The Spacecraft Tarot: Viking

The Emperor governs with a stern yet loving force.

The Emperor institutes clear rules, affirms strong boundaries, and values integrity and discipline above all else. He can be a sign that you have reached a point where you feel like you are in control of a situation — or that you are in need of an authoritative guidance to get you where you want to be.

In many traditional decks, the Emperor sits on a throne adorned with rams — symbols for Mars. His strong association with Mars, in addition to his other attributes, make him a perfect match with NASA’s Viking project.

Little was understood about Mars prior to space exploration. Earth-based telescopes in the 1960s could not distinguish Martian features smaller than 62 miles in size and revealed very little surface details about the planet, aside from the fact that certain areas changed shape and color during different times of the year — which many mistook for evidence of Martian plant life.

Efforts to explore Mars began only a few years after Sputnik, the world’s first artificial satellite, launched into orbit in 1957. NASA’s Jet Propulsion Laboratory (JPL)’s Mariner 2 spacecraft successfully completed the first close-up observations of another planet when it flew by Venus in late 1962, around the time that the team was approved to begin work on a similar mission — only this time, to Mars.

The goal of the Mariner Mars 1964 Project was to send two separate spacecraft to fly by the planet to take pictures and other detailed observations. Each of the 575-pound spacecraft carried seven instruments, including an imaging system, a dust detector, a radiation detector, and a magnetometer.

The first of the two spacecraft, Mariner 3, didn’t make it. After launching from Cape Kennedy Air Force Station, Florida, on November 5, 1964, the payload shroud failed to jettison from the spacecraft and the solar panels could not deploy. Teams worked quickly to redesign Mariner 4’s payload shroud before the launch window closed. Thankfully, Mariner 4 successfully launched on November 28, just two days before the window of opportunity ended.

Eight months later, on July 14, 1965, Mariner 4 made history when the spacecraft completed the first flyby reconnaissance of Mars, passing within 6,118 miles of the surface. During its flyby, the spacecraft captured 22 black and white photographs of the Red Planet. Too excited to wait for the translator machine to convert the data into a printed image, JPL team members used the data like a paint-by-number kit to draw their first close look of Mars.

When the imagery finally processed, the glimpses offered by Mariner 4 revealed a heavily-cratered, almost Moon-like terrain. Combined with extremely low measurements of atmospheric pressure and indications of a surface temperature of -148°F, Mariner 4 data made clear that, contrary to previous suspicions, the planet was not teeming with life at all — but rather, an inhospitable landscape.

However, as ground-breaking as they were, the limited number of Mariner 4 photographs and the small amount of surface area they covered did not accurately represent the broad diversity of geological features of the planet. Future spacecraft were needed to get closer and cover more ground to reveal more about true nature of Mars.

Learning from Mariner 4’s successes and shortcomings, JPL teams built and operated several more spacecraft in the Mariner series. Four years after Mariner 4 mission, the Mariner Mars 1969 project included two identical spacecraft, Mariner 6 and Mariner 7, each almost twice as heavy as Mariner 4, carrying even more scientific instruments, and zooming even closer to the planet.

Despite a malfunction during a countdown test on February 14, 1969, Mariner 6 and Mariner 7 launched without incident on February 25 and March 27, respectively. Following different trajectories, the two spacecraft arrived to Mars just five days apart from one another. On July 31 and August 5, each spacecraft flew within 2,130 miles of Mars, about twice as close as Mariner 4 had managed.

Despite being overshadowed by the Apollo 11 Moon landing happening around the same time, the Mariner Mars 1969 project made ground-breaking discoveries.

Compared to Mariner 4’s images of the planet, which only showed details as small as two miles and covered less than 1% of the planet’s surface, Mariner 6 and 7 covered 20% of the Martian surface with a resolution down to 900 feet. Scientists also managed to reconstruct a color image of the planet by combining three black-and-white images from Mariner 7 through different color filters. Instruments aboard the spacecraft indicated that the Martian atmosphere was less than 10% that of Earth’s atmosphere at sea level, and that it was composed almost entirely of carbon dioxide.

Mariner 7 also captured an image of the Martian moon Phobos, marking the first photograph of a planetary satellite taken by a spacecraft.

The next pair of identical Mariner spacecraft, Mariner 8 and Mariner 9, both launched in May 1971 from Cape Canaveral, Florida. Sadly, a couple minutes after Mariner 8 launched on May 9, a failed integrated circuit caused the rocket stage and payload to tumble out of the sky. The spacecraft was destroyed.

On May 30, 1971, Mariner 9 launched and beat the Soviet Union’s Mars 2 probe to the Red Planet, despite having launched 11 days later. On November 14, Mariner 9 became the first human-made object to enter orbit around another planet.

Mariner 9 blew previous Mariner discoveries out of the water: the orbiter mapped 85% of the Martian surface with over 7,000 pictures, painting spectacular pictures of a geologically active landscape. Mariner 9 identified massive canyon systems, features that could have been caused by flowing liquid, and 20 volcanoes — one of which was about 9 to 19 miles tall, larger than any volcano on Earth.

With flybys and orbits, the Mariner spacecraft series painted a clearer picture of Mars than anything Earth-based telescopes had been capable of. But even with the thousands of high-resolution images and other types of observations, only so much could be discovered from so high above the Martian surface. Although all signs pointed to Mars being a barren landscape void of life, the only way to make sure was to examine the planet up close — by landing on the surface.

The problem is that landing on Mars is extremely difficult. In the early 1970s, the Soviet Union tried and failed multiple times to land a spacecraft on the Martian surface. Mars 3 managed to soft-land on December 2, 1971, but stopped transmitting data mere seconds after landing.

The Entry, Descent, and Landing process (EDL) is challenging because when a spacecraft first enters the Martian atmosphere 100 miles above the surface, it is traveling about 18,000 miles per hour — and it has to slow down to one or two miles per hour by the time it touches ground seven minutes later. Not only does the spacecraft have to experience a significant reduction in speed in a very short amount of time, but it has to do this independently, due to communication delays caused by the vast distance between the Earth and Mars.

Teams at NASA’s Langley Research Center developed twin spacecraft, each consisting of an orbiter and a lander. The orbiter was inspired by none other than the Mariner spacecraft series. The two orbiter-lander pairs were named Viking 1 and Viking 2.

The first orbiter-lander pair, Viking 1, launched from Cape Canaveral Air Force Station on August 20, 1975 and Viking 2 launched a couple weeks later, on September 9, 1975. They each travelled for almost a year before reaching the Red Planet.

When each orbiter-lander pair reached Martian orbit, they spent about a month imaging the planet, searching for a good place to land. The Viking 1 lander separated from its orbiter and began its descent to the Martian surface on July 20, 1976, and Viking 2 followed over a month later, on September 3.

In order to survive EDL, the two Viking landers had to complete a complicated series of precise steps. The two landers each used an aeroshell to enter the upper layers of the Martian atmosphere. Once the landers reached the middle atmosphere, about four miles above the surface, a supersonic parachute opened and decreased their velocity by 90%. When the landers were about a mile above the ground, they separated from their aeroshells with the parachute and three retro-rockets fired to achieve a soft landing at about 4.5 miles per hour. Both Viking landers made history when they became the first NASA mission to land a spacecraft safely on the surface of Mars.

Viking 1 landed in Chryse Planitia, and Viking 2 landed 4,000 miles away, in Utopia Planitia, near the edge of the polar ice cap, allowing scientists to see a variety of Martian geological features.

Both the Viking orbiters and landers captured thousands of high-quality images. While the landers captured incredible details of topography and even aerosols floating in the atmosphere, the Viking orbiters captured the terrain from above, mapping almost the entirety of the Martian surface. The views revealed lava plains, cratered areas, and evidence of surface water. Viking lander data determined that the Martian surface is made of a type of iron-rich clay that contains a highly oxidizing substance that releases oxygen when it is wet. For the first time, Viking detected nitrogen in the Martian atmosphere. The Viking landers also measured a range of temperatures from the Martian surface, from as low as -190°F to as high as -10°F.

While water is the dominant source of weathering on Earth, Viking imagery revealed that wind is the primary agent that erodes the landscape and shapes the face of Mars. Atmospheric weathering on the landscape reduced rocks into fine particles that oxidize to create a reddish tint.

With a robotic arm and miniature biological laboratory, Viking 1 analyzed the first Martian soil sample. Although none of the three biology experiments aboard the landers found evidence of living microorganisms in the soil, the question of whether living organisms could have existed in the Martian past is still unanswered. Today’s Perseverance rover mission is currently caching samples of Martian soil to be collected and analyzed at a later date.

The Viking mission was only expected to continue for 90 days after landing on the Martian surface, but each spacecraft survived for years longer than planned. The longest-lasting Viking spacecraft — the Viking 1 lander — made its final transmission to Earth on November 11, 1982.

By the time the Viking mission wrapped up, the two Viking orbiters had captured 52,663 images of Mars and mapped about 97% of the surface at a resolution of 984 feet.

The Viking, like the Emperor, reminds us of the value of self-discipline and how it can be harnessed to reach our goals. A long line of missions to the Martian surface failed before Viking planted its footpads in the red dust. Persistence and patience are the ingredients that ferried the Viking project to its destination, and its success prepared us for future Martian missions to come.

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