50 years ago, a NASA spacecraft revealed Martian volcanoes

After a series of underwhelming Mars missions suggest Mars might be, well, boring, Mariner 9 revealed the Red planet it all its dusty and gargantuan glory.

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The view of the Martian south pole from the approaching Mariner 9 spacecraft.

You have to feel for Mariner 9. First, the spacecraft loses its twin, Mariner 8, in a launch failure just weeks before Mariner 9 itself was scheduled to blast off toward Mars on May 30, 1971. Not only would Mariner 9 travel to the Red Planet alone, but it would also do the work of two space probes.

But after six months, Mariner 9 arrives — 50 years ago, on November 13, 1971, it becomes the first spacecraft ever to enter orbit around another planet. It gets its cameras ready, points them at the Martian surface, and sees … nothing but fuzz. A global dust storm obscures the entirety of the planet’s surface features.

But hey, no problem. Mariner 9 is a robot without feelings, and with infinite patience — plus a reprogrammable computer. It can bide its time until finally taking its place as the crown jewel and penultimate mission of the Mariner planetary exploration program — the mission that first introduced us to the Mars we know today.

This Mariner 9 image of Mars’ moon Phobos was the first detailed view of the strange rock.


A string of failed NASA missions

The Mariner program launched in the early days of the U.S.-Soviet space race, with, well, a failure to launch. The Soviets sent the first spacecraft to Venus — Venera 1 — in May 1962. NASA’s answer, Mariner 1, intended to fly by Venus, was destroyed when its Atlas-Agena rocket malfunctioned on July 22, 1962.

Mariner was “one of the programs that I think the U.S. developed in its early years of space exploration that really showed us moving along that learning curve of how to do things in space,” National Air and Space Museum curator of planetary science and exploration Matt Shindell tells Inverse. But we did learn, and “U.S capabilities in space advanced one mission after another, first with flyby missions, and then eventually with orbits.”

Thankfully, since launch vehicles were less than reliable in those days, they built two spacecraft for that mission. Mariner 2, a sibling probe, became the first successful Mariner mission. Launching in August of 1962, “it flew by Venus and gave us our first data collected from another parent by an interplanetary spacecraft,” Shindell says. The Soviets lost radio contact with Venera 1 so it returned no data.

Mariner 3 was supposed to be the first Mariner mission to Mars, but like Mariner 1, it failed to launch. “It wasn’t that uncommon for these spacecraft,” Shindell says, though it’s rare today.

Mariner 4 was the first Mariner mission to make it to Mars, making a flyby on July 15, 1965, and providing the very first image of Mars taken from a spacecraft. Unfortunately, Mariner 4’s camera system was fixed to the spacecraft “in such as way that it couldn’t really be pointed or target while flying,” Shindell says, and only collected a handful of images of one swatch of the planet as Mariner 4 flew by.

Those images showed a cratered surface that looked disappointingly similar to the Moon, he says, giving the impression that “Mars was actually going to be a very boring planet,” without many insights to yield us.

Images from the Mariner 4 flyby of Mars.

The Mariner 6 and 7 flybys in 1969 were an improvement. With camera systems mounted on moveable platforms, they could target specific spots of the Martian surface and collected many more photos than Mariner 4.

But remarkably Shindell says, they still managed to miss the most interesting surface features of Mars — the massive canyons and the Solar System’s biggest volcano, Olympus Mons. “It was remarkably bad luck,” he says. “All they saw was that cratered terrain when there was so much more to potentially see.”

When Mariner 9 met Mars

Then came Mariner 8 and 9, a matching pair. The two spacecraft sported better cameras and, importantly it turned out, a more powerful computer system that could be reprogrammed remotely by engineers on Earth. They wouldn’t just take some snapshots while passing by. They would enter orbit and conduct a serious photographic survey of the Martian surface.

But then Mariner 8 blew up at launch, and Mariner 9 flew on alone. It reached Mars just in time to witness that planet-wide dust storm.

“I think they took it remarkably well,” Shindell says of the Mariner team. “It actually ended up being a really great boon of sorts for people who wanted to understand the Martian atmosphere better.”

The Mariner 9 spacecraft, the first to orbit another planet.


Of course, they knew they could wait awhile: the Mariner 9 team reprogrammed the spacecraft to hold off on its planned photographic survey until the storm lifted.

But Mariner 9 wasn’t entirely alone out there. The Soviet Union had also sent probes to Mars around the same time, with Mars 2 entering Mars orbit on November 27 and Mars 3 entering orbit on December 2.

Unfortunately for the Soviet scientists, the Mars spacecraft had a preprogrammed photography sequence, and was shooting on film, Shindell says. They used up all their shots before the dust storm lifted. “It just wasn’t a good year for the Russians,” he says, “but it was a great year for us, for the U.S.”

Eventually, the Martian dust storm began to fade, Shindell says, and like receding floodwaters, they revealed some remarkable terrain. “The first things that were revealed were the tips of those huge volcanoes in the Tharsis region of Mars, which included Olympus Mons, the largest volcano that we know of in Solar System,” he says.

Olympus Mons, the largest volcano in the Solar System, peaks above a Mars-wide dust storm in an image taken by Mariner 9.


Mariner 9 images also revealed a massive canyon system that dwarfs the Grand Canyon, and would stretch from New York to Los Angeles on Earth. “Valles Marineris takes its name from the fact that it was discovered by a Mariner spacecraft,” Shindell says.

Mariner 9 legacy — the creation of “Mars”

Mariner 9 would go on to operate for 349 days and take more than 6,800 photographs, enough to make a large photomosaic Martian globe, which happens to be Shindell’s favorite artifact at the National Air and Space Museum.

And while the later Viking orbiters and landers and follow on missions would go on to overshadow Mariner 9, documenting the Red Planet in greater detail from above and on the surface, it was Mariner 9, Shindell says that first revealed the Red Planet to us it is unique glory, from massive volcanoes to worldwide dust storms.

“Mariner 9 really did transform our view of Mars,” he says. “Mars became this dynamic planet that potentially had a lot to teach us about why our planet was the way it was versus why Mars went in the direction that it did.”

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