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decreasing rate. The questions that fascinate present day cosmologists include: How fast is the expansion decelerating? Is this decrease uniform in space and time? What will be the fate of the universe expansion forever or an eventual

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collapse into a "primordial fireball", followed by rebirth and

eternal recycling?

Although the Space Telescope may not provide definitive answers to these great questions, it can and will gather more understanding of them than we have ever known before. It can look ten times as far into space as the most powerful ground based telescopes and it has ten times the resolution, that is, it can discriminate between objects one-tenth as far apart. Thus, we may be able, for the first time, to see and study individual stars in distant galaxies. In addition to this immense scientific return, the task of fabrication of this telescope, placing it in orbit and rendering it operational is a fit challenge to the developing capability of man to engage in those applications of space technology that will be possible only when the Space Shuttle has become a functional reality.

A second example of long-term planning for space science deals with a NASA project that has been in the public eye for the past year, the landing of the Viking spacecraft on the surface of Mars. Planning for Viking began a decade earlier and our Board was continuously involved. The purpose of these landers was to make physical, chemical and biological measurements of the Martian surface and atmosphere; perhaps greatest attention attached to three experiments intended to ascertain

whether "life" exists on Mars. A recently released Space Science Board report evaluated the data from these experiments, and recommended a future course for biological investigations of Mars. The report says, "Viking has neither confirmed nor ruled out current or past Martian life. Organic compounds have not been detected. Although all three biology experiments have yielded signals that indicate chemical activity, the interpretation of the signals remains ambiguous or inconclusive. Abiogenic explanations seem likely for at least two of the experiments and probably for the third. We believe that it is preferable to predicate future strategy on the assumption that the signals are not biological in origin."

In other words, life may or may not exist on Mars but if so, Viking did not find it. The report goes on to say that if life does exist, it will be difficult to find; the report suggests looking in more favorable places, i.e., underneath the surface and at the edges of the polar ice caps. Importantly, the report recommends that "the long term objectives of exobiology and surface chemistry are best served by the return of an unsterilized sample to earth."

What is the significance of all of this to us here on earth? Again I quote from the Board's report, "It is customary to think that life exists only on planets that provide the proper conditions for its maintenance. But the realization is growing that life itself may modify a planet's surface and atmosphere to optimize conditions for its existence, Even if it were demonstrated that life does not now exist on Mars,

the question would remain whether Earth and Mars differed sufficiently in their early histories to permit the origin of life on the former but not the latter. Or alternatively, did both planets permit the origin of life and then diverge dramatically? If so, did the type and extent of life that

evolved play a major role in that divergence?

"These questions are of fundamental scientific interest, and they may also be questions of fundamental importance to all of us on Earth. We have clearly reached the point where human activities are exerting global effects on the composition of the Earth's surface, atmosphere and perhaps its temperature.

Atmospheric pollutants may affect the ozone layer and could modify the Earth's albedo." The burning of fossil fuels has already measurably increased the carbon dioxide content of the atmosphere, and some scenarios contemplated by our Geophysics Research Board predict serious, even devastating consequences if major fractions of our energy requirements continue to be derived from these sources, a process that would be markedly accelerated by large-scale transition from hydrocarbons to coal as our principal energy source. "Clearly the stability of equilibria and steadystate processes on the Earth's surface and in its atmosphere to human perturbants, and the role of the Earth's biota in this stability are matters or more than arcane interest. Since the surface of Mars provides a natural global system

for comparison with Earth, it seems likely that studies of biology, if any, and of chemical evolution on our neighboring planet will shed important light on these terrestrial ques

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Let me turn to a third example of scientific inquiry in which the significance of long-term planning becomes obvious climate. We are embarked on a comprehensive effort to understand both the short-range phenomena of weather and the long-term processes more properly called climate. Observations of earth from space have already demonstrated their power as a new and powerful tool for observing, measuring and cataloging conditions that influence climate on this planet. But what measurements should be made? How often? To what precisions, and for how long? These questions will be addressed in the proposed NASA Climate Program, a program that was formulated with assistance from the National Research Council. In 1976, at the request of NASA, a Coordinating Committee for the NASA Climate Program was appointed; this committee drew upon all of the resources of the NRC, viz., more than a dozen separate committees that have been studying climate dynamics for the past decade.

One of the principal contributions of this committee was a new way of looking at climate, not as one large hopelessly complex problem, as it had sometimes been viewed before, but by dividing it up into four distinct categories of problem

areas. The first category attempts to discern what is going

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on right now what is the water content of the soil? How much snow is stored in the mountains? What is the temperature of the oceans throughout the world? The second involves the prediction of weather in invididual regions of the globe on a time scale ranging from a month to a decade. This category offers the promise of progress in the near future and the initial impetus of NASA's Climate Program will be in this area, i.e., on the understanding of the seasonal and interannual climatic variations. The third category involves study of the reasons for the change of global climate over periods longer than a decade. Historically, significant global changes have occurred over periods as short as a few decades.

The last category involves an attempt to assess the significance of human activities on both regional and global climate. This goal is distinct from the others because the effects of man's activities are increasing rapidly. It is important because some trends may be essentially irreversible; contaminants introduced into the atmosphere or ocean она -a decade

during a single year may affect climate for decades or

centuries.

The data from these studies must be coordinated with the immense body of information gathered on Earth's surface by scientists of almost every nation. Taken together this is a huge logistical undertaking the success of which measured

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