The Soviet planetary probe Mars 2 was the first human-made object to impact the surface of the planet Mars. The mission proceeded according to plan until arrival at Mars on November 27, 1971. As the spacecraft approached the planet, Mars was enduring a severe planetwide dust storm that likely overwhelmed the Mars 2 lander and caused it to crash.
The 1971 Mars planetary launch window saw the successful flight of a new generation of Soviet Mars spacecraft. Mars 2 was launched at sixteen hours, twenty-two minutes, forty-nine seconds Greenwich mean time, on May 19, 1971, by a Proton booster from the Baykonur Cosmodrome in Kazakhstan, Soviet Union. This marked the first successful use of the giant 1,002,000-kilogram-thrust Proton booster in a Soviet planetary launch. Vladimir N. Chelomei was the designer of the Proton launch vehicle. After circling Earth once in a temporary parking orbit, Mars 2 was successfully injected into a planetary transfer orbit at seventeen hours, fifty-nine minutes on May 19, 1971. Its twin, the Mars 3 spacecraft, was launched May 28, 1971, and a third Soviet Mars launch failed on May 10, 1971, when booster failure left Cosmos 419 trapped in Earth orbit.
The new Mars probes weighed 4,650 kilograms, more than half of this weight being fuel for a rocket burn to enter Mars orbit. The probes consisted of two sections, the main spacecraft bus that would enter orbit around Mars and a 450-kilogram Mars landing capsule. The 4.1-meter-tall spacecraft were built around a 1.8-meter-diameter cylindrical body, which housed the fuel tanks containing nitric acid and amine-based propellants for the 9.86- to 18.89-kilonewton-thrust KTDU-425A course correction and Mars orbit insertion engine. A pressurized 2.3-meter-diameter toroidal flare at the base of the spacecraft bus carried the command, communications, and navigation equipment. Atop each Mars craft was a 1.2-meter-diameter sterilized landing capsule, nested under a 2.9-meter-diameter conical heat shield. Extending from the sides of the spacecraft were two 2.3- by 1.4-meter solar panels, spanning a total of 5.9 meters. Radiator panels for radiating excess heat were mounted on the back side of the solar panels. A 2.5-meter-diameter high-gain dish antenna extended from the side of the craft.
Mars 3 spacecraft.
During the flight to Mars, studies of the solar wind and cosmic rays were carried out. While en route to Mars, Mars 2 made three course corrections. The first was performed on June 17, when the craft was 7 million kilometers from Earth. The second was performed on November 20, a week before arriving at the planet. Before ejecting its landing capsule and entering Mars orbit on November 27, the spacecraft performed its third course correction using onboard sensors to measure Mars optically and to compute the duration of the engine burn.
The Mars 2 mission proceeded according to plan until arrival at Mars on November 27, 1971, after a flight of 192 days. As the Mars 2 spacecraft approached the planet, Mars was enduring a severe planetwide dust storm. The entire surface of the planet was obscured by layers of dust many kilometers thick, blown by several-hundred-kilometer-per-hour winds.
The Mars 2 orbiter only had enough fuel to enter Mars orbit without the 635-kilogram lander and heat shield combination. The spacecraft did not have the flexibility to wait safely in Mars orbit with the lander until the end of the gigantic Martian dust storm. Four and a half hours before the spacecraft entered orbit around Mars, the landing capsule and its 185-kilogram protective shell were ejected. A solid-propellant rocket motor shifted its path to intersect the planet while the main spacecraft entered an elliptical orbit around Mars.
The landing capsule was called an Automatic Mars Station (AMS). It used a hybrid aerodynamic and rocket-braking system to attempt a soft landing. The extremely thin Martian atmosphere complicated the descent. If the lander entered at too shallow an angle, it would not slow down and would escape into space again. If the entry angle were too steep, it would descend too fast for the parachute to operate properly.
The Mars 2 landing capsule entered the Martian atmosphere at a velocity of 6 kilometers per second. After aerodynamic braking using the craft’s heat shield, a decelerometer controlled the release of a drogue parachute, which was ejected while still descending at supersonic speed. This small chute pulled out the main parachute canopy, which remained in a reefed condition until slowing to Mach 1. At this velocity, the 15-meter-diameter main canopy was fully opened and the heat shield fell away. Because the Martian atmosphere is so thin at the surface, a landing using a parachute alone was not possible. While still falling at 90 meters per second, and at an altitude of 30 meters, a radar altimeter triggered a 10,000-kilogram-thrust retrorocket attached to the parachute lines, which fired for one second, cushioning the lander’s impact. After this landing, a smaller rocket then pulled the parachute off to one side so it would not cover the landing capsule. Touchdown occurred three minutes after atmospheric entry at Martian coordinates 45 degrees south, 58 degrees east, in an area 500 kilometers southwest of Hellas Basin, a 2,100-kilometer-diameter impact crater.
The landing capsule was spherical with an offset center of gravity to make it roll into an upright position on the surface. The upper half of the lander’s shell was designed to split open into four petals to stabilize the spacecraft on the surface. The Mars 2 lander was thought to have landed at a velocity of 20 meters per second with an impact of 500 g’s. Although the lander was designed to survive an impact shock of 1,000 g’s, there was no contact with the capsule after landing. It is assumed that the extensive planetwide dust storm enveloping Mars at the time of landing overwhelmed the lander and caused it to crash. Had it landed successfully, the capsule would have used atmospheric temperature and pressure sensors, a mass spectrometer for chemical analysis of the atmosphere, a wind anemometer, devices to measure the chemical and physical properties of the Martian soil, and panoramic television equipment to study the landing site. Stereoscopic views of the landing site were to be relayed by dual television cameras. Signals from the lander were to be relayed to Earth by the Mars 2 spacecraft orbiting the planet. No biological or life detection experiments were carried by the lander.
After the loss of the lander, the Mars 2 mission concentrated on Mars science from orbit. The spacecraft bus fired its retrorocket at twenty-three hours, nineteen minutes Greenwich mean time, on November 27, 1971, and entered an initial Mars orbit of 1,380 by 25,000 kilometers, inclined 48.9 degrees, with a period of eighteen hours.
The spacecraft investigated surface temperature and water vapor content in the Martian atmosphere. Using infrared sensors, Mars 2 could determine the thickness of the carbon dioxide atmosphere over various areas and thus build up a surface relief map. Surface reflectivity and the density of the atmosphere were also measured.
The Mars 2 orbiter also carried a wide-angle as well as a 4-degree-field-of-view telephoto camera. Twelve exposures of the Martian terrain were to be taken on photographic film and developed automatically for transmission to Earth using a 1,000-by-1,000-pixel facsimile scan system. Because the photographic sequence had been programmed in advance and could not be delayed, the global dust storm on Mars at the time Mars 2 arrived prevented successful surface photography. The Soviets later claimed that planetary imaging was only a “subsidiary role” in the mission. When the Mars 2 mission ended in March, 1972, the spacecraft had completed 362 orbits of the planet.
After seven failed Mars exploration attempts in the 1960’s, the Soviets designed a new generation of planetary exploration spacecraft weighing four times that of previous planetary probes. Extensive tests in Earth orbit of this new spacecraft were carried out by the Cosmos 379 and Cosmos 382 launches on November 24 and December 2, 1970.
Soviet accounts of the Mars 2 mission indicate that the design of the second-generation Mars probes was heavily influenced by prior experience with Venera and Luna missions to Venus and the Moon. The new spacecraft design was accomplished in a relatively short period of time by a new design team whose average age was under thirty. The chief designers were G. N. Babakin, Valentin Glushko, A. M. Isayev, Aleksandr Konopatov, and Vasily P. Mishin. The designers included Chelomei, Nikolai A. Pilyugin, and Mikhail Ryazanski. This indicated the Mars effort was being carried out by a new planetary team independent of the Venus and lunar exploration groups, and a new Soviet commitment to Martian exploration was under way.
The Mars 2 and 3 missions were carried out concurrently with the American Mariner 9 mission to Mars. Cold War tensions between the United States and the Soviet Union had eased by this time, and the heavy political emphasis placed on earlier space missions was less evident. In a cooperative move, a special teletype hotline was set up between the Jet Propulsion Laboratory
The giant Martian dust storm of 1971 was studied by the Mars 2 orbiter. Soviet space scientists concluded that the winds were not constant but occurred only in the initial phases of the storm. The fine dust blown to altitudes as high as 10 kilometers then took months to settle. Spectroscopic analysis of these dust clouds showed they were 60 percent silicon, ranging from 2 to 15 micrometers in diameter. The Soviets deduced further that, during the dust storm, the surface temperature of Mars dropped between 20 and 30 degrees Celsius because of blocked sunlight, while the atmosphere warmed up as it absorbed solar heat. When the dust storm ended, Martian surface temperatures ranged from 13 degrees Celsius in the Southern Hemisphere’s summer, to -93 degrees Celsius in the Northern Hemisphere’s winter. The northern polar cap had cooled down to -110 degrees Celsius.
Studies of the effects of the global Martian dust storm were instrumental in understanding the concept of “nuclear winter” as it applied to the aftermath of global nuclear war on Earth. Analysis of the cooling effects of the dust suspended in the atmosphere of Mars led to theories about global cooling and plant life extinction on Earth from similar effects caused by dust and smoke particles created by many simultaneous nuclear detonations.
Measurements by the Mars 2 orbiter indicated the planet’s atmosphere is primarily carbon dioxide with a surface pressure of only 5.5 to 6 millibars, or 0.5 percent that on Earth. Water vapor concentrations in the Mars atmosphere measured five thousand times less than in Earth’s atmosphere.
Observations showed that at 100 kilometers altitude, carbon dioxide is broken up by solar ultraviolet radiation into carbon monoxide molecules and oxygen atoms. Water vapor at high altitudes is broken down into atomic hydrogen and oxygen. Traces of atomic oxygen were found at altitudes of 1,127 to 1,287 kilometers in concentrations of 100 atoms per cubic centimeter.
Mars 2 showed that Mars possesses a very weak magnetic field and has an ionosphere only one-tenth as dense as Earth’s. Three featureless pictures of the Martian surface returned by the Mars 2 orbiter were shown on Moscow television on January 22, 1972.
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Boyce, Joseph M. Smithsonian Book of Mars. Washington, D.C.: Smithsonian Institution Press, 2002. Draws on Mars missions from 1965 to 2001 to provide details on Mars’s atmosphere, climate, surface, and interior. -
Gatland, Kenneth. Robot Explorers. London: Blandford Press, 1972. Chronology of Soviet and American lunar and planetary space exploration programs includes numerous color illustrations providing insights into the design and functions of American and Soviet lunar and planetary spacecraft. Descriptive narrative provides detailed results of all Soviet and American lunar and planetary exploration spacecraft and their missions. Suitable for general audiences. -
McDougall, Walter A. . . . The Heavens and the Earth: A Political History of the Space Age. New York: Basic Books, 1985. Well-researched and heavily documented work focuses on the key political and technological leaders of the time. Suitable for all audiences. -
Short, Nicholas M. Planetary Geology. Englewood Cliffs, N.J.: Prentice-Hall, 1975. Summarizes the accomplishments and scientific results of both American and Soviet lunar and planetary space programs. Stresses the chemical nature of the moon and inner planets, their geological similarities and differences, and their origins. College-level reading. Illustrated with many diagrams and photographs. -
Smolders, Peter. Soviets in Space. New York: Taplinger, 1974. Well-illustrated volume discusses all aspects of the Soviet space program. Concentrates on the successful portions of the Soviet space program as reported by the Soviet Union. Contains numerous diagrams and photographs illustrating the technical details of Soviet spacecraft and their missions. -
Turnill, Reginald. The Observer’s Spaceflight Directory. London: Frederick Warne, 1978. Lavishly illustrated summary of spaceflight activities by all nations provides chronologies of major manned and unmanned space missions. Technical narrative describes worldwide space activities by nation and program. Suitable for readers at high school and college levels. -
U.S. Congress. Senate Committee on Commerce, Science, and Transportation. Soviet Space Programs, 1976-1980. Part 2. Washington, D.C.: U.S. Government Printing Office, 1985. Presents comprehensive descriptions of all phases of unmanned Soviet space programs. Provides a detailed overview of the technical development of Soviet unmanned space activities, scientific investigations, and results. Recommended for general audiences. -
Wilson, Andrew. Solar System Log. London: Jane’s, 1987. Compilation of information on all manned and unmanned lunar and planetary spaceflights up to mid-1985 by all space-faring nations. Well-illustrated chronology of the history, spacecraft, mission, and discoveries of all deep space exploration missions. Suitable for all readers.
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