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Return-path: <ota+space.mail-errors@andrew.cmu.edu> X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from corsica.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/4YreOsK00UkVI0tU5h>; Tue, 8 Aug 89 05:24:08 -0400 (EDT) Message-ID: <YYreOiS00UkVM0rk5s@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 8 Aug 89 05:23:59 -0400 (EDT) Subject: SPACE Digest V9 #591 SPACE Digest Volume 9 : Issue 591 Today's Topics: Electronic Journal of the ASA Vol. I, No. I (Part I) ---------------------------------------------------------------------- Date: 22 Jul 89 18:22:17 GMT From: eedsp!chara!don@gatech.edu (Donald J. Barry) Subject: Electronic Journal of the ASA Vol. I, No. I (Part I) THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC Volume 1, Number 1 - August 1989 ########################### TABLE OF CONTENTS ########################### * Introduction: Welcome to the EJASA - Don Barry * ASA Membership Information - Don Barry * Astronomy Week in Georgia - Don Barry * Neptune: Rediscovery by Voyager 2 - Edward F. Albin * The One Dream Man: Robert H. Goddard, Rocket Pioneer - Larry Klaes * The CHARA Multi-Telescope Telescope - Hal McAlister * A View from Taiwan: Wean-Shun Tsay - Interview by Edmund G. Dombrowski ########################## Welcome to the EJASA by Don Barry President, Astronomical Society of the Atlantic Bridging the gulf between human creative impulse and shared knowledge lies the realm of communication, spanning the first primal sounds conjured by Australopithecus millions of years ago, culminating in the elegant crypticisms of modern mathematical typography. Arguably a neglected stepchild of science and art, the medium of scientific dissemination has always lagged its parent in both theory and practice. Science and scientific enlightenment has therefore depended on whim and luck for spread. Occasionally, in catastrophic turns, such as at the extinguishment of the mighty Alexandrian Library in the Second Century A.D., culture itself has fallen with the death of the communication medium which gave it life. Where would Science be without Sir Edmund Halley, who convinced (and funded) Sir Isaac Newton's PRINCIPIA MATHEMATICA, which stands as a lighthouse at the end of the empiricism of the lesser ages? When Boltzmann, moved by Maxwell's electromagnetic theory to quote Goethe's Faust: "Who was the God who wrote these lines," perhaps he should have paid equal tribute to the established system which facilitated the printing and communication of the Equations which would prove so inspiring to him. In the spirit of these modern times, then, the Astronomical Society of the Atlantic is embarking on a new venture. At a year's age, and from modest beginnings, the Society's printed Journal has grown into a sixteen-page monthly affair, sharing the knowledge and experience of professional and amateur astronomers alike. It is time for new growth, with a bent for the future. Currently disseminated to over forty amateur organizations, who enjoy, contribute, and further spread information on amateur astronomy, the Journal is going Electronic. Although continuing in printed form, the Journal will be published monthly on USENET and other computer networks under a different editor - Larry Klaes of Boston, Massachusetts. The Electronic Journal of the Astronomical Society of the Atlantic, EJASA for short, will reproduce the most suitable articles from the printed version, and will also feature submitted articles from the pool of astronomers - amateur and professional alike - on USENET, which will sometimes make their way into the printed Journal. The two publications will be "separate but equal", will expand readership, and will hopefully encourage serious amateur and professional astronomers to begin to consider the networks as attractive alternatives for publication of authentic research efforts. Although the Journal will begin on a popular level, it is intended that it eventually include articles of serious scientific content, although accessible to the usual reader of the astronomy and space discussion forums. In this adventure, we are poised at the crux of a new form of publishing. Our form, content, and direction will be dictated by the admittedly vague progress of computer networking. We ask for your patience, constructive criticism, and support in the coming year; and not in the least, we encourage the submission of articles for possible inclusion in the EJASA. It is our intent that amateurs across the nation view the EJASA as a resource for their benefit. We encourage the excerpting or full reprinting of articles in local amateur astronomy publications, and also the submission of personal efforts, in writing or software development, so that they may be added to the publicly accessible archives of the Society. From spoken, to written, to printed, to electronically stored, the word is a powerful element for conveyance of ideas. We hope that this latest effort in the scientific community through communication will be worthy of the technology on which it is built. ARTICLE SUBMISSIONS - Please send your on-line articles on astronomy and space exploration to Larry Klaes, EJASA Editor, at the following net addresses: klaes@renoir.dec.com, or ...!decwrl!renoir.dec.com!klaes, or klaes%renoir.dec@decwrl.dec.com If you cannot send your articles to Larry, please submit them to Don Barry, ASA President, at the following net addresses: don%chara@gatech.edu, or chara!don@gatech.edu You may also use the above net addresses for EJASA backissue requests and ASA membership information. DISCLAIMER - Submissions are welcome for consideration. Articles submitted, unless otherwise stated, become the property of the Astronomical Society of the Atlantic, and although they will not be used for profit, are subject to editing, abridgment, and other changes. This Journal is (c) copyright 1989 by the Astronomical Society of the Atlantic. ASA MEMBERSHIP INFORMATION The Electronic Journal of the Astronomical Society of the Atlantic is published monthly by the Astronomical Society of the Atlantic, Inc. The ASA is a non-profit organization dedicated to the advancement of amateur and professional astronomy and space exploration, and to the social and educational needs of its members. Membership is open to all with an interest in astronomy and space exploration. Members receive the ASA Journal (hardcopy sent through U.S. Mail), the Astronomical League's REFLECTOR magazine, and may additionally purchase discount subscriptions to ASTRONOMY, DEEP SKY, and TELESCOPE MAKING magazines. For information on membership application, contact Alan Fleming, ASA Treasurer, at 2515 N.E. Expressway, Apt. N-2, Atlanta, Georgia 30345, U.S.A. ASA Officers and Council - President - Don Barry Vice President - Bill Bagnuolo Secretary - Scott Mize Treasurer - Alan Fleming Board of Advisors - Bill Hartkopf, David Dundee, Anita Kern EJASA Editor - Larry Klaes Georgia Star Party Chairman - Chris Lee Advertising Committee - Paul Pirillo, Willie Skelton Space Shuttle Trip Committee - Chris Castellaw Sales Committee - Jim Bitsko Society Librarians - Julian Crusselle, Toni Douglas Telephone the Society Info Line at (404) 264-0451 for the latest ASA News and Events. ASTRONOMY WEEK IN GEORGIA by Don Barry The Astronomical Society of the Atlantic, in collaboration with the Georgia Department of Natural Resources, and the Center for High Angular Resolution Astronomy, has rejuvenated an old tradition in Georgia: Astronomy Week. The Governor will declare the week of August 11-18 as Astronomy Week in Georgia, sponsored by the Society and the Department of Natural Resources. During this week, encompassing the Perseids and a Total Lunar Eclipse, members and other affiliates will trek across the state to parks and historic sites and bring our hobby to the public at large. For this, we need you. There are nearly twenty parks that we have initially targeted. And helping to share your favorite hobby is easier than ever. Being There The most essential part of sharing Astronomy is being there. Park Rangers will coordinate each park's activities in collaboration with the members who volunteer. Can you tell people what a meteor is? Arrange to host an afternoon question and answer session. Do you know the constellations? Arrange to point out a few at an evening stargaze. Do you own a telescope? Arrange to show the planet Saturn and the Moon to those interested. If two or more volunteer for a park, each can host activities he or she is most comfortable with. Park Rangers are often familiar with the sky's constellations, and can assist. What's To Show - Perseids Astronomy Week begins on Friday, August 11. The Perseid meteor shower, the strongest annual meteor shower, peaks on Friday and Saturday evenings, but continues at lesser intensity through the next week. More than 60 meteors an hour may be seen in the morning hours of Saturday and Sunday. The Perseid shower is believed to consist of debris left by Comet Swift-Tuttle, last seen in the Nineteenth Century. Earth passes through this debris stream once a year, producing the meteor shower. Most of the meteoroids in the stream are sand-grain size, while the larger ones may reach the size of a small pebble. These small icy rocks heat to tremendous temperature when they strike the atmosphere at high speed, forming a meteor trail. For all the fireworks, though, there is really very little debris in the meteor stream. The planet Earth, plowing through space at 48 kilometers (30 miles) per second, scours a visible window a over 160 kilometers (100 miles) on a side atop the observer, and cleaning a million cubic miles of space a second. One meteor a minute on average means that there is only a small meteoroid contained in sixty million cubic miles. That's empty! What's To Show - Saturn The Moon, initially past first quarter, will brighten the sky until the early morning hours on this first weekend, and by Monday or Tuesday will be up most of the night. Deep sky observation won't be easy, but Saturn, the most awe-inspiring planet of all, will be easily placed in the southern sky, brightly shining above the teapot of Sagittarius. In even the smallest telescopes, Saturn's rings, which are composed of material much resembling the average Perseid meteor, shine brightly around the planet. First seen by Galileo Galilei (who only saw them as "ears" on the planet due to his low-power telescope), the ring-like form was not discovered until Christian Huygens, the Dutch physicist and telescope-maker, first turned his improved instruments upon this world in the late Seventeenth Century. What's To Show - Constellations In the south will be found the easily recognizable constellations of Scorpius, the Scorpion, and Sagittarius, the Archer. The Scorpion, marked by the bright red star Antares, and a long tail complete with sharp stinger, is one of those few constellations which realistically resemble the object they depict. The Archer, immediately to the left, more immediately resembles at Teapot than a man with drawn bow. The teapot appears to be boiling, as steam emerges from the spout in the form of the Milky Way, and rises to the zenith of the sky in the early summer evening. Along this "milky" path can be seen many beautiful objects in binoculars. Fuzzy patches are star clusters of hundreds or thousands of stars. Some are clouds of gas in which new stars are being born. Some, such as the easy binocular object M22 (the M is for Messier, the astronomer who catalogued this celestial object), which is visible just above and to the right of the tip of Sagittarius' teapot, are globular clusters, consisting of a hundred thousand stars apiece. Overhead, the Summer Triangle shines in majesty, encompassing the constellations of Cygnus, the Swan; Lyra, the Lyre; Aquila, the Eagle; and the minor constellations of Sagitta, the arrow; and Delphinus, the Dolphin. The bright stars of the Triangle are Vega, the seat of the Lyre; Deneb, the tail-star of the Swan; and Altair, the heart of the Eagle. To the north, Cassiopeia, the Queen's Throne, circles Polaris, the North Star. Below and to the northeast, rising at midnight, Perseus, the slayer of the snake-haired Medusa, appears. From his body appear to emanate the fiery Perseids. Meteors and Perspective First noticed during a massive shower of meteors in 1799, each meteor of a shower appears to point backwards to a common point in the sky. They don't all start at this point, but merely appear to point backwards to this location. The explanation is best provided by analogy. In a light rain shower, as in a meteor shower, raindrops are moving together in the sky, with relatively little speed relative to one another, though they fall quite rapidly with respect to the observer. If one is in a car moving through the rain, the raindrops appear to zoom past, and if one is moving rapidly enough, they may appear nearly horizontal out the car's window. They seem to come from a point ahead of the car, straight up if the car is not moving, but closer to the forward horizon as the car accelerates. As Earth moves through space, the combination of its motion and the meteor shower's own motion means that meteors will appear as raindrops, and that they will point back, as raindrops do, to a "vanishing point", just as in perspective all parallel lines (such as railroad tracks) appear to meet at the horizon. The location of this vanishing point, or "radiant", allows one to determine the speed and direction of the meteor shower through space. The Lunar Eclipse On Wednesday evening, August 16, the ultimate event of Astronomy Week will occur. The Moon, at full phase, will pass precisely behind Earth from the Sun, and therefore be shadowed by Earth's disk. At 9:22 p.m. EDT, the Moon will enter the darkest part of Earth's shadow, the umbra. This is the part of the shadow in which all of the Sun's light is blocked. Any passing creatures on these sections of the Moon would see the Sun in total eclipse. Shortly after 10 p.m., the Moon will be entirely immersed in the umbra, and will resemble a dim, beautiful copper penny in the sky, being colored reddish orange by sunlight bent around Earth's edge by our atmosphere. Shortly before midnight, the Moon will begin to exit the umbra, and last contact will take place at 12:52 a.m. A few hours after it began, the spectacle will be over; but the fortunate public who see it in state parks, enlightened by you, our members and emissaries, will remember it for a lifetime. Where To Go? The Georgia Department of Natural Resources has identified a number of parks who are being approached, and with whom arrangements are being made. These include: Amicalola Falls, North Georgia Unicoi, North Georgia Vogel, North Georgia Cloudland Canyon, Northwest Georgia Red Top Mountain, Atlanta Vicinity Sweetwater Creek, Atlanta Vicinity Panola Mountain, Atlanta Vicinity Fort Yargo, Atlanta Vicinity Hard Labor Creek, East Georgia Elijah Clark, Augusta Vicinity Indian Springs, Macon Vicinity John Tanner, West Georgia F. D. Roosevelt, West Georgia George T. Bagby, Southwest Georgia Reed Bingham, South Georgia Little Ocmulgee, South Georgia Georgia Veterans, South Georgia Laura S. Walker, Southeast Georgia Skidaway Island, Savannah Vicinity Etowah Indian Mounds, Atlanta Vicinity Volunteer! At our next two meetings before Astronomy Week, a packet containing brochures of each of the parks above will be available for inspection and signup. Sharing the joy of Astronomy is its own reward. Reaching out to the public is our most noble activity, for it spreads our own knowledge and makes it endure. Rangers at each park will arrange complimentary camping privileges, and perhaps more for those places involving a larger commute. Details of your contribution at a park will be arranged between you and the Park Ranger. You can contribute to whatever degree you feel comfortable. We will have a brochure detailing the events of Astronomy Week, and facts on the eclipse, the Perseids, and the summer sky for your distribution at the park. Your patience, willingness to share, and enthusiasm is the only remaining ingredient to be added to make Astronomy Week a rewarding success. NEPTUNE: REDISCOVERY BY VOYAGER 2 by Edward F. Albin Since its discovery in 1846, much has been learned of the distant eighth planet from the Sun, Neptune. In a feat of human ingenuity, the discovery of this world was based only on theories about planetary orbits. Through the telescope, Neptune appears not much more than a faint disk of light, with two companion moons. But our knowledge will dramatically change when a small robotic spacecraft, named Voyager 2, skims remarkably close to the planet's cloud tops in August of this year. Upon doing so, this emissary from Earth, which departed almost 12 years ago, will rediscover a place that has until now eluded the close scrutiny of astronomers. New worlds are literally about to unfold before us as "the little spacecraft that could" makes its final planetary flyby and forever leaves the bonds of our solar system. Discovery of an Eighth Planet It wasn't long after the discovery of the seventh planet, Uranus, that astronomers began to think of the possibility of a world circling the Sun at an even greater distance. This notion of an eighth planet was well founded. For one thing, celestial mechanics, the science of where a planet should be in its orbit, was tested and well understood. But, Uranus, the newest addition to the collection of wandering worlds, didn't seem to behave properly according to the mathematical theories that described its movement about the Sun. There was a discrepancy between theory and observation, or to put it plainly, Uranus wasn't where it was supposed to be in the sky. Such observations could have meant that there was another as yet unknown world just waiting to be discovered. This riddle of Uranus' position in the sky fascinated a young Englishman. John Couch Adams, a twenty-two year old student of astronomy and mathematics at Cambridge University, vowed to solve this mystery after completing his studies. Unknown to Adams, across the English channel in France, another astronomer, Urbain Jean Joseph LeVerrier, a young assistant at the Paris Observatory, had a similar notion. LeVerrier had been given the task of tackling the Uranus "problem". After completing his degree "brilliantly", Adams set about to solve this astronomical problem. Having spent many months in research, he was convinced that the position of a new planet had revealed itself through his computations. Adams was confident that an entirely new world, almost 4.8 billion kilometers (3 billion miles) from the Sun, could be glimpsed simply by turning a telescope of sufficient power towards a point in the constellation Capricornus. Excited about this, Adams was encouraged to contact Sir George Biddell Airy, Astronomer Royal. Unfortunately, Airy wasn't impressed. Apparently, in his post he had read many absurd letters containing crackpot ideas, and so this great piece of work was discarded with the other rubbish. Unknown to Airy, had he aimed his great instruments where Adams had indicated, a new planet would have been observed only 1.25 degrees away. After badgering Airy, Adams became discouraged, knowing that a telescopic search would be delayed. Meanwhile, LeVerrier solved the riddle independently some eight months later. The position of the new planet was announced to the world in June of 1846. Airy, having learned of this development from the great Paris Observatory, was stunned to find that LeVerrier's predicted position was almost identical to that of an earlier suggestion that he had totally disregarded. Airy immediately recognized that an Englishman, John Couch Adams, had prior claim to this discovery, but his blunder might very well cost Adams his rightful credit. On September 23, 1846, Johann Galle, an astronomer with the Berlin Observatory, had received a letter from LeVerrier. Galle had been asked to direct his telescope to the predicted location of the suspected planet. On that very evening, Galle, joined by a young assistant, Heinrich d'Arrest, saw for the first time a world that would later be known as Neptune. Only an hour into the search, discovery was made. The new planet was an intruder in the surrounding star field, and it showed a disk, quite unlike the tiny pinpoints of light that were recognized as stars. It was 143 years ago that the existence of an eighth planet from the Sun became known. Fortunately, both Adams and LeVerrier received equal credit for the discovery. First seen through the mind's eye, and then with the telescope, Neptune awaits rediscovery by a robotic spacecraft in August of 1989. The excitement that must have been generated by the addition of a new world to our solar system will be rejuvenated as Voyager 2 zooms by for a close look. The Planet Taking almost 165 years to revolve around the Sun, Neptune won't complete one revolution since its discovery until 2011. Although it appears nothing more than a tiny green disk through the finest telescopes, astronomers have learned much about this distant place. We know that Neptune is a big planet, about 48,000 kilometers (30,000 miles) in diameter, and we know that it spins on its axis once every 17 hours, 50 minutes. Neptune's green color is due to methane gas present in the atmosphere. However, like the other gas giants (Jupiter, Saturn, and Uranus), hydrogen and helium are the most abundant gases found. Below the beautiful green-tinted atmosphere lies a vast ocean of liquid hydrogen. Such a sea of gas is possible only because of the tremendous weight and therefore pressure caused by the overlying gasses. Probing still deeper into Neptune brings us to a layer of ice; that is, ice composed of a mixture of methane, ammonia, and water. Speculation suggests that at the center of this world there is a rocky core some 16,000 kilometers (10,000 miles) across. Almost as fascinating as the planet itself are its two moons, Triton and Nereid. They orbit Neptune at 352,000 and 5,440,000 kilometers (220,000 and 3.4 million miles), respectively. Triton exhibits synchronous rotation (shows the same face to the planet at all times) as is common of many moons in the solar system, but Triton is very unusual in that it orbits the planet in a retrograde (backwards to the usual direction, counterclockwise) direction. Discovered only one month after the planet itself, Triton is a natural satellite about the same size as our moon. This moon has attracted much attention because of many bizarre characteristics, including its composition which is very different from that of a typical outer planet moon. Instead of being composed chiefly of ice, Triton, for some reason, is mostly made up of rocky materials. Astronomers would expect to find such a satellite in the inner parts of the solar system. Evidence also suggests that an atmosphere and ocean might also be present. Two compounds, methane and nitrogen, have been detected in the moon's surface. It is not certain if the methane is in a frozen of gaseous state, but one theory holds that at the temperatures encountered at Neptune's distance from the Sun, it is reasonable to expect to find an atmosphere composed of methane. Nitrogen is also present, and at the frigid temperatures expected this gas would also be found only in the liquid form. In other words, there must be oceans of nitrogen covering portions of the surface of Triton. These gasses, when frozen, appear colorless, but through the eyepiece of a telescope, Triton has a distinct red color. Organic molecules, formed when ultraviolet light interacts with mixtures of methane, ammonia, and water, might best explain the reddish color. Not much is known about Neptune's other moon, Nereid. It revolves in the proper direction but has a very eccentric orbit, more so than any other moon in the solar system. Due to its small size, less than 560 kilometers (350 miles) across, little has been learned about its surface properties. It seems that Neptune does have a ring of sorts, just as all the other gas giants do. This ring, like many things about this world, is unusual. The ring appears to be segmented or just a partial ring, orbiting some 72,000 kilometers (45,000 miles) above the cloud tops. Over the past 140 years, much has been learned about this distant planet. However, the rediscovery of Neptune awaits us with the flyby of Voyager 2. The Spacecraft Voyager 2 began its "grand tour" of the outer solar system some twelve years ago. The odyssey started from Cape Canaveral, Florida, on August 20, 1977. On that day a Titan/Centaur rocket lifted Voyager 2 into low Earth orbit, and then, within one hour from launch, it boosted the spacecraft on its way to Jupiter at a speed of more than 9.6 kilometers (6 miles) per second. Having a mass of 810 kilograms (1,800 pounds), Voyager 2 is one of the most sophisticated spacecraft ever sent to explore other worlds. A large radio antenna always tracks Earth as the spacecraft travels towards the outer reaches of the solar system. Although the spacecraft is transmitting data with a mere 23 watts of power (equivalent to the power of a refrigerator light bulb), NASA's tracking system, known as the Deep Space Network, can follow it even at distances greater than Neptune. Computers onboard Voyager 2 are capable of receiving prerecorded sets of instructions that allow the spacecraft to operate for days or weeks autonomously. All systems are powered by three radioisotope thermoelectric generators which provide about 400 watts of electrical power. Voyager 2 carries an impressive battery of scientific instruments capable of investigating its surroundings directly or remotely. Direct sensing instruments "feel" magnetic fields and associated charged particles. Remote sensing instruments can be thought of as the "eyes" of the spacecraft. They are used to detect electromagnetic radiation (light) being emitted or reflected by the planet, moon, or ring currently under study; but most of all, remote sensing instruments provide us with the wonderful pictures often obtained from planetary explorer missions. Along with its cousin, Voyager 1 (which will not fly by Neptune), Voyager 2 has shown us the outer planets as never seen before. In July of 1979, Voyager 2 made its closest approach to the largest planet in the solar system, Jupiter. Together, the Voyagers discovered the rings of Jupiter, found three new satellites, and returned spectacular photographs of the four Galilean moons. Two years later, in August of 1981, Voyager 2 passed the beautifully ringed planet, Saturn. Again, many remarkable discoveries were made. This time seven new moons were found, and the rings were resolved into many thousands of individual bands. Saturn was the last planetary encounter for Voyager 1, but the second explorer continued on to the seventh planet, Uranus, where a spectacular flyby occurred in January of 1986. Ten new moons were discovered, and new information and images were returned showing the planet, its rings, and moons in fascinating detail. After three incredibly successful encounters, showing that the outer planets are more than blurry smudges of light, Voyager 2 on its mission of discovery pushes onward toward Neptune. With the actual flyby still several months ahead, the onboard instruments have already turned their eyes in the direction of this green jewel, watching and patiently waiting as it grows larger and brighter with each passing day. The Encounter Three and a half years since departing Uranus, Voyager 2 has endured, once again, the immense lonely distances separating the planets. Designed to explore Jupiter and Saturn only, Voyager 2 has long outlasted its "warranty". In the latter part of August 1989, the tiny spacecraft will make a daring pass over the cloud tops of Neptune. The approach on this last planetary encounter will place Voyager 2 some 16 times closer than its flyby of Uranus, 20 times closer than at Saturn, and an incredible 55 times closer than the encounters with Jupiter. This veteran of three spectacular planetary missions is approaching Neptune on a trajectory that has been dubbed the "polar crown". What this means is that Voyager 2 will first encounter the planet from the south, swinging past the equatorial region, and then make its closest approach, only a few thousand kilometers above the cloud tops, over the north pole. The mission does not stop there. Several hours later, the spacecraft passes Triton's mysterious surface by only 40,000 kilometers (25,000 miles). However, the tiny moon Nereid will only be viewed from over 4.8 million kilometers (3 million miles) away. Making such a close pass by Neptune does have its dangers, however. Not knowing the exact extent of the atmosphere may cause some problems. If the outer atmosphere reaches further into space than currently calculated, drag on the spacecraft may affect its trajectory as well as cause some damage, for Voyager was not designed to function under such conditions. The difficulty of detecting the dimensions and extent of Neptune's rings might also prove lethal. Even small particles of dust and ice have the potential of destroying a planetary vehicle traveling at such great speeds; but, the greatest fear is of the possibility of flying through intense radiation belts. It is not understood if the planet has such trapped radiation since magnetic fields and auroras haven't been observed thus far. If Neptune has dangerous levels of trapped radiation, it is hoped that they will be detected at least a few days before the encounter as was the case for the Uranus flyby. Since Neptune will virtually be rediscovered in the late summer of 1989, one wonders what Adams and LeVerrier might have thought about Voyager 2 and its mission. Astonishingly, many millions of people across the world will simultaneously see images returned over almost 4.8 billion kilometers (3 billion miles) of space, showing us new worlds in breathtaking detail. What do scientists expect to find in these images? For one thing, we'll know what Neptune looks like. Details of its clouds and unknowns about its two satellites will be gathered. No longer will this planet be just a tiny smudge of light in the eyepiece of a telescope, but a place with characteristics that make it unique among the worlds found within our solar system. Many factors (e.g., composition of gasses, temperature, chemical processes, wind speed, etc.) are at work controlling the appearance of Neptune, and it is expected that it is going to look different from the other gas giants observed thus far. The questions surrounding the nature of Triton's possible atmosphere and ocean may also be resolved. Chances are promising that many new moons will be discovered. Upon completion of its duties at Neptune, Voyager 2 will have, once again, given us much data and photographs to add to the growing library of information on planetary objects. This catalog, by the way, contains pictures that cover most of the planets - from Mercury to Uranus; but what about Pluto? Can Voyager 2 complete our catalog, and what about its fate upon leaving the solar system? Unfortunately, a flyby of Pluto is impossible. Pluto's position in its journey about the Sun is such that there is no practical way to swing Voyager 2 by for a close look; but, as is the case for its predecessors, Pioneers 10 and 11 and Voyager 1, it will continue to function while departing the solar system. Traveling at 59,200 kilometers (37,000 miles) per hour and traversing 528 million kilometers (330 million miles) each year, Voyager 2 is expected to continue transmitting data until the year 2015. Afterwards, the vehicle will forever leave the vicinity of the Sun and drift among the stars of the Milky Way Galaxy. Calculations show that some 40,000 years into the future, Voyager 2 will come within 1.6 light years of a red dwarf star in the constellation of Andromeda called Ross 248. The vast distances separating the stars will probably ensure that this tiny spacecraft, which showed us many wonders concerning other worlds in our system, will drift eternally in interstellar space, never again to be seen or touched by living beings, whether from our world or another that has happened to spawn life; but since the chances are not impossible, and the important consequences which could be made by an encounter with another intelligent race with star-faring capabilities are so great, a gold record has been placed on the Voyagers, containing images and sounds of Earth to help give those who encounter the probes some idea of the human race who built them. Conclusion First discovered 143 years ago, Neptune is on the verge of being totally rediscovered in just a few short months. Although currently labeled as the eighth most distant world from the Sun, Neptune is currently the most distant. The high elliptical orbit of Pluto sometimes allows it to wander a bit closer to the Sun; in fact, Pluto will retain its status as second most distant planet until the end of this century. So in a real sense, Voyager 2 will truly cross the boundaries of the solar system, speeding off to a fate that is quite unknown to us at present. Observers have only a few short months to ponder the mysteries of Neptune in the starry sky. Through the eyepiece of the telescope this planet still retains many secrets that have piqued the curiosity of generations of astronomers. However, all of this will change in August. From that point on, Neptune will become a real place, a place shown for the first time by images beamed across vast stretches of empty space. Before all of the wonderful pictures appear on the front pages of newspapers, one should try to take a last glimpse at this distant orb, and for the final time see it as only a blob of light, as John Adams and Urbain LeVerrier must have so many years ago. If you do not own a telescope, visit your local planetarium or astronomical Society. You will be sure to find many eager enthusiasts willing to let you peer through their instruments. It is fitting that Neptune will put on a nice display in the evening sky when our tiny emissary is at closest approach. During the month of August, Neptune can be found in the southern sky at sunset. Embedded among the stars of the constellation Sagittarius, the planet is almost lost within the thickest groupings of stars of our galaxy, the Milky Way. However, to make matters easier, the ringed-jewel Saturn is located just to the southwest. Even though plans for other expeditions to Neptune have not been drawn up (but you can bet they exist in the minds of modern explorers), the wealth of information returned by Voyager 2 will open new chapters of unknowns. For now, however, the rediscovery of Neptune is enough to occupy inquisitive scientists for some time to come. ----------------------end part 1------------------------- -- Donald J. Barry (404) 651-2932 | don%chara@gatech.edu Center for High Angular Resolution Astronomy | President, Astronomical Georgia State University, Atlanta, GA 30303 | Society of the Atlantic ------------------------------ End of SPACE Digest V9 #591 *******************