NASA History Division Office of Policy and Plans NASA Headquarters Washington, DC 20546
February 2001
NASA SP-2000-4521
Humans to Mars
Fifty Years of Mission Planning, 1950–2000
by David S. F. Portree
NASA History Division Office of Policy and Plans NASA Headquarters Washington, DC 20546 Monographs in Aerospace History Series Number 21 February 2001
Library of Congress Cataloging-in-Publication Data
Portree, David S. F. Humans to Mars: fifty years of mission planning, 1950–2000/by David S. F. Portree. p. cm.–(Monographs in aerospace history; no. 21) (NASA publication SP) Includes bibliographical references and index.
- Space flight to Mars–Planning. 2. United States. National Aeronautics and Space Administration. I. Title. II. Series. III. NASA SP ; no. 4521. TL799.M3 P67 2000 629.45'53–dc21
Contents
Foreword
The planet Mars has long held a special fascination and even mythic status for humans. While not the closest planet to Earth, scientists have considered it to be the planet that most closely resembles Earth and thus is the other planet in our solar system most likely to contain life. Since before the space age began, people have wondered about the "red planet" and dreamed of exploring it.
In the twentieth century, robotic spacecraft and then human space flight became a reality. Those who wanted to explore Mars in person felt that this might finally become a reality as well. The Apollo program, which put twelve Americans on the surface of the Moon, certainly encouraged the dreamers and planners who wanted to send astronauts to Mars. Indeed, many people in and out of the National Aeronautics and Space Administration (NASA) have felt that human exploration of Mars is the next logical step in human space flight after the Moon.
Clearly, however, many obstacles have remained. Human travel to and from Mars probably would take many months at best. Thus the biomedical and psychological implications of such long-duration missions are daunting. The logistics of getting enough food, water, and other supplies to Mars are also challenging at best. What would astronauts do once they got to Mars? How long would they stay on the planet's surface and how would they survive there before returning to Earth? The financial cost of sending humans to Mars would almost surely be measured in billions of dollars. Aside from technical and financial issues, there remains the political question of why we should send humans to Mars at all.
David Portree takes on these questions in this monograph. By examining the evolution of 50 mission studies over the past 50 years, he gives us a sense of the many options that Mars human space flight planners in the United States have explored. Portree covers a wide variety of ideas for human exploration of Mars, ranging from Wernher von Braun's of the 1950s to the Space Exploration Initiative of 1989. These concepts, culled from a much larger pool of studies, range from hugely ambitious flotilla-style expeditions to much leaner plans. This monograph provides historians, space policy practitioners, and other readers with a very valuable overview of how much planning has already been done. If humans do go to Mars any time in the near future, it is quite conceivable that their mission profile will resemble one of the plans described here.
A number of people helped to produce this monograph. In the NASA History Office, M. Louise Alstork edited and proofread the manuscript, while Stephen J. Garber and Nadine J. Andreassen also assisted with editing and production. The Printing and Design Office developed the layout and handled the printing. Shawn Flowers and Lisa Jirousek handled the design and editing, respectively, while Stanley Artis and Warren Owens saw this work through the publication process.
This is the twenty-first in a series of special studies prepared by the NASA History Office. The Monographs in Aerospace History series is designed to provide a wide variety of aerospace history investigations. These publications are intended to be tightly focused in terms of subject, relatively short in length, and reproduced in an inexpensive format to allow timely and broad dissemination to researchers. Thus they hopefully serve as useful starting points for others to do more in-depth research on various topics. Suggestions for additional publications in the Monographs in Aerospace History series are welcome.
Roger D. Launius Chief Historian National Aeronautics and Space Administration October 25, 2000
Preface
The story of the dreams and the unbuilt spaceships for flights to Mars should be recorded so that in the future people can examine past ideas of space travel just as we can examine the unconsummated ideas of Leonardo da Vinci by reading his notebooks. Years from now people should be able to decide for themselves whether they want to go to Mars or if they prefer to stay earthbound. But let us not destroy the dream, simply because we do not wish to pursue it ourselves. (Edward Ezell, 1979) 1
In the past half century, visionary engineers have made increasingly realistic plans for launching astronauts to Mars to explore the planet. This monograph traces the evolution of these plans, taking into account such factors as on-going technological advancement and our improving knowledge of the red planet.
More than 1,000 piloted Mars mission studies were conducted inside and outside NASA between about 1950 and 2000. Many were the product of NASA and industry study teams, while others were the work of committed individuals or private organizations. Due to space limitations, only 50 mission studies (one per year, or less than 5 percent of the total) are described in this monograph. The studies included are believed to be representative of most of the technologies and techniques associated with piloted Mars exploration. 2
In addition to tracing the evolution of mission concepts, this monograph examines piloted Mars mission planning from a policy standpoint. Mars plans are affected by their societal context and by the policies that grow from that context. When the human species eventually decides to send a piloted mission to Mars, the political environment in which it develops will have at least as much impact on its shape as technology, human factors, and the Martian and interplanetary environments. Hence, it stands to benefit the space technologist to study the ways in which policy has shaped (and thwarted) past Mars plans. This idea may seem obvious to some readers, yet the history of piloted Mars mission planning shows that this truism has often been ignored or imperfectly understood, usually to the detriment of Mars exploration.
This history should be seen as a tool for building toward a future that includes piloted Mars exploration, not merely as a chronicle of events forgotten and plans unrealized. The author hopes to update and expand it in 15 or 20 years so that it tells a story culminating in the first piloted Mars mission. Perhaps a university student reading this monograph today will become a member of the first Mars mission crew tomorrow.
The author gratefully acknowledges the assistance provided by the following: Robert Ash, Donald Beattie, Ivan Bekey, John Charles, Benton Clark, Aaron Cohen, John Connolly, Mark Craig, Dwayne Day, Michael Duke, Louis Friedman, Kent Joosten, Paul Keaton, Geoffrey Landis, John Logsdon, Humboldt Mandell, Wendell Mendell, George Morgenthaler, Annie Platoff, Marvin Portree, Gordon Woodcock, and Robert Zubrin. Thanks also to the Exploration Faithful at NASA's Johnson Space Center for their insights and encouragement these past several years. Finally, thanks to Roger D. Launius, NASA Senior Historian, for soliciting this work and providing overall guidance.
David S. F. Portree Houston, Texas, September 2000
A Note on Measurement
In this monograph, measurements are given in the units used in the original study. Tons are U.S. tons (short tons) unless specified as metric tons. Measurements not associated with a specific study are given in the metric system.
Chapter 1: On the Grand Scale
Will man ever go to Mars? I am sure he will—but it will be a century or more before he's ready. In that time scientists and engineers will learn more about the physical and mental rigors of interplanetary flight—and about the unknown dangers of life on another planet. Some of that information may become available within the next 25 years or so, through the erection of a space station above the Earth . . . and through the subsequent exploration of the Moon. (Wernher von Braun, 1954) 1
Von Braun in the Desert
At the beginning of serious Mars expedition planning in the United States stands German rocket pioneer Wernher von Braun. From 1945 to 1950, von Braun was interned at White Sands Proving Ground in New Mexico with about 60 other German rocket engineers spirited out of Nazi Germany by the U.S. Army at the end of the Second World War. Under Hitler, they had developed the first large liquid-propellant rocket, the V-2 missile, at the Nazi rocket base of Peenemünde; in the United States, they shared their missilery experience by preparing and launching captured V-2s under Army supervision.
In 1947 and 1948, to relieve boredom, von Braun wrote a novel about an expedition to Mars. Frederick Ordway and Mitchell Sharpe wrote in their history The Rocket Team that von Braun's novel "proved beyond doubt that its author was an imaginative scientist but an execrable manufacturer of plot and dialog." 2 Perhaps understandably, the novel never saw print. In 1952, however, its appendix, a collection of mathematical proofs supporting its spacecraft designs and mission plan, was published in West Germany as Das Marsprojekt. The University of Illinois Press published the English-language edition as The Mars Project a year later. 3 By then von Braun and many of his German colleagues were civilian employees of the Army Ballistic Missile Agency (ABMA) at Redstone Arsenal in Huntsville, Alabama.
Von Braun described a Mars expedition "on the grand scale," with ten 4,000-ton ships and 70 crewmembers. 4 He assumed no Earth-orbiting space station assembly base. His spacecraft were assembled from parts launched by three-stage winged ferry rockets. Nine hundred fifty ferry flights would be required to assemble the Mars "flotilla" in Earth orbit. Von Braun estimated that each ferry rocket would need 5,583 tons of nitric acid and alcohol propellants to place about 40 tons of cargo into orbit, so a total of 5,320,000 tons of propellants would be required to launch all ten Mars ships. To provide a sense of scale he pointed out that "about 10 per cent of an equivalent quantity of high octane aviation gasoline was burned during the six months' operation of the Berlin Airlift" in 1948-49. 5 Von Braun estimated total propellant cost for launching the expedition into Earth orbit at $500 million.
Seven vessels in von Braun's plan were assemblages of girders and spheres without streamlining designed for the round-trip Mars voyage. Incapable of landing, they featured inflatable fabric propellant tanks and personnel spheres. Three one-way ships would each have a winged landing glider in place of a personnel sphere. At the appointed time, the flotilla's rocket engines would ignite to put the ships on a minimum-energy Earth-to-Mars trajectory. As Earth shrank behind, the Mars ship crews would discard empty Earth-departure propellant tanks and settle in for an eight-month weightless coast.
The members of the first Mars expedition would be the first humans to see the planet up close. No robotic explorers would precede them; von Braun did not anticipate the technological advancements that enabled automated explorers.
From Mars orbit they would turn telescopes toward Mars' equator to select a site for a surface exploration base camp. The first Mars landing site, however, would be determined at the time the expedition left Earth. One landing glider would deorbit and glide to a sliding touchdown on skids on one of the polar ice caps. Von Braun chose the polar caps because he believed them to be the only places on Mars where the crew could be certain of finding a smooth landing site. In von Braun's plan, the first people on Mars would abandon their glider on the ice cap and conduct a heroic 4,000-mile overland trek to the chosen base camp site on Mars' equator. There they would build a landing strip for the pair of wheeled gliders waiting in orbit. This Mars landing approach is unique to von Braun's work.