On Aug. 7, 1980, NASA's Viking 1 spacecraft ended its epic and historic mission on the Red Planet.

Viking 1 was the first spacecraft to successfully land on Mars. It was one of two Viking missions NASA launched in 1975 to go look for evidence of life on Mars. Each of the Viking missions were composed of an orbiter and a lander. Viking 1's orbiter took photos of the Martian surface that helped NASA decide where to drop the lander.

• Viking 1: The Historic First Mars Landing in Pictures

After four years of orbiting Mars, the orbiter ran out of attitude-control propellant, so NASA had to shut it down. The lander continued its scientific observations for another three years before it lost contact with NASA in 1983.

Why it mattered

NASA's Viking 1 mission is most well-known for making the first truly successful landing on Mars, but the mission was more than just a huge lander. Viking 1 actually consisted of two spacecraft, the Viking 1 Lander and the Viking 1 Orbiter. The two spacecraft rode to Mars together, with the lander separating from the orbiter ahead of its landing on the Red Planet.

In fact, NASA sent FOUR Viking spacecraft to Mars in total. The Viking 2 mission also carried both a Lander and Orbiter. But the Viking 1 probes were the first of that wave. The two orbiters were based on NASA's general Mariner 9 spacecraft bus, but more sophisticated. They carried three primary instrument suites: A two-camera imaging system; infrared spectrometer for water vapor mapping; and an infrared radiometer for thermal mapping.

The Viking missions were only planned to last 90 days, but both the lander and orbiter lasted years beyond their design lifetime. The Viking 1 Orbiter studied Mars for four years, orbiting the planet 1,488 times before shutting down on orbit 1,489 on Aug. 7, 1980.

The Viking 1 and Viking 2 Orbiters captured a combined 52,663 high-resolution photos of Mars, mapping about 97% of its surface with a resolution of about 984 feet (300 meters). They also snapped photos of Mars' two moons, Phobos and Deimos, in great detail, far surpassing what NASA achieved with the Mariner 9 Mars orbiter in 1971.

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On Aug. 6, 2012, NASA's Curiosity rover successfully touched down on the Martian surface.

At the time, the Curiosity rover was the biggest and most ambitious Mars rover that NASA ever launched. Its landing involved a new kind of maneuver that had never been tried before using something called a "sky crane." Like previous rovers that have landed on Mars, Curiosity used a parachute and rocket engines to slow down as it descended through the Red Planet's atmosphere.

But while other rovers used airbags to cushion the last part of the fall, Curiosity's rocket-propelled sky crane hovered over the ground and gently lowered it with cables. Touchdown was confirmed at 1:31 a.m. EDT (0531 GMT), though it was 10:31 p.m. PDT on Aug. 5 at Curiosity's JPL control room.

• 15 Amazing Mars Photos by NASA's Curiosity Rover

Why it mattered

The Curiosity Mars rover was built by engineers and scientists at NASA's Jet Propulsion Laboratory in Pasadena, California. The space center's motto is ambitious: "Dare Mighty Things." With Curiosity, JPL may have dared more mightily than it ever had before.

First, there's the rover's immense size. It weighs nearly 1 ton on Earth and is the size of a small car. It's powered by a nuclear battery and was the first of a new family of massive rovers to land on Mars. The sky crane landing approach was a big departure from the direct touchdowns of the Viking landers, as well as the bouncy airbag landings of the Mars Pathfinder, Spirit and Opportunity missions.

It all had to go right autonomously during a time NASA called the "7 minutes of terror" — the time it took for the landing, which would happen faster than the rover could get instructions from flight controllers on Earth due to the signal travel time to reach Mars. And it all worked spectacularly.

Curiosity not only aced its landing at Gale Crater on Mars, but it changed Mars landings forever. NASA repeated the feat nine years later with the successful landing of the Perseverance rover at Jezero Crater on Mars in February 2021. Curiosity and Perseverance are the largest rovers ever to explore Mars and set a new benchmark for what is possible on other planets.

As of this writing, Curiosity has spent 14 years exploring Mars, drilling into rocks and finding new clues about water on Mars and the planet's potential habitability in the ancient past. It's still going strong, even if it got a rock stuck on its drill for a few days earlier this year.

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