50 Years of NASA History

Origins

Like all historical events, the birth of NASA must be placed in the context of its times. Following World War II, the United States was in direct competition with the Soviet Union (the superpower that in 1991 disbanded into several sovereign nations including the Russian Federation, Kazakhstan, the Ukraine, etc.) for the hearts and minds of people around the world. It was not for the most part a shooting war, but a "Cold War," a test of two very different systems of government. Technology was one means of measuring success and projecting power, and nothing was more powerful than the intercontinental ballistic missiles (ICBMs) being developed in the wake of World War II to deliver warheads.

It was these missiles that brought human technology to the brink of space, and it was the Soviet Union's launch of Sputnik on Oct. 4, 1957, that first put an object into orbit around Earth. Passing overhead with its faint radio signal as people watched and listened, the 183-pound satellite was a powerful symbol. It was followed in November by the even larger Sputnik II, which carried the dog Laika. Only in late January 1958 was the United States able to answer the challenge with Explorer 1, hoisted aloft by the Army's rocket team led by Wernher von Braun, using rocket technology developed from World War II. Though a small spacecraft weighing only 30 pounds, it discovered what are now known as the Van Allen radiation belts, named for the University of Iowa scientist Dr. James Van Allen, launching the new discipline of space science. Explorer 1 was followed in March by the Navy's Vanguard 1, 6 inches in diameter and weighing only 3 pounds.

NASA's birth was directly related to the launch of the Sputniks and the ensuing race to demonstrate technological superiority in space. Driven by the competition of the Cold War, on July 29, 1958, President Dwight D. Eisenhower signed the National Aeronautics and Space Act, providing for research into the problems of flight within Earth's atmosphere and in space. After a protracted debate over military versus civilian control of space, the act inaugurated a new civilian agency designated the National Aeronautics and Space Administration (NASA). The agency began operations on Oct. 1, 1958.

NASA began by absorbing the earlier National Advisory Committee for Aeronautics (NACA), including its 8,000 employees, an annual budget of $100 million, three major research laboratories – the Langley Aeronautical Laboratory in Virginia, the Ames Aeronautical Laboratory in California, and the Lewis Flight Propulsion Laboratory in Ohio – and two smaller test facilities. It quickly incorporated other organizations (or parts of them), notably the space science group of the Naval Research Laboratory that formed the core of the new Goddard Space Flight Center in Greenbelt, Md., the Jet Propulsion Laboratory managed by the California Institute of Technology for the Army, and the Army Ballistic Missile Agency in Huntsville, Ala., where Wernher von Braun's team of engineers was developing large rockets.

Within months of its creation, NASA began to conduct space missions, and over the last 50 years has undertaken spectacular programs in human spaceflight, robotic spaceflight, and aeronautics research. NASA today carries on the nation's long tradition of exploration dating back at least to Lewis and Clark. In addition to its headquarters in Washington, D.C., NASA facilities include 10 centers around the country staffed by nearly 19,000 employees. Its proposed budget for fiscal year 2009 is $17.6 billion.

Human Spaceflight

Looking back after 50 years, we can distinguish several eras of human spaceflight at NASA. The first era can be broadly termed the Apollo moon race era. President John F. Kennedy's challenge on May 25, 1961, of "achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth," put in motion events that will be forever remembered not only as a technological and managerial feat, but also an extraterrestrial adventure that gave humanity a new perspective on its home planet. Following the Soviet Union's launch of Yuri Gagarin in April 1961, and driven by Kennedy's challenge, the United States launched its own astronauts in capsules with the mythical names of Mercury, Gemini and Apollo. The suborbital flights of Alan Shepard and Gus Grissom in 1961, the first orbital flight of John Glenn in 1962, and the subsequent one-man flights of project Mercury proved that humans could survive in space. During this heady period, the astronauts became a new breed of national hero, admired for their courage and dedication to exploring the new frontier of space. The two-man Gemini flights of 1965-1966 demonstrated that humans could fly in space, undertake complex rendezvous and docking operations, and even leave the spacecraft for extra-vehicular activity (EVA).

All of this activity during the early 1960s was in the service of the Apollo program to land humans on the moon. Despite a deadly fire during ground tests of the Apollo capsule in early 1967, in December 1968, Americans first rounded the moon, and succeeded in landing on the moon's Sea of Tranquility in July 1969. For sheer excitement it was hard to beat, as Neil Armstrong and Buzz Aldrin set down on the lunar surface with seconds of fuel to spare. For one day the world seemed united, as hundreds of millions around the world watched with fascination. Five more flights landed on the moon, culminating with the flight of Apollo 17 in December 1972. In all, 12 men walked on the surface of the moon, and including their time in the lunar excursion module, spent just a few minutes less than 300 hours on the lunar surface. The societal effect of the Apollo program was profound, no more so than in its view of Earth from the moon. The photographs of "Earthrise," and of the full Earth as a blue marble suspended in space, fragile and without national boundaries, changed humankind's view of Earth forever.

A fitting conclusion to the Apollo moon race era, after the brief American experience in operating the Skylab orbiting space station in 1973-74, brought competition full circle to cooperation. In 1975, the United States and the Soviet Union achieved the first international human spaceflight, the Apollo-Soyuz Test Project.

The next major era in human spaceflight began in April 1981, with the maiden voyage of the space shuttle Columbia, the world's first reusable spacecraft. The space shuttle was approved as an initiative by President Nixon in 1972. At the program's peak, four shuttle orbiters, each capable of carrying large satellites (payloads of up to 50,000 pounds) both to and from orbit and of helping to assemble component parts of the International Space Station, were in service.

The space shuttle demonstrated that a spacecraft could take off vertically and glide to an unpowered airplane-like landing, with crews of five to seven astronauts. While the space shuttle goals of low cost and routine access to space were not met, what was officially called the Space Transportation System (STS) amassed several significant accomplishments. Among them were more than a score of commercial satellites deployed prior to the Challenger accident in 1986; the placement in orbit of major scientific missions including Galileo, Magellan, and Chandra, and the launching and servicing missions of the Hubble Space Telescope; Spacelab and SPACEHAB missions with their material, microgravity and life sciences experiments; deployment of the Tracking and Data Relay System (TDRS) constellation; and numerous flights in support of the Mir and International Space Station. Humanity's first attempt to build and operate a reusable spacecraft was an impressive achievement in itself.

Along with these, the shuttle program has seen the depths of tragedy. On Jan. 28, 1986, a leak in the joints of one of two solid rocket boosters attached to the shuttle orbiter Challenger caused the main liquid fuel tank to explode 73 seconds after launch, killing all seven crew members. On Sept. 29, 1988, the shuttle successfully returned to flight and NASA flew 87 successful missions before tragedy struck again on Feb. 1, 2003, with the loss of the orbiter Columbia and its seven astronauts during re-entry. Three shuttle orbiters remain in NASA's fleet: Atlantis, Discovery and Endeavour. NASA's plan is to fly out the remaining shuttle missions through 2010 for the purposes of International Space Station assembly and servicing of the Hubble Space Telescope.

The space station era, intimately related to the shuttle era, was the result of another presidential decision, announced in Ronald Reagan's State of the Union address in January 1984. The mature accomplishments of this largest human made object ever to orbit the Earth remain to be seen, but one achievement not to be underestimated was international cooperation. Originally dubbed Freedom, over the years it became the International Space Station, encompassing 15 partners, including the Russian Federal Space Agency, the Japan Aerospace Exploration Agency, the Canadian Space Agency and the member nations of the European Space Agency. The first elements of the space station were launched in 1998, and permanent habitation began when the Expedition 1 crew arrived on Nov. 2, 2000. With this milestone, civilization had reached a point beyond which there would likely always be humans living and working in space. The facility orbits Earth nearly 16 times every day, at an inclination of 51 degrees. A total of 10 main pressurized modules are currently scheduled to be part of the ISS by its completion date in 2010. Fully assembled, the ISS will be composed of about 925,000 pounds of hardware – five times the size of Skylab – brought to orbit in about 40 separate launches over the course of more than a decade. With the addition of the Columbus laboratory in February 2008, the International Space Station is about 60 percent complete.

Currently, logistics for the ISS is supported by the space shuttle, and Russian Progress and Soyuz vehicles. Future logistics/resupply missions will also be provided by the European Automated Transfer Vehicle (ATV) and Japan's H-II Transfer Vehicle (HT). NASA's Orion crew exploration vehicle (CEV) and commercial systems supplied to the space agency in a unique procurement called Commercial Orbital Transportation Services Demonstration (COTS) for space station crew and cargo transportation services also will support ISS logistics in the future.

Consistent with NASA's current agenda for space exploration, the ISS will serve as an engineering test bed for flight systems and operations critical to NASA's exploration mission. U.S. research on the ISS will concentrate on the long-term effects of space travel on humans and engineering development activities in support of exploration. The ISS also is used for research in the life sciences, physical sciences, and Earth observation. Quite aside from the scientific accomplishments and expertise gained from a large construction project in space, the international cooperation fostered during construction and operations was no small achievement.

The space shuttle and International Space Station were low Earth orbit projects, and many longed for the days of more distant destinations. They pointed out that after traversing a quarter million miles to the moon and back eight times from 1968-1972, in all the years afterward humans traveled no further than 386 miles from their home planet – during the Hubble Space Telescope servicing mission of STS-82 in 1997. They longed to return to the moon and go onto Mars. They were given hope when President George H.W. Bush announced his Space Exploration Initiative in 1989 on the 20th anniversary of the first moon landing. But projected costs and political realities spelled doom for this venture within two years.

History came full circle on Jan. 14, 2004, when President George W. Bush, in an address at NASA Headquarters, called for a return of humans to the moon and a long-term push for a human mission to Mars. The shuttle would be phased out by 2010 and all space station work would concentrate on human factors necessary for trips to the moon and Mars. A new era in human spaceflight had begun. NASA's new space exploration plans seek to return humans to the moon by 2020, and eventually take them to Mars. For the first time since the Apollo era, a new human-rated rocket and crewed capsule are being designed. The Ares I rocket and the Orion crew exploration vehicle capsule will be joined by a reusable lunar lander and a pressurized rover for transport over the moon's surface. As part of a new global exploration strategy, the return to the moon will begin with a lunar outpost at the south pole by 2024, where sunlight for power generation is more plentiful and where volatile gases may be available for nuclear power. The outpost, planned to serve as a departure point for future human Mars missions, may also provide hydrogen and oxygen, components of fuel for those missions. One of the possible locations for the outpost is near Shackleton crater, named after Ernest Shackleton, explorer of Earth's South Pole.

Space, Earth and Life Sciences Lunar and Planetary Exploration

Over the last 50 years NASA has launched a spectacular array of robotic spacecraft with a great variety of purposes. Naturally, NASA began by targeting the closest celestial body, the moon. While the Russia Luna series probed the moon, in the 1960s NASA sent the Ranger, Lunar orbiter and Surveyor spacecraft to undertake a preliminary reconnaissance, preparing the way for humans. For two decades in the post-Apollo era NASA launched no further lunar missions, but in the 1990s Clementine and Lunar Prospector resumed analysis of the lunar surface. More spacecraft were scheduled to study the moon as the vanguard for the new human spaceflight program.

The moon, only a quarter of a million miles away, was the equivalent of our backyard compared to the much more distant planets. Venus, dubbed Earth's sister planet, was visited first by a series of Mariner spacecraft in the 1960s, and then by the Pioneer-Venus and Magellan missions. The Russians even succeeded in landing descent modules from the Venera spacecraft on Venus and returning data. It became clear during the course of the Space Age that Venus was about as far from Earth's sister planet as could be imagined. In the true spirit of exploration, what was once thought to be a lush planet ripe for life was instead revealed to be an alien environment, with an atmosphere composed of 95 percent carbon dioxide and crushing pressures of 75 to 100 Earth atmospheres, causing a greenhouse-induced temperature of 900 degrees Fahrenheit. To top it off, the Venusian clouds were found to be composed of sulfuric acid. In the early 1970s the other inner planet, the rocky planet Mercury, was studied by Mariner 10, revealing a cratered moon-like surface, a tenuous helium atmosphere, temperature swings between plus and minus 300 degrees Fahrenheit, and a magnetic field.

Looking outward from the sun, space scientists found one of their most alluring targets: the legendary planet Mars. Once thought to be criss-crossed by canals built by a race of Martians, Mariner 4 in 1964 revealed a cratered Martian surface reminiscent of the moon, causing some to lose interest in what seemed to be a dead and uninteresting world. But by 1971, Mariner 9 showed a much more complex surface, including what appeared to be dry river beds. Water was a necessary ingredient for life, and this raised speculation about past life on Mars. In 1976, during America's bicentennial year, two Viking spacecraft – in a difficult feat not to be repeated for two decades – landed on the surface of Mars and began a series of experiments that yielded a huge amount of information about the Red Planet. Of particular interest were the biology experiments, which produced controversial results. At least one of the Principal Investigators still believes his experiment showed indications of life, but the consensus of the other scientists was that the Martian surface harbored active chemistry rather than biology.

Two decades later, Pathfinder and its Sojurner rover provided spectacular images from the surface of the Red Planet, and the Mars Global Surveyor and Mars Odyssey returned scientific data and images from orbit, including evidence of recent water activity. The remarkably long-lived and productive Mars Exploration Rovers, Spirit and Opportunity, continued the exploration, while the European Mars Express orbited overhead. As is the case with the moon, there is no doubt that these robotic spacecraft will lead the way for human exploration of Mars – it is only a matter of when. And as with the moon, there is no question that Martian exploration can have a profound impact in a number of ways. Mars is the nearest planet, and thus the most likely candidate for human habitation. A Mars colony, probably following on the heels of a lunar colony, will raise profound technical, scientific and ethical questions.

The search for life on Mars will have even more significant implications. If life is found and it is of independent origin from Earth, Mars will have served as a test case for life in the universe. If life is found on two planets so close together, it means that life will likely arise on planets throughout the universe wherever the conditions are right.

Beyond Mars is the realm of the gas giant planets. Pioneers 10 and 11 were indeed pioneers in the sense of the first reconnaissance of the planets Jupiter and Saturn in the mid-1970s. Jupiter, Saturn, Uranus and Neptune yielded beautiful photographs and many surprises with the missions of Voyager 1 and 2. Launched in the summer of 1977, both Voyager spacecraft were designed to last five years, and both encountered Jupiter and Saturn between 1979 and 1981. After the flyby of Saturn's moon Titan, Voyager 1 took a trajectory north of Saturn's orbital plane out of the solar system, while Voyager 2 headed onward to Uranus and Neptune, courtesy of a gravity assist and a rare planetary alignment. After encountering Uranus in 1986 and Neptune in 1989, Voyager 2 took a southward trajectory out of the solar system. The last Voyager images were taken Valentine's Day, 1990, when Voyager 1 looked back from 3.7 billion miles to take a portrait of seven of the nine planets in our own solar system, including the "pale blue dot" that is Earth. The data the Voyagers returned revolutionized our knowledge of the outer planets and their intriguing panoply of satellites. Today, the Voyagers are heading toward the void of interstellar space, carrying two golden records containing greetings to whatever creatures may find it from various leaders and citizens of planet Earth. The Galileo mission orbiting Jupiter from 1995 to 2003, topped off by the arrival of the Cassini/Huygens spacecraft at Saturn in 2004, continued to revolutionize our knowledge of the gas giant planets, while the European Space Agency's Huygens probe landing on the surface of Titan added to our knowledge of the solar system's suite of bizarre satellites.

Amazingly, over the last two decades a variety of spacecraft have also voyaged to six comets and several asteroids. In 1986 an armada of spacecraft visited the famous Halley's comet, including two Russian spacecraft (Vega 1 and 2), two Japanese spacecraft (Sagigake and Suisei), and the European Space Agency's Giotto. In 1999 NASA launched a comet sample return mission known as Stardust. In January 2004 the spacecraft flew within 149 miles of the nucleus of comet Wild 2, collected samples of comet dust, and stored them in a return capsule. After a roundtrip journey of some 2.88 billion miles, the capsule returned to Earth with its precious sample on Jan. 15, 2006. Deep Impact, another NASA Discovery mission, brought yet another approach to comet exploration – impacting a comet and studying the subsequent debris for clues to the origin of the solar system. After a journey of 171 days and 268 million miles, on July 3, 2005, the Deep Impact flyby spacecraft released it 820-pound impactor on a course for Comet Tempel 1. The following day it impacted the comet's 14-kilometer-long nucleus at 23,000 miles per hour, producing a spectacular flash of light and a crater of undetermined depth. Analysis of the ejection plume showed large amounts of organic material, confirming that during its history, Earth might have been infused with organics from similar comets. In addition, images from three cameras showed what appear to be impact craters, never before seen on a comet and of unknown origin. Other data indicates that the nucleus is extremely porous, a fluffy structure weaker than powdered snow.

Solar Science

The sun, our nearest star, a mere 8 light-minutes away, compared to 4.5 light-years for the next star, the Alpha Centauri system. A nuclear furnace generating prodigious amounts of energy, the sun provides the conditions necessary for life on Earth. It is a matter of practical importance that we know how the sun works, as well as a matter of theoretical importance, since its proximity gives us the best information on how other sun-like stars work.

After early observations from sounding rockets, the study of the sun from space began, naturally enough, from Earth orbit. The Orbiting Solar Observatory (OSO) was a series of eight orbiting observatories that NASA launched between 1962 and 1971. Seven of them were successful, and studied the sun at ultraviolet and X-ray wavelengths. The OSO spacecraft photographed the million-degree solar corona, made X-ray observations of a solar flare, and enhanced our understanding of the sun's atmosphere among its many other achievements.

The Apollo Telescope Mount, though inelegantly named, was an innovative program for astronauts to observe the sun from Skylab, the orbiting space station that made use of hardware in the aftermath of the Apollo program. It was the most important scientific instrument aboard Skylab, which operated for eight months beginning in May 1973. Unhampered by the limits of telemetry, the astronauts brought solar photographs back to Earth, including X-ray observations of solar flares, coronal holes, and the corona itself.

Attempts to observe the sun beyond Earth orbit are more recent. Ulysses, known before launch as the International Solar Polar Mission, was deployed in October 1990 from the space shuttle Discovery. It was a joint mission of NASA and the European Space Agency designed to gain a new perspective of the sun by viewing its polar regions. Making use of a gravity assist from Jupiter, Ulysses passed the sun's south pole in 1994 and its north pole a year later. It repeated these passes in 2000 and 2001, and did so again in 2006 and 2007. With the first pass of Ulysses, scientists discovered unknown complexities of the sun and its surroundings, including different speeds of the solar wind. Ulysses – named after Homer's Greek adventurer – did not carry imaging instruments, and focused on the sun's environment rather than its surface. Fifteen years after launch, the spacecraft remains in good health.

SOHO, also a joint American-European project, is another epic solar voyage still under way. Launched Dec. 2, 1995, its array of instruments were designed to study the solar wind, as well as the sun's outer layers and interior structure. In order to do this, it was placed in an orbit 1.5 million kilometers from Earth, at a point known as the L1 Lagrangian point, where the combined gravity of Earth and sun keep it in an orbit locked to the Earth-sun line. Though still far from the sun, this location, about four times the distance of the moon in the direction of the sun, is ideal for long-term uninterrupted observations with Earth out of the way.

SOHO's scientific findings have been phenomenal. It has imaged the structure of sunspots below the surface, measured the acceleration of the wind from the sun (streams of protons and electrons traveling at 1 million miles per hour!), discovered coronal waves and solar tornadoes, and found more than 1,000 comets. Moreover, it has revolutionized our ability to forecast space weather, and provided data on the variability of the sun's energy, both of which affect us directly on Earth. Both still images and movies showing the dynamic sun's prominences, flares, spots, coronal mass ejections, and otherwise lively gyrations fill the SOHO Web site at http://sohowww.nascom.nasa.gov.

Designed for a nominal mission of two years, it has now passed the 10-year mark. With its nine European and three American principal investigators, SOHO is also another example of international cooperation in space. It was built by companies in 14 European countries, and is operated from Goddard Space Flight Center.

Earth Science

We now take for granted photographs of weather and Earth resources data from space, as well as navigation and worldwide communications made possible by satellite. Along with human and robotic missions, the late 20th century will be remembered collectively as the time when humans not only saw Earth as a fragile planet against the backdrop of space, but also utilized near-Earth space to study the planet's resources, to provide essential information about weather, and to provide means for navigation that was both life-saving and had enormous economic implications. Worldwide satellite communications brought the world closer together, a factor difficult to estimate from a cost-benefit analysis. Under the guiding principle that NASA was a research and development organization, rather than one that undertook routine observations, in its early years NASA spun off some of its Earth applications programs to other agencies or to the private sector. Between 1962 and 1965 the semi-private Communications Satellite Corporation (COMSAT) and the International Satellite Communications Consortium (INTELSAT) were formed. The first weather satellite, the Television Infrared Operational Satellite (TIROS), originated in the Department of Defense and was taken over by NASA when it was formed in 1958. NASA also began development of the next-generation NIMBUS weather satellite, but once it became operational the function was turned over to the Department of Commerce's Weather Bureau. In 1972, NASA's Earth resource satellite program began with the launch of Landsat 1, the first of a series that continued with Landsat 7, launched in 1999. The Earth resources satellites have also been subject to controversy over control and commercial viability, having been run by the National Oceanic and Atmospheric Administraation (NOAA) and the private sector during their history. Landsat is now managed by NASA but the data is collected and distributed by the U.S. Geological Survey.

The first two decades of the Space Age were used to determine the capabilities of Earth-observing satellites. Satellites for specific purposes, such as TIROS for weather, were largely piecemeal efforts. Only in the 1980s were steps taken toward a more comprehensive plan for studying the entire Earth system on a global scale. Following a number of studies, in 1987 the "Ride Report" on Leadership and America's Future in Space recommended that NASA adopt a Mission to Planet Earth as one of its four overriding themes. The centerpiece of Mission to Planet Earth was to be the Earth Observing System. Originally envisioned as a $17 billion program over 10 years, it was scaled back to $11 billion and then $8 billion in 1992. After much rescoping and reshaping of the program, in 1999 Terra, the first of three flagship polar-orbiting spacecraft was launched. It was followed by Aqua in 2002 and Aura in 2004. As a result of cooperation between NOAA, NASA, and the U.S. Air Force, a National Polar-Orbiting Environmental Satellite System (NPOESS) is now under long-term development. Despite being subjected to the politics of climate change and global warming, these satellites and others are making, and will continue to make, significant contributions to Earth science.

Space Astronomy and Astrophysics

In addition to spectacular images and data from Earth, sun and planets, space exploration has proven useful for observations well beyond the solar system. From their vantage point above Earth's atmosphere, satellites could peer at the heavens at wavelengths not visible from Earth. From 1972-1981 the Orbiting Astronomical Observatory (OAO), also known as Copernicus, observed many objects at ultraviolet and X-ray wavelengths. In the late 1970s and early 1980s, the High Energy Astronomy Observatories (HEAOs) observed the sky in both gamma ray and X-ray. And in 1983, the Infrared Astronomical Satellite (IRAS), a joint project of the United States, the Netherlands and the United Kingdom, performed the first infrared survey of the entire sky.

Arguably more than any other single program, NASA's Great Observatories revealed the mysteries of the universe at many wavelengths – the Hubble Space Telescope (1990- ), the Compton Gamma Ray Observatory (1991-2000), the Chandra X-ray Telescope (1999- ), and the Spitzer Infrared Telescope (2004- ). In its storied history, the Hubble Space Telescope has observed objects within the solar system a few light-hours away to galaxies billions of light-years distant, including those revealed in the Hubble Deep Field. It has discovered circumstellar material and extrasolar planets, confirmed the widespread existence and nature of black holes, and refined the age of the universe. Because it observed in visible wavelengths, the Hubble Space Telescope also inspired the public with some of the most memorable images of the cosmos, including the towering Eagle Nebula, the fantastic forms of planetary nebulae, and a variety of galaxy shapes.

NASA has not only undertaken voyages in space, but also in time. Thanks to the finite speed of light, NASA has even succeeded in making several voyages to the beginning of time. In 1989, it launched the Cosmic Background Explorer (COBE), and within hours detected the primordial seeds of galaxies and clusters of galaxies – small variations in the temperature of the cosmic background radiation first detected in 1964 – the blueprint from which our universe formed. In 2006, the Nobel Prize for physics was jointly awarded to NASA Goddard Space Flight Center senior project scientist Dr. John C. Mather, and to University of California at Berkeley scientist Dr. George Smoot for their contributions to the COBE project. In 2001 the Wilkinson Microwave Anisotropy Probe (WMAP) was launched, and its high resolution observations confirmed and extended the results of COBE. The satellite also provided more evidence of the rapid "inflation" of the universe at its beginning, verifying and refining the leading theory of the origin of the universe. And it pinned down the age of the universe, within 100,000 years, to 13.7 billion years. It yielded information on the dark matter content of the universe. And it provided unprecedented detail on the origin of the universe and the evolution of the first stars and galaxies.

Collectively, NASA astronomy and astrophysics spacecraft, from the early probes of the 1970s and 1980s to the Great Observatories of the 1990s and the 21st century, yielded the secrets of cosmic evolution from the big bang to the present. While the great question of extraterrestrial life – currently being addressed by NASA's Astrobiology and Origins programs – remains unanswered, we can now begin to see our planet's place in the 13.7-billion-year history of the cosmos.

Life Sciences and Astrobiology

Discussions about life sciences at NASA began within the first year of the Agency's founding. In July 1959, NASA's first administrator, T. Keith Glennan, appointed a Bioscience Advisory Committee, which reported in January 1960 that NASA should not only be involved in a traditional and obviously necessary space medicine role in support of manned spaceflight, but should also investigate the effects of extraterrestrial environments on living organisms, and undertake a search for extraterrestrial life. In the spring of 1960 NASA set up an Office of Life Sciences at headquarters and by August, with the possibility of planetary missions on the horizon, it had authorized the Jet Propulsion Laboratory (JPL) to study the type of spacecraft needed to land on Mars and search for life. In order to study chemical evolution, the conditions under which life might survive, and a variety of issues related to origins of life, NASA's first life sciences laboratory was also set up at Ames Research Center in 1960. Because it was also related to space science, during its history NASA's life science program has often fallen under the space science organization.

Also among the early life science concerns at NASA was planetary protection – both of planets on which spacecraft might land, and of our own home planet – the problem of back-contamination with returning spacecraft or samples. In the search for extraterrestrial life, contamination of another planet would be an irreversible disaster. Conversely, back contamination of our planet raised an Andromeda Strain scenario, named for a science fiction novel and movie (1971) about a fictional satellite returning to Earth carrying a deadly extraterrestrial organism. NASA has maintained a strong planetary protection program since those early days.

NASA's life sciences program also carried out a variety of successful missions in space, beginning with the Biosatellite program in 1967. The biosatellites carried frog eggs, amoeba, bacteria, planets and mice, and collected data regarding the effects of zero gravity on life. Beginning in 1975, the United States also cooperated for 20 years with the Soviet Union's Cosmos/Bion missions. Life sciences research also took place on human spaceflight missions. Europe's Spacelab, a pressurized module flown on the space shuttle, made possible several dedicated life sciences missions during the 1990s. Space life sciences research is also planned aboard the International Space Station, particularly as it applies to long-term human missions to the moon and Mars.

Meanwhile, in the area of exobiology, at its NASA Ames laboratories, the agency had continued its research on the origins of life. But by far the largest investment of time and funding was the Viking project, two spacecraft that orbited and landed on Mars in 1976. Although there were some ambiguities in the biology experiments, the consensus was that Viking did not detect life on Mars. Although no spacecraft returned to the Red Planet for two decades after Viking, the exobiology program continued to fund cutting-edge research in the life sciences.

The year 1996 saw a revival of exobiology under the name astrobiology, fueled by NASA's announcement of possible nanofossils in a Mars rock, and by the discovery of extrasolar planets. Origins of life studies also fed into the new optimism about extraterrestrial life. Scientists found life at extreme pressures and temperatures around deep-sea hydrothermal vents, fueled by energy and nutrients seeping from Earth's crust. More generally, life was found in a variety of extreme environments, including caves, inside deep rock, and in highly acidic and salty conditions. These discoveries showed that life was much more adaptable than previously thought. At the same time, the discovery of complex organics in molecular clouds in space, at the level of amino acids, gave credence to the idea that life could be ubiquitous because its building blocks were common in outer space.

Astrobiology took advantage of these new developments to considerably broaden exobiology. Astrobiology placed life in the context of its planetary history, encompassing the search for planetary systems, the study of biosignatures, and the past, present and future of life. Astrobiology science also added new techniques and concepts to exobiology's repertoire, in the attempt to answer one of humanity's oldest and most profound questions.

Aeronautics

NASA's first "A" is sometimes downplayed in the midst of its spectacular space achievements. But building on its roots in the National Advisory Committee for Aeronautics (NACA), NASA from its beginnings conducted research on aerodynamics, wind shear, flight safety, and other important topics using wind tunnels, flight testing, and computer simulations.

Wind tunnels, though not the most glamorous technology, were essential to relatively low-cost testing of aircraft performance before the aircraft were actually built.

NASA had inherited a variety of wind tunnel facilities from its NACA centers, many of them constructed during World War II at Ames, Lewis and Langley. Each wind tunnel had its own characteristics, depending on the size of the aircraft or models being tested, and whether they were being tested at subsonic, transonic and supersonic speeds. By the dawn of the Space Age, hypersonic tunnels were constructed with their own unique characteristics and capabilities. Wind tunnels were also used to test the atmospheric dynamics of the Mercury, Gemini and Apollo capsules, and eventually the space shuttle. They continue to be a vital tool for aeronautics research.

In the area of real flight testing, from its beginning NASA assumed responsibility for the X-15 hypersonic aircraft, capable of speeds exceeding Mach 6 (4,500 miles per hour) at altitudes of 67 miles, reaching the very edge of space. Between 1959 and 1968, three X-15 aircraft completed 199 flights, and contributed greatly to knowledge about hypersonic aerodynamics and structures eventually needed for spaceflight, including the space shuttle. The X-15 was air-launched by B-29s, B-50s, and eventually B-52s. Its "control room," located at the NASA (now Dryden) Flight Research Center in the California desert, advanced from a portable van to a more formal permanent room that later served as the model for the famous mission control at Johnson Space Center. Synergies between aeronautics and human spaceflight also appeared in other ways; today it is a little-known fact that Neil Armstrong began as an X-15 pilot working for NACA, and that eight other X-15 pilots flew high enough to be qualified as astronauts according to U.S. standards (50 miles). Many other astronauts were test pilots on other high-performance aircraft. NASA also cooperated with the Air Force in the 1960s on the X-20 Dyna-Soar program, which was designed to fly humans into orbit. The program was eventually cancelled, but the ideal of winged spacecraft never died.

NASA also conducted significant research on high-speed aircraft flight efficiency, maneuverability and safety, research that was often applicable to lower speed airplanes. NASA scientist Richard Whitcomb invented the "supercritical wing," specially shaped to delay and lessen the impact of shock waves on transonic military aircraft. It had a significant impact on civil aircraft design. From 1963 to 1975, NASA conducted a research program on "lifting bodies," aircraft without wings. During the 1970s, several of NASA's aeronautics centers also undertook a variety of aeronautics research using the SR-71 Blackbird in the Mach 3 range. Such research was useful for diagnostics systems on the shuttle, and also paved the way for the shuttle to glide to a safe unpowered landing.

During the 1980s NASA and the Department of Defense began the development of a hypersonic National Aerospace wPlane known as the X-30, and later worked on a hypersonic X-33 project. For a variety of reasons these never reached production. In 2004, the X-43A aircraft used innovative scramjet technology to fly at 7,000 miles per hour, almost 10 times the speed of sound, setting a world's record for air-breathing aircraft. It reached an altitude of 110,000 feet over the Pacific Ocean.

In addition to its better-known spaceflight achievements, during its first 50 years NASA thus continued in the forefront of flight, carrying on from the humble beginnings of the Wright brothers at Kitty Hawk.

Why We Explore

The vast scope of NASA's work inevitably raises questions about cost, motivation, and sustainability in a world with so many other problems. The question "should we explore?," whether the frontiers of aeronautics or the furthest reaches of outer space, must be seen in deep historical context, not in the context of passing politics or whims. The historical connections are fully recognized at NASA today. When announced in January 2004 the concept of orienting NASA's program to the human and robotic exploration of the moon, Mars and beyond was billed as "a new spirit of discovery," and the implementation plan was titled "A Journey to Inspire, Innovate and Discover." Indeed, Americans tend to place their space endeavors in the long tradition of exploration, and historians have argued the Space Age ushered in a new Age of Exploration.

The continued exploration of space is, however, a choice we must make. As historian Stephen J. Pyne has argued, "Exploration is a specific invention of specific civilizations conducted at specific historical times. It is not … a universal property of all human societies. Not all cultures have explored or even traveled widely. Some have been content to exist in xenophobic isolation." Ming China's abandonment of its massive fleets in the early 15th century is often cited, even by Chinese historians, as a poor decision that hampered Chinese civilization for centuries, and left the world open to European discovery. Historian and former librarian of Congress Daniel Boorstin called the withdrawal of the Chinese into their own borders "catastrophic … with consequences we still see today."

The question whether we should explore when there is so much that needs to be done on Earth is both an ethical and a public policy question. Quite aside from the short term benefits of applications satellites, national security, jobs and inspiration to the young, much of NASA's impact is long-term, and it is always tempting to sacrifice long-term goals for short-term needs. Today there are ample reasons one might argue not to continue space exploration. But we should recall the sentiment of H.G. Wells many years ago that "Human history becomes more and more a race between education and catastrophe." We are still in that race today, and surely space exploration expresses humanity's most noble aspirations.