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Just steps away from High Bay 1, where many of NASA’s pioneering robotic missions have been assembled, is the first image of Mars ever seen on television, broadcast in 1965.
The groundbreaking image is part of a small exhibit tucked away in a corner of the second floor of the Spacecraft Assembly Facility on the campus of NASA’s Jet Propulsion Laboratory in Pasadena.
But the depiction, which represented the first photo of another planet taken from space, isn’t a photo at all.
Instead, it’s a “color by numbers” representation of data, which was captured and sent to Earth by NASA’s Mariner 4 spacecraft on July 15, 1965, as the probe made its closest approach to Mars.
Mariner 4’s historic encounter with Mars was just the beginning of a series of missions that changed the way we see our planetary neighbors. While the actual photo was also released, the hand-colored image continues to captivate all who see it at JPL.
“The first time I encountered this was almost right when I started working here at JPL, which was 17 years ago,” said David Delgado, cultural strategist in The Studio at JPL. “It’s just this object of curiosity and wonder. You can’t just walk by it. The story is so powerful.”
The first to visit other planets
In 1962, Mariner 2 became the first spacecraft to visit another planet when it flew by Venus. The milestone encouraged NASA engineers to push ahead with an even more ambitious project: capturing photos of planets from space.
There was a lot riding on the Mariner 4 mission. It was one of a twin set of spacecraft designed to take images of Mars, and the first one failed.
Mariner 3 launched on November 5, 1964, but it lost power just eight hours later when the payload shroud didn’t jettison and its solar panels never unfurled. With a quickly redesigned shroud, Mariner 4 launched three weeks later on November 28 before going on a 228-day trip to reach Mars.
Attached to the spacecraft was a television camera to reveal how the planet looked at close range from a spacecraft, along with six science instruments to study the Martian surface and atmosphere.
Interest in obtaining images of other planets from space was part of the space race of the 1960s for a reason. The best map of Mars at the time was from the late 1800s and came from Percival Lowell’s observations, made using his private Lowell Observatory in Flagstaff, Arizona. And the highest-resolution image was captured by an Earth-based telescope in 1956.
Mariner 4 flew 6,118 miles (9,845.5 kilometers) above the Martian surface on the night of July 14, capturing 22 images of the planet.
The spacecraft carried the first digital imaging system used outside of Earth. The machine converted the camera’s analog signal into a digital format and slowly transmitted the data back to Earth at a rate of 8 1/3 bits per second. The bit rate meant that it took 10 hours to relay a single image back to Earth.
The transmission was incredibly slow by today’s standards, given that the Perseverance rover regularly sends back batches of high-resolution images from Mars.
Meanwhile, members of the press had gathered at JPL and eagerly awaited the release of the first photo.
As the anxiety built, some members of the Mariner 4 team decided to take matters into their own hands.
An unexpected art project
The tape recorder capturing data aboard Mariner 4 was never meant to be used. The equipment was a spare, but because Mariner 3 never reached Mars, all hopes were riding on Mariner 4’s instruments to work. There was a chance the tape recorder wouldn’t function properly.
During the long wait for the first images, Richard Grumm, who oversaw the tape recorder operations, and members of his team began to convert the digital data from Mariner 4 into ones and zeros on ticker tape, according to a project about the image compiled by Dan Goods, visual strategist in The Studio at JPL.
The team stapled 3-inch-wide strips to a movable wall and decided to literally color by numbers based on the brightness of each pixel. The team saw these efforts as a way to validate if the tape recorder was working and capturing light reflected off the planet.
Grumm ran down to a local art store in search of chalk. His idea was to use different shades of gray, but the store only had a set of colored pastels.
He and his team created a color key using brown, red and yellow pastels, and while the choice seems intentional because the colors reflect Mars’ actual color palette, Grumm was only thinking of what would best mimic a white to black gradient.
“There’s a lot of serendipity held within this image,” Delgado said of the surprisingly accurate colors.
As the team colored in the numbers, the edge of the planet emerged. Dark brown was used to reflect the void of space. The lightest colors represented Mars, and orange depicted clouds in the Martian atmosphere. Dark registration marks from the camera lens also appeared.
Not only was the camera working and taking images, but the data was good.
“People were just really scared that this mission wasn’t going to work,” Delgado said. “This image that we see here is the result of engineers really trying to validate their hardware to make sure that it was working right.”
Despite the best efforts of the communications team at JPL, journalists glimpsed the “color by numbers” image before the actual photo was released, and the artwork became the first shot of Mars from space to be seen on TV.
Later, the piece of wall covered in colored ticker tape was cut out, framed and gifted to JPL Director William Pickering.
All 22 images were returned by Mariner 4 between July 15 and August 3, 1965. Together, they revealed craters on the Martian surface and clouds floating above in the atmosphere, both of which surprised scientists. Mariner 4 happened to pass over some of the oldest terrain on Mars, which looked more like the heavily cratered surface of the moon.
The snapshots showed less than 1% of the Martian surface, missing the more diverse features on the planet’s surface that later missions such as Viking 1 would capture.
Mariner 4’s initial documentation of Mars kicked off a desire to better understand the red planet that continues to this day as the Perseverance and Curiosity rovers, Ingenuity helicopter, and a fleet of orbiters work to unlock more Martian secrets.
“The ability to see something for the first time, it changes the way that I think we feel about ourselves,” Delgado said. “The process of being able to reach out is to understand what’s out there, and it also feels like the process of understanding who we are within the context of it all.”
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