TO THE MOONS OF MARS

S. FRED SINGER

It's time for NASA to rally around a new manned mission

The US space program is approaching a decision point. If cost overruns and other problems continue to plague the International Space Station, NASA’s manned programs may well be phased out. For the sake of all its programs, NASA needs a bold new project to fire up the American public’s enthusiasm and support for space exploration.

The exploration of the planet Mars and its two moons would be a good choice for NASA—and a good demonstration of America’s technical leadership. The mission would involve putting a manned habitat and laboratory into orbit around Mars, or on one of its moons. The goal would be to allow scientists to explore in detail the geography, chemistry, and evolution of Mars and its moons, and answer once and for all whether life forms existed on Mars.

Like many space scientists who have worked with instrumented satellites, I was once wholeheartedly in favor of unmanned space flight only. I now believe that there are special situations where a manned mission can be more cost-effective and achieve greater benefits than an unmanned one. Aside from maintenance of satellites like the Hubble Space Telescope, which requires an occasional human presence, Mars exploration is one of those few examples. Though some would argue that unmanned missions can explore our universe with far less risk and expense than manned missions, there is only so much to be learned from unmanned probes. A manned mission to the Martian moons also would be more cost-effective and take less time than a series of unmanned probes to Mars. It also would be superior in cost and scientific returns to a manned base on the planet.

SCIENCE FICTION VS. TRUE EXPLORATION

At the beginning of the space age, there were grandiose plans to put dozens of people in space colonies—for no obvious purpose. One of the first Mars proposals, the Empire Mission proposed by Wernher von Braun at NASA’s Marshall Spaceflight Center, featured a flotilla of dozens of manned vehicles landing on Mars to establish a base there. This plan didn’t go anywhere, as we were then working with limited propulsion systems that could barely lift a few pounds of payload into orbit.

After a formal study by NASA in 1971, interest in Mars missions waned. The nation was occupied with the Nixon scandals and the oil crisis. Cost concerns, rather than technical feasibility, became a deterrent to the introduction of new proposals for a manned mission to Mars. A decade ago, NASA put the price tag for a Moon/Mars program at nearly $500 billion. The idea died quickly and only served to put the kibosh on all manned planetary programs.

Outside the government, private organizations like the National Space Society and the Planetary Society did yeoman work to keep the flame alive. In 1981, a group of graduate students at the University of Colorado organized the “Mars Underground” and held the first conference on “The Case for Mars.” Among the new ideas presented on mission strategies, spacecraft design, life-support systems, surface activities, and material processing, one of the more interesting conclusions was that the two Martian moons could be used as “an inexpensive manned beachhead to Mars.”

To explore Mars, humans must be in the loop somewhere to direct the mission and evaluate information. Yes, humans could be sitting in Houston directing unmanned rover vehicles, but would face time delays of hours between commands that depend on rapid information feedback.A far better alternative would be to put humans on the surface of one of the Martian moons, directing rovers on the planet remotely but in real time (fractions of a second). An additional advantage is that the problem of data transmission to Earth would be eased if humans near Mars could filter scientific information and make autonomous decisions based on data and samples. Conducting research at the site also avoids the potentially serious problem of back contamination from Martian material. We simply don’t know what potentially dangerous organisms exist on Mars.

Astronauts would also be able to direct extremely precise probes to the Martian atmosphere and the planet’s surface and subsurface, collect telemetered information, and immediately launch additional probes based on this information. This potential for sequential follow-up experimentation has an important scientific advantage. Samples from the Martian surface could be analyzed rapidly by a laboratory on the Martian moon Deimos, for example, and more detailed explorations then launched on the basis of the results. A single manned mission would accomplish as much or more than a series of unmanned explorations launched over several decades.

Though there are many benefits to manned exploration of Mars, there is ample opposition to be overcome. Over the years, scientific groups of various persuasions have fought vehemently against funding for NASA’s one remaining manned research program, the International Space Station (ISS). This view is rather shortsighted, as the ISS and its public appeal help bolster funding for other areas of space science, including unmanned research programs. There comes a point when detailed measurements of the ionosphere of a distant planet or the oddities of its moons don’t excite much public response and don’t contribute a great deal of fundamental science. In fact, the ISS should take on the clearly defined long-term goal of becoming the staging platform for a manned expedition to Mars.

DEFINING THE MISSION

We’ve put humans in Earth orbit and on the Moon. Mars is the obvious target for the next step, human planetary exploration. Mars is relatively close, with only a moderate gravity field, which will make orbit maneuvers less costly. And, quite simply, a manned Mars mission has the greatest scientific payoff.

A manned Mars mission is the logical follow-on to the Space Station and a way to capitalize on this huge investment in money, time, and technology. The ISS, a marvel of engineering and scientific collaboration among 16 nations, is expected to be completed by 2004. The station will include six laboratories and is scheduled to perform many different scientific experiments. But the ISS can and should take on a larger role as a testing platform. The station would become a training ground for interplanetary explorers, whose adaptation and psychological responses could be monitored while still in Earth orbit.

Once we consider a manned mission to Mars, there is a wide range of options, including a simple Mars flyby, with immediate return to Earth; establishing a Mars orbiter, which would permit a longer stay near Mars; transferring orbits to land on a Martian moon; landing on Mars itself; or even erecting permanent structures on Mars for an extended stay.

The estimated costs for each of these types of missions range just as widely. As many of the technologies for propulsion, life support, and other needs are evolving rapidly, it would be premature to discuss precise mission costs. But some projections can be made, based on ISS cost estimates. A simple Mars flyby, for instance, might cost perhaps $25 billion, with much of the cost linked to putting the rocket propellants into Earth orbit. Putting a manned spacecraft in orbit around Mars would cost slightly more, reflecting the additional propellant needed for orbit maneuvers.

Setting up a permanent station on Deimos, one of the two Martian moons, would likely emerge as the best option in terms of costs and benefits. This plan would involve somewhat higher costs than the flyby or orbiter options, but would be significantly less expensive than landing on Mars or establishing a station on the Martian surface (see sidebar). Most important, it can be accommodated within the current NASA budget once the ISS is completed. The price tag would be a fraction of the $500 billion projected cost for the more elaborate Moon/Mars program envisaged a decade ago.

The components of the Mars mission would be assembled and launched from Earth orbit, rather than from Earth. There would be a huge advantage in launching from Earth orbit, as only modest amounts of thrust would be needed to achieve escape velocity. Chemical propellants for the Mars mission would be ferried into Earth orbit by the space shuttle or a cheaper “space truck.” If a Russian-style nuclear reactor is available as a source of power for the Mars-bound spacecraft, the project costs could be significantly lowered by incorporating electric propulsion technology, reducing the weight of the chemical propellant needed to reach Mars.

The Mars mission itself could be assembled in stages, much like the work on the ISS. Propellants and other heavy components, including a spare module and reentry vehicles, would be positioned in orbit around Mars over a period of several years. These would be unmanned transits, so well-proven “gravity assist” procedures from Venus could be used to save on propulsion.

The spacecraft/habitat carrying the Mars explorers would have to make the trip more quickly than the unmanned “slow freight,” though. It must traverse Earth’s radiation belts rapidly to minimize exposure to radiation. And the life-support systems would have to sustain the astronauts for a much shorter time.

Was there once water on Mars? This Mars Orbiter Camera image suggests that water once flowed in the Newton Crater, a large basin approximately 178 miles in diameter.

WHAT CAN WE LEARN FROM MARS?

Many scientists agree that exploration of Mars will likely yield significant scientific returns, far surpassing the exploration of any other body in the solar system. Here are just a few of the secrets that may be revealed:

Comparative planetology. Studying the origin and development of Mars will yield new information about the origin of planetary bodies, including Earth. Specific investigations would use surface and subsurface samples, followed by chemical, petrological, and isotopic analyses at the Deimos laboratory (where the vacuum system required by many instruments is freely available). Of particular interest would be the sedimentary sequences laid down in ancient Martian oceans, as well as the Martian interior, its tectonics, mountain building, and chemical differentiation. Seismic exploration would be conducted by stations set up on Mars’ surface, and magnetic and gravity surveys by low-altitude satellites. Communication and relay satellites would be needed, while Martian GPS satellites could give precise locations of samples retrieved by unmanned rover vehicles.

Martian meteorology and the Martian climate. The Martian atmosphere exhibits weather phenomena and shows changes on several interesting time scales, from days to years. While the composition and thickness of the Martian atmosphere is different from our atmosphere, there are also similarities, including a nearly identical planetary rotation period. Studying the Martian climate would reveal new information on the evolution of the atmosphere or mechanisms of climate change on Earth. Detailed observations of weather changes on Mars will also provide a challenging test for theories and atmospheric models developed to account for changes in Earth’s weather.

And past climate changes on Mars could also be useful in determining the sun’s role in climate change. Of special interest would be a temporal correlation of such changes with the precession of the Mars axis, and the periodic changes in obliquity and orbit eccentricity.We would also want to study whether Mars had surface water at some point, how the water was lost, and how these findings might then correlate with climate change on Earth. Large numbers of fresh soil samples would have to be examined, which would be another rationale for manned missions.

A final reason to understand climate change on Mars is that we may need to test ideas about protecting the atmosphere of Earth. It should be possible, for instance, to modify the Martian atmosphere either by adding trace gases or by releasing gases from the polar cap. Advanced thinkers have even developed schemes to “terraform” Mars’ atmosphere and turn it into one where agriculture can flourish and humans can survive without space suits.

The origin of life and life forms. Mars is the only realistic target for astrobiological searches in the solar system. There are three possibilities: Life exists today; life evolved but no longer exists; or life never evolved on Mars. The discovery of existing life would be tremendously exciting. But the other two possibilities would also represent discoveries of profound importance.

Life forms on the Martian surface and deep below the surface may reveal some surprises. One has to be prepared for unusual life forms as we look for cryptolife or fossil life. Proving that life had originated on Mars independent from life on Earth would constitute a major breakthrough for biologists, not to mention philosophers and theologians.

It is customary to think that life develops only on planets that provide the proper conditions for its maintenance. But the realization is growing, as embodied in the Gaia Hypothesis, that life itself may modify a planet’s surface and atmosphere to optimize conditions for its existence. Even if it were demonstrated that life does not now exist on Mars, the question would remain whether Earth and Mars differed sufficiently in their early histories to permit the origin of life on one but not the other. Or, alternatively, did both planets permit the origin of life and then diverge dramatically? If so, did the type and extent of life that evolved play a major role in that divergence?

These questions are of great scientific interest, but are also of fundamental importance to all life forms on Earth.We have reached the point where human activities are exerting global effects on the Earth’s atmosphere and climate.

While science is generally considered to be the main objective of planetary exploration, a mission to Mars offers opportunities for international cooperation and national prestige. Economic returns could come from resource exploitation and technological spin-offs. An estimated $100 billion will have been invested in the International Space Station, so it makes eminent sense to use this station as the staging platform for manned exploration of Mars. Other NASA programs would be strengthened as precursor programs to the Mars mission. In the final analysis, though, we should explore Mars for the sheer adventure of exploration.

S. Fred Singer (CC ’57) is director of the Science & Environmental Policy Project in Arlington, Virginia, and professor emeritus at the University of Virginia. A pioneer in space research, he did early calculations on the orbit evolution and origin of the Martian moons and was the first director of the US Weather Satellite Service.

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