Mars 3

• 1. Introduction

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  Mars 3 touched down on the surface of Mars on the 2nd of December, 1971, making history as the first spacecraft ever to achieve a soft landing on another planet. Ninety seconds after landing, it began transmitting. Twenty seconds later, it stopped. What came through was a partial image of just 70 lines, described by V. G. Perminov, the lead designer for Mars and Venus spacecraft at the Lavochkin design bureau, as "a gray background with no details." Then silence. How did a mission that traveled millions of kilometers across space fail in just over a minute? And what did the orbiters, which kept circling Mars for months afterward, actually find?

• 2. Twin Probes, One Goal

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  Mars 3 was launched on the 28th of May, 1971, nine days after its twin, Mars 2, lifted off atop a Proton-K rocket with a Blok D upper stage. The two probes were identical. Each carried a combined launch mass of 4,650 kilograms, stood 4.1 meters tall, and stretched nearly 6 meters across once the solar panels deployed. Each consisted of an orbiter and an attached lander, designed to work together from arrival at Mars through to surface operations.

  The orbiter's job was broad. It was built to study the topography of the Martian surface, analyze soil composition, measure atmospheric properties, and monitor solar radiation, the solar wind, and the magnetic fields of both interplanetary space and Mars itself. It also served, critically, as a communications relay to pass signals from the lander back to Earth. That relay function would prove to be the weakest link in the entire system.

• 3. A Planet-Wide Dust Storm

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  When Mariner 9 arrived at Mars on the 14th of November, 1971, just two weeks before Mars 2 and Mars 3 reached their destination, planetary scientists encountered something unprecedented. The entire Martian atmosphere was choked with what scientists described as "a planet-wide robe of dust, the largest storm ever observed." The surface was completely obscured.

  The Soviet mission computers could not be reprogrammed remotely. With the storm raging and no ability to delay, both Mars 2 and Mars 3 released their landers immediately as planned. The orbiters then spent a significant share of their available data resources photographing featureless dust clouds. Mars 3's orbiter, meanwhile, had run into its own mechanical trouble: a partial loss of fuel left it unable to achieve its planned 25-hour orbit. Instead, the engine performed a shortened burn, placing the spacecraft into a highly elliptical orbit with a period of 12 days and 19 hours.

• 4. Descent and Failure

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  Mars 3's descent module separated from the orbiter at 09:14 UT on the 2nd of December, 1971, four hours and 35 minutes before the spacecraft reached Mars. The module entered the Martian atmosphere at roughly 5.7 kilometers per second. Aerodynamic braking, parachutes, and retrorockets brought it down to a soft landing.

  The landing capsule itself weighed 358 kilograms and measured 1.2 meters in diameter. It was fitted with four triangular petals that would open on the surface to right the spacecraft and expose its instruments. Those instruments included two television cameras with a full 360-degree view, a mass spectrometer for atmospheric study, sensors for temperature, pressure, and wind, and devices to measure the mechanical and chemical properties of the surface. A mechanical scoop was included to search for organic materials and signs of life. The capsule had been sterilized before launch to avoid contaminating the Martian environment.

  The transmission that began 90 seconds after landing lasted only 20 seconds before going silent. Whether the fault lay with the lander itself or with the communications relay on the orbiter remains unknown. One leading explanation is that the powerful dust storm may have triggered a coronal discharge, damaging the communications system. The same storm would also account for the poor lighting in the single gray image that survived.

• 5. The PrOP-M Rover

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  Tucked aboard the Mars 3 lander was a rover that almost no one talks about: the PrOP-M, a 4.5-kilogram vehicle designed to explore the surface while tethered to the lander by a 15-meter umbilical cable. The rover traveled on wide flat skis, with two small metal rods serving as obstacle-avoidance sensors. Because radio signals from Earth would take too long for direct remote control, the rover was built to navigate autonomously.

  The plan was to place the PrOP-M on the surface using a manipulator arm after landing, then let it move through the cameras' field of view, stopping every 1.5 meters to take measurements with its dynamic penetrometer and radiation densitometer. The tracks it left in the Martian soil were themselves intended as data, with scientists hoping to read the surface's material properties from the imprint of the skis. Because contact was lost with the lander so quickly, it remains unknown whether the rover was ever deployed.

• 6. What the Orbiters Found

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  While the lander's story ended in seconds, the Mars 3 orbiter continued working for months. It transmitted data from December 1971 through March 1972, with transmissions continuing through August. On the 22nd of August, 1972, after 20 orbits, the mission was officially declared complete.

  Combined with its twin Mars 2, the orbiters returned 60 pictures and a substantial body of scientific measurements. The data revealed mountains reaching as high as 22 kilometers. Surface temperatures ranged from -110 degrees Celsius to +13 degrees Celsius, and surface pressures measured between 5.5 and 6 millibars. Water vapor in the Martian atmosphere was found to be 5,000 times less concentrated than in Earth's atmosphere. The base of the ionosphere began at altitudes between 80 and 110 kilometers. Grains from dust storms were detected as high as 7 kilometers up. The combined results enabled the creation of surface relief maps and yielded new data on the Martian gravity and magnetic fields.

• 7. Found Decades Later

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  On the 11th of April, 2013, NASA announced that the Mars Reconnaissance Orbiter may have spotted the Mars 3 hardware still sitting on the Martian surface. The HiRISE camera aboard the MRO captured images showing what appear to be the parachute, retrorockets, heat shield, and the lander itself. The find was not made by professional researchers scanning mission data. It was made by amateur space enthusiasts working through publicly available archived images, combing the Martian landscape for hardware placed there more than four decades earlier.