Mars and Human History

Humans have known and have been fascinated by Mars since before recorded history. Thirty six centuries ago, the ancient Babylonians noted Mars’s apparent looping motion across the sky and its changing brightness. In ancient India, Mars appeared to be a fire in the sky. The Greeks and Romans considered the planet the personification of their god of war because of its red color.

In 1609, Johannes Kepler discovered a way to accurately predict the motion of Mars across the sky by concluding that Mars was a world that moves around the sun in a ellipse rather than a circle as Copernicus suggested. Galileo proved that Mars was an actual world by showing it in his telescope for the first time.

As telescopes improved, astronomers could see polar icecaps, clouds, haze, and shifting color patterns on the Martian surface, all which suggested a habitable world. In 1877 an Italian astronomer named Giovanni Schiaparelli thought he saw thin lines across the Martian landscape that he called “canali” (Italian for “channels”). This name was mistranslated to mean “canals,” which suggested intelligent life on Mars. In the United States, Percival Lowell seized on the canals as proof of a Martian civilization, advanced enough to move water across a whole world.

The modern era of Mars exploration began to take shape in the early 1960s, even as the race to put the first man on the Moon was occurring. This era has, so far, consisted of a series of robotic probes launched, primarily, by the United States.

Mariner 4

Mariner 4 was launched by NASA in November of 1964. On July 15th, 1965 it passed by Mars successfully at 9,846 km, returning visual and other data from the red planet. The images beamed back to Earth showed a crater strewn surface much like that of the Moon. No canals or any signs of life, intelligent or otherwise, were found. Mariner 4’s instruments proved that the atmosphere of Mars was about .07 percent as thick as that of Earth, too thin to support life as we know it.

Mariner 6/7

The next NASA mission to Mars consisted of a pair of flyby probes, Mariner 6, launched in February of 1969, and Mariner 7, launched in March of 1969. Mariner 6 passed by Mars at a distance of 3431 km on July 31st, 1969. Mariner 7 passed by Mars at a distance of 3430 km on August 5th, 1969.

The two Mariner probes beamed back a number of images back to Earth that showed that Mars, unlike in the images sent by Mariner 4, was very much unlike the Moon. While once again no canals or signs of life were found, the images showed a volcano, plains without impact craters, and areas of chaotic hills. The Martian south pole was found to be comprised almost entirely of frozen carbon dioxide. The surface pressure of the Martian atmosphere was measured to by between 6 and 7 millibars. The spectrometers showed that Mars was very cold (-123°C at the south pole), and that Mars' thin atmosphere was almost all carbon dioxide. The spacecraft instruments measured UV and IR emissions and radio refractivity of the Martian atmosphere, Radio science refined the measurements of Mars’ mass, radius, and shape.

Mariner 9

Mariner 9 was launched in May of 1971 and in November of 1971 became the first artificial satellite to orbit another planet. A planet-wide dust storm which obscured all of Mars’ features delayed the mapping mission for about a month. Mariner 9 provided the first global map of the Martian surface, providing 7329 images. These included the first detailed views of the martian volcanoes, including Olympus Mons, 600 kilometers across at its base and 25 kilometers tall, Valles Marineris, a canyon up to 100 kilometers wide and 10 kilometers deep that would reach from Los Angeles to New York, the polar caps, and the satellites Phobos and Deimos. Data returned by Mariner 9 provided the first evidence that Mars had rivers and lakes at one time. The spacecraft gathered data on the atmospheric composition, density, pressure, and temperature and also the surface composition, temperature, gravity, and topography of Mars.

Viking 1/Viking 2

The two Viking probes were launched from Earth in 1975 and entered Mars orbit in 1975. Each Viking consisted of two space craft, an orbiter and a lander. Each orbiter had a pair of cameras and instruments for mapping surface temperature and atmospheric humidity. Each lander included a weather station, a seismometer for detecting "marsquakes," instruments for analyzing soil, and a stereo TV camera.

The Viking 1 lander touched down on the Chryse Planitia in the northern lowlands on July 20th, 1976, exactly seven years after the first Apollo moon landing. Its video cameras took the first pictures of the Martian surface. Its landing site was a desolate plain of dark, rounded rocks, probably volcanic, and red dust under a pink sky. Though Viking 1 landed at about the equivalent latitude of the Sahara Desert, temperatures ranged from a high of -10°C (14°F), and to a numbing low of -90°C (-130°F). Winds were light, at about thirty kilometers an hour.

The Viking 2 lander touched down on Utopia Planitia, closer to the Martian North Pole about two months later. The Viking 2 landing site is rockier than that of Viking 1; it is flat with a few low, crater hills in the distance. Its winter night temperatures dropped to -120°C (-184°F). In winter, a thin layer of water frost was present for several months.

The Viking landers discovered no life, even microbial. The robot arms of the landers scooped up some soil for analysis with instruments designed to detect signs of life. The instruments cooked the soil, soaked it, and fed it nutrient broth. Although the soil contained no organic material, a few experiments seemed to indicate signs of living organisms. However, after years of debate, most scientists now agree that the life signs came from unusual minerals in the soil, and that Mars' surface, at least around the two Viking landing sites, is lifeless.

In the meantime, the two Viking orbiters mapped the Martian surface and analyzed its surface temperature and atmosphere. The orbiters’ instruments discovered an abundance of water in the Martian atmosphere. Over 5200 images were taken of the Martian surface, mapping the red planet in greater detail than ever before. Insights into Mars’ volcanoes, water, and ancient history are being studied to this day.

The Birth of Faster, Better, Cheaper

The Viking program concluded in 1982. Fourteen years would pass before another successful exploration mission to Mars was executed. During this time, four space craft were sent to Mars, one American and three Russian. In January 29, 1989, the two Russian Phobos 2 space craft entered Mars orbit. Contact was lost with these vehicles shortly before they were to pass within thirty meters of the Martian moon Phobos and release two landers. In August, 1993, the American Mars Observer probe was lost as it was preparing to enter Mars Orbit. In November, 1996, the Russian Mars 96 probe failed to enter into a Mars cruise trajectory, after reentering the Earth’s atmosphere, crashed somewhere in the Pacific Ocean.

Taking note that planetary probes, such as Galileo, Cassini, and the lost Mars Observer, had tended to cost in the range of a billion dollars and more and take almost a decade to build and prepare for launch, NASA instituted a policy called “Faster, Better, Cheaper.” A series of probes would be built that would cost than a few hundred million, including launch and operations costs, and would take two or three years to prepare. Instead of a few, large, expensive probes being launched over a long period of time, many, smaller, less expensive proves would be launched instead.

Mars Pathfinder

The first Mars mission to be executed under the Faster, Better, Cheaper policy was the Mars Pathfinder. Mars Pathfinder consisted of a lander that would have its touch down on the Martian surface softened by an air bag and a mini rover named Mars Sojourner, named after the African American historical figure Sojourner Truth.

Mars Pathfinder was launched on December 4th, 1996 and landed near the mouth of the Ares Valles valley on July 4th, 1997. The lander and the Sojourner rover each contained a camera and between them returned over 16,000 images from the Martian surface,. The Sojourner rover executed fifteen chemical analyses of various rocks in the vicinity of the landing site. Data on winds and other weather phenomenon, including several dust devils, were returned. Evidence of running water on the Martian surface in the ancient past was uncovered.

Mars Global Surveyor

Mars Global Surveyor was launched on November 7th, 1996 and entered Martian orbit on September 12th, 1997. It spent a year and a half regularizing its orbit using a technique known as aerobreaking, in which it used the Martian atmosphere to slow its speed. It started its mapping mission in March, 1999 from a low polar orbit. Mars Surveyor spent a year and a half mapping the entire Martian surface in greater detail than hitherto achieved, as well as conducting extensive studies of the Martian atmosphere, interior, and magnetic field. Mars Global Surveyor has begun an extended mission and is still operational

"Faster, Better, Cheaper" Fails

The next two Martian probes were lost because, many believe, the policy of "Faster, Better Cheaper" failed. Too much was attempted for too little money and not enough time.

Mars Climate Orbiter, meant to be a Mars weather satellite and a communications relay for its companion probe, the Mars Polar Lander, was launched in December, 1998. It was lost while attempting to enter Mars orbit on September 23rd, 1999 when it likely entered the planet’s atmosphere and burned up. A subsequent investigation found that cutbacks in money spent on tracking, combined with incorrect values in a look-up table in the spacecrafts software (use of the English measurement pounds force instead of the metric measurement newtons) were to blame for the lost of the space craft.

Mars Polar Lander was launched in January, 1999. It would have dug for water ice near the Martian South Pole. A pair of tiny probes designed to penetrate the Martian surface, called Deep Space 2, piggy-backed on the Mars Polar Lander. Mars Polar Lander and Deep Space 2 were lost on arrival to Mars on December 3rd, 1999. Subsequent investigations blamed shortcomings in project management and preflight testing for the loss of the probe.

The lost of the Mars Climate Orbiter and the Mars Polar Lander resulted in a reevaluation of the Faster, Better, Cheaper policy. Subsequent NASA planetary probes would not be so cheap.

Mars Odyssey

Mars Odyssey was launched on April 7th, 2001 and entered Mars orbit on October 24th, 2001. Similar to Mars Climate Orbiter, Mars Odyssey carried instruments for the measurement of minerals, the location of deposits of water, and the measurement of radiation on the Martian surface. The mission of Mars Odyssey is currently ongoing and data returned from it is being used to locate sites for future landers.

Mars Express

Mars Express is the first successful robotic probe to Mars launched and operated by the European Space Agency. It launched in June of 2003 and arrived in Mars orbit on December 25th, 2003. Mars Express is designed to search for subsurface water, as well as to analyze Mars’ atmosphere, structure, geology and composition. Mars Express also carried a British built lander, called the Beagle 2, which crashed when attempting to land on the Martian surface. Mars Express also carries a communications relay for landers, The mission of Mars Express is ongoing.

Mars Exploration Rovers (Spirit and Opportunity)

Mars Exploration Rover A, later named Spirit, was launched on June 10, 2003 and arrived on Mars in the Gusev Crater on January 4th, 2004. Mars Exploration Rover B, later named Opportunity, was launched on July 7th, 2003 and landed in the Terra Meridiani on January 25th, 2004. Both vehicles landed with the aid of an aeroshell, parachutes, retro rockets, and air bags previously used by Mars Pathfinder. Both rovers are essentially robotic geologists, with instruments designed to study rocks and soil and to uncover evidence of ancient water activity. The rovers also have cameras for determining the mineralogy, texture, and structure of the local terrain. The rovers are capable of moving about a hundred meters a day along the Martian surface. Spirit and Opportunity are bigger and faster, with more range and more instruments than did Mars Sojourner. Their mission, over a year after landing on the Martian surface, is ongoing.

Humans to Mars

As successful as many of the robotic missions to Mars have been in the past forty years, most space experts believe that in order to completely understand the Red Planet, eventually human explorers must follow. Robots can perform only the tasks they are programmed to do. An imperfect solution is using teleoperation, which is when an Earth-bound human commands a robot on Mars, such as Opportunity and Spirit, to do a task. As much as 20 minutes must pass between a command beamed from Earth to the command being executed on Mars, eating up time and limiting the tasks that can be performed.

A human can accomplish in a day or so what a robot can do during the entire life of its mission. Traveling across miles of unknown terrain, he can observe all sorts of intuitive clues, as his eye can see the equivalent of millions of high-resolution images, picking up details easily missed by any robot's camera. With delicate pick-and-spade work, he can collect samples of rocks and other materials and take them to a lab to examine them more closely, reacting immediately to unexpected results. No robot can do all of that with the skill and speed of a human being.

For nearly sixty years, since Wernher von Braun proposed sending a fleet of ships with seventy astronauts to Mars in his 1946 study Marsprojekt, there have been dozens of human Mars expedition proposals, American, Russian, and private. By the 1960s, NASA had settled on a space craft concept using the NERVA nuclear thermal rocket which had been tested successfully on a static test stand. The Soviets had a number of concepts using a nuclear electric engine in a space craft to be launched by their super heavy lift rocket, the N1. A Mars expedition was seriously proposed for NASA as a part of a post Apollo space program in 1969. The first Mars expedition would have taken place some time in the 1980s. Budget politics of the time foreclosed any consideration of a humans to Mars program for the foreseeable future and the idea was soon shelved. With their N1 rocket proving to be unworkable, the Soviets soon followed suit.

Proposals for Mars expeditions appeared in reports issued by the National Commission on Space and the Ride Commission in the 1980s. President George H. W. Bush proposed a human expedition to Mars in 1989 as part of his Space Exploration Initiative. However, as in 1989, budget politics and the huge cost of sending people to Mars foreclosed the idea. President Clinton, upon winning election to the Presidency, cancelled the Space Exploration Initiative.

Mars Direct

In 1991, a team at Martin Marietta led by Robert Zubrin, in conjunction with NASA Ames, proposed a revolution in Mars exploration thinking. Mars Direct envisioned a series of space craft to be launched on a super heavy lift launch vehicle, dubbed the Ares. The first launch would deliver an unmanned Earth Return Vehicle (ERV) to the Martian surface. After landing an on-board production plant would generate methane/oxygen propellants for the ERV’s return trip to Earth. The second launch would deliver a four person crew for eighteen months of Mars exploration. Then the crew would use the ERV to return to Earth. Because the expedition would not have to carry all of the fuel needed to Mars, the weight, size, and cost of the Mars ships would be greatly reduced. Zubrin has estimated that Mars Direct, rather than costing the hundreds of billions of other Mars expedition concepts, would cost just twenty billion dollars.

Vision for Space Exploration

In the wake of the Columbia shuttle disaster, President George W. Bush has proposed a Vision for Space Exploration, which would eventually include human expeditions to Mars. How these expeditions would happen is still a work in progress. Very likely the space craft would be powered by a nuclear thermal rocket engine such as the NERVA. Also, Zubrin’s concept of manufacturing rocket fuel on Mars would be used as a cost saving measure.

Why Mars?

Mars, despite its inhospitable nature, is the planet in the Solar System that is most like the Earth. Data uncovered by robotic probes have suggested that Mars was even more Earthlike in the distant past, with a thick atmosphere, running water, and perhaps complex life. Martian microbes may have survived in some form, perhaps underneath the Martian surface. Scientists are excited at the idea of finding extraterrestrial life, albeit in microbial form. The discovery of such life might have profound implications for our view of ourselves in the universe.

Other visionaries, such as Robert Zubrin, believe that Mars may become the home of a “new branch of human civilization.” Just as pioneers settled the Americas in the 17th through 19th Centuries, future pioneers may settle Mars and create a new human community on the Red Planet. Mars would literally become the new frontier of the 21st and subsequent centuries. Some suggest that, using terraforming techniques, Mars can be returned to its pristine, prehistoric condition, with a breathable atmosphere, rivers, oceans, and life that can exist without mechanical life support systems. In the distant future, human beings may be able to walk on the Martian surface as humans do on the Earth. Mars would no longer be the Red Planet, but a second Blue Planet as the human species extends itself beyond the Earth, across the Solar System, and eventually, to the stars.