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Lindheimer Observatory: Dedicatory Address

The Call of Space

Fred L. Whipple
Professor of Astronomy, Harvard University
Director, Smithsonian Astrophysical Observatory

The Lindheimer Astronomical Research Center, located at the northeastern tip of the new James Roscoe Miller Campus, commands an unparalleled view of the northern and eastern sky. The first phase of the Center, dedicated May 4, was made possible by funds provided by members of the family of the late Chicago philanthropist, Benjamin F. Lindheimer, and a grant from the National Science Foundation. The twin 70-foot towers of the Center contain 40-inch and 16-inch reflecting telescopes-the former financed primarily by a gift from the A. Montgomery Ward Founoation; the latter financed primarily by a gift from the Hans D. lsenberg Foundation, a grant from the National Science Foundation, and University funds.

To revisit old friends is one of the greatest pleasures of life, and to share with them the culmination of a successful project fills one's cup to overflowing. Thus, I am elated by this invitation of Northwestern University to help dedicate the Lindheimer Astronomical Research Center. Knowing from personal experience the extraordinary effort and persistence required to bring about such an accomplishment, I sincerely congratulate my old friend, Professor J. Allen Hynek, and his many associates who have worked to this end.

Naturally, I congratulate the donor, Mrs. Benjamin F. Lindheimer and her family, who have had the vision to support this space- and future-oriented enterprise. I particularly note that today, when scientists rely so greatly upon the federal government for the support of their research, we find here that a highly successful practice of the free enterprise system has, with imagination and with the cooperation of the U.S. National Science Foundation, led to this beautiful house for the increase of astronomical knowledge and understanding. The fine instruments housed here, I gather, are also contributions from individuals and foundations.

My subject, "The Call of Space," means even more to me than the current widespread interest in the conquest or the exploration of space by man and his vehicles, remarkable as are these manifestations of human ingenuity and skill. To me, it is the call of space that has insistently motivated all astronomers throughout all ages to observe and to attempt to explain the great unknowns of the universe about and beyond us. The call of space is part of the motivating force that has led man beyond a purely animal existence to great artistic and intellectual expression.

It is also a call in time as well as in space, for the finite speed of light carries us back to antiquity in our study of distant objects in the sky. With the naked eye we can see back two million years in time, to the great spiral galaxy in Andromeda. It may actually be true that, on a clear day, we can see forever into the past. . . .

Astronomy recognizes no boundaries in time, nor in space, nor among the peoples and cultures of the world. It is scientifically international and interdisciplinary. Thus, this new scientific complex is not called the Lindheimer Observatory, but the Lindheimer Astronomical Research Center-suggesting its devotion to the utilization of all possible techniques in the search for knowledge about our great physical universe. . . .

The space program represents to me the most profound expression in all time of man's vital desire to master his environment, not to remain trapped by unnecessary natural fetters. It appears to be the next-to-last physical frontier to be explored-the last being the deep earth, unless, by some amazing chance, we should discover a new explorable dimension in space-time.

Our great national space program, executed by the vital and dynamic National Aeronautics and Space Administration, is best known for its remarkable feats of carrying man into space and making it possible for him to survive and operate in that hostile environment. The equally remarkable scientific results from the program have thus been overshadowed because of the well-justified popular interest in man's space exploits, involving the expectation that he will soon set foot on the moon and actually explore our companion planet in space. Hence, I shall mention a few of the scientific results from the space program.

Our whole scientific attitude toward the moon as a planet has been changed because of the revealing close-up photographs and the landings obtained by the Russian probes, and by the U.S. Ranger, Orbiter, and Surveyor vehicles. This new evidence indicates strongly that the moon is an active "geological" body rather than a dead fossil, but its magnetic field is negligible, indicating no significant internal currents. How active the moon may be can only be determined from a full battery of scientific instrumentation, both manned and unmanned, as we penetrate the ancient records extending back for possibly billions of years. The surface has turned out to be, as we expected, a low-density, fairly weak porous material not covered by loose dust, a material mostly thrown about as a consequence of meteoritic impact. We still are not certain whether the moon loses or gains mass by meteoritic impact.

Photographs of the moon's backside surprised us by the dearth of large maria, or so-called seas, adding another problem to our evolutionary list. The important questions now concern the moon's internal structure and temperature, its level of "geological" activity, and the resolution of major problems concerning its origin. Did the moon in some fashion originate from the earth? Or was it independently formed close to the earth, at least very much closer than it is today? Or was it, conceivably, captured? We must wait for answers to these questions, but we can wait with confidence of their solution. Without the space program, it is doubtful that we might ever be scientifically confident.

The almost unbelievable observations of Mars made by the Mariner IV make us also confident that answers to similar questions will be forthcoming about our enigmatic neighbor in space, Mars. The huge craters, evidence of heavy meteoritic impact, were no surprise to those of us who were familiar with the frequency of meteoritic bodies in space. We are somewhat disappointed, however, to find that the Martian atmosphere is less dense than anticipated, so that we are not yet certain whether a parachute-type landing will be possible through a one per cent equivalent of earth's atmosphere surrounding that small planet.

Since Mars is an order of magnitude more massive than the moon there is little doubt, by analogy, that we will find Mars to be far more active "geologically" than is the moon, but since, like the moon, it has no measurable magnetic field, it must have small internal motions. Thus, I am certain that we will make prime discoveries of extreme significance in the study of Mars, including the definite probability for the discovery of indigenous life forms. Such a discovery would have profound effects on man's outlook on life and toward himself.

A most important, and little publicized scientific result of the space program concerns the precise measurements of the continuous ejection of gas from the sun's surface-ie., the solar wind and the irregularities in this wind produced by solar flares and other highly violent activities on or near the sun's surface. Every second, the sun throws off a million tons of gas, mostly hydrogen and helium, at a velocity of some 400 kilometers per second, spreading out through space as far as we can see. This material is highly ionized, i.e., highly charged, at a very high temperature, some 100,000 degrees Fahrenheit, and carries with it magnetic fields.

We now understand how comets produce these magnificent tails which have been a mystery since man first was frightened by "hairy" stars in the sky. The solar wind with its high-temperature electrons ionizes the gases from the evaporating nucleus of a comet and produces a physical force on the ions. Because of the magnetic lines of force, like the strands of a fish net, the solar wind can selectively enmesh the charged atoms and molecules in the comet's atmosphere and carry them away from the sun to form comet tails, which in some cases have been seen 100 million miles from the nucleus of the comet. The uncharged or neutral atoms and molecules, however, slip through the net like minnows, apparently little disturbed. The fine dust, as we have long known, is pushed back by the pressure of the solar light and appears to be little affected by the solar wind.

The magnetic fields of the solar wind rotate with the sun nearly as a solid mesh, even though the particles that carry the field are moving almost radially away from the sun. The effect is like that of a rotating garden hose, from which the stream is a spiral, made of particles that move radially outward. The greatest of the interplanetary observatories, Mariner IV, after passing Mars, has sent back signals from the earth's orbit on the opposite side of the sun, 300 million kilometers distant. This happy result stems from the use of the 210-foot radio telescope dishes set up by NASA for the observation of space vehicles. Hence, we now observe the solar particle emanations sent off from the other side of the sun and how they behave in space.

We have long known that bright flares on the sun produce geomagnetic effects, northern lights, and phenomena in the earth's ionosphere, but now we can measure the actual progress of these spacial jets as they force their way through the solar wind and encounter the earth's magnetic field.

The Van Allen belts of highly charged and highly energetic ions held near the earth by its magnetic field were only a theoretical possibility before actual measurements by satellites. Now, we have direct knowledge and improving theories of the interaction of the interplanetary wind and storms with the ionized material about the earth. In fact, the earth's magnetosphere, like a ship at sea, throws up a bow wave in the solar wind and a wake hundreds of thousands of kilometers behind. Even the non-magnetic moon produces such a wake, though the bow wave is as yet unmeasured.

For Venus, the Mariner II space probe gave substantial evidence that the radio radiation and reflections are truly from the surface of the planet, rather than from a possible ionosphere. This strengthened the then strong suspicion that the surface of the planet was indeed very hot, of the order of 500 degrees Fahrenheit, and therefore an unsatisfactory abode for life. The gravitational deflection of Mariner II also contributed to our knowledge concerning the mass of Venus. There is very much still to be learned about Venus and it is to be hoped that an instrumented landing can be effected, although the high temperature may be a serious deterrent. Much more physical evidence concerning its atmosphere, the extent of this atmosphere, and the internal solid structure could be obtained from an instrumented probe in orbit about the planet.

Thus, we find that the moon, Mars, and Venus all lack strong magnetic fields like the earth's. Hence, they possess no Van Allen belts of highly energetic ions.

We have learned much about the tiny bodies in the solar system from studies of ineteorites fallen to the ground, and from meteors seen, photographed, or detected by radar reflections from their ionized trails. But the coarse and fine dust particles striking the atmosphere have eluded our ground observing devices. Their punctures of carefully devised surfaces on Explorer and Pegasus satellites, however, have completed the story. Thus, we find that a hundred tons or so of small bodies, mostly dust, strike the earth every day. On the moon, this influx redistributes a centimeter to a few centimeters of surface material in a million years. - - . If the rate has been consistent, sizeable craters have been covered up on the moon, making useless the crater counts at diameters of less than ten or more meters as measures of impact rates.

We are wallowing in ignorance concerning detailed information about comets, asteroids, other satellites than our moon, and the major planets, particularly Jupiter. The potential of the space exploration program with regard to studies of these bodies is so enormous that no discussion can be effective in our short time here. All the information obtainable, however, should shed important light on the evolution of the solar system, giving us some insight into the critical processes that brought the entire system into being some 4.7 billion years ago.

I shall not encroach on the three-day conference here at Northwestern on the subject of space spectroscopy. It deals with the exciting study of the universe by radiation to which atmospheric absorption renders us blind instrumentally as well as visually at the surface of the earth. Infrared, ultraviolet, and all radio radiations flow freely in space as do x-rays and the even more energetic gamma-rays. The sun, stars, and gaseous clouds send us crucial information in these regions of the spectra. Even though gamma-ray sources are not yet certainly observed, the x-rays have already given us exciting information about the sun, about other known objects, and about new still mysterious energy sources in space-neutron stars? The planned programs for large space instruments and telescopes, manned and unmanned, should answer some of our major questions about the universe. More important, these programs will give us many surprises and raise a host of new questions, a spur to man's future progress.

The Lindheimer Astronomical Research Center has answered the call of space. With its instrumental feet planted solidly on earth, and its instrumental arms extending in space, particularly with the possibility of astronaut Professor Henize guiding sensing devices in satellites, it has indeed sound expectations for a proud future.

Excerpts as printed in the Spring 1967 Northwestern Review.

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