Earth is a planetary jewel. Abundantly watered, teeming with life, it is unique in the solar system. Yet it is no anomaly. It has a scientifically logical place in the sun's family of planets.
But throughout their evolution, human beings have lived too close to home to fully appreciate Earth's planetary role. It has taken the Olympian view of a weather satellite, the homeward glance of a moon explorer, or the first geological survey of Mars to give us a more cosmic perspective.
This new dimension that spaceflight brings to human experience may be the most important dividend of the first quarter-century of the US National Aeronautics and Space Administration (NASA).
We tend to take NASA for granted now. Yet when President Eisenhower signed the National Aeronautics and Space Act on July 29, 1958, an organization unique among US federal agencies was born.
It was charged with developing space technology, expanding scientific knowledge of the solar system and the universe, aiding national defense, and fostering international cooperation in peaceful space ventures. Alone among federal agencies, it also was required by law to ''provide for the widest practicable and appropriate dissemination of information concerning (its) activities and the results thereof.''
In other words, all humanity was to share the benefits of the new perspective.
It is a mandate that has brought the benefits of orbital weather observations and satellite communications around the world. It enables other nations to use US satellites to map their own resources. It has allowed scientists from many lands to join in space research. It has made the fruits of that research widely available to everyone through an open public relations program and NASA's own books, films, and pamphlets. It even helps schoolchildren share the adventure of space science by flying their experiments on the shuttle.
This is a unique achievement in a contentious world. Indeed, the US space program might well have turned out to be much more restrictive.
Ironically, it took the action of the Soviet Union to produce the NASA marvel. Sputnik catches the US napping The agency was born of the turmoil that followed the surprise appearance of the first Soviet satellite, Sputnik 1, Oct. 4, 1957. The United States was caught napping, although it did not seriously lag behind the Soviets in space capability.
The US had a vigorous rocketry program. This was being used to develop military missiles and, to a much lesser extent, to explore Earth's upper atmosphere. The country also was preparing to launch its own scientific satellite in Project Vanguard. This was a contribution to the program of the International Geophysical Year, as was Sputnik 1. Indeed, the United States could have beaten the Soviets into orbit had Wernher von Braun's Army missile team been allowed to do so. (It was restrained in favor of the Vanguard effort.) The von Braun team underscored this point by orbiting the first US satellite - Explorer 1 - on Jan. 31, 1958, after the first Vanguard rocket had exploded on the pad.
Nevertheless, as pointed out by the late Homer Newell, former associate administrator of NASA and a NASA historian, ''Had it not been for the shock generated by Sputnik, the American space program would probably have evolved into one largely devoted to military objectives - with space science as an adjunct.''
In his history of US space science (''Beyond the Atmosphere'': NASA publication SP; 4211), Dr. Newell explains that, after Sputnik, ''a strong quick response was deemed essential. . . . The United States was competitive in space even as the country deplored its loss of leadership. Leadership was the key word. To be competitive was not enough.''
The issue was who would build that leadership. The Department of Defense (DOD) was ready and willing. But US scientists, especially, wanted a civilian agency free of the entanglements of military secrecy.
On Jan. 4, 1958, the American Rocket Society and the Rocket and Satellite Research Panel, an unofficial organization of scientists, published a paper calling for a civilian National Space Establishment. The two groups had been urging this for several months. On March 5, a presidential commission on governmental organization, the Bureau of the Budget, and the new office of presidential science adviser sent Mr. Eisenhower a joint memo recommending a civilian agency built around the old National Advisory Committee for Aeronautics. This resonated with Eisenhower's own desire for civilian control.
One of the Army's greatest generals, Eisenhower nevertheless was deeply suspicious of what he called the military-industrial complex. He was determined it would not co-opt the nascent space program. Accordingly, on April 2, Eisenhower sent Congress a message requesting an agency along the lines of the memo. His message stressed that ''a civilian setting for the administration of the space function would emphasize the concern of our nation that outer space be devoted to peaceful and scientific purposes.'' NASA opens for business
The proposal became law July 29. NASA opened for business Oct. 1. Within a week, it had launched Project Mercury - the start of the US manned space program. Then it settled down to what would prove to be an enduring squabble - deciding what to do in space.
NASA was born with built-in tensions.
If it is to aid national defense and yet be civilian and open, how does it divide up the work with the DOD? And what of the issue of secrecy? Some of the information NASA would disseminate so freely under its mandate would always be considered ''sensitive'' by the military.
In the early days of weather satellites, some military people worried that the pictures might give too much away. There is ongoing concern about how detailed earth resource photos should be. Geodetic satellites - used for precise measurements of Earth's shape and of distances on Earth - are especially controversial. Newell notes: ''To the scientists the precise location of different points on the earth's surface relative to each other was vital for checking newly emerging theories about the movement of the earth's crust. But to the military those data would determine the position of potential military targets. . . . The conflict was fundamental.''
Such conflict remains fundamental. It will never be fully resolved. NASA has had to deal with it on a case-by-case, subject-by-subject basis, with policy evolving as needed. The issue has arisen again with use of the space shuttle.
Of larger concern is the issue of military use of space itself. The US ratified the United Nations space treaty in October 1967. Among other things, it prohibits military use of space except for reconnaissance and similarly passive purposes. President Johnson called it ''a permanent disarmament agreement for outer space.''
This sounds like an echo from the past. In 1899, four years before the Wright brothers invented the airplane, the Hague Peace Conference urged that no aircraft ever be used in combat. Reconnaissance and other passive uses would be allowed, but discharge projectiles or explosives from aircraft was prohibited. Within 15 years, World War I saw the introduction of aircraft used as fighters and bombers.
Now the US and the Soviet Union are developing killer satellites and dreaming of laser battle stations. The issue of military use of space is far from settled.
NASA also faced dissension within the US scientific community. Should the space program emphasize big, bold projects or proceed with smaller, more numerous efforts? There was continuing opposition to the Apollo moon program by those who claimed it drained funds from space science. Research, they said, was better carried out with unmanned probes. The same debate hangs over the shuttle today. Here again is an issue that will never be finally resolved.
But as the young agency struggled to get its act together, it made one crucial decision. Rocket designers were accustomed to initial failures with new vehicles. NASA management opted for initial success. This set the tone for the entire program.
Experienced experts said it couldn't be done. Even von Braun's rocket ''stars'' were outraged at what they considered an impossible task. But von Braun himself backed the concept.
NASA top management began insisting on ''zero defects'' in manufacture. They instituted detailed planning and supervision for every phase of a project. Newell explains: ''NASA could not afford to regard failure as acceptable under any guise. Success had to be sought on the first try. . . .''
The policy paid off. Launch rocket performance went from very poor during NASA's first two years to better than 90 percent success a decade later. Von Braun's powerful Saturn moon rockets worked the first time. The probability of a space mission's success came to be considered very high. The Pioneer 11 space probe, for example, still functions even though it has left the solar system. And Voyager 2 is on its way to Uranus after making spectacular surveys of Jupiter and Saturn.
Having acquired a philosophy of success, NASA rose to President Kennedy's challenge to put a man on the moon by 1970. It developed the weather satellites, which send the cloud pictures seen on the nightly TV news. It pioneered communications satellite technology and the first earth resource survey satellites. Its planetary program was turning what had once been distant lights in the sky into places to be visited by robot spacecraft and known in intimate detail. Urged to 'swashbuckle'
It was only natural, as the 1970s opened, for US space planners to dream larger dreams. NASA administrator Thomas O. Paine urged his people to ''swashbuckle.'' He spoke of lunar bases and called a large space station ''the next logical step.'' Von Braun, brought to NASA headquarters by Dr. Paine, pushed for a Mars landing by 1990. Vice-President Spiro T. Agnew, as chairman of President Nixon's Space Task Group, also championed manned planetary expeditions.
But it was not to be. In general, the Nixon administration wanted a more restrained and ''balanced'' space program. Development of the space shuttle was approved. But NASA was put on a ''level'' budget. After Skylab and the US-Soviet joint spaceflight in the early 1970s, the Apollo system, built at such great expense, was phased out. It was considered too costly to be adapted for further use. NASA had been put on hold.
The 1970s did bring major unmanned expeditions to the planets, including the landing of Viking spacecraft on Mars. But these fulfilled earlier plans. The decade ended with a sense of frustration on the part of planetary scientists.
Now one wonders if NASA may be ripe for a renaissance. The shuttle is operating. The Reagan administration is building a new planetary program - one that emphasizes simpler, less costly missions and spacecraft. And, as President Reagan himself has said, the shuttle has ''raised our expectations once more. It started us dreaming again.''
Soviet progress toward a permanently manned space station may be an added spur. Certainly NASA's current administrator, James M. Beggs, thinks it's time for a US space station. Saying he expects White House approval in six to 12 months, he recently told Congress, ''If the United States does not take this step, we will lose our preeminence in space.''
Presidential science adviser George A. Keyworth II says he thinks ''the country would take a major thrust in space very seriously.'' Noting that a space station ''is only an intermediate step in a more ambitious long-range goal of exploring the solar system,'' he asks space planners to ''lay those ideas out.''
Who knows? By the time NASA celebrates its 50th anniversary, we may consider moon bases and Mars outposts as mundane as weather satellites, manned spaceships , and other such old-fashioned things, which seemed so hopelessly romantic before NASA was born.