The Mars rover Curiosity, now just days from landing on the Martian surface, is something of a technological marvel, unlike anything that has come before it. It packs some of the most high-tech scientific hardware ever sent into space aboard a robotic spacecraft, delicate tools and complex systems that will allow it to conduct the most sophisticated science ever performed on the surface of Mars.
But first NASA engineers have to slow it from 13,000 miles per hour to zero in just seven minutes and place carefully into an extremely hostile environment. It’s a delicate act, an art form really, but it’s been done before. Curiosity doesn’t stand alone, but on the shoulders of giants.
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Curiosity’s landing will be the most technologically dazzling landing on another planet ever conceived by human spaceflight engineers, but it isn’t happening without the benefit of experience. Since the 1960s, the United States and Russia (then the Soviet Union) have been building expensive, sophisticated machines and slamming them into other planetary bodies. Some missed their targets completely, some were crushed like soda cans, some were bashed to pieces, and some lucky few made it long enough to beam a signal back home.
Thus far we’ve landed on nearby planets, faraway moons, and fast-moving asteroids zipping through our celestial neighborhood. We’ve delivered stationary landers, exploratory rovers, and in one case an orbiter that was never intended to touch down on anything at all. Take a spin through the history of robotic space landings–the ones in which everything that could’ve gone wrong didn’t.
Luna 9, the First Lunar Soft Landing, February 1966
The Soviet Union’s Luna 9 spacecraft was the first to achieve a lunar soft landing and survive to transmit photographic data back to Earth. Launched on the last day of January 1966, Luna 9 truly made a crash landing, bouncing several times (it impacted at roughly 14 miles per hour, slowed by a retrorocket and then four onboard engines) before coming to rest in a region known as Oceanus Procellarum (Ocean of Storms) on February 3, 1966. Several minutes later its four “petals” opened up and stabilized the spacecraft on the surface. It’s sensor payload consisted only of a radiation detector and a small upward facing camera. A turret-mounted rotating mirror mounted above the camera allowed it to capture 360 imagery from its stationary position on the lunar surface. Luna 9 transmitted data to Earth in seven radio sessions totaling just more than 8 hours. These transmissions included three series of TV pictures–the first taken from the moon’s surface–as well as panoramic views of the lunar frontier. Radiation data was also returned. Three days later the batteries died and Luna 9’s mission was terminated. But despite its short duration, by simple virtue of its landing Luna 9 settled something that was previously uncertain–that the lunar surface could support a spacecraft (Luna 9 weighed about 220 pounds). Some models at that point in time showed that the lunar regolith wasn’t load-bearing; any spacecraft that landed there would sink into the moon’s powdery surface. Luna 9 placed a manned mission to the moon firmly within the realm of possibility.
Surveyors: America’s First Moon Landers, June 1966
The Surveyor missions were the first attempts by the United States to make soft landings on the moon, and five of the seven spacecraft proved American technology up to the task, including the very first one (Surveyor 1). The Surveyors were originally intended to be their own stand-alone science missions but were quickly folded into support missions for the Apollo program as the space race heated up. Surveyor 1 marked the first soft landing for the U.S. on June 2, 1966 (four months after Luna 9), but all seven Surveyor spacecraft served to develop and validate NASA’s ability to put a spacecraft on a lunar intercept trajectory, make the proper maneuvers to place a spacecraft at a predetermined point on the lunar surface, and to communicate with mission control on Earth across a quarter-million miles. They also all served as scouts for potential Apollo landing sites. All except Surveyors 2 and 4, that is–those two crashed upon arrival. Pictured: Surveyor 3.
Lunokhod 1, the First Moon Rover, November 1970
Though by this time Americans had already walked on the moon, the Soviets launched a series of lunar rovers to the moon between 1969 and 1977 under the program heading Lunokhod (or “moonwalker”). The first Lunokhod didn’t make it through launch (it was given the designation “1A”) but the second, Lunokhod 1, touched down at the moon’s “Sea of Rains” on November 17, 1970, aboard the spacecraft Luna 17. Though the Soviets had lost the race to the moon, they did have something novel in Lunokhod 1. It was the first remote-controlled rover to land on another planetary body. Luna 17 deposited Lunokhod 1 on the lunar surface via dual ramps that deployed from the spacecraft. Once on the surface, Lunokhod 1 demonstrated many of the rover technologies that are still employed today: special lubricants that keep moving parts working at different atmospheric pressures, electric motors, a radioisotope heater to keep it warm during the lunar night, and solar panels that charge its batteries during the day. It operated for just short of one year, traveling more than 34,000 feet and transmitting 20,000 pictures during that time. It also created the modern paradigm for rovers that would be followed for decades.
Venera 7, Interplanetary Explorer, December 1970
Venera 7 was part of a series of probes designed to study the atmosphere and surface of Venus. Some were crushed on the way to the surface by the immense pressure present there (93 times that of Earth), but seventh time’s a charm. Venera 7 entered the Venusian atmosphere on December 15, 1970 and jettisoned its landing capsule, which this time made it all the way to the surface for a successful soft landing via aerodynamic braking and a parachute. The capsule extended its antenna as designed and beamed signals back to Earth for 35 minutes before suddenly going silent. Then, mysteriously, another 23 minutes of very weak signal were recorded from Venera 7’s lander a few weeks later. It was the first man-made spacecraft to successfully land on another planet and transmit data back to Earth.
Mars 3, Almost a Perfect Mars Landing (Orbiter Pictured), December 1971
The Soviet Mars Program was a string of mixed successes and failures launched between 1960 and 1973 in an attempt to put unmanned spacecraft in orbit around and on the surface of Mars. Some found orbit but failed to soft-land their descent modules. Some missed orbit completely. But Mars 3 should be recognized for making the first successful soft-landing on the Martian surface even if the mission lasted all of 20 seconds. After the failure of the identical Mars 2 mission to soft-land its descent module just a few days prior, Mars 3 managed to put its descent module on the proper downward trajectory. Atmospheric braking, parachutes, and retrorockets combined to slow the lander adequately, and after a 4.5-hour descent it landed–in the middle of a massive dust storm. No one can be sure, but mission controllers speculate that these storms were the reason the Mars 3 lander was only able to establish a line of communication with Earth for a mere 20 seconds before its instruments stopped working. The Mars 2 and Mars 3 orbiters continued to ring the planet for the next year, returning a wealth of topographic and atmospheric data, so the missions weren’t a total loss for the program. And Mars 3 proved that, with a little better luck, the Martian surface was within reach of robotic spacecraft.
Viking 1 Lands on Mars, July 1976
The first really successful robotic exploration of Mars came in 1976, when the Viking 1 and Viking 2 spacecraft, launched the year before, each successfully deposited their landers on the Martian surface via soft landing. The orbiters continued to orbit, measuring atmospheric water vapor and thermally mapping the planet in infrared. On the surface, the landers took 360-degree pictures of the Martian surface, took temperature readings, analyzed soil samples, and otherwise gave planetary scientists the bulk of their body of knowledge of Martian geology and geography that would serve them for the next two decades. Unlike Mars 3, these missions were not short-lived. The entire Viking program wasn’t shut down until May of 1983. The Viking 1 lander operated for more than six years on the Martian surface, and even then only ceased function after human error during a software update caused critical parts of its communication programming to be overwritten, terminating its link with Earth. Pictured: the view from Viking 1
Mars Pathfinder Lands, July 1997
Post-Viking, NASA turned its attention to Earth orbit and its newly commissioned space shuttles, but in on July 4, 1997, NASA landed the first mobile rover on the Red Planet. The Mars Pathfinder mission placed both a stationary lander (renamed Carl Sagan Memorial Station upon landing) and a small robotic rover (named Sojourner for civil rights crusader Sojourner Truth) on the Martian surface via an untried soft landing system that relied on parachutes to slow the spacecraft down and a casing of airbags to allow it to bounce (at least fifteen times) and roll to a stop on the Martian surface. Though designed to right itself, the spacecraft happened to come to a rest right side up. The lander then deployed the rover and both proceeded to outlive their operational lives several times over–the lander by three times its designed lifetime of 30 days, and the rover by 12 times its designed lifetime of seven days. From landing to the final transmission of data on September 27, 1999, the Pathfinder mission delivered 2.3 billion bits of information back to earth, including more than 17,000 images, 15 chemical analyses from soil and rock samples, and myriad weather and atmospheric data. Pathfinder provided the strongest evidence yet that Mars was once warm and wet, and informed the design of future Mars missions that would follow.
NEAR Shoemaker, the Unintended Asteroid Lander, February 2001
NASA’s Near Earth Asteroid Rendezvous Shoemaker (NEAR Shoemaker, named for planetary scientist Gene Shoemaker) was designed to study asteroid 433 Eros, one of the largest asteroids in Earth’s orbital neighborhood. It was not designed to land on it. But after orbiting 433 Eros for nearly a year, snapping some 160,000 images along the way and creating the first real body of data about asteroid composition and properties, the opportunity was too good for mission handlers to pass up. As it approached the end of its life in 2001, NASA mission handlers chose to attempt a landing on the asteroid’s surface. NEAR Shoemaker continued snapping images all the way down, gathering pictures from as close as 400 feet that clearly resolved features the size of a golf ball. The spacecraft touched down moving a mere 4 miles per hour on February 12, 2001 and continued transmitting data to Earth until the end of that month, making it the first spacecraft to successfully orbit, land upon, and transmit data from an asteroid.
Mars Exploration Rovers Spirit and Opportunity, January 2004
Following the success of Mars Pathfinder, NASA crafted the Mars Exploration Rover Mission around dual rovers launched in tandem in summer 2003, named Spirit and Opportunity. The two rovers were designed as robot geologists, tasked with seeking clues to Mars’ terrestrial and hydrological history. Both landed successfully on opposite sides of the Red Planet within weeks of one another in January of 2004 and began exploring. Then they just kept going. Both Spirit and Opportunity have far outlived their three-month planned lifespans by more than two dozen times, returning from “hibernation” over and over again (during the Martian winter they power down and rely on internal heaters to keep their circuitry intact). Spirit’s mission was finally terminated last year after it failed to wake up from its hibernation state after more than six years of exploration (Spirit was already rendered immobile back in 2010 after becoming stuck in a sand pit near the Martian equator). And as of this writing Opportunity continues roving, exploring the Endeavour crater and preparing for another Martian winter. Between the two of them, Spirit and Opportunity have by far generated more and better data about the Martian surface and geology than any other exploratory mission–and far more than even the most optimistic NASA mission planner could have expected.
Huygens, The Outer Solar System Explorer, January 14, 2005
Mars exploration is amazing, but the oft-forgotten Huygens probe could very well be the most interesting planetary lander humankind has ever sent into space. Carried by the Saturn-exploring Cassini spacecraft for seven years all the way to the outer solar system, the ESA-designed Huygens was jettisoned from Cassini in January of 2005 and made the first and only spacecraft landing in the outer solar system on the surface of the Saturnalian moon Titan. Mission designers had little idea what to expect for this landing, so Huygens was designed to land on both dry land or in an ocean. Ideally, it would transmit data for a few hours during its descent through the atmosphere and–if mission handlers were lucky–for a short time from the surface. Not only did it beam back two-and-a-half hours worth of data and images during its descent through the atmosphere, but after landing in the mud along a shoreline Huygens beamed back data from Titan’s surface for a full 70 minutes. It remains the most distant spacecraft landing ever achieved.
Hayabusa Lands on Itokawa, November 2005
NASA’s NEAR Shoemaker made the first landing on an asteroid, but it was the Japanese Space Agency’s Hayabusa probe that actually lived to tell the tale. Launched in 2003 on a trajectory to intercept the asteroid Itokawa, Hayabusa landed on the asteroid’s surface in November 2005, collected samples from the surface of the asteroid (a first), and returned them to Earth, providing the only samples of asteroid material scientists have ever seen. But it almost didn’t happen. Upon landing on Itokawa, the projectiles designed to blast dust from the surface up into Hayabusa’s collection chambers didn’t fire. Only the dust kicked up upon landing was available for collection, and mission controllers had no idea if any of it had actually been contained aboard the spacecraft. For five years researchers were left wondering whether Hayabusa had been a bust as they waited for it to make its return journey to Earth. Sure enough, their patience paid off. Hayabusa returned some 1,500 particles from the asteroid, marking only the third time a space exploration mission has returned samples from another planetary body.
Mars Phoenix Lander Touches Down, May 2008
With two robot geologists already roving the Martian surface and a handful of orbiters overhead, NASA (along with several partners including the University of Arizona, which led the mission) sent the Mars Phoenix Lander to a region near the Martian north pole to search for environments suitable for microbial life and research the historical hydrology of the planet. In May 2008 it landed and operated until November of that year. During that time, the stationary Phoenix lander examined deposits of underground water ice detected by the Mars Odyssey orbiter and found several interesting things hiding in the Martian soil and near-surface ice, including evidence for the occasional presence of thawed water near the surface and traces of perchlorate, an oxidizing agent found on Earth that is sustenance for some kinds of microbial life (and toxic to others). It also observed snow falling from cirrus clouds. Phoenix was never meant to survive the Martian winter however. Though it outlasted its three-month life expectancy by two months, it sent its last transmission in November of 2008, and upon the return of sunlight to the region the Mars Reconnaissance Orbiter was able to observe severe ice damage to Phoenix’s solar panels. The mission was formally terminated in May of 2010.
