outer space: Definition from Answers.com

For years the issue of international competition and cooperation in space has dominated much space exploration policy. Indeed, it is impossible to write the history of spaceflight without discussing these themes in detail. The early U.S. space exploration program was dominated by international rivalry and world prestige, and international relations have remained a powerful shaper of the program since. From the time of the creation of the National Aeronautics and Space Administration (NASA), all of its human spaceflight projects—the Apollo program, the space shuttle, and the space station—have been guided in significant part by foreign relations considerations.

In the 1950s and 1960s the United States and the Soviet Union were locked in the "Moon race," an intensely competitive Cold War struggle in which each sought to outdo the other. No cost seemed too high; no opportunity to best the rival seemed too slight. U.S. astronauts planted the American flag on the surface of the Moon when the great moment came in 1969. The irony of planting that flag, coupled with the statement that "we came in peace for all mankind," was not lost on the leaders of the Soviet Union, who realized that they were not considered a part of "all mankind" in this context.

The Freedom of Space Doctrine

From before the beginning of the space age, U.S. leaders sought to ensure the rights of free passage of spacecraft anywhere in the world. In a critical document, "Meeting the Threat of Surprise Attack," issued on 14 February 1955, a group of academics, industrialists, and the military, working at the request of President Dwight D. Eisenhower, raised the question of the international law of territorial waters and airspace, in which individual nations controlled those territories as if they were their own soil. That international custom allowed nations to board and confiscate vessels within territorial waters near their coastlines and to force down aircraft flying in their territorial airspace. But outer space was a territory not yet defined, and the United States called for it to be recognized as free territory not subject to the normal confines of territorial limits.

"Freedom of space" was extremely significant to those concerned with orbiting satellites, because the imposition of territorial prerogatives outside the atmosphere could legally restrict any nation from orbiting satellites without the permission of those nations that might be overflown. U.S. leaders thought that the Soviet Union might clamor for a closed-access position if the United States was the first to orbit a satellite. President Dwight D. Eisenhower, committed as he was to development of an orbital reconnaissance capability to spy on the Soviet Union as a national defense initiative, worked to ensure that no international bans on satellite overflights occurred.

Eisenhower tried to obtain a "freedom of space" decision on 21 July 1955 when he attended a summit conference in Geneva, Switzerland. The absence of trust among states and the presence of "terrible weapons," he argued, provoked throughout the world "fears and dangers of surprise attack." He proposed a joint agreement "for aerial photography of the other country," adding that the United States and the Soviet Union had the capacity to lead the world with mutually supervised reconnaissance overflights. The Soviets promptly rejected the proposal, saying that it was an obvious American attempt to "accumulate target information."

Eisenhower bided his time and approved the development of reconnaissance satellites under the strictest security considerations. Virtually no one, even those in high national defense positions, knew of this effort. The WS-117L program was the prototype reconnaissance satellite effort of the United States. Built by Lockheed's Missile Systems Division in Sunnyvale, California, the project featured the development of a two-stage booster known as the Agena and a highly maneuverable satellite that took photographs with a wide array of natural, infrared, and other invisible light cameras. This early military space effort, while a closely guarded secret for years, proved critical to the later development of the overall U.S. space program.

The Soviets proved singularly inhospitable to Eisenhower's entreaties for "freedom of space," but that changed in a rather ironic way on 4 October 1957 when Sputnik 1 was launched and ushered in the space age. Since the Soviet Union was the first nation to orbit a satellite, flying as it did over a multitude of nations, including the United States, it established the precedent of "freedom of space." It overflew international boundaries numerous times without provoking a single diplomatic protest. On 8 October 1957, knowing the president's concern over the legality of reconnaissance satellites flying over the Soviet Union, Deputy Secretary of Defense Donald Quarles told the president: "The Russians have … done us a good turn, unintentionally, in establishing the concept of freedom of international space." Eisenhower immediately grasped this as a means of pressing ahead with the launching of a reconnaissance satellite. The precedent held for Explorer 1 and Vanguard 1, and the end of 1958 saw established the tenuous principle of "freedom of space."

Launching Nasa

Sputnik kicked off an intensely competitive space race in which the two superpowers sought to outdo each other for the world's accolades. At a fundamental level a primary reason for NASA's emergence was because of U.S. rivalry during the Cold War with the Soviet Union—a broad contest over the ideologies and allegiances of the nonaligned nations of the world in which space exploration emerged as a major area of contest. From the latter 1940s the Department of Defense had pursued research in rocketry and upper atmospheric sciences as a means of assuring American hegemony. A part of the strategy required not only developing the technology for war, but also pursuing peaceful scientific activities as a means of demonstrating U.S. leadership worldwide. A major step forward came in 1955 when Eisenhower approved a plan to orbit a scientific satellite as part of the International Geophysical Year (IGY) for the period 1 July 1957 to 31 December 1958, a cooperative effort to gather scientific data about the Earth. The Soviet Union quickly followed suit, announcing plans to orbit its own satellite.

The Naval Research Laboratory's Project Vanguard was chosen on 9 September 1955 to support the IGY effort. The Eisenhower administration did so largely because the Vanguard program did not interfere with high-priority ballistic missile development programs—it used the non-military Viking rocket as its basis—while a U.S. Army proposal to use the Redstone ballistic missile as the launch vehicle waited in the wings. The Redstone was being developed by Wernher von Braun and a team of engineers as a response to ballistic missile advances by the Soviet Union and was designed to carry a warhead a distance of two hundred miles on a preplanned trajectory. Project Vanguard enjoyed exceptional publicity throughout the second half of 1955 and all of 1956, but the technological demands upon the program were too great and the funding levels too small to ensure success.

A full-scale crisis resulted when the Soviets launched Sputnik 1, the world's first artificial satellite, as its IGY entry. This had a "Pearl Harbor" effect on American public opinion, creating an illusion of a technological gap and providing the impetus for increased spending for aerospace endeavors, technical and scientific educational programs, and the chartering of new federal agencies to manage air and space research and development.

Sputnik led directly to several critical efforts aimed at "catching up" to the Soviet Union's space achievements, among them: (1) a wide-ranging review of the civil and military space programs of the United States (scientific satellite efforts and ballistic missile development); (2) establishment of a presidential science adviser in the White House who had responsibility for overseeing the activities of the federal government in science and technology; (3) creation of the Advanced Research Projects Agency in the Department of Defense and consolidation of several space activities under centralized management; (4) creation of the National Aeronautics and Space Administration to manage civil space operations for the benefit "of all mankind" by means of the National Aeronautics and Space Act of 1958; and (5) passage of the National Defense Education Act of 1958 to provide federal funding for education in scientific and technical disciplines.

More immediately, the United States launched its first Earth satellite on 31 January 1958, when Explorer 1 documented the existence of radiation zones encircling the Earth. Shaped by the Earth's magnetic field, what came to be called the Van Allen radiation belt partially dictates the electrical charges in the atmosphere and the solar radiation that reaches Earth. The Explorer 1 launch also began a series of scientific missions to the Moon and planets in the latter 1950s and early 1960s.

As a direct result of this crisis, NASA began operations on 1 October 1958, absorbing the resources of the National Advisory Committee for Aeronautics intact, including its 8,000 employees, an annual budget of $100 million, three major research laboratories—Langley Aeronautical Laboratory, Ames Aeronautical Laboratory, and Lewis Flight Propulsion Laboratory—and two smaller test facilities. NASA quickly incorporated other organizations into the new agency. These included the space science group of the Naval Research Laboratory in Maryland, the Jet Propulsion Laboratory managed by the California Institute of Technology for the U.S. Army, and the Army Ballistic Missile Agency in Huntsville, Alabama. Eventually NASA created several other centers and by the early 1960s had ten located around the country.

NASA began to conduct space missions within months of its creation, and during its first twenty years NASA carried out several major programs:

Human space-flight initiatives: Mercury's single astronaut program (flights during 1961 to 1963) to ascertain if a human could survive in space; Project Gemini (flights 1965–1966) with two astronauts to practice space operations, especially rendezvous and docking of spacecraft and extravehicular activity (EVA); and Project Apollo (flights 1968–1972) to explore the Moon.
Robotic missions to the Moon (Ranger, Surveyor, and Lunar Orbiter), Venus (Pioneer Venus), Mars (Mariner 4, Viking 1 and 2), and the outer planets (Pioneer 10 and 11, Voyager 1 and 2).
Aeronautics research to enhance airplane safety, reliability, efficiency, and speed (X-15 hypersonic flight, lifting body flight research, avionics and electronics studies, propulsion technologies, structures research, aerodynamics investigations).
Remote-sensing Earth satellites for information gathering (Landsat satellites for environmental monitoring).
Applications satellites for communications (Echo 1, TIROS, and Telstar) and weather monitoring.
Skylab, an orbital workshop for astronauts.

In no case were these cooperative ventures with other nations, because the Cold War patina that overlay everything done by NASA during its first thirty years necessitated that the United States demonstrate its unique technological capability vis-à-vis the Soviet Union.

The Lunar Landing Program

When U.S. astronauts planted the flag on the surface of the Moon in 1969 it signaled the final triumph of the United States over the Soviet Union in the space race, nothing more nor less. Indeed, this singular achievement of Project Apollo during NASA's early years—one that was particularly focused on demonstrating American preeminence as a spacefaring nation to the people of the world—made possible the cooperative ventures that followed.

The effort to land Americans on the Moon came about because of a unique confluence of political necessity, personal commitment and activism, scientific and technological ability, economic prosperity, and public mood. When President John F. Kennedy announced on 25 May 1961 his intention to carry out a lunar landing program before the end of the decade, he did so as a means of demonstrating U.S. technological virtuosity. In so doing Kennedy responded to perceived challenges to U.S. world leadership not only in science and technology but also in political, economic, and especially military capability.

For the next eleven years Project Apollo consumed NASA's every effort. It required significant expenditures, costing $25.4 billion in 1960s dollars over the life of the program to make it a reality. Only the building of the Panama Canal rivaled the Apollo program's size as the largest nonmilitary technological endeavor ever under-taken by the United States; only the Manhattan Project was comparable in a wartime setting.

The first mission to capture public attention was the flight of Apollo 8. On 21 December 1968 it took off atop a Saturn V booster from the Kennedy Space Center in Florida. Three astronauts were aboard—Frank Borman, James A. Lovell, Jr., and William A. Anders—for a historic mission to orbit the Moon. After Apollo 8 made one and a half Earth orbits, its third stage began a burn to put the spacecraft on a lunar trajectory. It orbited the Moon on Christmas Eve and then fired the boosters for a return flight. It splashed down safely in the Pacific Ocean on 27 December. Two more Apollo missions occurred before the climax of the program, but they did little more than confirm that the time had come for a lunar landing.

That landing came during the flight of Apollo 11, which lifted off on 16 July 1969 and, after confirmation that the hardware was working well, began the three-day trip to the Moon. Then, on 20 July 1969 the lunar module—with astronauts Neil A. Armstrong and Edwin E. "Buzz" Aldrin aboard—landed on the lunar surface while Michael Collins orbited overhead in the command module. After checkout, Armstrong set foot on the surface, telling millions who saw and heard him on Earth that it was "one small step for [a] man—one giant leap for mankind." Aldrin soon followed him out and the two explored their surroundings and planted an American flag but omitted claiming the land for the United States, as had been routinely done during European exploration of the Americas. They collected soil and rock samples and set up scientific experiments. The next day they rendezvoused with the Apollo capsule orbiting overhead and began the return trip to Earth, splashing down in the Pacific Ocean on 24 July.

Five more landing missions followed at approximately six-month intervals through December 1972, each of them increasing the time spent on the Moon. The scientific experiments placed on the Moon and the lunar soil samples returned have provided grist for scientists' investigations ever since. The scientific return was significant, but the program did not answer conclusively the age-old questions of lunar origins and evolution. Three of the latter Apollo missions also used a lunar rover vehicle to travel in the vicinity of the landing site, but despite their significant scientific return none equaled the public excitement of Apollo 11.

Even as Project Apollo proceeded, the United States and the Soviet Union—as well as other nations—crafted in 1967 the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, commonly known as the Outer Space Treaty. Its concepts and some of its provisions were modeled on its predecessor, the Antarctic Treaty. Like that document it sought to prevent "a new form of colonial competition" and the possible damage that self-seeking exploitation might cause.

After years of discussion this treaty became a possibility on 16 June 1966 when both the United States and the Soviet Union submitted proposals to the United Nations. While there were some differences in the two texts, these were satisfactorily resolved by December 1966 in private consultations during the General Assembly. This allowed the signature of the treaty at Washington, London, and Moscow on 27 January 1967. On 25 April the U.S. Senate gave unanimous consent to its ratification, and the treaty entered into force on 10 October 1967. This treaty has remained in force and both provides for the nonmilitarization of space and directs use of the Moon and other celestial bodies exclusively for peaceful purposes. It expressly prohibits their use for establishing military bases, installations, or fortifications; for testing weapons of any kind; or for conducting military maneuvers. After the treaty entered into force, the United States and the Soviet Union began to collaborate in several joint space enterprises.

Toward a Trajectory for Cooperative Efforts in the 1970s

With the successful completion of the Apollo program, everyone realized that the United States was the unquestioned world leader in scientific and technological virtuosity, and continued international competition seemed pointless. President Richard M. Nixon, who took office in January 1969, made it clear that there would be during his leadership no more Apollo-like space efforts. Coupled with this was the desire of those working for a continuation of an aggressive space exploration effort, and the result, predictably, was the search for a new model. While successfully continuing to tie space exploration to foreign relations objectives, now the linkage would be based more on cooperation with allies rather than competition with the nation's Cold War rival. From the 1970s NASA leaders increasingly emphasized visible and exacting international programs. All of the major human space flight efforts, and increasingly as time progressed minor projects, have been identified with international partnerships, particularly with America's European allies.

The European Space Agency was created in 1975 after the space race of the Cold War gave way to worldwide cooperation. Its aims are to provide cooperation in space research and technology. Its ten founding members were France, Germany, Italy, Spain, the United Kingdom, Belgium, Denmark, the Netherlands, Sweden, and Switzerland. Ireland, Austria, Norway, Finland, and Portugal joined later, and Canada is considered a cooperating state. The agency acts for Europe in a global way by promoting creative interaction and collaboration with other global space agencies, aerospace industries, and civilian space activities. In addition, there is a cooperation of international space law and a practical sharing of resources, research, and personnel.

The Cold War context in which the U.S. civil space program arose in 1958 ensured that foreign policy objectives dominated the nature of the activity. This led to the need for cooperative ventures with U.S. allies. The U.S. Congress said as much in the National Aeronautics and Space Act of 1958, the legislation creating NASA. In this chartering legislation Congress inserted a clause mandating the new space agency to engage in international cooperation with other nations for the betterment of all humankind. This legislation provided authority for international agreements in the broad range of projects essential for the development of space science and technology in a naturally international field. NASA's charter provided the widest possible latitude to the agency in undertaking international activities as the means by which the agreed goal could be reached. The scope of NASA's international program has been fortified since that time by repeated involvement with the United Nations, bilateral and multilateral treaties, and a host of less formal international agreements.

The central question for the United States has always been how best to use space exploration as a meaningful foreign policy instrument. At times an odd assemblage of political, economic, and scientific-technological objectives emerged to guide the development of international programs. The most fundamental of these objectives were the overarching geopolitical considerations, without which there would have been no space exploration program at all, much less a cooperative effort. Cooperative projects in space were thought to create a positive image of the United States in the international setting, an image that in the early years of the space age was related to the greater battle to win the "hearts and minds" of the world to the democratic-capitalistic agenda, and after the Cold War to ensure continued goodwill between the United States and the European community. Such cooperation also was thought to encourage both European unity and American relations to collective European entities.

Equally important, the United States pursued two overarching economic objectives with its cooperative space efforts. First, cooperative projects expanded the investment for any space project beyond that committed by the United States. (Kenneth S. Pedersen, NASA director of international programs in the early 1980s, opined that "by sharing leadership for exploring the heavens with other qualified spacefaring nations, NASA stretched its own resources and was free to pursue projects which, in the absence of such sharing and cooperation, might not be initiated.") Second, cooperative projects might also help to improve the balance of trade by creating new markets for U.S. aerospace products. Finally, a set of important scientific and technological objectives have motivated U.S. international cooperative efforts in space, including the idea that such efforts enhance the intellectual horsepower applied to any scientific question, thereby increasing the likelihood of reaching fuller under-standing in less time. These initiatives also have helped to shape European space projects along lines compatible with American goals, encourage the development of complementary but different experiments from European scientists, and ensure that multiple investigators throughout the international partnership make observations that contribute to a single objective.

In light of these macro-national priorities, NASA has always wrestled with how best to implement the broad international prospects mandated in legislation and polity in line with its own specific history and goals. NASA leadership developed very early, and it remained in place until an international partnership was required to build the International Space Station (ISS) in the early 1990s. As a result of that history, a set of essential features have guided the agency's international arrangements with European partners, among them, that cooperation is undertaken on a project-by-project basis, not on an ongoing basis for a specific discipline or general effort; that each cooperative project must be both mutually beneficial and scientifically valid; that scientific-technical agreement must precede any political commitment; that funds transfers will not take place between partners, but each will be responsible for its own contribution to the project; that all partners will carry out their part of the project without technical or managerial expertise provided by the other; and that scientific data will be made available to researchers of all nations involved in the project for early analysis.

From the NASA leadership's point of view, moreover, cooperative projects offered two very significant advantages in the national political arena. First, at least by the time of the lunar landings, the leadership recognized that every international partnership brought greater legitimacy to the overall project. This important fact was not lost on NASA Administrator Thomas O. Paine in 1970, for instance, when he was seeking outside sponsorship of the space shuttle program and negotiating international agreements for parts of the effort. Second, although far from being a coldly calculating move, agreements with foreign nations could also help to insulate space projects from drastic budgetary and political changes. American politics, which are notoriously rambunctious and shortsighted, are also enormously pragmatic. Dealing with what might be a serious international incident resulting from some technological program change is something neither U.S. diplomats nor politicians relish, and that fact could be the difference between letting the project continue as previously agreed or to dicker over it in Congress and thereby change funding, schedule, or other factors in response to short-term political or budgetary needs. The international partners, then, could be a stabilizing factor for any space project, in essence a bulwark to weather difficult domestic storms.

Perhaps the physicist Fritjof Capra's representative definition of a social paradigm is appropriate when considering the requirements for space projects in the United States in the aftermath of the Apollo Moon landings. While Apollo was seen as an enormous success from a geopolitical and technological standpoint, NASA had to contend with a new set of domestic political realities for its projects thereafter, and a radical alteration had taken place in what Capra described as the "constellation of concepts, values, perceptions and practices shared by a community, which forms a particular vision of reality that is the basis of the way the community organizes itself." International cooperative projects helped NASA cope with that changing social paradigm.

Impediments to International Cooperation in Space

At the same time that critical objectives at both the national and agency levels might be achieved through cooperative space projects both individually and collectively, there were genuine and not inconsiderable impediments to undertaking international programs. The most important was that NASA would lose some of its authority to execute the cooperative program as it saw fit. Throughout its history the space agency had never been very willing to deal with partners, either domestic or international, as equals. It tended to see them more as hindrance than help, especially when they might get in the way of the "critical path" toward any technological goal. R. Buckminster Fuller in his 1982 book Critical Path discussed the evolution of technology involving project scheduling and resource allocation. Assigning an essentially equal-partnership responsibility for the development of some critical system or instrument meant giving up the power to make changes, dictate solutions, and control schedules and other factors. Partnership, furthermore, was not a synonym for contractor management—something agency leaders understood very well—and NASA was not very accepting of full partners unless they were essentially silent or at least deferential. Such an attitude mitigated against significant international cooperation in space efforts, and difficulties arose whenever any project was undertaken.

In addition to this concern, some technologists at NASA, but even more so at the U.S. Department of State, expressed fears that bringing foreign nations into any significant space project really meant giving those nations technical knowledge that only the United States held. Only a few nations were spacefaring at all, and only a subset of those had launch capabilities. Many American leaders voiced reservations about the advisability of ending technological monopolies. The prevention of technology transfer in the international arena was an especially important issue to be considered.

NASA officials understood that European space leaders were aware of these issues and that the latter understandably took a guarded approach toward dealing with American overtures in space. They also believed that this watch-and-wait attitude was not solely due to the United States, although it may have been the deciding factor, but also related to the unique difficulties of European space activities. Senior NASA officials were also convinced that the history of European involvement in space had been marked by difficulties in obtaining long-term commitments to specific programs in which participating nations had a reasonable part. And long-term, highly focused projects required centralized management capable of enforcing order on a diverse set of interests. Americans recognized that NASA had its own difficulties on this score, but with national and language barriers added in, the demands were daunting. Finally, the costs of involvement in such endeavors with the United States were not inconsiderable. The financial, organizational, and political issues of European space activity had long been understood by leaders in the field, but they had not been fully resolved. Unfortunately, NASA's efforts have long been insufficient to fully resolve them.

The Record of International Cooperation in Space

From its inception in 1958 to 2000, NASA concluded nearly 2,000 cooperative agreements with other nations for the conduct of international space projects. While most of these were bilateral in focus—such as the very first, which led to the Alouette mission with Canada in 1962—some, and increasingly so, have been multinational efforts. These agreements resulted in 139 cooperative science projects with European nations between 1962 and 1997: 29 in the earth sciences, 23 in microgravity and life sciences, and 87 in space sciences.

When this development is explored over time there are some interesting trends. First, there were small numbers of projects in the 1960s—something to be expected—but they began to rise precipitously during the late 1960s and peak in the first third of the 1970s. This coincided with the downturn in the NASA budget from a high in 1965 to a low in 1973. In the 1980s and 1990s this trend also accelerated in relation to the political realities of the era.

Is there a correlation between the demise of the NASA budget and increased international cooperative ventures with other nations? Probably, but it is also related to the emphasis on détente and international relations of the Nixon administration in the late 1960s through mid-1970s. This seemed to collapse in the early 1980s, perhaps in relation to the rise of the NASA budget during the Reagan buildup and the renewal of Cold War hostilities. If this is a correct analysis, one would expect the number of cooperative efforts to rise in response to the drastic cuts in the NASA budget undertaken by the Clinton administration in the 1990s. Such was indeed the case, but more in relation to the former Soviet Union than with international partners.

The International Space Station

In 1984, as part of its interest in reinvigorating the space program, the Reagan administration called for the development of a space station. In a "Kennedyesque" moment, Reagan declared in his 1984 State of the Union address that "America has always been greatest when we dared to be great. We can reach for greatness again. We can follow our dreams to distant stars, living and working in space for peaceful, economic, and scientific gain. Tonight I am directing NASA to develop a permanently manned space station and to do it within a decade."

The dream of a space station had been omnipresent within NASA since the 1950s, when a station had been envisioned as a necessary out-post in the new frontier of space. The station, however, had been forced to the bottom of the priorities heap in the 1960s and 1970s as NASA raced to the Moon and then went on to build the space shuttle. When the shuttle first flew in April 1981, the space station reemerged as the priority in human space flight. Within three years space policymakers had persuaded Reagan of its importance, and NASA began work on it in earnest.

From the outset both the Reagan administration and NASA intended space station Freedom to be an international program. Although a range of international cooperative activities had been carried out in the past, the station offered an opportunity for a truly integrated effort. The inclusion of international partners, many with rapidly developing spaceflight capabilities, could enhance the effort. In addition, every partnership brought greater legitimacy to the overall program and might help insulate it from drastic budgetary and political changes. Inciting an international incident because of a change to the station was something neither U.S. diplomats nor politicians relished, and that fact, it was thought, could help stabilize funding, schedule, or other factors that might otherwise be changed in response to short-term political needs.

NASA officials pressed forward with international agreements among thirteen nations to take part in the space station Freedom program. Japan, Canada, and the nations pooling their resources in the European Space Agency agreed in the spring of 1985 to participate. Canada, for instance, decided to build a remote servicing system. The European Space Agency agreed to build an attached pressurized science module and an astronaut-tended free-flyer, a vehicle to transport an astronaut and equipment away from a spacecraft. Japan's contribution was the development and commercial use of an experiment module for materials processing, life sciences, and technology development. These separate components, with their "plug-in" capacity, eased somewhat the overall management (and congressional) concerns about unwanted technology transfer.

Almost from the outset, the space station program was controversial. Most of the debate centered on its costs versus its benefits. One NASA official remembered that "I reached the scream level at about $9 billion," referring to how much U.S. politicians appeared willing to spend on the station. To stay within budget, NASA pared away at station capabilities, in the process eliminating functions that some of its constituencies wanted. This led to a rebellion among some former supporters. For instance, the space science community began complaining that the space station configuration under development did not provide sufficient experimental opportunity. Thomas M. Donahue, an atmospheric scientist from the University of Michigan and chair of the National Academy of Science's Space Science Board, commented in the mid-1980s that he thought the government should be honest about the goals of the station, and "if the decision to build a space station is political and social, we have no problem with that … but don't call it a scientific program."

Because of the cost challenges, redesigns of space station Freedom followed in 1990, 1991, 1992, and 1993. Each time, the project got smaller, less capable of accomplishing the broad projects envisioned for it, less costly, and more controversial. As costs were reduced, capabilities also had to diminish, and increasingly political leaders who once supported the program questioned its viability. It was a seemingly endless circle, and some leaders suggested that the United States, the international partners, and the overall space exploration effort would be better off if the space station program were terminated.

In the latter 1980s and early 1990s a parade of space station managers and NASA administrators, each of them honest in their attempts to rescue the program, wrestled with Freedom and lost. They faced on one side politicians who demanded that the jobs aspect of the project—itself a major cause of the overall cost growth—be maintained, with station users on the other demanding that Freedom's capabilities be maintained, and with people on all sides demanding that costs be reduced. The incompatibility of these various demands ensured that station program management was a task not without difficulties.

Just as the Cold War was the driving force behind big NASA budgets in the 1960s, its end was a critical component in the search for a new space policy in the 1990s. Cold War rivalries no longer held real attraction as a selling point for an aggressive space exploration program at least by the mid-1980s. Accordingly, when he became NASA administrator in 1992, Daniel S. Goldin worked to salvage the space station effort with a total redesign that brought the significant space capabilities of the former Soviet Union into the effort. The demise of the Cold War, and the collapse of the Soviet Union, created a dramatically changed international situation that allowed NASA to negotiate a landmark decision to include Russia in the building of an international space station. On 7 November 1993 the United States and Russia agreed to work together with the other international partners to build an International Space Station for the benefit of all.

This strikingly new spin on international relations regalvanized support for the program, and for the next eight years building the ISS dominated the efforts of all the spacefaring nations. In the post–Cold War era this decision provided an important linkage for the continuation of the space station at a time when many were convinced that for other reasons—cost, technological challenge, return on investment—it was an uninviting endeavor.

As a lead-in to the ISS, twenty years after the world's two greatest spacefaring nations and Cold War rivals staged a dramatic docking in the Apollo-Soyuz Test Project during the summer of 1975, the space programs of the United States and Russia again met in Earth orbit when the space shuttle Atlantis docked to the aging Russian Mir space station in June-July 1995. "This flight heralds a new era of friendship and cooperation between our two countries," said NASA's Goldin. "It will lay the foundation for construction of an International Space Station later this decade."

The docking missions conducted through 1998 represented a major alteration in the history of space exploration. They also portended considerable controversy. For example, several accidents took place aboard the aging Russian space station that called into question the validity of American involvement in a Russian program that might compromise the safety of American astronauts aboard. Mishaps on Mir in 1996–1998 included a fire inside the station, failure of an oxygen generator, leaks in the cooling system, a docking accident that damaged both the station and the spacecraft to be docked to it, and the temporary malfunction of an attitude control system.

These accidents triggered criticism of U.S.–Russian cooperation in the shuttle-Mir program. That criticism emphasized the safety of the astronauts and the aging character of Mir, noting it was in such bad shape that no meaningful scientific results could be achieved aboard the station. Most asked that Russia deorbit Mir and thereby bring it to "an honorable end," something that finally took place in the spring of 2001. Only with the launch of the first elements of the International Space Station in the autumn of 1998 did public criticism subside on the role of the shuttle-Mir missions in the American space program.

Other questions about the International Space Station program, however, did not subside even with first-element launches in 1998. In addition to schedule and budget concerns, many complained about the integral part played by Russia in building the International Space Station. Most observers agreed that the fundamental problems associated with Russian participation in the space station program could be reduced to a few fine points, as stated by Representative F. James Sensenbrenner, Jr., chair of the House Committee on Science, in 1998: "One, the Russians failed to follow through on their funding commitments, and two, the Clinton administration brought the Russians into the project for the wrong reasons, placed the Russians in the critical path, and routinely let them off the hook for their failures."

Some warned of complications with Russian involvement as early as September 1993, when President Clinton formally invited the Russian government to join the project, ostensibly as a gesture of goodwill to the former Cold War enemy. In reality, the invitation to the Russians involved gaining Russian compliance with the Missile Technology Control Regime, a voluntary arrangement among twenty-seven countries to control the export of weapons of mass destruction. The Clinton administration admitted as much to Congress on 20 April 1994, when the U.S. ambassador to Russia James Collins was asked by Representative Ralph M. Hall, "Give me a 1 to 10 on whether or not we are building the space station with Russia to achieve a particular foreign policy objective such as Russian compliance with the Missile Technology Control Regime." Ambassador Collins replied, "Getting Russia into the Missile Technology Control Regime and bringing it into willingness to comply with those guidelines is a very important objective." This proved unsuccessful, however, as the Russian Space Agency continued selling missile technology to so-called rogue nations. According to Sensenbrenner, American "nonproliferation goals for cooperating with the Russians in the civil space area have not been realized."

Even more than this, the Russians were integrated deeply into the critical path of International Space Station assembly. If they failed to deliver their modules on schedule, ISS assembly had to wait, and every slippage on the part of the Russian Space Agency stretched out the overall station schedule. NASA had assumed a position of complete reliance on Russia for the service module—sole provider of oxygen, avionics, reboost, and sanitary facilities—until much later in the assembly process. This meant, in simple terms, that the entire program was held hostage pending resolution of Russia's internal economic and political problems and external goodwill.

With the belated launch of the Russian service module in July 2000, however, it became clear that international competition had been firmly replaced with cooperation as the primary reason behind huge expenditures for space operations. As the dean of space policy analysts John M. Logsdon concluded, "there is little doubt, then, that there will be an international space station, barring major catastrophes like another shuttle accident or the rise to power of a Russian government opposed to cooperation with the West."

While the challenges of completing the ISS remained quite real, as the twenty-first century dawned the dream of a permanent presence in space seemed on the verge of reality. Before the end of 2000 the first ISS crew inhabited the station. Furthermore, the spacefaring nations of the world had accepted ISS as the raison d'être of their space efforts. Only through its successful achievement, space advocates insisted, would a vision of space exploration that includes all nations venturing into the unknown be ultimately realized. This scenario makes eminent sense if one is interested in developing an expansive space exploration effort, one that leads to the permanent colonization of humans on other planets. At the end of the century, that debate continued. What no one was sure of was how this would unfold in the next century.

Twenty-First-Century Issues in Space Cooperation

In the last decade of the twentieth century U.S. space policy entered an extended period of transition. This was true for several reasons. For one thing, U.S. preeminence in space technology was coming to an end as the European Space Agency developed and made operational its superb Ariane launcher, and the agency's ancillary space capabilities made it increasingly possible for Europe to "go it alone." At the same time, U.S. commitment to sustained leadership in space activities overall waned, and significantly less public monies went into NASA missions. U.S. political commitment to cooperative projects seemingly lessened as well: for example, the United States refrained from developing a probe for the international armada of spacecraft that was launched toward Comet Halley in 1984–1985 and withdrew part of its support from the controversial International Solar Polar Mission to view the Sun from a high altitude, renamed Ulysses and launched in 1990. Of those cooperative projects that remained, NASA increasingly acceded to the demands of international collaborators to develop critical systems and technologies. This overturned the policy of not allowing partners into the critical path—something that had not been accepted in earlier development projects—and was in large measure a pragmatic decision on the part of American officials. Because of the increasing size and complexity of projects, according to Kenneth Pedersen, more recent projects had produced "numerous critical paths whose upkeep costs alone will defeat U.S. efforts to control and supply them." He added, "It seems unrealistic today to believe that other nations possessing advanced technical capabilities and harboring their own economic competitiveness objectives will be amenable to funding and developing only ancillary systems."

In addition to these important developments, in the 1990s the rise of competitive economic activities in space mitigated the prospects for future activities. The brutal competition for launch business, the cutthroat nature of space applications, and the rich possibilities for future space-based economic activities such as asteroid mining were rapidly creating a climate in which international ventures might once again become the exception rather than the rule. John Krige astutely commented in 1997 that "collaboration has worked most smoothly when the science or technology concerned is not of direct strategic (used here to mean commercial or military) importance. As soon as a government feels that its national interests are directly involved in a field of R&D, it would prefer to go it alone." He also noted that the success of cooperative projects may take as their central characteristic that they have "no practical application in at least the short to medium term."

The sole exception to this perspective might be when nations decide that for prestige or diplomatic purposes it is appropriate to cooperate in space. A concern existed that in the United States, where economic competitiveness in space was such a powerful motivation for "going it alone," and where prestige and diplomacy seemed to have taken a backseat to nationalistic hyperbole, that with every passing year there would be less tolerance for large-scale cooperative, and by extension difficult, projects in space. Indeed, there was a constant reduction under way in government spending for space exploration and open discussions of strategies on how to shift the thrust of space flight to the private sector. That would, of necessity, curtail international space exploration activities, with less funding available for scientific space missions, the very missions that are natural candidates for cooperative work. Corporations, that may well provide the greatest share of investment for space flight in the United States in the twenty-first century would be loathe to engage in partnerships in which their technological advantages might be compromised. The proliferation of space technology throughout the world, especially to those nations perceived as rogue states, may well prompt U.S. leaders to clamp down on anything that smacks of technology transfer. (This has already been seen in relation to the supposed satellite technology transferred inadvertently to the People's Republic of China through Hughes Aerospace Corp.) Finally, the disagreeable experiences of such cooperative projects as the International Space Station might sour both national and NASA officials on future endeavors. It is certain, for example, that it will be a long time before anyone in authority in the United States will sign on to an international project of similar complexity.

Conclusions

One of the key conclusions that we might reach about both the course of international cooperation between the United States and other international partners is that it has been an enormously difficult process. Apropos is a quote from Wernher von Braun, that "we can lick gravity, but sometimes the paperwork is overwhelming." Perhaps the hardest part of spaceflight is not the scientific and technological challenges of operating in an exceptionally foreign and hostile environment but in the down-to-earth environment of rough-and-tumble international and domestic politics. But even so, cooperative space endeavors have been richly rewarding and overwhelmingly useful, from all manner of scientific, technical, social, and political perspectives.

Kenneth Pedersen observed in a public forum in 1983 that "international space cooperation is not a charitable enterprise; countries cooperate because they judge it in their interest to do so." For continued cooperative efforts in space to proceed into the twenty-first century it is imperative that those desiring them define appropriate projects and ensure that enough national leaders judge those projects as being of interest and worthy of making them cooperative. Since the 1960s space-exploration proponents have gained a wealth of experience in how to define, gain approval for, and execute the simplest of cooperative projects. Even those have been conducted only with much trial and considerable force of will. For those involved in space exploration it is imperative that a coordinated approach to project definition, planning, funding, and conduct of future missions be undertaken. Only then will people be able to review the history of international programs and speak with pride about all of their many accomplishments while omitting the huge "but" that must follow in considering all of the difficulties encountered.

Bibliography

Bonnet, Roger M., and Vittorio Manno. International Cooperation in Space: The Example of the European Space Agency. Cambridge, Mass., 1994. A prize-winning study of the philosophy and inner workings of internationally supported space exploration projects.

Bulkeley, Rip. The Sputnik Crisis and Early United States Space Policy: A Critique of the Historiography of Space. Bloomington, Ind., 1991. An important discussion of early efforts to develop civil space policy in the aftermath of Sputnik. It contains much information relative to the rivalry between the United States and the Soviet Union.

Divine, Robert. The Sputnik Challenge. New York, 1993. Contains insights into the space program as promoted by the Eisenhower administration.

European Science Foundation and National Research Council. U.S.–European Collaboration in Space Science. Washington, D.C., 1998. An official research report on collaborative issues in space science.

Frutkin, Arnold W. International Cooperation in Space. Englewood Cliffs, N.J., 1965. An interesting early discussion of the possibilities and problems of international cooperation written during the height of the Cold War by NASA's head of international relations.

Handberg, Roger, and Joan Johnson-Freese. The Prestige Trap: A Comparative Study of the U.S., European, and Japanese Space Programs. Dubuque, Iowa, 1994. An interesting study of the various programs and their development.

Harvey, Brian. The New Russian Space Programme: From Competition to Collaboration. Chichester, England, and New York, 1996. A solid history of the development of the Soviet space program through the mid-1980s. It has several chapters on the race to the Moon, describing what information was available before the end of the Cold War.

Harvey, Dodd L., and Linda C. Ciccoritti. U.S.–Soviet Cooperation in Space. Miami, Fla. 1974. A detailed exploration of the competition and cooperation in space exploration by the two superpowers of the Cold War era through the détente that led to the joint Apollo-Soyuz Test Project.

Johnson-Freese, Joan. Changing Patterns of International Cooperation in Space. Malabar, Fla., 1990. An interesting exploration of the movement from competition to cooperation in space exploration.

Kay, W. D. "Space Policy Redefined: The Reagan Administration and the Commercialization of Space." Business and Economic History 27 (fall 1998): 237–247. A reassessment of the space policy of the Reagan administration.

Krige, John. "The Politics of European Collaboration in Space." Space Times: Magazine of theAmerican Astronautical Society 36 (September–October 1997): 4–9. A lucid analysis of the difficult political issues involved in international collaboration in space.

Kuhn, Thomas S. The Structure of Scientific Revolutions. Chicago, 1970. A classic analysis of how science changes perspective using the Copernican revolution as a case.

Launius, Roger D. NASA: A History of the U.S. Civil Space Program. Malabar, Fla., 2000. A short history of the U.S. civilian space efforts with documents.

Launius, Roger D., John M. Logsdon, and Robert W. Smith, eds. Reconsidering Sputnik: Forty Years Since the Soviet Satellite. Amsterdam, 2000. A collection of essays on various aspects of the Sputnik crisis of 1957.

Launius, Roger D., and Howard E. McCurdy, eds. Spaceflight and the Myth of Presidential Leadership. Urbana, Ill., 1997. A collection of essays on presidents Eisenhower, Kennedy, Johnson, Nixon, Ford, and Carter with addition discussions of international cooperation and the role of the presidency in shaping space policy.

Logsdon, John M. "The Development of International Space Cooperation." In John M. Logsdon, ed. Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program. Vol. 2. External Relationships. Washington, D.C., 1996. An essential reference work with key documents in space policy and its development.

——. Together in Orbit: The Origins of International Participation in Space Station Freedom. Washington, D.C., 1998. An excellent short account of the international coordination for the space station.

McDougall, Walter A. "The Heavens and the Earth": A Political History of the Space Age. New York, 1985. A Pulitzer Prize–winning book that analyzes the space race to the Moon in the 1960s.

Pedersen, Kenneth S. "Thoughts on International Space Cooperation and Interests in the Post–Cold War World." Space Policy 8 (August 1992): 215–224. A fine discussion of the problems of international collaboration in space.

Shaffer, Stephen M., and Lisa Robock Shaffer. The Politics of International Cooperation: A Comparison of U.S. Experience in Space and Security. Denver, Colo., 1980. A political science study of the subject.

— Roger Launius

For other uses, see Outer space (disambiguation).

The boundaries between the Earth's surface and outer space, at the Kármán line, 100 km (62 mi) and exosphere at 690 km (430 mi).

Outer space (often simply called space) comprises the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations.

Contrary to popular understanding, outer space is not completely empty (i.e. a perfect vacuum), but contains a low density of particles, predominantly hydrogen plasma, as well as electromagnetic radiation, magnetic fields and neutrinos. Theoretically, it also contains dark matter and dark energy.

The term outer space was first recorded by the English poet Lady Emmeline Stuart-Wortley in her poem "The Maiden of Moscow" in 1842,^[1] and also later attested to the writings of HG Wells in 1901.^[2]. The shorter term space is actually older, first used to mean the region beyond Earth's sky in John Milton's Paradise Lost in 1667.^[3]

1 Environment
- 1.1 Temperature
- 1.2 Effect on human bodies
2 Boundary
3 Space versus Orbit
4 Regions
5 References
6 See also
7 External links

Environment

Outer space is the closest approximation of a perfect vacuum. It has effectively no friction, allowing stars, planets and moons to move freely along ideal gravitational trajectories. But no vacuum is truly perfect, not even in intergalactic space where there are still a few hydrogen atoms per cubic centimeter.^{[citation needed]} (For comparison, the air we breathe contains about 10¹⁹ molecules per cubic centimeter.) The deep vacuum of space could make it an attractive environment for certain industrial processes, for instance those that require ultraclean surfaces.

Stars, planets, asteroids, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary: the density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 1 Pa at 100 kilometres (62 mi) of altitude, the Kármán line which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the sun and the dynamic pressure of the solar wind, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre.

Temperature

All of the observable universe is filled with large numbers of photons, created during the Big Bang, the so-called cosmic background radiation, and quite likely a correspondingly large number of neutrinos called the cosmic neutrino background. The current temperature of the photon radiation is about 3 K (−270.15 °C; −454.27 °F).

Effect on human bodies

Boundary

Traditionally, there was no clear boundary between Earth's atmosphere and space, as the density of the atmosphere gradually decreases as the altitude increases. Nevertheless, several boundaries have been set, namely:

The Fédération Aéronautique Internationale has established the Kármán line at an altitude of 100 kilometres (62 mi) as a working definition for the boundary between aeronautics and astronautics. This is used because above an altitude of roughly 100 km, as Theodore von Kármán calculated, a vehicle would have to travel faster than orbital velocity in order to derive sufficient aerodynamic lift from the atmosphere to support itself.
The United States designates people who travel above an altitude of 50 miles (80 km) as astronauts.
NASA's mission control uses 76 miles (122 km) as their re-entry altitude, which roughly marks the boundary where atmospheric drag becomes noticeable, (depending on the ballistic coefficient of the vehicle), thus leading shuttles to switch from steering with thrusters to maneuvering with air surfaces.

In 2009, scientists at the University of Calgary reported detailed measurements with an instrument called the Supra-Thermal Ion Imager (an instrument that measures the direction and speed of ions), which allowed them to determine that space begins 118 kilometres (73 mi) above Earth. The boundary represents the midpoint of a gradual transition over tens of kilometers from the relatively gentle winds of the Earth's atmosphere to the more violent flows of charged particles in space, which can reach speeds well over 600 miles per hour (1,000 km/h).^[10]^[11]

This was only the second time that direct measurements of charged particle flows have been conducted at this region, which is too high for balloons and too low for satellites. It was however the first study to include all the relevant elements for this kind of determination – for example, the upper atmospheric winds.

The instrument was carried by the JOULE-II rocket on January 19, 2007, and traveled to an altitude of about 124 miles (200 km). From there it collected data while it was moving through the "edge of space".^[10]

Space versus Orbit

To perform an orbit, a spacecraft must travel faster than a sub-orbital spaceflight. A spacecraft has not entered orbit until it is traveling with a sufficiently great horizontal velocity such that the acceleration due to gravity on the spacecraft is less than or equal to the centripetal acceleration being caused by its horizontal velocity (see circular motion). So to enter orbit, a spacecraft must not only reach space, but must also achieve a sufficient orbital speed (angular velocity). For a low-Earth orbit, this is about 7,900 m/s (28,440.00 km/h; 17,671.80 mph); by contrast, the fastest airplane speed ever achieved (excluding speeds achieved by deorbiting spacecraft) was 2,200 m/s (7,920.00 km/h; 4,921.26 mph) in 1967 by the North American X-15.^[12] Konstantin Tsiolkovsky was the first person to realize that, given the energy available from any available chemical fuel, a several-stage rocket would be required. The escape velocity to pull free of Earth's gravitational field altogether and move into interplanetary space is about 11,000 m/s (39,600.00 km/h; 24,606.30 mph) The energy required to reach velocity for low Earth orbit (32 MJ/kg) is about twenty times the energy required simply to climb to the corresponding altitude (10 kJ/(km·kg)).

There is a major difference between sub-orbital and orbital spaceflights. The minimum altitude for a stable orbit around Earth (that is, one without significant atmospheric drag) begins at around 350 kilometres (220 mi) above mean sea level. A common misunderstanding about the boundary to space is that orbit occurs simply by reaching this altitude. Achieving orbital speed can theoretically occur at any altitude, although atmospheric drag precludes an orbit that is too low. At sufficient speed, an airplane would need a way to keep it from flying off into space, but at present, this speed is several times greater than anything within reasonable technology.

A common misconception is that people in orbit are outside Earth's gravity because they are "floating". They are floating because they are in "free fall": they are accelerating toward Earth, along with their spacecraft, but are simultaneously moving sideways fast enough that the "fall" away from a straight-line path merely keeps them in orbit at a constant distance above Earth's surface. Earth's gravity reaches out far past the Van Allen belt and keeps the Moon in orbit at an average distance of 384,403 kilometres (238,857 mi).

Regions

Space is not a perfect vacuum: its different regions are defined by the various atmospheres and "winds" that dominate within them, and extend to the point at which those winds give way to those beyond. Geospace extends from Earth's atmosphere to the outer reaches of Earth's magnetic field, whereupon it gives way to the solar wind of interplanetary space. Interplanetary space extends to the heliopause, whereupon the solar wind gives way to the winds of the interstellar medium. Interstellar space then continues to the edges of the galaxy, where it fades into the intergalactic void.

Geospace

Aurora australis observed by Discovery, May 1991.

Geospace is the region of outer space near the Earth. Geospace includes the upper region of the atmosphere, as well as the ionosphere and magnetosphere. The Van Allen radiation belts also lie within the geospace. The region between Earth's atmosphere and the Moon is sometimes referred to as cis-lunar space.

Although it meets the definition of outer space, the atmospheric density within the first few hundred kilometers above the Kármán line is still sufficient to produce significant drag on satellites. Most artificial satellites operate in this region called low earth orbit and must fire their engines every few days to maintain orbit. The drag here is low enough that it could theoretically be overcome by radiation pressure on solar sails, a proposed propulsion system for interplanetary travel. Planets are too massive for their trajectories to be affected by these forces, although their atmospheres are eroded by the solar winds.

Geospace is populated at very low densities by electrically charged particles, whose motions are controlled by the Earth's magnetic field. These plasmas form a medium from which storm-like disturbances powered by the solar wind can drive electrical currents into the Earth’s upper atmosphere.

During geomagnetic storms two regions of geospace, the radiation belts and the ionosphere, can become strongly disturbed. These storms increase fluxes of energetic electrons that can permanently damage satellite electronics, disrupting telecommunications and GPS technologies, and can also be a hazard to astronauts, even in low-Earth orbit. They also create aurorae seen near the magnetic poles.

Geospace contains material left over from previous manned and unmanned launches that are a potential hazard to spacecraft. Some of this debris re-enters Earth's atmosphere periodically.

The absence of air makes geospace (and the surface of the Moon) ideal locations for astronomy at all wavelengths of the electromagnetic spectrum, as evidenced by the spectacular pictures sent back by the Hubble Space Telescope, allowing light from about 13.7 billion years ago — almost to the time of the Big Bang — to be observed.

The outer boundary of geospace is the interface between the magnetosphere and the solar wind. The inner boundary is the ionosphere.^[13] Alternately, geospace is the region of space between the Earth’s upper atmosphere and the outermost reaches of the Earth’s magnetic field.^[14]

Interplanetary

Main article: Interplanetary medium

Interplanetary space consists of the space around the Sun and planets of the Solar System. It extends out to the heliopause where the influence of the galactic environment starts to dominate over the magnetic field and particle flux from the Sun. Interplanetary space is defined by the solar wind, a continuous stream of charged particles emanating from the Sun that creates a very tenuous atmosphere (the heliosphere) for billions of miles into space. This wind has a particle density of 5–10 protons/cm³ and is moving at a velocity of 350–400 km/s.^[15] This distance and effectiveness of the heliopause varies depending on the activity level of the Sun, and hence the solar wind.^[16] The discovery since 1995 of extrasolar planets means that other stars must possess their own interplanetary media.^[17]

The volume of interplanetary space is an almost pure vacuum, with a mean free path of about one astronomical unit at the orbital distance of the Earth. However, this space is not completely empty, and is sparsely filled with cosmic rays, which include ionized atomic nuclei and various subatomic particles. There is also gas, plasma and dust, small meteors, and several dozen types of organic molecules discovered to date by microwave spectroscopy.^[18]

Interplanetary space contains a magnetic field generated by the Sun.^[15] There are also magnetospheres generated by planets such as Jupiter, Saturn and the Earth that have their own magnetic fields. These are shaped by the influence of the solar wind into the approximation of a teardrop shape, with the long tail extending outward behind the planet. These magnetic fields can trap particles from the solar wind and other sources, creating belts of magnetic particles such as the Van Allen Belts.

Interstellar

Main article: Interstellar medium

Interstellar space is the physical space within a galaxy not occupied by stars or their planetary systems. The interstellar medium resides – by definition – in interstellar space.

Intergalactic

Main articles: Intracluster medium and Cosmic microwave background

Intergalactic space is the physical space between galaxies. Generally free of dust and debris, intergalactic space is very close to a total vacuum. Certainly, the space between galaxy clusters, called the voids, is nearly empty. Some theories put the average density of the universe as the equivalent of one hydrogen atom per cubic meter.^[19]^[20] The density of the universe, however, is clearly not uniform; it ranges from relatively high density in galaxies (including very high density in structures within galaxies, such as planets, stars, and black holes) to conditions in vast voids that have much lower density than the universe's average.

Surrounding and stretching between galaxies, there is a rarefied plasma^[21]^[22] that is thought to possess a cosmic filamentary structure^[23] and that is slightly denser than the average density in the universe. This material is called the intergalactic medium (IGM) and is mostly ionized hydrogen, i.e. a plasma consisting of equal numbers of electrons and protons. The IGM is thought to exist at a density of 10 to 100 times the average density of the universe (10 to 100 hydrogen atoms per cubic meter). It reaches densities as high as 1000 times the average density of the universe in rich clusters of galaxies.

The reason the IGM is thought to be mostly ionized gas is that its temperature is thought to be quite high by terrestrial standards (though some parts of it are only "warm" by astrophysical standards). As gas falls into the Intergalactic Medium from the voids, it heats up to temperatures of $105$ K to $107$ K, which is high enough for the bound electrons to escape from the hydrogen nuclei upon collisions. At these temperatures, it is called the Warm-Hot Intergalactic Medium (WHIM). Computer simulations indicate that on the order of half the atomic matter in the universe might exist in this warm-hot, rarefied state. When gas falls from the filamentary structures of the WHIM into the galaxy clusters at the intersections of the cosmic filaments, it can heat up even more, reaching temperatures of $108$ K and above.

References

^ OED[outer space]
^ "Etymonline : Outer". http://www.etymonline.com/index.php?search=outer+space&searchmode=none. Retrieved 2008-03-24.
^ Douglas Harper (November 2001). "Space". The Online Etymology Dictionary. http://www.etymonline.com/index.php?term=space. Retrieved 2009-06-19.
^ "Human Body in a Vacuum". NASA. June 03, 1997. http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html. Retrieved 2009-06-19.
^ ^a ^b ^c ^d ^e Harding, Richard M (1989). Survival in Space: Medical Problems of Manned Spaceflight. Routledge. ISBN 0-415-00253-2.
^ Billings, Charles E. (1973). "Barometric Pressure". in edited by James F. Parker and Vita R. West. Bioastronautics Data Book (Second ed.). NASA. NASA SP-3006.
^ Geoffrey A. Landis (7 August 2007). "Human Exposure to Vacuum". www.geoffreylandis.com. http://www.geoffreylandis.com/vacuum.html. Retrieved 2009-06-19.
^ Webb P. (1968). "The Space Activity Suit: An Elastic Leotard for Extravehicular Activity". Aerospace Medicine 39: 376–383.
^ Tamarack R. Czarnik. "Ebullism at 1 Million Feet: Surviving Rapid/Explosive Decompression". www.geoffreylandis.com. http://www.geoffreylandis.com/ebullism.html. Retrieved 2009-06-19.
^ ^a ^b Andrea Thompson (09 April 2009). "Edge of Space Found". space.com. http://www.space.com/scienceastronomy/090409-edge-space.html. Retrieved 2009-06-19.
^ L. Sangalli, D. J. Knudsen, M. F. Larsen, T. Zhan, R. F. Pfaff, and D. Rowland (2009). "Rocket-based measurements of ion velocity, neutral wind, and electric field in the collisional transition region of the auroral ionosphere". Journal of Geophysical Research (American Geophysical Union) 114: A04306. doi:10.1029/2008JA013757. http://www.agu.org/pubs/crossref/2009/2008JA013757.shtml. Retrieved 2009-06-19.
^ Linda Shiner (November 01, 2007). "X-15 Walkaround". Air & Space Magazin. http://www.airspacemag.com/history-of-flight/x-15_walkaround.html. Retrieved 2009-06-19.
^ "Report of the Living With a Star Geospace Mission Definition Team" (PDF). NASA. September 2002. http://www.lws.nasa.gov/documents/geospace/geospace_gmdt_report.pdf. Retrieved 2007-12-19.
^ "LWS Geospace Missions". NASA. http://www.lws.nasa.gov/missions/geospace/geospace.htm. Retrieved 2007-12-19.
^ ^a ^b Papagiannis, Michael D. (1972). Space Physics and Space Astronomy. Taylor & Francis. pp. 12–149. ISBN 0677040008.
^ Phillips, Tony (2009-09-29). "Cosmic Rays Hit Space Age High". NASA. http://science.nasa.gov/headlines/y2009/29sep_cosmicrays.htm. Retrieved 2009-10-20.
^ Frisch, Priscilla C.; Müller, Hans R.; Zank, Gary P.; Lopate, C. (May 6-9, 2002). "Galactic environment of the Sun and stars: interstellar and interplanetary material". in Mario Livio, I. Neill Reid, William B. Sparks. Astrophysics of life. Proceedings of the Space Telescope Science Institute Symposium. Baltimore, MD, USA: Cambridge University Press. pp. 21–34. ISBN 0-521-82490-7. Bibcode: 2005asli.symp...21F.
^ Flynn, G. J.; Keller, L. P.; Jacobsen, C.; Wirick, S. (2003). "The Origin of Organic Matter in the Solar System: Evidence from the Interplanetary Dust Particles". in R. Norris and F. Stootman. Bioastronomy 2002: Life Among the Stars, Proceedings of IAU Symposium #213. San Francisco: Astronomical Society of the Pacific. Bibcode: 2004IAUS..213..275F.
^ Davidson, Keay & Smoot, George. Wrinkles in Time. New York: Avon, 2008: 158-163
^ Silk, Joseph. Big Bang. New York: Freeman, 1977: 299.
^ Jafelice, Luiz C. and Opher, Reuven (July 1992). "The origin of intergalactic magnetic fields due to extragalactic jets". Royal Astronomical Society. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992MNRAS.257..135J. Retrieved 2009-06-19.
^ "99.999% plasma". The Plasma Universe Wikipedia-like Encyclopedia. 25 May 2009. http://www.plasma-universe.com/index.php/99.999%25_plasma. Retrieved 2009-06-19.
^ James Wadsley et al. (20 August 2002). "The Universe in Hot Gas". NASA. http://antwrp.gsfc.nasa.gov/apod/ap020820.html. Retrieved 2009-06-19.

External links

Look up intergalactic in Wiktionary, the free dictionary.

Wikiquote has a collection of quotations related to: space

Wikimedia Commons has media related to: Space

Wikinews has related news: Portal:Space

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Donate to Wikimedia

		Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more
		Hacker Slang. The Jargon File. Copyright © 2007. Read more
		US Foreign Policy Encyclopedia. Encyclopedia of American Foreign Policy. Copyright © 2002 by The Gale Group, Inc. All rights reserved. Read more
		Games. Copyright © 2008 All Media Guide, LLC. Content provided by All Game Guide Â® , a trademark of All Media Guide, LLC. All rights reserved. Read more
		Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Outer space". Read more

outer space

Roots & Influences

Contents