Category: Viking

After over six years of continuous operation and data gathering on the planet Mars, the Viking 1 lander – having outlived the power supply aboard its orbiter and now transmitting its observations directly to Earth – is inadvertently silenced during what is intended to be a remote upgrade of its on-board software. Ground controllers are never able to establish contact with Viking 1 again. Its record of continuous operation on another planet is not broken until 2010, when Viking 1 is outlasted by NASA’s Opportunity rover.

Two years after the shutdown of its orbiter leaves it sending observations of the Martian environment back to Earth at a low bit rate, the Viking 2 lander’s batteries are depleted and the second spacecraft to land on Mars shuts down permanently. Its three-and-a-half-year operational lifespan has been a bonus round for a robotic vehicle expected to function for a few months in Mars’ harsh weather.

Less than two years after arriving at Mars, the “mothership” orbiter that delivered the Viking 2 lander to the red planet is permanently shut down. Having lost most of its fuel to a leak, the Viking 2 orbiter can no longer be commanded to change orbit, and is placed in a parking orbit. Without an orbiter to relay its findings to, Viking 2 continues operating on the surface of Mars for two more years, sending data directly to Earth at a lower bit rate.

NASA’s Viking 2 orbiter closes to within 40 miles of Mars’ small outermost moon, Deimos, the first spacecraft to visit the tiny moon up close. Deimos is found to be cratered and irregularly shaped, confirming the likelihood that it is an asteroid that once strayed close enough to Mars to fall into orbit.

NASA’s Viking 2 lander confirms a surprising finding first detected in black-and-white images just days earlier: Mars has naturally occurring frost. Scientists try to determine, from images alone, if the frost forms from condensation due to overnight cold (as on Earth), or through some other atmospheric mechanism. But the finding does confirm enough moisture in the atmosphere to condense on the Martian surface, decades before surface water is confirmed on the red planet.

NASA’s Viking 2 lander, launched from Earth almost exactly a year earlier touches down on Martian soil in the Utopia Planitia region. One of Viking 2’s three landing legs comes down on a rock, leaving the entire lander at an eight-degree angle to the ground. Identical to Viking 1, Viking 2 has its own soil sampling arm, though its series of tests for biological reactions within the soil produce inconclusive results (including at least one “positive” test for signs of life, later attributed to inorganic chemical reactions). Viking 2 will also later confirm that water exists, at least briefly, on the surface of Mars in the form of frost.

The Viking 1 orbiter, observing Mars from orbit while relaying data from the Viking 1 lander to Earth, snaps a close-up view of the Martian moon Phobos from within 5,000 miles. Though more distant from Phobos than Mariner 9’s closest pass in 1972, the Viking cameras are vastly superior, revealing greater detail even at greater distances; craters as small as 13 miles across can be seen in the images. JPL scientists and mission planners are already developing ideas for future Mars missions, including unmanned landers with wheeled rovers.

Viking 1 makes a soft landing on Mars, the first spacecraft to do so intact (the Soviet space program had been attempting to put landers on Mars, some of them including rudimentary rovers, since 1962). It successfully transmits the first picture from the Martian surface back to Earth within seconds, and successfully gathers soil samples for analysis. Viking 1’s orbiter mothership will later shut down in 1980, but the lander itself functions until 1982. Viking 1’s landing takes place on the seventh anniversary of the first manned moon landing.

NASA launches the Viking 2 lander and orbiter, designed and operated by Jet Propulsion Laboratory, aboard a Titan IIIE rocket bound for Mars. The combined Viking 2 spacecraft will take nearly a year to reach Mars, achieving orbit in August 1976 and surveying the surface for suitable landing sites before the northern plain named Utopia Planitia is selected for a September 1976 landing attempt.

The Viking 1 unmanned space probe, built by NASA and the Jet Propulsion Laboratory, lifts off en route to the planet Mars. Intended to gather and study soil samples on-site on the Martian surface, Viking 1 will take eleven months to reach the red planet. Viking 1 is not the first attempt to land a spacecraft on Mars; the Soviet Union has been attempting such a feat since the 1960s.

NASA begins making detailed plans for a pair of orbiter/lander spacecraft, now named Viking, to be sent to Mars in the mid 1970s (possibly as early as 1973). With more recent Mariner missions having revealed a number of major challenges, including a thin atmosphere which won’t significantly slow a heavy object such as a landing vehicle, mission planners have to consider entirely new methods of reentry (as opposed to the Earthlike atmosphere that was expected as recently as 1964). The twin Viking spacecraft will not lift off until 1975.