Without a doubt, the most memorable live event I had witnessed as a teenage space enthusiast was the landing of Viking 1 on the surface of Mars on the morning of July 20, 1976 when I was 14 years old – seven years to the day after the Apollo 11 Moon landing. While I had been increasingly aware of NASA’s Mars landing plans as the early 1970s unfolded, my interest in Viking and its search for life on Mars was supercharged in 1974 when I watched a summer rerun of an episode of the then-new PBS science show, Nova, entitled “The Search for Life” (see “Growing Up in the Space Age: Summer Vacations in the ‘70s”). Over the next couple of years, my interest in Viking was further fueled by literature I had received by mail from NASA outlining the Viking project and its experiments. With the encouragement of my 8th grade Earth science teacher, Mr. L’Herault, I even performed some of the student experiments outlined in the Viking educational literature I had obtained during that school year preceding the landing.
One of the many educational publications I received from NASA in the months leading up to the Viking 1 landing on Mars. (NASA)
As Americans were engaged in celebrations of the nation’s bicentennial as July 1976 began, I was also busy keeping track of every aspect of the upcoming Viking 1 landing attempt in this pre-internet age by watching news coverage on TV as well as reading the local daily newspaper and the latest issues from my new subscription to Sky & Telescope magazine. Armed with the literature I received from NASA as well as a map of Mars from the February 1973 issue of National Geographic, I was well prepared for this historic event.
A diagram of the Viking lander showing its major components and experiments. Click on image to enlarge. (NASA)
I got up at about 6:00 AM EDT on the morning of Tuesday, July 20 to watch the live coverage of the Viking landing on TV – a tough thing for a 14-year old night owl to do in the middle of a summer school vacation. As I listened intently to the announcements of each milestone reached during descent, Viking 1 finally came down for a soft landing 17 seconds later than scheduled at 11:53:06 GMT at 22.27° N, 47.95° W in Chryse Planitia about 28 kilometers from its target point. Because of the time needed for the signals from the Viking lander to travel back to Earth at the speed of light, the news of the successful landing finally arrived here on Earth 19 minutes later at 8:12 AM EDT. Seconds after its soft landing, the Viking 1 lander started a preprogrammed sequence of events including the acquisition of its first images of the Martian surface.
A diagram with the outline of the Viking lander features illustrating the location of the first pair of preprogrammed images to be taken by Camera 2 when Viking 1 landed on Mars. Click on image to enlarge. (NASA)
The Viking landers each sported a pair of 7.3-kilogram cameras on their upper deck mounted 0.822 meters apart to provide stereo views of the landscape. Unlike the vidicon-based cameras used on NASA’s robotic Surveyor lunar landers a decade earlier which returned individual frames of the scene (see “Surveyor 1: America’s First Moon Lander”), the Viking Lander cameras used a scanning mirror to reflect the scene onto a set of a dozen light-sensitive photodiodes. The nodding motion of the mirror allowed one column of the scene to be scanned before the camera turret rotated stepwise in azimuth to allow the adjacent columns to be scanned one at a time. Each camera could scan up to 342.5° in azimuth and from 40° above to 60° below the horizon. Earlier Soviet Luna, Mars and Venera landers used devices the Soviets called “telephotometers” which operated on a similar principle (see “Luna 9: The First Lunar Landing” and “Venera 9 & 10 to Venus“).
Cutaway diagram showing the major components of the cameras carried by the Viking Landers. Click on image to enlarge. (NASA)
The array of a dozen detectors allowed the scene to be scanned in six spectral bands for color and near infrared imaging at a scale of 0.12° per pixel or black and white images with a finer image scale of 0.04° per pixel with four different focus steps ranging from 1.9 to 13.3 meters. Each image column scan was broken up into 512 pixels digitized to 6 bits. The scanning rate was synchronized with the 16,000 bits per second transmission rate using the Viking Orbiters as a relay (as was being done for these first images from Viking 1) or the 250 bits per second rate for direct transmission to Earth via the Lander’s dish-shaped, high gain antenna. The images could also be stored on a 40 megabit tape recorder for later transmission.
This schematic shows the operation of the Viking Lander camera from scanning the scene to the reconstruction of the image back on Earth. Click on image to enlarge. (NASA)
Acquisition of the first image was started 25 seconds after landing using Camera 2 on the Viking 1 lander. It was a high-resolution, black and white image of a 70° by 20° strip immediately in front of the lander covering a distance of 1.5 to 2.0 meters from the camera and included a view of the Footpad 3 on the right side. Although the image was scanned in five minutes, it took 20 minutes for the data to be relayed back to Earth via the Viking 1 orbiter. Back on Earth, we watched as the image on TV was refreshed a few pixel columns at a time from left to right. The first features readily identifiable in the image were a tiny dune-like feature and a rock. As the scene was filled in, numerous small rocks up to ten centimeters across came into view in the dusty soil.
The first image of the surface of Mars returned by Camera 2 on the Viking 1 Lander shortly after its touchdown on July 20, 1976. The left side of the image appears brighter due to dust kicked up by the landing which settled as the 5-minute scan proceeded. Click on image to view a full-resolution version. (NASA/JPL)
As we watched the first image coming in on Earth, Viking 1 had already begun to take a lower-resolution 300° panorama using Camera 2 providing a fuller view of the landing site out to the horizon. Taken at the equivalent of 4:17 PM local time on Mars, the scan was completed in nine minutes and proceeded to be relayed back to Earth. The rock-strewn landscape included dusty deposits with a surprisingly bright sky caused by the dust suspended in the thin Martian atmosphere.
The second image returned by Viking 1 using Camera 2 provided a panoramic view of the landing site on Chryse Planitia. Click on image to view a full-resolution version. (NASA/JPL)
In the days that followed, Viking transmitted more images and data about the conditions on the surface of the Red Planet. It would be the Viking 1 lander’s second Sol on the Martian surface before it took its first color image. After being transmitted back to Earth, initial publicly released versions of the image showed a blue sky and a salmon colored surface. It was only in later versions, which had been properly calibrated and color balanced, that the true rust red color of the surface was revealed along with a dust-laden red sky instead of the expected blue color. Over the coming weeks, Viking 1 performed its life detection experiments but yielded ambiguous results because of what are now recognized as faulty assumptions made in the experiments’ design (see “Viking and The Question of Life on Mars, Part 2”). Contact with the Viking 1 lander would continue until November 11, 1982 when a faulty command sent by a skeleton crew of ground controllers resulted in loss of contact after 2,600 Sols on the Martian surface. After the landing of Viking 2 on September 3, 1976 (see “First Pictures: Viking 2 on Mars – September 3, 1976”), it would be almost 21 years before NASA would land on Mars again (see “First Pictures: NASA’s Mars Pathfinder – July 4, 1997“).
The first color image from the surface of Mars taken by Viking 1 on July 21, 1976. Click on image to view a full-resolution version. (NASA/JPL)
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Related Reading
“Growing Up in the Space Age: Summer Vacations in the ‘70s”, Drew Ex Machina, July 22, 2019 [Post]
“First Pictures: Viking 2 on Mars – September 3, 1976”, Drew Ex Machina, September 3, 2020 [Post]
“Viking & The First Seismometers on Mars”, Drew Ex Machina, November 21, 2018 [Post]
“Viking and The Question of Life on Mars, Part 1”, SETIQuest, Vol. 3, No. 3, pp. 1-6, Third Quarter 1997 [Article]
“Viking and The Question of Life on Mars, Part 2”, SETIQuest, Vol. 3, No. 4, pp. 1-7, Fourth Quarter 1997 [Article]
General References
Michael M. Mirabito, The Exploration of Outer Space with Cameras, McFarland, 1983
Andrew Wilson, Solar System Log, Jane’s Publishing, 1987
The Martian Landscape, NASA SP-425, 1978