The Space Race
Long before the existence of spacecraft, people were dreaming about the day when exploring Mars would be possible. Even the most sophisticated, high-powered telescopes could not reveal close enough views of the red planet to thoroughly understand it. For that, it would take powerful rockets that could blast off from Earth, spiral millions of miles through space, and get close enough to Mars to actually study it.
One person who dreamed of Mars exploration from a young age was Robert Goddard. After reading H.G. Wells's novel War of the Worlds , Goddard had become enchanted with the idea of space flight. At the age of sixteen he recorded his thoughts in a diary: "It was one of the quiet, colorful afternoons of sheer beauty which we have in October in New England, and as I looked toward the fields at the east, I imagined how wonderful it would be to make some device which had even the possibility of ascending to Mars, and how it would look on a small scale, if sent up from the meadow at my feet." 17 Determined to build such a device, Goddard began to design rockets. He launched his first creation in 1926 from his aunt's farm. Even though the small rocket rose just forty-one feet and stayed in the air for only two and a half seconds, it was the first rocket ever propelled by liquid fuel.
Throughout the years, Goddard continued to develop more rocket designs, one of which was the world's first multistage rocket. His concept was based on the principle that a spacecraft could gain the greatest speed and altitude if it were propelled into space by a large rocket and one or more small rockets. After providing the necessary power, the large rocket would jettison, or drop off. Relieved of the extra weight, the spacecraft could then accelerate and continue on its way, jettisoning additional rockets if necessary during the flight. The multistage rocket went on to become one of the most important inventions of space exploration.
While Goddard was developing rockets on the East Coast, a group of young men on the opposite side of the country were doing their own experiments. The group established an aeronautics laboratory at the California Institute of Technology in Pasadena, which later became known as the Jet Propulsion Laboratory (JPL). They built both solid-fuel and liquid-fuel rockets, initially for U.S. military use during World War II. In 1958, when JPL became affiliated with the newly created NASA, it assumed the mission of specializing in exploring the solar system beyond Earth.
The Race Begins
Goddard and the JPL group were designing rockets at a time when the world was becoming more focused on space exploration. By international agreement, July 1957 to December 1958 was declared as the International Geophysical Year (IGY), a time devoted to worldwide study of Earth, including its oceans, atmosphere, and solar system. Several years before, the United States had announced its plans to rocket-launch a tiny artificial satellite during IGY. The satellite would be fitted with equipment that could map Earth's surface from space.
The USSR also announced a plan to launch a satellite, but the United States did not take the announcement seriously. It was not aware of the Soviets' progress in developing long-distance rockets such as the Semiorka , which was powered by twenty engines. So on October 4, 1957, when Semiorka launched a satellite called Sputnik into orbit, the world—especially the United States—was caught off guard. Sputnik was equipped with instruments such as a thermometer and radio transmitters, and once it reached its orbit, it began circling Earth and transmitting atmospheric information back to Moscow. Before Sputnik had completed its journey through space, the USSR launched a second satellite, Sputnik 2 , that was six times larger than the first. This satellite also contained a passenger, a dog named Laika. Unfortunately, Laika died just four days after launch when the cabin overheated, and Sputnik 2 's batteries failed after only six days in space. But even in the face of that failure the Soviets had proven something to the world: The race to explore the skies had begun, and they were clearly in the lead.
The Soviet victory was seen as America's failure. It was glaring proof that the USSR had accomplished what America was not yet able to do. Also, the satellite mission was perceived as a threat to the United States because of hostilities between the two superpowers, as science journalist Paul Raeburn explains: "It was a dazzling engineering achievement, and it was a powerful Cold War victory, raising fears in the United States that the Soviets might have the capability to strike the United States with a nuclear missile launched from Europe." 18
America in Space
In response to the Soviet Union's progress, the United States accelerated efforts to launch its own satellite. On December 6, 1957, the Vanguard , a rocket built by a U.S. Navy team, blasted off from Florida's Cape Canaveral. However, it failed to develop enough power to lift off the launching pad and toppled over on its side, exploding into flames. It was a crushing blow for America, but JPL engineers quickly began working on a second spacecraft called Orbiter. This was a different kind of project for the group because instead of building a rocket, as had been JPL's previous focus, this would be a satellite designed to sit on top of a separate missile. Once the satellite was launched, it would separate from its launch vehicle and float in space on its own.
On January 31, 1958, a rocket supplied by the U.S. Army blasted off into space, carrying its payload: America's first artificial satellite, renamed Explorer 1. The bullet-shaped satellite, which weighed just thirty pounds, encircled Earth every 114.8 minutes, for a total of twelve and a half orbits per day. During its time in space, the satellite transmitted information about atmospheric temperatures and radiation, as well as the presence of tiny meteorites called micrometeorites (often called shooting stars). The last transmission was received from Explorer on May 23, 1958, nearly four months after its launch.
America had entered the space race, but there was much work to be done before probes (exploratory spacecraft) could be sent to Mars. One of NASA's biggest challenges was charting the best path, or trajectory, for a spacecraft to follow on its journey. Timing was critical because in order to reduce the need for fuel, as well as keeping the trip as short as possible, launches needed to coincide with oppositions. This limited time span was known as the launch window; it started about fifty days before each opposition and lasted no more than four weeks. If the opportunity were missed, the next mission would have to wait two more years. NASA's Ron Koczor explains how trajectories work and why they are so important:
Rockets are barely powerful enough to cover the vast distances in interplanetary space, so trajectories are always chosen to make maximum use of the relative motions and positions of Earth and the target planet. For instance, when Mars and Earth are in opposition—meaning lined up and on the same side of the sun—they are closest to each other, and closer is better for fuel-guzzling rockets. Launches are planned so spacecraft can arrive sometime around opposition. Another thing to remember is that for most of its journey to Mars, the spacecraft is coasting. As it leaves Earth, it accelerates to escape velocity [how fast an object must travel to escape from the pull of Earth's gravity] and then the engines are cut off until the ship approaches Mars. When the spacecraft arrives, its engines are used to slow it down until Mars's gravity can capture it. There may be minor course corrections during flight, but these are usually short bursts of power to maintain the correct path. 19
Another critical issue NASA had to consider when planning a Mars mission was spacecraft design. The rocket needed to be large enough to accommodate a collection of heavy equipment but still light enough to lift off the launching pad and propel the spacecraft during its journey. Also, it had to be shielded from the extreme friction of Earth's and Mars's atmospheres, which creates temperatures as hot as the surface of the sun. As NASA scientists prepared for Mars exploration, they decided to send two spacecraft on all future missions because the chances were greater that at least one would arrive at its destination intact.
Failed Martian Pursuits
While the Americans were addressing the challenges of the first U.S. Mars mission, the Soviets were aggressively pursuing their own Mars exploration goals—and once again they were in the lead. During October 1960, the USSR attempted two missions known as flybys, so named because a spacecraft would fly past Mars rather than attempting to circle the planet or land on it. In both cases, the spacecraft failed to achieve their orbits and were lost. Two years later the Soviets attempted three more missions that were no more successful than their predecessors. The first spacecraft broke apart soon after reaching its orbit, and the impact sent debris whirling through the atmosphere. All contact was lost with the second spacecraft when it was about 66 million miles from Earth, and the third was destroyed before it exited Earth's atmosphere.
The Soviets refused to give up on their goal of Mars exploration, but their efforts were rewarded with one dismal failure after another. A probe launched in 1964 was nearing Mars when transmissions suddenly stopped and it was presumed lost. Two more spacecraft were launched in 1969; the first caught fire and exploded during its ascent into space, and the second failed almost immediately after liftoff.
The First Mars Rovers
After years of failed attempts, the Soviet Union's luck seemed to change when two spacecraft reached Mars in 1971. The first, called Mars 2 , was launched on May 19, while Mars 3 followed a few days later. These probes were unlike any that had been launched before, because each was composed of two parts: an orbiter that would orbit Mars and a lander that would be released by the orbiter onto the planet's surface. Once each lander was on the ground, panels would open up to reveal a small roving vehicle designed to scoot along the planet's surface by using skis attached to its sides. Both "rovers" were fitted with scientific instruments for measuring the chemical properties of the soil and the composition of the atmosphere. They were also equipped with mechanical scoops to search for organic signs of life and cameras to photograph the Martian surface.
The Soviet mission started out well, but it did not go according to plan. Mars 2 crashed while attempting to land, and although Mars 3 managed to land successfully, its transmissions back to Moscow stopped just twenty seconds after it touched down. Soviet scientists had no idea what happened, but the one photograph they received provided a possible clue. When the spacecraft had arrived on Mars, one of the greatest dust storms ever recorded was raging across the planet. Since the photograph was dark and showed no details, scientists suspected that Mars 3 had been tipped over by the fierce Martian winds, which caused its radio link to be broken.
Although neither of the Soviet rovers accomplished its intended mission, Mars 2 (in spite of its crash landing) earned the distinction of being the first human-made object to ever reach the Martian surface. The orbiters fared a little better, both completing their journeys around Mars. They sent back a series of photographs, but because of the dust storm the images were no more discernible than the photo taken by Mars 3. The spacecraft were able to take measurements of the planet's temperature, gravity, and magnetic fields, though, and these findings were transmitted back to Moscow.
An American President's Vision
The Soviet Union was highly secretive about its Mars missions, so the details were not known for many years. However, the United States was well aware of the Soviets' aggressive pursuit of space exploration, and that fueled America's interest in its own space program. No one was more enthusiastic about the effort than the country's newly elected president, John F. Kennedy. In a May 25, 1961, speech, Kennedy stressed the need for America to make space exploration a high priority: "Now it is time to take longer strides—time for a great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on earth." To emphasize how serious he was about America's space program, Kennedy asked Congress for funds to develop a rocket that could "someday [provide] a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself." 20
With the president's official endorsement, NASA enthusiastically began to plan America's future space
In December 1962, the Venus-bound Mariner 1 blasted off. However, a seemingly minor computer problem—a stray semicolon in the guidance software—caused the launch vehicle to fail, which sent the spacecraft tumbling into the Atlantic Ocean. Fortunately for NASA, the second spacecraft, Mariner 2 , launched successfully, exiting Earth's atmosphere and sweeping past Venus, where it took detailed measurements of the planet's temperatures and atmosphere. After scientists analyzed the readings, which showed an atmosphere that was thick and choking and temperatures that were hot enough to melt solid metal, they determined that Venus could not possibly harbor any form of life. So, NASA turned its attention toward Mars. The next opposition would occur in two years, and the United States planned to send two spacecraft millions of miles through space on a journey to the red planet.
Destination: The Red Planet
As the time drew closer for America's first Mars voyage, scientists had high expectations for what the mission would reveal. Most of them hoped some form of life would be found—vegetation, insects, perhaps some species of animals. Some, like astronomer Earl C. Slipher, even clung to the belief that Percival Lowell had been right about the canals. Over the years, Slipher had taken more than one hundred thousand photographs of Mars, which he used to produce a detailed map of the Martian surface. He also discovered a massive dark region that he believed was evidence of vegetation. Slipher died in 1964, so he never saw Mars exploration come to fruition, but his faith in the planet's ability to harbor life lived on in the minds and hearts of many scientists. In fact, it was Slipher's map that was initially used as a chart for U.S. voyages to Mars—and the map clearly showed Lowell's network of canals.
America's first Mars exploration attempt would be a flyby mission. The two spacecraft, Mariner 3 and Mariner 4 , carried instruments that would measure the planet's radiation, magnetic fields, and atmospheric pressure, as well as cameras for photographing the Martian surface. To provide power after leaving Earth's atmosphere, each was equipped with thousands of solar cells mounted on four large solar panels. The panels were designed to face the sun during most of the flight, and would collect solar energy and convert it into electrical power.
On November 5, 1964, Mariner 3 's launch rocket blasted off on schedule, but just nine hours later the voyage came to an end. A fiberglass nose cone, designed to protect the spacecraft's instruments from the friction of Earth's atmosphere, did not jettison as planned. Instead, the shield remained in place, weighing the spacecraft down and preventing its solar panels from collecting the sun's energy. As a result, its batteries lost power and the mission failed. The second spacecraft was ready to go, but the liftoff had to be postponed. Unless engineers determined what had gone wrong the first time, Mariner 4 was destined to suffer the same fate as its twin.
Only three weeks remained in the launch window so the situation was urgent, as author Franklin O'Donnell describes:
The race against the clock had begun and engineers had only one month to get it ready to depart for the red planet. The next few days became what some outside observers hail as JPL crisis engineering at its best. Working with contractors and partners, JPL created what in engineering [jargon] is known as a 'tiger team'—a small, nimble group of its best people with a mission to quickly diagnose and fix a problem. 22
In just four days, engineers discovered that the problem was a structural defect in the launch vehicle's nose cone, rather than a problem with the spacecraft. Within three weeks they had designed and built a new shield, tested it, and installed it on the rocket that had been waiting on the launch pad in Florida. On November 28, 1964, three weeks after the first launch failed, Mariner 4 blasted into space and headed toward Mars.
From Elation to Shock
After a seven-month journey, Mariner 4 reached its Mars orbit on July 14, 1965. The spacecraft's trajectory
When the fuzzy images of the Martian surface finally began to appear, however, the mood at NASA changed from euphoria to stunned silence. For years, Mars and Earth were thought to be very much alike, so scientists expected to see many similarities. Instead, they stared with disbelief at a planet that was scarred with enormous craters and looked every bit as dead and lifeless as Earth's own moon. Scientific author Robert Godwin describes the reaction at NASA as the photos began to come into focus:
The 22 grainy black and white pictures returned by Mariner 4 changed mankind's notion of Mars forever. No canals, no ancient cities. . . . For many it was a disillusioning blow that almost killed the romance of the red planet forever. The science fiction writers would be forever forced to revise their Martian fables, no more Barsoom and the beautiful Princesses, no elegant crystal cities or lush jungle landscapes. The masterworks of Burroughs and Bradbury would finally have to be appraised in a different way, as great literary works from a different and more romantic era. 23
The Exploration Continues
As shocking as Mariner 4 's findings were, they did little to diminish scientists' desire to continue with Mars exploration. Most of them still believed that Mars and Earth had been nearly identical when they were formed, and now—even more than before—they wondered what had happened to cause such drastic changes. Also, the spacecraft had been able to photograph only 1 percent of the Martian surface, so it was possible that the rest of the planet was different. NASA intended to find out if this was the case.
In 1969 the United States launched two more Mars probes, hoping that their findings would be more promising. Like their predecessors, Mariner 6 and Mariner 7 were flyby spacecraft, but they were heavier and more advanced versions of Mariner 4. Each was equipped with two television cameras and scientific instruments that could measure the temperature, pressure, and chemical composition of the Martian atmosphere. Together they sent back two
The next two Mariner missions were launched in 1971. Unlike their flyby predecessors, these spacecraft were orbiters capable of mapping the entire Martian surface over a long period of time. Much to NASA's dismay, the first spacecraft, Mariner 8 , was lost when one of its rockets failed to ignite. However, its twin successfully reached its Mars orbit—but immediately encountered the same sort of fierce dust storm that had likely crippled the Soviet Union's Mars 3 lander. Blinded by the thick, swirling dust, Mariner 9 's cameras were unable to transmit any images for more than a month. Once the dust finally cleared, Mariner 9 began sending photographs and as scientists studied them, they soon realized they had grossly misjudged Mars. The images clearly showed that only a portion of the planet was heavily cratered and barren, while other areas were covered with diverse geological features. For the first time, close-up photographs revealed details of the immense Valles Marineris and Tharsis Bulge, as well as enormous volcanoes such as Olympus Mons, the north and south polar caps, and winding valleys and channels that looked like they had been carved by ancient rivers or floods. Scientists were also able to see close-up images of the two Martian moons, Phobos and Deimos.
Mariner 9 's orbit lasted for a year, and during that time the spacecraft transmitted more than seven thousand photos of Mars. It also provided a vast amount of information about the planet's atmospheric composition, density, pressure, and temperature, as well as data about surface composition, temperature, and gravity. The findings were invaluable, and they enhanced the intrigue of Mars more than any mission had before, as planetary scientist Bruce Murray explains: "Lowell's Earthlike Mars was forever gone, but so was the moonlike Mars portrayed by our first three flyby missions. . . . The Mars revealed by Mariner 9 was not one-dimensional; it was an intriguingly varied planet with a mysterious history. The possibility of early life once more emerged." 25