moon, had found success with a Venus probe, and once again set its sights on Mars.

A new Soviet Mars exploration series called M-69 had been born two years earlier. It involved a non-stop schedule of exhaustive work to make it to the 1969 launch window. The goal of the program was to explore Mars with an orbiter and release a probe that would examine the Martian atmosphere. Science instruments included three television cameras, water vapor and radiation detectors, and several spectrometers. The mission also was designed to gather information that could be used to attempt a soft landing on the Martian surface in 1971. These were two spacecraft that were never officially announced by the Soviet Union. M-69 was a name that appeared in later Soviet publications. American documents list them as Mars 1969A and Mars 1969B.

The launch of Mars 1969A seemed to proceed smoothly. The first two stages of the Proton rocket operated normally, but the third stage caught fire and exploded. A few days later, Mars 1969B was on the launch pad at Baikonur. But it, too, would never see the Red Planet. Once again the Proton exploded, this time almost immediately after lift-off spewing deadly rocket fuel over the entire launch complex. The Proton rocket, its payload, and two years of hard work ended in a fireball.


Mariner 6: Feb. 5, 1969
Mariner 7: March 27, 1969

In July of 1969, Mariner 6 and 7 were closing in on Mars, but all eyes were focused on the Moon. On July 20 astronaut Neil Armstrong made space exploration history when he took a "giant leap for mankind." As America was enjoying this magnificent accomplishment, the twin Mariner probes examined the surface and atmosphere of Mars.

Mariner 6 successfully flew by Mars on July 31. It returned 75 images of surface features near the equator and carried out several atmospheric experiments. But this successful finish had a shaky start. Mariner 6 was a heavy vehicle and it needed a powerful rocket. It was the first mission to launch on the new, more robust Atlas/Centaur. But a few days before lift-off, a faulty switch on the Atlas caused a loss of pressure. The booster started to buckle. Fast thinking and pressurized pumps saved the structure. Mariner 6 was quickly moved to another Atlas/Centaur and the spacecraft was still able to launch on schedule.

Mariner 7 encountered the Red Planet on Aug. 4, but it, too, had a problem. A battery exploded a few days before reaching Mars. The damage affected the imaging system and engineers scrambled to fix it. Luckily, the spacecraft carried something new on board - a reprogrammable computer. With the imaging problem solved, Mariner 7 was able to record more than 100 pictures of Mars including several close-ups of the planet's southern hemisphere.

By the end of the mission, the wide and narrow-angle television cameras on the twin probes returned 200 images including a picture of the Martian moon Phobos. Mariner 4 had seen a Mars that was moon-like, but now a somewhat more interesting planet was coming into focus. Still, none of the images gave any real hint that Mars might be a planet with spectacular surface features and a geologically complex past.

The Mariner craft also carried science instruments that measured ultraviolet and infrared radiation and found dust and clouds in the Martian atmosphere. Like Mariner 4, a radio-occultation experiment confirmed the presence of a thin atmosphere at very low pressure.

Mariner 6 and 7 were the last successful US spacecraft to use the flyby method to explore Mars. There was more trouble ahead, but the Mariner series would end on a high note with an orbiter called Mariner 9.


Zond 2: Nov. 30, 1964
Zond 3: July 18, 1965

The Soviet Union also took advantage of the launch window to Mars in 1964. Two days after America launched Mariner 4, the USSR put Zond 2 into space. But the fate of the two spacecraft would be very different.

Like Mariner 4, Zond 2 was supposed to image the martian surface on a flyby trajectory. Science equipment included instruments to detect ozone, radiation, and micrometeorites. An experimental attitude control system consisted of six electric plasma jet engines. But only two days after lift-off, Zond 2 was in trouble. The probe's power output was cut in half when one of its solar panels failed to open. Under these conditions, scientific experiments took a backseat to maintaining contact with the spacecraft. But efforts to communicate with Zond 2 failed in May of 1965. While Mariner 4 was returning the first close-up images of the martian surface in July of that year, Zond 2 was silent. The spacecraft passed Mars on Aug. 6, but no information was returned.

The USSR routinely launched planetary spacecraft in pairs. But Zond 2's sister ship Zond 3 did not see lift-off until July of 1965, a time far outside of the normal launch window for Mars. This late launch date made a flyby of Mars impossible, but still allowed for an engineering test flight of the spacecraft. Because the USSR had experienced several failures of planetary craft, a test of their spacecraft systems seemed appropriate. Zond 3 was put on a Mars trajectory and the Soviets announced that they would be conducting scientific research in interplanetary space. But there was an additional goal to this mission. Less than two days after lift-off, Zond 3 passed by the moon and returned 25 images of the far side of the lunar surface. It used a photo-television system with automatic film processing. Film was exposed through a series of lenses, processed, and then scanned by a television camera that sent the signals to Earth.

Zond 3 also carried instruments to monitor the solar wind, cosmic rays, magnetic fields, and radio emissions. It reached the orbit of Mars, though of course the planet was not there due to the launch time. Still, Zond 3 was regarded as a success. It proved that the USSR had a camera system that could return high quality photographs and it proved that Soviet planetary spacecraft could function properly for long periods of time in deep space. Zond 3 went into orbit around the Sun, and contact was maintained until March of 1966 when it was at a distance of more than 337 million miles from Earth.


Mariner 3: Nov. 5, 1964
Mariner 4: Nov. 28, 1964

The next launch window for Mars was open and this time America was ready. Mariner 3 and 4 would join the growing list of craft, both piloted and robotic, that ventured into space. It was a time when the United States was transitioning from the single-pilot Mercury Project to the dual-pilot Gemini missions. The Soviets had completed their Vostok missions, and had just become the first to launch a multi-person crew in a mission called Voskhod 1.

Mariners 3 and 4 were part of NASA's plan to explore the planets, using twin robotic spacecraft to increase the odds of success. The idea proved to be a sound one. Mariners 1 and 2 were destined for a flyby of Venus back in 1962, but only Mariner 2 was successful. Mariners 3 and 4 were to fly by the Red Planet and return images of its surface. Only Mariner 4 made it.

Mariner 3 encountered trouble immediately after launch. The aerodynamic shield, or "fairing", that protected the spacecraft during the rocket's ascent through the Earth's atmosphere failed, and the crippled Mariner 3 never entered the proper trajectory for Mars.

After a frantic effort to redesign and test the Atlas launch vehicle's fairing in just three weeks, Mariner 4, was launched and became the first successful mission to Mars. It flew past Mars on July 14 and 15, 1965 and was the first spacecraft to return close-up images of the surface. It was a moment in history that would forever change ideas about life on Mars. Fanciful theories about canals and vegetation were put to rest. In Mariner 4's 21 pictures, the Red Planet was seen to be barren and riddled with craters. An experiment to measure the composition of the martian atmosphere also dashed long-held hopes that Mars might be a twin of Earth. As the craft passed behind the planet, its radio signal was attenuated by the atmosphere. Scientists analyzed this "radio occultation" data and calculated that the atmosphere of Mars was very thin and surface pressure very low. They combined these results with previous Earth-based research and found that the martian atmosphere was composed mostly of carbon dioxide gas.

Mariner 4 also carried instruments to study cosmic dust, solar plasma, radiation belts, and magnetic fields. It continued past Mars and returned data until October of 1965. Contact with the spacecraft resumed again when it approached Earth late in 1967. A few tests were conducted until the radio signal became so weak the mission was terminated on December 21 of that year.

Mars had finally revealed a few of its secrets.


Sputnik 29 (Korabl 11): Oct. 24, 1962
Mars 1: Nov. 1, 1962
Sputnik 31 (Korabl 13): Nov. 4, 1962

Earth and Mars were once again in the proper alignment for a launch attempt and the USSR was ready. The country's robust space program had seen cosmonaut Yuri Gagarin become the first man to orbit the Earth in 1961. Astronaut John Glenn didn't make the trip until February of '62. The USSR was also flexing its military muscle. The Cuban missile crisis had the Cold War at full tilt. America and the world were anxious about any Soviet launch activity.

Sputnik 29 has a variety of names because the USSR did not acknowledge its existence. The spacecraft was supposed to photograph Mars on a flyby trajectory. The payload included a camera and several pieces of science equipment to gather data on martian radiation and magnetic fields. But Sputnik 29 failed to reach Earth orbit and broke apart when the Molnya rocket's fourth-stage engine failed. When US radar detected the chunks of metal, there was a brief moment of fear that the Soviets had begun a nuclear attack.

The second Soviet Mars attempt that fall appeared to be a success. The spacecraft was well on its way to the Red Planet and was returning a hefty supply of interplanetary data. The Soviet Union felt confident enough to tell the world about this accomplishment and gave the vehicle an official name - Mars 1. The primary objective of Mars 1 was the same as that of its predecessor -- to gather photographs of the planet on a flyby trajectory. The spacecraft was equipped with a television camera and science equipment to measure magnetic fields and cosmic radiation. But about halfway through the journey, on March 21, 1963, its signal was lost. Scientists estimate that its closest approach to the planet was probably on June 19, 1963, but Mars 1 was silent.

Sputnik 31 was another spacecraft never acknowledged by the Soviets. It was designed to put a lander on Mars. This time, the craft reached Earth orbit but failed while firing the rocket motor that would have put it on a trajectory for Mars. Sputnik 31 broke up into several large pieces and US radar tracked the debris once again.

Mars won the second round.


Marsnik 1 & 2: Oct. 10 & 14, 1960

It was the dawn of the "space race." The Soviet Union had launched Sputnik in 1957. This was the first artificial satellite and a resounding victory for the Soviets during the Cold War. The United States was caught by surprise and scrambled to put its own satellite into orbit. Reaching the moon was the eventual goal for both countries, but planetary exploration was also in the works. In 1960, the Soviets launched what would have been their first planetary probe - Marsnik 1. It was designed to investigate the interplanetary space between Earth and Mars and then fly by the Red Planet to gather images of its surface. The Soviets also wanted to test their ability to receive radio signals from such long distances and learn how the stress of spaceflight affected science instruments. The craft stood about 2 meters high and carried five science instruments on its exterior. A camera was tucked inside and was to have taken pictures of the martian surface through a viewport. Marsnik 1 also had two solar panels for power and a high gain antenna for radio communications. But the launch of Marsnik 1 was a failure. Its launch vehicle did not produce enough thrust to put the probe into the proper trajectory for Mars, and it fell back to Earth. Marsnik 2 was identical to Marsnik 1. The third stage of its rocket also failed during launch four days later. Mars had won the first round.

Web content editor/writer: Pamela R. Smith