Sixty years ago, specifically on July 15, 1965, NASA's Mariner 4 mission forever changed our perception of the Red Planet. Its images, captured from a distance of just 9,846 kilometers above the surface, were the first-ever recorded photographs of another planet. Those blurry, black-and-white images of Mars' crater-strewn landscape, displayed on televisions across America, shattered the then-romantic notions of canals and lush life, opening a new chapter in space exploration. The mission team was so eager to see the results from the spacecraft's camera that while they waited for the actual image transmission, they even manually created a "paint-by-numbers" image, assigning colors to specific data values. Their effort was not far from the truth, and the desolate landscape that Mariner 4 captured spurred the imagination of future scientists and engineers, who continued to work on a series of missions, each revealing Mars in a way it had never been seen before. Since then, millions of images of Mars have been taken, many of them stunning in their own right. The images that follow highlight some of the "first" ways the agency has used imaging to help unlock the secrets of Mars.

Viking 1: First Touch with Mars

On July 20, 1976, history was made when the Viking 1 spacecraft became the first to successfully land on Mars. The first high-resolution image it sent back to Earth showed a dry, rocky landscape, which dashed scientists' hopes of discovering life on the surface. But the sharp images that followed from the lander's 360-degree cylindrical scanning camera emphasized the scientific value of observing Mars from the ground and fueled excitement for a more ambitious visit: a robotic spacecraft that could drive across this alien world. The Viking mission, consisting of two orbiters and two landers (Viking 1 and Viking 2), was a turning point in Mars exploration. In addition to imaging the surface, the landers also conducted biological experiments in search of signs of life, although the results were ambiguous and did not provide conclusive proof. Nevertheless, Viking provided invaluable data on the atmosphere, soil, and geology of Mars, laying the groundwork for future missions.

Portrait of Mars from the Viking 1 Orbiter

As the twin Viking landers descended to Mars, each was launched from an orbiter that used cameras to map Mars in a way that Earth-based telescopes could not. They began taking images even before the landers touched down, continuing to operate until 1980. That year, the Viking 1 orbiter captured images that were later stitched together into a defining portrait of Valles Marineris – the "Grand Canyon of Mars." This vast canyon system, over 4,000 kilometers long, up to 200 kilometers wide, and up to 7 kilometers deep, had been discovered earlier, but the Viking orbiters provided the first detailed images of its impressive scale and complex geology. Mapping from orbit allowed scientists to study the global features of Mars, including polar caps, volcanoes, and ancient river valleys, providing key insights into the planet's geological history and climate change.

Sojourner Begins Exploration

When NASA returned to the surface of Mars on July 5, 1997, with the Pathfinder lander and the microwave-sized Sojourner rover, much had changed on Earth since the days when Mariner 4's images were broadcast to television viewers. Now, the internet brought 24-hour news to personal computers, allowing a young generation of space enthusiasts to witness the cautious first steps of a new form of planetary exploration. The panoramic images from the ground were the first since Viking and, as part of NASA's "faster, better, cheaper" initiative, offered more detail at a relatively lower cost. Sojourner, the first rover to successfully operate on Mars, was a technology demonstrator, but despite its small size (about 10.6 kg), it provided invaluable data on the composition of rocks and soil. Its ability to move across the surface and conduct experiments at different locations marked the beginning of the era of mobile Mars exploration, paving the way for much larger and more capable rovers to follow.

Spirit and Opportunity: Traces of Water and Dust Devils

In 2004, NASA's twin golf-cart-sized rovers, Spirit and Opportunity, descended upon the Red Planet, beginning a new phase of Martian exploration. Equipped with panoramic cameras mounted on a mast and microscopic imagers on a robotic arm, these mobile spacecraft allowed scientists, engineers, and the entire world to discover new terrain daily. They captured vivid views of Martian landscapes and revealed details of pebble-sized "blueberries" – hematite spherules that were key evidence of the past presence of water on Mars. Mars began to seem less like an unknown world and more like a place with recognizable features. On March 31, 2016, Opportunity even captured the passage of a dust devil, providing a dynamic insight into the Martian atmosphere. Both rovers far outlasted their planned mission durations, providing a decade of invaluable data and discoveries that revolutionized our understanding of Mars' geological and climatic history, especially regarding the existence of liquid water.

MRO and HiRISE: Sharp Views from Orbit

Since Viking, a series of increasingly advanced orbiters have arrived at Mars with new scientific tools and cameras. Using ever more sophisticated imagers, they have mapped the planet's hills and valleys, identified significant minerals, and found buried glaciers. The camera that has been in operation on NASA's Mars Reconnaissance Orbiter (MRO) since 2006, the High-Resolution Imaging Science Experiment (HiRISE), often captures individual dunes, boulders, and craters, as is the case with this image of Victoria Crater taken on July 18, 2009, revealing features that were blurry in previous images. HiRISE is capable of capturing images with a resolution of 30 centimeters per pixel, which allows for the recognition of objects the size of a kitchen table. This extraordinary capability has enabled not only detailed geological mapping but also the identification of potential landing sites for future rovers (and perhaps even astronauts), as well as monitoring changes on the Martian surface, such as seasonal changes in the polar caps and the activity of dust storms. MRO, with its suite of instruments, continues to provide crucial data on the Martian atmosphere, climate, and subsurface water.

Curiosity and Perseverance: Unprecedented Color and Detail

Both Curiosity and Perseverance arrived at Mars (on August 5, 2012, and February 18, 2021, respectively) equipped with cameras that pack millions of pixels into their images and see farther into the distance than Spirit or Opportunity ever could. They also have upgraded arm-mounted cameras for studying fine details like sand particles and rock textures. Perseverance went a step further than Curiosity in several ways, including high-speed cameras that showed its parachute unfurling and the flight of its rocket-powered jetpack during entry, descent, and landing on Mars. Another advancement can be seen in each vehicle's hazard avoidance cameras, which help rover drivers spot rocks they might run into. As seen in the first images each rover sent back, Curiosity's black-and-white cameras were upgraded to color and higher resolution for Perseverance, providing clearer views of the surface. Curiosity has been searching for signs of ancient habitable environments in Gale Crater, while Perseverance in Jezero Crater is actively searching for signs of ancient microbial life and collecting rock and regolith samples for future return to Earth. These rovers represent the pinnacle of robotic exploration of Mars, combining advanced scientific instruments with exceptional visual capabilities.

Ingenuity: First Flight on Another Planet

Just as Pathfinder brought the tiny Sojourner rover to Mars, NASA's next-generation rover, Perseverance, carried the Ingenuity helicopter. In addition to proving that flight in the thin Martian air is possible, Ingenuity used a commercial, off-the-shelf color camera to capture aerial views during 72 flights. During one of those flights, on August 22, 2023, Ingenuity even spotted Perseverance in the distance in Belva Crater – another first on the Red Planet. Ingenuity was a technology demonstrator, designed to show the feasibility of controlled flight in the extremely thin Martian atmosphere. Its unexpected success and longevity have opened up a whole new dimension of Mars exploration. Future Mars helicopters could scout paths ahead for rovers and find scientifically interesting spots for robots and astronauts, dramatically increasing the area that can be explored and the speed at which it can be done. The ability for aerial reconnaissance will revolutionize mission planning and allow access to terrain that is otherwise inaccessible to rovers.

About the Missions and Collaboration

It is important to note that behind these impressive achievements were thousands of dedicated scientists and engineers from various institutions. NASA's Jet Propulsion Laboratory (JPL), which is managed for the agency by Caltech in Pasadena, California, built Mariner 4, the Viking 1 and 2 orbiters, Pathfinder, Sojourner, Spirit and Opportunity, Curiosity, Perseverance, and Ingenuity. JPL continues to manage the Curiosity and Perseverance rovers, ensuring their continuous operation and data collection. Lockheed Martin Space in Denver built MRO and supports its operations, while JPL manages the mission. The University of Arizona, in Tucson, manages HiRISE, which was built by BAE Systems in Boulder, Colorado. The Viking 1 and 2 landers were built by Martin Marietta; the Viking program was managed by NASA's Langley Research Center in Hampton, Virginia. JPL managed operations for the Viking landers and orbiters. This complex network of collaboration between government agencies, academic institutions, and private companies is crucial for the success of such ambitious and far-reaching space missions, which continue to expand the boundaries of human knowledge and exploration.

The original article was published on the NASA Jet Propulsion Laboratory portal.
Source: Advances in NASA Imaging Changed How World Sees Mars
Author: Andrew Good / Karen Fox / Molly Wasser