1. The Time Has Come

The time has come for America to set itself a bold new goal in space. The recent celebrations of the 40th anniversary of the Apollo Moon landings have reminded us of what we as a nation were once able to accomplish, and by so doing have put the question to us: are we still a nation of pioneers? Do we choose to make the efforts required to continue to be the vanguard of human progress, a people of the future; or will we allow ourselves to be a people of the past, one whose accomplishments are celebrated not in newspapers, but in museums? There can be no progress without a goal. The American space program, begun so brilliantly with Apollo and its associated programs, has spent most of the subsequent four decades without a central goal. We need such an overriding goal to drive our space program forward (Zubrin 1997). At this point of history, that goal can only be the human exploration and settlement of Mars (Mitchell & Staretz, 2010; Schmitt 2010; Schulze-Makuch & Davies 2010).

Some have said that a human mission to Mars is a venture for the far future, a task for “the next generation.” Such a point of view has no basis in fact (Zubrin 1997). On the contrary, the United States has in hand, today, all the technologies required for undertaking an aggressive, continuing program of human Mars exploration, with the first piloted mission reaching the Red Planet Mars within a decade. We do not need to build giant spaceships embodying futuristic technologies in order to go to Mars. We can reach the Red Planet with relatively small spacecraft launched directly to Mars by boosters embodying the same technology that carried astronauts to the Moon more than a quarter-century ago. The key to success comes from following a travel light and live off the land strategy that has well-served explorers over the centuries humanity has wandered and searched the globe. A plan that approaches human missions to the Red Planet in this way is known as the “Mars Direct” approach. Here’s how it would work.

2. The Mission

At an early launch opportunity, for example 2018, a single heavy lift booster with a capability equal to that of the Saturn V used during the Apollo program is launched off Cape Canaveral and uses its upper stage to throw a 40 tonne unmanned payload onto a trajectory to Mars. Arriving at Mars 8 months later, it uses friction between its aeroshield and Mars' atmosphere to brake itself into orbit around Mars, and then lands with the help of a parachute (Zubrin 1997). This payload is the Earth Return Vehicle (ERV), and it flies out to Mars with its two methane/oxygen driven rocket propulsion stages unfueled. It also has with it 6 tonnes of liquid hydrogen cargo, a 100 kilowatt nuclear reactor mounted in the back of a methane/oxygen driven light truck, a small set of compressors and automated chemical processing unit, and a few small scientific rovers.

As soon as landing is accomplished, the truck is telerobotically driven a few hundred meters away from the site, and the reactor is deployed to provide power to the compressors and chemical processing unit. The hydrogen brought from Earth can be quickly reacted with the Martian atmosphere, which is 95% carbon dioxide gas (CO₂), to produce methane and water, and this eliminates the need for long term storage of cryogenic hydrogen on the planet's surface. The methane so produced is liquefied and stored, while the water is electrolyzed to produce oxygen, which is stored, and hydrogen, which is recycled through the methanator. Ultimately these two reactions (methanation and water electrolysis) produce 24 tonnes of methane and 48 tonnes of oxygen. Since this is not enough oxygen to burn the methane at its optimal mixture ratio, an additional 36 tonnes of oxygen is produced via direct dissociation of Martian CO₂. The entire process takes 10 months, at the conclusion of which a total of 108 tonnes of methane/oxygen bipropellant will have been generated. This represents a leverage of 18:1 of Martian propellant produced compared to the hydrogen brought from Earth needed to create it. Ninety-six tonnes of the bipropellant will be used to fuel the ERV, while 12 tonnes are available to support the use of high powered chemically fueled long range ground vehicles. Large additional stockpiles of oxygen can also be produced, both for breathing and for turning into water by combination with hydrogen brought from Earth. Since water is 89% oxygen (by weight), and since the larger part of most foodstuffs is water, this greatly reduces the amount of life support consumables that need to be hauled from Earth.

The propellant production having been successfully completed, in 2020 two more boosters lift off the Cape and throw their 40 tonne payloads towards Mars. One of the payloads is an unmanned fuel-factory/ERV just like the one launched in 2018, the other is a habitation module containing a crew of 4, a mixture of whole food and dehydrated provisions sufficient for 3 years, and a pressurized methane/oxygen driven ground rover. On the way out to Mars, artificial gravity can be provided to the crew by extending a tether between the habitat and the burnt out booster upper stage, and spinning the assembly. Upon arrival, the manned craft drops the tether, aero-brakes, and then lands at the 2018 landing site where a fully fueled ERV and fully characterized and beaconed landing site await it. With the help of such navigational aids, the crew should be able to land right on the spot; but if the landing is off course by tens or even hundreds of kilometers, the crew can still achieve the surface rendezvous by driving over in their rover; if they are off by thousands of kilometers, the second ERV provides a backup. However assuming the landing and rendezvous at site number 1 is achieved as planned, the second ERV will land several hundred kilometers away to start making propellant for the 2020 mission, which in turn will fly out with an additional ERV to open up Mars landing site number 3. Thus every other year 2 heavy lift boosters are launched, one to land a crew, and the other to prepare a site for the next mission, for an average launch rate of just 1 booster per year to pursue a continuing program of Mars exploration. This is only about 15% of the rate that the U.S. currently launches Space Shuttles, and is clearly affordable. In effect, this dogsled approach removes the manned Mars mission from the realm of mega-fantasy and reduces it to practice as a task of comparable difficulty to that faced in launching the Apollo missions to the Moon (Zubrin 1997).

The crew will stay on the surface for 1.5 years, taking advantage of the mobility afforded by the high powered chemically driven ground vehicles to accomplish a great deal of surface exploration. With an 12 tonne surface fuel stockpile, they have the capability for over 24,000 kilometers worth of traverse before they leave, giving them the kind of mobility necessary to conduct a serious search for evidence of past or present life on Mars - an investigation key to revealing whether life is a phenomenon unique to Earth or general throughout the universe. Since no-one has been left in orbit, the entire crew will have available to them the natural gravity and protection against cosmic rays and solar radiation afforded by the Martian environment, and thus there will not be the strong driver for a quick return to Earth that plagues conventional Mars mission plans based upon orbiting mother-ships with small landing parties. At the conclusion of their stay, the crew returns to Earth in a direct flight from the Martian surface in the ERV. As the series of missions progresses, a string of small bases is left behind on the Martian surface, opening up broad stretches of territory to human cognizance.

3. We Can Afford It

Such is the basic Mars Direct plan. In 1990, when it was first put forward, it was viewed as too radical for NASA to consider seriously, but over the next several years with the encouragement of then NASA Associate Administrator for Exploration Mike Griffin, the group at Johnson Space Center in charge of designing human Mars missions decided to take a good hard look at it. They produced a detailed study of a Design Reference Mission based on the Mars Direct plan but scaled up about a factor of 2 in expedition size compared to the original concept. They then produced a cost estimate for what a Mars exploration program based upon this expanded Mars Direct would cost. Their result; $50 billion, with the estimate produced by the same costing group that assigned a $400 billion price tag to the traditional cumbersome approach to human Mars exploration embodied in NASA's 1989 "90 Day Report." I believe that with further discipline applied to the mission design, the program cost could be brought down to the $30 to $40 billion range. Spent over ten years, this would imply an annual expenditure on the order of 20% of NASA’s budget, or about half a percent of the US military budget. It is a small price to pay for a new world.

4. Killing the Dragons

Opponents of human Mars exploration frequently cite several issues which they claim make such missions to dangerous to be considered at this time. Like the dragons that use to mar the maps medieval cartographers, these concerns have served to deter many who otherwise might be willing to enterprise the exploration of the unknown. It is therefore fitting to briefly address them here.

4.1. Radiation: It is alleged by some that the radiation doses involved in a Mars mission present insuperable risks, or are not well understood. This is untrue. Solar flare radiation, consisting of protons with energies of about 1 MeV, can be shielded by 12 cm of water or provisions, and there will be enough of such materials on board the ship to build an adequate pantry storm shelter for use in such an event. The residual cosmic ray dose, about 50 Rem for the 2.5 year mission, represents a statistical cancer risk of about 1%, roughly the same as that which would be induced by an average smoking habit over the same period.

4.2. Zero Gravity: Cosmonauts have experienced marked physiological deterioration after extended exposure to zero gravity. However a Mars mission can be flown employing artificial gravity generated by rotating the spacecraft. The engineering challenges associated with designing either rigid or tethered artificial gravity systems are modest, and make the entire issue of zero-gravity health effects on interplanetary missions moot.

4.3. Back Contamination: Recently some people have raised the issue of possible back-contamination as a reason to shun human (or robotic sample return) missions to Mars. Such fears have no basis in science. The surface of Mars is too cold for liquid water, is exposed to near vacuum, ultra violet, and cosmic radiation, and contains an antiseptic mixture of peroxides that have eliminated any trace of organic material. It is thus as sterile an environment as one could ask for. Furthermore, pathogens are specifically adapted to their hosts. Thus, while there may be life on Mars deep underground, it is quite unlikely that these could be pathogenic to terrestrial plants or animals, as there are no similar macrofauna or macroflora to support a pathogenic life cycle in Martian subsurface groundwater. In any case, the Earth currently receives about 500 kg of Martian meteoritic ejecta per year. The trauma that this material has gone through during its ejection from Mars, interplanetary cruise, and re-entry at Earth is insufficient to have sterilized it, as has been demonstrated experimentally and in space studies on the viability of microorganisms following ejection and reentry (Burchell et al. 2004; Burchella et al. 2001; Horneck et al. 1994, 1995, 2001, Horneck et al. 1993; Mastrapaa et al. 2001; Nicholson et al. 2000). So if there is the Red Death on Mars, we’ve already got it. Those concerned with public health would do much better to address their attentions to Africa.

4.4. Human Factors: In popular media, it is frequently claimed that the isolation and stress associated with a 2.5 year round-trip Mars mission present insuperable difficulties. Upon consideration, there is little reason to believe that this is true. Compared to the stresses dealt with by previous generations of explorers and mariners, soldiers in combat, prisoners in prisons, refugees in hiding, and millions of other randomly selected people, those that will be faced by the hand-picked crew of Mars 1 seem modest. Certainly psychological factors are important (Bishop 2010; Fielder & Harrison, 2010; Harrison & Fielder 2010; Suedfeld 2010). However, any serious reading of previous history indicates that far from being the weak link in the chain of the piloted Mars mission, the human psyche is likely to be the strongest link in the chain as Apollo astronauts have testified (Mitchell & Staretz 2010; Schmitt 2010).

4.5. Dust Storms: Mars has intermittent local, and occasionally global dust storms with wind speeds up to 100 km/hour. Attempting to land through such an event would be a bad idea, and two Soviet probes committed to such a maelstrom by their uncontrollable flight systems were destroyed during landing in 1971. However, once on the ground, Martian dust storms present little hazard. Mars’ atmosphere has only about 1% the density of Earth at sea-level. Thus a wind with a speed of 100 km/hr on Mars only exerts the same dynamic pressure as a 10 km/hr breeze on Earth. The Viking landers endured many such events without damage.

Humans are more than a match for Mars’ dragons.

5. Why Do It? But why do it? There are three reasons.

Reason 1: For the Knowledge. During the summer of 1996, NASA scientists revealed a rock ejected from Mars by meteoric impact which showed strong evidence of life on Mars in the distant past (McKay et al., 1996). If this discovery could be confirmed by actual finds of fossils on the Martian surface, it would show that the origin of life is not unique to the Earth, and thus by implication reveal a universe that is filled with life and probably intelligence as well. From the point of view of humanity learning its true place in the universe, this would be the most important scientific enlightenment since Copernicus.

Robotic probes can help out in such a search, but by themselves are completely insufficient (Drake, 2010; Gage 2010; Schmitt 2010). Fossil hunting requires the ability to travel long distances through unimproved terrain, to climb steep slopes, to do heavy work and delicate work, and to exercise very subtle forms of perception and on-the-spot intuition. All of these skills are far beyond the abilities of robotic rovers. Geology and field paleontology requires human explorers, real live rockhounds on the scene (Schmitt 2010). Drilling to reach subsurface hydrothermal environments where extant Martian life may yet thrive will clearly require human explorers as well. Put simply, as far as the question of Martian life is concerned, if we don’t go, we won’t know.

Reason # 2: For the Challenge. Nations, like people, thrive on challenge and decay without it. The space program itself needs challenge. Consider: Between 1961 and 1973, under the impetus of the Moon race, NASA produced a rate of technological innovation several orders of magnitude greater than that it has shown since, for an average budget in real dollars virtually the same as that today ($19 billion in 2010 dollars). Why? Because it had a goal that made its reach exceed its grasp. It is not necessary to develop anything new if you are not doing anything new. Far from being a waste of money, forcing NASA to take on the challenge of Mars is the key to giving the nation a real technological return for its space dollar.

A humans-to-Mars program would also be an challenge to adventure to every child in the country: "Learn your science and you can become part of pioneering a new world." There will be over 100 million kids in our nation's schools over the next ten years. If a Mars program were to inspire just an extra 1% of them to scientific educations, the net result would be 1 million more scientists, engineers, inventors, medical researchers and doctors, making innovations that create new industries, finding new medical cures, strengthening national defense, and increasing national income to an extent that dwarfs the expenditures of the Mars program.

Reason # 3: For the Future: Mars is not just a scientific curiosity, it is a world with a surface area equal to all the continents of Earth combined, possessing all the elements that are needed to support not only life, but technological civilization. As hostile as it may seem, the only thing standing between Mars and habitability is the need to develop a certain amount of Red Planet know-how. This can and will be done by those who go there first to explore.

Mars is the New World. Someday millions of people will live there. What language will they speak? What values and traditions will they cherish, to spread from there as humanity continues to move out into the solar system and beyond? When they look back on our time, will any of our other actions compare in value to what we do today to bring their society into being?

Today, we have the opportunity to be the founders, the parents and shapers of a new and dynamic branch of the human family, and by so doing, put our stamp upon the future. It is a privilege not to be disdained lightly.

6. Conclusion

In conclusion, the point needs to be made again. We are ready to go to Mars. Despite whatever issues that remain, the fundamental fact is that we are much better prepared today to send humans to Mars than we were to send people to the Moon in 1961, when John F. Kennedy initiated the Apollo program. Exploring Mars requires no miraculous new technologies, no orbiting spaceports, and no gigantic interplanetary space cruisers (Zubrin 1997). We can establish our first outpost on Mars within a decade. We and not some future generation can have the eternal honor of being the first pioneers of this new world for humanity. All that's needed is present-day technology, some 19th century industrial chemistry, some political vision, and a little bit of moxie.

Biographical Information: Dr. Robert Zubrin, an astronautical engineer, is President of the Mars Society and author of "The Case for Mars: The Plan to Settle the Red Planet and Why Must," published by the Simon and Schuster.

Bishop, S. L. (2010). Moving to Mars: There and back again, Journal of Cosmology, 12, 3711-3722.

Burchella, M. J., Manna, J., Bunch, A. W., Brandob, P. F. B. 2001. Survivability of bacteria in hypervelocity impact, Icarus. 154, 545-547.

Burchell, J. R. Mann, J., Bunch, A. W. (2004). Survival of bacteria and spores under extreme shock pressures, Monthly Notices of the Royal Astronomical Society, 352, 1273-1278.

Drake, B. G. (2010). Human Exploration of Mars: Challenges and Design Reference Architecture 5.0. Journal of Cosmology, 12, 3578-3587.

Fiedler, E. R., & Harrison, A. A. (2010). Psychosocial Adaptation to a Mars Mission, Journal of Cosmology, 12, 3685-3693.

Gage, D. W. (2010). Mars Base First: A Program-level Optimization for Human Mars Exploration. Journal of Cosmology, 12, 3904-3911.

Harrison, A. A., Fiedler, E. R. (2010). Mars, Human Factors and Behavioral Health, Journal of Cosmology, 12, 3685-3693.

Horneck, G. (1993). Responses ofBacillus subtilis spores to space environment: Results from experiments in space Origins of Life and Evolution of Biospheres 23, 37-52.

Horneck, G., Becker, H., Reitz, G. (1994). Long-term survival of bacterial spores in space. Advances in Space Research, Volume 14, 41-45.

Horneck, G., Eschweiler, U., Reitz, G., Wehner, J., Willimek, R., Strauch, G. (1995). Biological responses to space: results of the experiment Exobiological Unit of ERA on EURECA I. Advances in Space Research 16, 105-118.

Horneck, G., et al., (2001). Bacterial spores survive simulated meteorite impact Icarus 149, 285.

McKay, D.S., Everett, K.G., Thomas-Keprta, K.L., Vali, H., Romanek, C.S., Clemett, S.J., Chillier, X.D.F., Maechling, C.R., Zare, R.N. (1996) Search for past life on Mars: possible relic biogenic activity in Martian meteorite ALH84001. Science, 273, 924-930.

Mastrapaa, R.M.E., Glanzbergb, H., Headc, J.N., Melosha, H.J, Nicholsonb, W.L. (2001). Survival of bacteria exposed to extreme acceleration: implications for panspermia, Earth and Planetary Science Letters 189, 30 1-8.

Mitchell, E. D., & Staretz, R. (2010). Our Destiny – A Space Faring Civilization? Journal of Cosmology, 12, 3500-3505.

Nicholson, W. L., Munakata, N., Horneck, G., Melosh, H. J., Setlow, P. (2000). Resistance of Bacillus Endospores to Extreme Terrestrial and Extraterrestrial Environments, Microbiology and Molecular Biology Reviews 64, 548-572.

Schmitt, H. H. (2010). Apollo on Mars: Geologists Must Explore the Red Planet, Journal of Cosmology, 12, 3506-3516.

Schulze-Makuch, D., & Davies, P., (2010). To boldly go: A one-way human mission to Mars, Journal of Cosmology, 12, 3619-3626.

Suedfeld, P. (2010). Mars: anticipating the next great exploration, Journal of Cosmology, 12, 3723-3740.

Zubrin, R. (1997). The Case for Mars: The Plan to Settle the Red Planet and Why Must, Simon and Schuster, NY.