"The planet Mars," writes Robert Zubrin, "is a world of breathtaking scenery, with spectacular mountains three times as tall as Mount Everest, canyons three times as deep and five times as long as the Grand Canyon, vast ice fields, and thousands of kilometers of mysterious dry riverbeds. Its unexplored surface may hold unimagined riches and resources for future humanity, as well as answers to some of the deepest philosophical questions that thinkingmen and women have pondered for millennia. . . . But all that Mars holds will forever remain beyond our grasp unless and until men and women walk its rugged landscapes." 34
In one paragraph, Zubrin explains why human exploration of Mars is such an important aspect of any future space exploration. Only humans have the ability to see, feel, and touch the red planet, ponder their surroundings, and draw conclusions based on their discoveries. Though it is true that scientists have gained a wealth of knowledge from space missions, until human beings can travel to Mars and explore it for themselves, many of its mysteries will forever remain unsolved.
Many years before any spacecraft paid a visit to Mars, scientists were thinking about the possibilities of human exploration. One such scientist was the late Wernher von Braun, a rocket designer who left his native Germany and moved to the United States
During the 1950s, von Braun wrote a series of articles for a popular magazine called Collier's. He told of his ambitious plans for Mars exploration, but he also cautioned that because of all the unknowns, the journey would not be possible for nearly a century. By the end of ten years, however, he had formed an entirely different conclusion. In an article written for a November 1965 issue of Astronautics & Aeronautics , von Braun stated that a manned mission to Mars would be possible by the year 1982, and he urged that such a mission be considered a high priority:
You will have gathered from my paper here that I am an optimist with respect to our space program. However, even if those pessimists should prevail with their gloomy predictions that science has brought mankind close to the abyss, and that it's only a short time before man will blow himself up on this planet, let me suggest that even that seems to indicate that we should pursue this course of going to Mars. In fact, we should indeed hurry, so that we can establish a foothold on a new planet as long as we have one left to take off from. 36
In 1969 von Braun made a formal presentation to NASA in which he explained in great detail his plans for a human expedition to Mars. He was highly regarded by government officials because of his role in developing the Saturn V , an enormous rocket that launched the crew of America's first mission to the moon. In his Mars presentation, von Braun expressed his belief that "the next frontier is manned exploration of the planets." 37 Of course, 1982 came and went and no humans set foot on Mars. But according to Platoff, von Braun's theories were inspiring to scientists, and his work was a major influence on NASA's overall long-term plan for human interplanetary missions: "Basic elements of von Braun's Mars Project—such as the use of reusable shuttle-like ferry vessels, orbital assembly, and multiple spacecraft to reach Mars—continued to show up in proposals for human journeys to the Red Planet." 38
Even though von Braun died in 1977, his passion and enthusiasm for human Mars exploration is still very much alive today. Aside from the excitement of such a mission, the main reason scientists feel strongly about sending humans to Mars is rather simple: People have capabilities that machines do not. Even with today's advanced technology, there are limitations to what robots can do, and robots rely solely on people to think for them by providing precise, detailed instructions. For instance, the Spirit and Opportunity rovers have mechanical arms to lift rocks and soil off the ground, instruments to analyze the material, and cameras to take high-quality photographs. But they cannot actually see or feel what they have found or make judgments about it. They do not have human intelligence, intuition, or reasoning ability, nor do they have life experience that could help them make decisions or form conclusions. If their surroundings quickly change, they are at the mercy of people to tell them how to adapt to the changes so they can survive. Those qualities and abilities are inherently human.
Since the time of Viking 1 and 2 , searching for Martian life (past or present) has been a priority of nearly every mission. This is especially true in light of recent discoveries that water was once abundant on the red planet, because the probability of finding past or present organic life is now greater than ever. That search for life could be performed infinitely better by humans than by robots, as Zubrin explains:
Since it is unlikely that there is life today on the Martian surface, the search for Martian biology will largely be a search for fossils. Small robotic rovers with their limited range and long communication time delay . . . are a very poor tool for conducting such a search. . . . Fossil searches require mobility, agility, and the ability to use intuition to immediately follow up very subtle clues. Human investigators—rock hounds—are required. If Mars is to be made to give up its secrets, "people who do not shrink from the dreary vastness of space" will have to go there themselves. 39
Scientists do not necessarily agree on how or when a manned mission to Mars should occur, but most agree that many questions, including the question about Martian life, can be answered only when human beings can explore the red planet. Plus, according to scientist Michael Duke, humans could do the work in a fraction of the time that it takes robots. Even though manned voyages to Mars would take longer to plan and implement than today's robotic missions, Duke says much more scientific work would be accomplished in less time: "Humans could do the same science on Mars in one or two years as robots could do in 100 to 200 years." 40
Human astronauts who take the bold step of traveling on the very first Mars expedition will not be blind to the risks involved. Long before they board the spacecraft, they will know what to expect—and they will also know there is a chance that they might never return to Earth. In a report for NASA, authors Stephen Hoffman and David Kaplan make this uncertainty very clear:
The human exploration of Mars will be a complex undertaking. It is an enterprise that will confirm the potential for humans to leave our home planet and make our way outward into the cosmos. Though just a small step on a cosmic scale, it will be a significant one for humans, because it will require leaving Earth with very limited return capability. The commitment to launch is a commitment to several years away from Earth, and there is a very narrow window within which return is possible. 41
Currently, there is no exact date when a crewed mission will be sent to Mars. However, in a speech given in January 2004, President George W. Bush announced additional financial support for NASA to prepare for future journeys, which would include sending humans back to the moon by 2020 as the first step toward exploring other planets: "The moon is a logical step toward further progress and achievement. With the experience and knowledge gained on the moon, we will then be ready to take the next steps of space exploration: human missions to Mars and to worlds beyond. . . . We do not know where this journey will end. Yet we know this: Human beings are headed into the cosmos." 42
Most experts say a manned Mars mission could likely occur by the year 2025, but before that can happen, many hurdles must be overcome. A spacecraft would need to carry people, gear, food, and machinery, which means it would be about thirty times heavier than any spacecraft developed for previous missions. Landing such a craft would be a daunting challenge: Bouncing as high as a five-story building would not work quite as well for humans as for robots. Another consideration is determining a suitable landing site on the Martian surface where people could "set up camp." Because Mars has a total surface area of more than 200 million square miles, astronauts will be able to explore only a fraction of it. If a spaceship should inadvertently land in a bleak, desolate area thousands of miles from regions worth exploring, the entire mission could be wasted.
One of the greatest risks of a human expedition to Mars is the voyage itself, which would be extremely trying for astronauts. The journey would last six months or longer, and for most of that time they would experience microgravity, or the feeling of weightlessness. Though floating on air may look like fun, it can cause serious physical problems. On past space voyages, astronauts have suffered from disorientation, dizziness, congestion, headaches, and nausea. Someone exposed to microgravity over a much longer period of time could develop more severe ailments, including weak and brittle bones from loss of bone mass, atrophied muscles, kidney stones, and other serious physical problems. Scientists are studying ways to counter the effects of weightlessness, such as providing a source of artificial gravity or providing ways for astronauts to exercise during the journey. At this time, however, microgravity still poses one of the greatest risks for long-distance space travel.
Another danger of such a lengthy voyage is the trillions of micrometeorites shooting through the solar system. These fiery fragments of comets and asteroids may be as tiny as a grain of sand or as large as a golf ball, and they are constantly flying through space from every direction at speeds of over a hundred thousand miles per hour. A Mars-bound spacecraft would likely be pummeled by micrometeorites throughout much of its journey, which could lead to serious damage. Equally dangerous in deep space are the high levels of radiation caused by solar flares and galactic cosmic rays. Unlike on Earth, where the magnetic field forms a protective bubble against radiation, no such protection exists in space. Just as a spacecraft must be strong enough to stand up against micrometeorites, it must also have some kind of shield that can absorb or block as much radiation as possible. If this radiation penetrates a spacecraft, not only can it damage or destroy the vehicle and its instruments, but it can also be deadly to the astronauts.
Assuming the astronauts aboard a Mars-bound spacecraft can survive the perilous six-month journey, the risks they have endured along the way will drop considerably once they arrive at their destination. They may encounter some micrometeorites on the ground, but they will not be bombarded by the objects flying at them from every which way. Also, even though Martian radiation levels are higher than Earth's, the planet itself serves as a shield against the extreme radiation found in deep space. The astronauts will still feel the effects of Mars's low gravity because it is so much weaker than Earth's, but they will no longer have to endure weightlessness. However, there are still many new risks that await astronauts who step outside their spacecraft for the first time. They will experience hostile conditions that no human has ever faced before—and the proper space suit is the only thing that will save their lives.
One of the biggest risks for humans visiting Mars is the planet's low-pressure atmosphere. Air pressure keeps blood and body fluids liquid and flowing. When it is too low, the fluids in a person's body can boil, lose heat quickly, and then evaporate, which can lead to rapid death. David Akin, a professor at the University of Maryland's Space System Laboratory, describes a simulated experience: "I remember hearing a NASA astronaut talk about an experiment in which he was exposed to a sudden, temporary loss of pressure. He said the first thing he thought was, 'Oh ——!' Then he had this interesting feeling of saliva boiling on his tongue. Then he passed out." 43 In order to protect astronauts from the perilous low-pressure atmosphere, space suits must be pressurized. Specialized breathing apparatuses must also be worn because the Martian atmosphere contains extremely high levels of carbon dioxide and only the slightest traces of oxygen and nitrogen. If astronauts were to breathe the Martian air, they could lose consciousness in as little as fifteen seconds and die shortly thereafter.
The extreme climate and weather conditions found on Mars pose another hazard. Because the Martian climate is extremely cold, space suits would have to be heated. Maintaining comfortable body temperatures is difficult, though, because it can be one temperature at the surface of Mars and twenty or thirty degrees cooler only five feet above it. If a space suit is not designed with that in mind, an astronaut's upper body could be freezing while his or her legs were roasting. In addition, Mars is extremely dusty, and the fine silt hovers in the atmosphere. No one knows for sure whether the dust is toxic, but scientists
Developing space suits for a Mars expedition is a complicated, lengthy process that would take many years. Joe Kosmo, a NASA engineer who designs space suits, says that, unlike astronauts on prior space missions, those who visit Mars will likely spend several years living and working there. That would rule out the bulky attire worn by astronauts on shuttle missions. Even with Mars's low gravity, shuttle space suits would still weigh more than a hundred pounds, and the astronauts wearing them would quickly become exhausted. The ideal space suit will provide the protection astronauts need yet be lightweight enough to be comfortable when worn for long periods of time, as NASA's Phil West explains: "We know how to make a suit you could live in on Mars, but not one that can be effectively manipulated to do jobs there. Such a suit would have to have extremely flexible joints and mix-and-match parts for easy replacement. It would be relatively lightweight, maybe 30 to 40 pounds, but extremely reliable because it would be used for dozens of missions." 44 Even though that suit does not currently exist, Kosmo says the right technologies and materials do exist—now it is just a matter of determining exactly how the suit needs to perform while it is being worn. "The first astronauts on Mars are going to behave like geologists," says Kosmo. "They'll be looking for evidence of life, of water. They'll be poking around, getting down on their hands and knees to look at rocks or drill for samples. They're going to need a really robust suit." 45 NASA is in the process of testing several different models, but until one meets all the necessary criteria, a human expedition to Mars will have to wait.
Sometime in the distant future, it may be possible for travelers to hop into supersonic spaceships, zoom off to Mars for a week's vacation, and then fly back to Earth, but right now that scenario is found only in science-fiction books. When astronauts finally do make the journey to Mars, they can expect to be away from home for two or three years. With such an extended visit to the red planet, they cannot possibly take enough food, supplies, water, fuel, and equipment with them. Instead, they will have to live off the land, much like the early settlers did during frontier days. Robert Zubrin believes wholeheartedly in that idea:
Living off the land—intelligent use of local resources—is not just the way the West was won; it's the way the Earth was won, and it's also the way Mars can be won. . . . It should come as no surprise that local resources make such a difference in developing a mission to Mars, or anywhere else for that matter. Consider what would have happened if [American explorers] Lewis and Clark had decided to bring all the food, water, and fodder needed for their transcontinental journey. Hundreds of wagons would have been required to carry the supplies. Those supply wagons would need hundreds of horses and drivers. A logistics nightmare would have been created that would have sent the costs of the expedition beyond the resources of the America of [Thomas] Jefferson's time. 46
Zubrin's belief in the importance of human Mars exploration inspired him to create his own mission plan called Mars Direct. Based on his "intelligent use of local resources" philosophy, Zubrin's program features a crewed Mars mission that would be simpler, cheaper, and more successful than traditional mission plans. A crew of astronauts would make the six-month journey to Mars, where they would stay for about a year and a half. Two landers would make the trip: One shaped like a gigantic tuna fish can would transport the astronauts to Mars and serve as their home during the trip, and a second spacecraft would bring them back to Earth. With the help of computerized robots, the astronauts would recycle oxygen and water and make their own fuel by combining ingredients brought from Earth with CO 2 in the Martian atmosphere. Future missions, according to Zubrin's plan, would expand on the first, with more explorers traveling to Mars, living off the land, building greenhouses to grow food, and eventually creating a thriving Martian colony.
Some scientists dismiss Zubrin's plan as too simplistic or far-fetched, although most agree that making use of Martian resources is an excellent idea. That is especially true for creating fuel from the Martian atmosphere, which could shave millions of dollars off a mission's cost. But no matter what the details of the first human Mars expedition, there are still too many unknowns and risks to embark on it in the very near future. Until it is deemed safe to send humans traveling through space on their way to the red planet, Mars exploration will have to be performed by robots. And along with making valuable discoveries, the robots can actually pave the way for human exploration.
According to NASA scientist Doug Ming, robots will be invaluable in answering complicated questions before humans ever set foot on Mars. They can determine where the ground is strong enough to support the landing of spacecraft and identify the best locations to construct buildings.
Ming says that everything scientists learn from current robotic missions can help immensely in planning future Mars travel that involves humans:
Space navigators still incorporate sky charts drawn by Babylonian star gazers to send spacecraft on a perfect trajectory to Mars today. Humans going to Mars—soon or even thousands of years from now—will depend on what we learn from our current robotic missions to create the right spacesuits, habitats, and roving vehicles humans will someday drive on Mars. Robots will probably even deliver our first building materials to Mars, so when humans first land, robots will have paved the way for us in more ways than one. 48
Other space missions in the planning phases will also pave the way toward human Mars exploration. For instance, America's Mars Reconnaissance Orbiter , scheduled for launch in August 2005, will scour the Martian surface for water and photograph rocks and other objects as small as a beach ball. This close-up view will enable the spacecraft to search for suitable landing sites for future sample-return missions, considered to be the most exciting and scientifically rewarding Mars explorations ever attempted. Both the European Space Agency and NASA are planning sample-return missions around 2011, during which a robotic spacecraft will travel to Mars, collect soil and rock samples, and return the samples to Earth for analysis. This type of mission will provide scientists with their first hands-on opportunity to study Martian surface material, and will allow them to test a spacecraft's ability to leave Mars and make the long journey back to Earth.
No one knows for sure when humans will make the first voyage to Mars, but the time will definitely come when they do. And when that happens, it will be the magical realization of a dream that has survived for centuries, as Paul Raeburn writes:
Thousands of years after the ancients gazed at Mars with fear and fascination, it remains among the most mysterious and intriguing bodies in the heavens. The exploration of the Earth's surface is nearly complete, and Mars represents a new frontier, a dazzling new destination to fire the imaginations of today's explorers. The technology to send a human mission to Mars is now within reach. And it is conceivable that, some time in the twenty-first century, scientists may join science fiction writers in the exploration of Mars, as human beings, for the first time, step onto the cold red dust of the Martian surface. 49