THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC Volume 1, Number 2 - September 1989 ########################### TABLE OF CONTENTS ########################### * ASA Membership Information - Don Barry * Our Closest Neighbors in the Milky Way Subdivision - Ingemar Furenlid and Tom Meylan * Profiles in Astronomy: Albert Whitford - Edmund Dombrowski, Sethanne Howard, and Don Barry * Amateur Telescopes, Yesterday and Today - Bill Bagnuolo * Stopping Space and Light Pollution - Larry Klaes and Phil Karn ########################### 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 Travel 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. ARTICLE SUBMISSIONS - Please send your on-line articles on astronomy and space exploration to Larry Klaes, EJASA Editor, at the following net addresses: klaes@wrksys.dec.com, or ...!decwrl!wrksys.dec.com!klaes, or klaes%wrksys.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 Copyright (c) 1989 by the Astronomical Society of the Atlantic. OUR CLOSEST NEIGHBORS IN THE MILKY WAY SUBDIVISION by Ingemar Furenlid and Tom Meylan Our closest known stellar neighbors in the Milky Way Galaxy - excluding Earth's Sun - are the stars in the Alpha Centauri system. The two main components in this triple system are called Alpha Centauri A and Alpha Centauri B. The third component, which is actually the closest of the three, is called Proxima (for proximity) Centauri and is a faint M dwarf star of visual magnitude 11.05. The trinary star system is located approximately 4.3 light-years from Earth. Alpha Centauri A is quite similar to the Sun and has been called a solar twin, which it is not, but more about that later. Co-author Ingemar Furenlid traveled to Chile a few years ago to use the excellent facilities of the European Southern Observatory (ESO) for a detailed study of the spectrum of this star. Flying down the length of South America along the Andes is a beautiful experience; the approach to Santiago de Chile is announced by the Aconcagua summit, a 7,800-meter (26,000-foot) landmark in the Andes, towering over the other peaks. As an ESO observer I was met at the airport by an agent carrying a big sign with my name. He placed me in a cab and I was promptly taken to the "guest house". Next morning, I was off to a smaller airport for a memorable flight to La Serena up north and closer to the observatory. The flight, in a seven-seater twin, was done on the last day of one of the biggest storms in recorded history; it was the finest roller coaster I ever rode! The runway in La Serena was a big lake, and the pilot's comforting words during final approach were: "Let's give it a try, at least we won't burn." Hanging forwards in our seat belts through cascades of water, we experienced the plane coming to a full stop in only 45 meters (150 feet)! A big van took the ESO party 160 kilometers (100 miles) to the mountain, where we arrived in time for dinner prepared by the world famous (among astronomers) chef, Mr. Schuhmacher. My purpose was to conduct a spectroscopic analysis of Alpha Centauri A, and to do this, I made observations with a special purpose telescope called the coude auxiliary telescope, located in a separate tower next to the 3.6-meter (11.9-foot) telescope building. A coude focus is located in a fixed place, independent of where the telescope is aimed. In this case, the coude room housing the echelle spectrometer, and the observing room are both in the 3.6-meter building. This is one of the finest spectrographs in the world and observing here was a delight. Surrounded by TV screens, counters, touch screens, and keyboards, I felt as if I were in a satellite. In a typical setup, the observer runs the spectrometer and the night assistant brings in the stars. This run was easy for the assistant, as most observations were of the same star. Most of the spectrum of Alpha Centauri A in the range of 3900 (blue) to 7600 (red) angstroms was observed in pieces 50 angstroms long in such a way that the resulting data had unusually high resolution and precision. All went fine: The weather after the storm was excellent, and the last needed spectrum was recorded in the morning of the last night. Afterwards, we were in a rush to get to bed after the long night. The night assistant, however, rushed too quickly, and on the way down from the telescope hit a snowbank and rolled his car upside down. He crawled out from under it and walked to his quarters to sleep, and some friends righted it the next day. During all these observations I was never near the telescope, but I did remember to walk over to the tower before the last night to see the beautiful alt-alt 1.5 meter (4.9-foot) reflector. Back at Georgia State University the data were reduced in standard fashion and the process of analysis started. The spectra were obtained for a very careful chemical abundance analysis of the Alpha Centauri system. The chemical analysis of stars has come a long way from early qualitative determinations of composition made merely by identifying the spectral line signatures of elements as previously determined in the laboratory. Now it is possible to compare very high quality numerical data collected at the observatory to numerical results produced by sophisticated computer models of the atmospheres of the stars, and in this way one can make high precision quantitative determinations of the abundances of the stars. Before spectra can be interpreted, the effects introduced by the electronic equipment must be removed from the raw data. A diode array called a Reticon records the light in the spectrometer, and collects charge on each pixel dependent on how much light was collected. Charge also collects on pixels even in the dark, and this needs to be measured and subtracted away from the data. Also, each pixel in the Reticon responds to light with different efficiency, and this problem must be treated as well. For the most part, once these instrumental effects are taken care of, the spectrum is ready for analysis. One is left with a string of numbers which give the intensity of light recorded by each pixel. This string of data must be scaled to a standard level, called the continuum, which represents the amount of light that would be radiated by the star if atoms were not absorbing certain wavelengths of light in the star's atmosphere. After that one needs to find the relationship between the wavelengths of light observed and the pixels on the chip. In other words, one wants to know which wavelength of light was shining on each pixel. This relationship is called the dispersion solution, and has a relatively simple mathematical form. Once the spectrum is scaled and the dispersion solution has been found, the spectrum is ready to be measured. When the spectrum is plotted as a graph, with wavelength running horizontally and the intensity vertically, features called absorption lines - caused by specific chemical elements absorbing certain wavelengths of light - appear as dips in the plot. The strength of each absorption line is measured by finding the area that the dip covers. The absorption lines are the key to chemical analysis. If two stars are exactly alike in temperature and size, then the star with a higher abundance of chemical elements like carbon, oxygen, or iron, will show stronger absorption lines. In photographs the lines will look darker, or when graphed, they will be deeper. To measure compositions, we commonly use the Sun as a standard, because we know its composition better than that of any other star. Excellent spectra exist of the Sun from which measurements of the strengths of its absorption lines have been made. The strengths of these lines, together with known atomic constants for atoms found in the Sun's atmosphere, and sophisticated models of stellar atmospheres, allow us to measure the absolute composition of the Sun. Using the same model used to calculate the Sun's composition on a similar star, this gives the relative abundances directly, as a ratio of the strengths of absorption features. For stars which are dissimilar, a more complicated process is required, in which differences in the atmospheres of the stars must be accounted for. When we take the final model calibrated by the Sun and apply it to the spectrum of Alpha Centauri A, we get the following results: Physically, we find the star to have a temperature of 5,700 degrees K (Kelvin), which is 90 degrees K cooler than the Sun. It appears that the surface gravity is roughly one-half to two-thirds the strength of the Sun's, indicating that it is also somewhat further along in its evolution than the Sun. This agrees well with the fact that Alpha Centauri A is about one-tenth more massive than the Sun, as found by studies of its orbit, which also means that it ages more rapidly than the Sun. Chemically, we find that the atomic elements from carbon through zinc are enriched in Alpha Centauri A relative to the Sun by about 35 percent. This enriched composition is also supported by recent calculations of the interior structure of the star, which is strong evidence that the result is correct. The difference in composition between Alpha Centauri A and the Sun also give us clues as to what caused the enrichment. The heaviest element which is enriched is zinc, and there are also large enrichments of sodium, aluminum, manganese, and copper. Furthermore, the enrichment in carbon, oxygen, and iron is somewhat smaller. These three findings are consistent with enrichment by a massive supernova explosion. We conclude that the material which formed the Alpha Centauri system was affected by one more supernova than the material which formed the Sun. It is a long, arduous path to the observatory. From the observatory to the final result, the road is no less arduous. However, from our planet we have done some very high quality long-range sensor scanning, and determined to high precision the physical and chemical characteristics of a very distant body. The precision is in fact good enough to begin to piece together some of the "family" history of our closest neighbors in the Milky Way Subdivision. Alpha Centauri A is sufficiently different from the Sun that we can say for sure it is not a twin! PROFILES IN ASTRONOMY: ALBERT WHITFORD by Edmund Dombrowski, Sethanne Howard, and Don Barry Editor's Note: Albert Whitford is one of the elder deans of Astronomy, a Professor Emeritus at Lick Observatories, and was for many years their Director. He was interviewed in January of 1989 at the American Astronomical Society meeting in Boston, Massachusetts by Society members. Sethanne: Dr. Whitford, I find it interesting that you never took an astronomy course. How did you become interested in astronomy? Whitford: I came into astronomy after having started graduate study in physics, you know, atomic spectroscopy, starting in 1932. It was during the Depression and I was offered a job working with an astronomer where I was doing a technical chore that he needed to have done, that physicists were supposed to know more about, measuring very small currents, and the currents introduced me to astronomy. The astronomer was Joel Stebbins; he's deceased now, but for a long time he was Secretary of the Astronomical Society, and President later. One thing led to another: I made a successful device for measuring very small currents from photoelectric cells, with which he was measuring the light from stars and galaxies, and it brought me to Mt. Wilson Observatory helping him, and finally I became an astronomer without ever starting out to study it at all; and I never have, as Sethanne says, I have learned it by teaching it and studying the journals. The subjects I worked on over the years involved for a long time the photoelectric measurement of the brightness of galaxies, and finally photoelectric scanning of spectral distribution and the strength of the various spectral features that one could get that way. Then came a period of administrative responsibility - I came to Lick Observatory and as head of it had to get the 3-meter (10-foot) telescope, which was supposed to be done, working and instrumented, a long hard struggle, but it works very well, and has the instrumentation I'm glad to report, that in the hands of those who have come after is really excellent and is being kept on the forefront. My interest in galaxies moved me to see what could be done by looking harder at the center of our own. In the bulge of the galaxy there were some windows where one could see through the dust clouds, between rifts in the dust clouds, all the way through to the bulge, and with modern instruments one can analyze these stars and find out how they compare with giant stars near the Sun, and count them. And that's what has kept me occupied in the post-retirement years. My observatory and University that I serve have been very kind and have given me a chance to keep on doing research with grants and trips to the Southern Hemisphere where this part of the galaxy is up there and not down there! I've had a very rewarding time in post-retirement years and I like to come to an astronomical meeting once in a while. Some people I remember and there are a lot of people whose names I've seen in the journals, and some people I just can't imagine where they came from until I see their names on poster papers. Ed: What's the status at Lick observatory right now? Any new things being done? Whitford: It is on a mountain, it's 100 years old, the original telescope still works, though we've got to shore up the dome because an earthquake more or less shook it apart; and it's being done, and it will go on working on a more restrictive program. The 3-meter (10-foot) reflector, when it was built, was next to the 200-inch (500-centimeter) [Mount Palomar reflector telescope], and now it's thirteenth or eighteenth in the world, but it is a first rate telescope. The difficulty is that San Hosea has gotten big. It's only 13 miles (21 kilometers) away, so the sky is brighter. The search for a dark sky site finally led to a project to build a very big telescope on Mauna Kea, and in getting the resources to do it, we joined with Caltech as equal partners. A Caltech Alumnus is providing the capital cost and the University of California is providing the design and the guarantee of the operating cost for the first ten years. That's being built now; there are problems still with us in getting the mirror segments produced, but they seem to be in sight of a solution, and I hope I'll live to see it delivering starlight. I've been to Mauna Kea; the success of the California-French-Hawaii telescope proves that it is indubitably a very superior site - wonderful seeing there. Don: We've had a chance to do some speckle interferometry on that telescope, and you really can tell the qualitative character of the speckles show the seeing is excellent. Sethanne: Do you think the projections made by NASA that in a few years there will be an enormous need for astronomers is valid? Whitford: I haven't studied it as much as they have, all I can say is that all the projections that there are too many people in the pipeline haven't seemed to come true; that the interest explosion in the various avenues of investigating the Universe in all spectral bands has somehow attracted or marshaled that kind of support. There's much to be discouraged about in how much interest the National Science Foundation is taking in astronomy. The total picture, I think, still gives no reason to despair. But I wring my hands about the starving national observatories, which have been great institutions. Ed, Sethanne, and Don: Thank you for your time, Dr. Whitford. Whitford: You are very welcome. AMATEUR TELESCOPES, YESTERDAY AND TODAY by Bill Bagnuolo Over the last fifteen to twenty years, there has been a revolution in large telescope design. In contrast, during the period from 1945 to 1975, all large telescopes resembled the Mount Palomar 500-centimeter (200-inch) reflector. Less noticed is that an equally large change has occurred in amateur telescope design. The following is a summary of the changes in amateur telescopes over the past twenty years, between 1968 and 1988: Telescope Types - When I was in high school, circa 1964, the dominant amateur telescope was the old reliable 15-centimeter (6-inch) f/8 reflector. These telescopes were sold by Edmund Scientific and Criterion for about $200 ($750 in 1988 dollars). Larger telescopes made by Cave and others cost $450 ($1,500), and a 31.25-centimeter (12.5-inch) reflector cost $1,200 ($4,000). More adventuresome (and well-to-do) amateurs bought Celestron 20-centimeter (8-inch) catadioptric telescopes for $800 ($3,000). Because of these large costs many amateurs made their own mirrors. Some amateurs also bought 7.5-centimeter (3-inch) refractors for about $300 ($1,125). Today, after the "Dobsonian Revolution", aperture fever has struck. Many amateurs have 25- and 32.5-centimeter (10- and 13-inch) Dobsonians, by Coulter or homemade. Note that these telescopes are also much cheaper: A 32.5-centimeter (13-inch) Coulter is about one-seventh the cost of an old Cave 31.25-centimeter (12.5-inch), although the Cave had a much better mount. Amateurs still have 20-centimeter (8-inch) Celestron and Meade catadioptrics, as in the 1960s. Among the more expensive telescopes, refractors have recently made a comeback, particularly in the 12.5- to 17.5-centimeter (5- to 7-inch) sizes. Optics - Because of the high cost of mirrors, many amateurs in the 1960s ground their own mirrors: A 20-centimeter (8-inch) cost about $370 in 1988 dollars. I made seven mirrors at the Adler Planetarium mirror shop in Chicago, Illinois. Today, most amateurs buy their mirrors, even the larger sizes. Because of this, I think that amateurs are less sophisticated today when it comes to optics than in the past. At the Adler Planetarium, people routinely made Cassegrains, Maksutovs, and even off-axis systems. Today, most amateurs just build big "dumb" telescopes. The Los Angeles Astronomical Society recently built a 77.5-centimeter (31-inch) telescope, an impressive feat of mechanical design; but the optical design was just that of a f/4.5 Newtonian- Dobsonian. Sites - Skies were much better twenty years ago and not coincidentally amateur telescopes were very heavy and immobile. I used to drag my 15-centimeter (6-inch) telescope (weighing 31.5 kilograms/70 pounds) out into the backyard. Now trips to dark sites are far and telescopes are built for portability. Some amateurs, like the professionals, have started to consider ways to improve local seeing conditions, by minimizing turbulence in the tube or around the dome or site. Equipment - Many amateurs have cameras for astrophotography as in the 1960s. In addition, recently amateurs have used photometers for recording star variability and lunar occultations, and some use electronic cameras. Three competing firms have recently started selling CAT (Computer Aided Telescopes) that can automatically slew a telescope to a number of objects in succession. To conclude, amateurs now have generally much better telescopes at a much lower cost than twenty years ago; but they no longer have the dark sites in which to use their telescopes. Although the mechanical design of telescopes has improved, the neglect of home-brew optics has resulted in a decline of average optical skill in the amateur. STOPPING SPACE AND LIGHT POLLUTION Editor's Note: The increasing problem of space debris threatens to cut off our access to low Earth orbit completely. This and the ever-increasing number of lights from our growing cities also threaten to disrupt amateur and professional observations of the night skies. The following two articles discuss the issue and what can be done about it from several different approaches: Larry Klaes writes: For over thirty years now the human race has been launching all types of vehicles into the Universe, creating an immense "cloud" of human-made objects orbiting Earth and slowly expanding into the Solar System and interstellar space. While many of the satellites in space are of benefit to our society, many more are now inactive, floating around Earth serving no purpose at present. In addition to dead satellites and rocket boosters, there are also thousands of pieces of metal scrap and paint flecks from rockets and satellites which have disintegrated in orbit for one reason or another; and the satellite cloud is growing all the time. At present there is a one in thirty chance that a Space Shuttle could be struck by some man-made orbital debris; by 2010 the chances will be reduced to one in four. This cloud represents a danger on many levels: In space, this debris is orbiting Earth at 28,800 kilometers (18,000 miles) per hour (the minimum velocity needed to achieve and stay in orbit); while some of it will eventually be dragged into Earth's atmosphere and burn up, many more are in orbits which will last for millennia! As more functioning manned and unmanned vehicles are launched into orbit, the risk of being struck and killed/destroyed by this debris - no matter how small - grows constantly. Even a grain-sized particle could hit with the impact of a rifle bullet! And people and places on Earth's surface are not immune from the dangers of falling debris: If an object is large enough, it will not burn up completely and strike the surface. The Soviet nuclear-powered COSMOS satellite that hit Canada in 1978 and the United States SKYLAB space station that hit Australia in 1979 are good examples of debris too big to disintegrate on reentry and the consequences which result. Satellite debris also interferes with astronomical observations. The incredibly sensitive instruments professional astronomers use can be "thrown off" by passing satellites and man-made debris. Even more threatening, just recently the French were stopped from launching a huge balloon ring satellite to commemorate Paris' Eiffel Tower's one hundredth anniversary. Many astronomers opposed the ring satellite, as it would have been the size and visual brightness of the full Moon as viewed from the ground and would have interfered with observations. They were also concerned that it might start companies advertising in space with huge satellite "billboards", which some are considering! Along with light pollution on the ground from ever-growing cities, astronomers - and those who just enjoy looking at the stars - are having their work cut out for them. The International Dark-Sky Association is an organization designed to help deal with our growing light pollution problem, while not compromising public safety in the process. For more details, write to: Dr. Dave Crawford Kitt Peak National Observatory P.O. Box 26732 Tucson, AZ 85726 You can also receive a brochure on an important meeting of astronomers and other scientists who discussed the problems of light pollution in Washington, D.C., on August 13-16, 1988, by writing to Dr. Tomas Gergely, National Science Foundation, Dept. of Astronomy, 1800 G St., NW, Washington, DC 20550. Now I know some of you are probably asking yourselves: "How can I possibly stop and/or clean up space debris? I'm afraid I don't have much access to a Space Shuttle with a huge vacuum cleaner; also, I and other average citizens did not personally make the pollution now flying over our heads!" I am well aware of this, and naturally this is a project for a major government and/or corporation to handle; but as is always pointed out, such organizations won't do much of anything unless it personally affects them and/or the citizens they are supposed to serve say something about it - in other words, write to your Congressman; it does a lot more good than you might think. Tell them there should be a major program to start picking up the useless satellite and rocket debris orbiting Earth. It can be done using the Space Shuttle, or even relatively cheaply using robot satellites which can attain orbits where the Shuttle cannot; and what is even better is that the debris need not be returned to pollute Earth. For one thing, some old, deactivated satellites are now part of space history, and deserve to be returned to Earth for placement in our museums. Others still have valuable parts which can be reused and/or recycled; and as for the truly useless debris, if it is small enough it can be deorbited to burn up completely on reentry, or launched into the Sun with no harmful effects to our star. The debris can also be placed in safe containers and launched into solar orbit away from Earth, or even out of the Solar System, but I do not care for this plan, as it does not destroy the debris, and just leaves the hazard for future space travelers when humanity start to colonize this and other star systems. I would like to point out that I am aware these clean-up plans are not for the immediate future, as I understand the difficulties in orbital mechanics, such as trying to send an object towards the Sun, etc., but I hope they will inspire the start of such projects when it is more feasible. I am also aware of the recent Air Force project designed to deorbit booster rockets earlier than normal for previous missions, to make Low Earth Orbit (LEO) a bit less cluttered; I personally approve of this, but it might be more beneficial if we could recover the boosters and other debris for scrap metal, if nothing else. I just feel that something should be started relatively soon, so that it does not become too late for us to do anything about it by the time we are socially and technologically ready. It would be horrible to think that we might trap ourselves on this planet with our own space debris circling the globe, making space launchings too risky to attempt. This is an extreme view in some ways, but not impossible. Besides the fact that human-made debris is potentially dangerous to satellites and humans, why else should we "clean up" space? Because it will help the future of our space programs, which in turn benefits all of society. These very clean-up projects will get us more involved in space exploration and colonization. We will colonize the other planets and star systems someday, and we cannot continue to bring our pollution and poor management habits with us. Space leaves very little room for error and bad planning. What you say to those who will guide our future in space can have a lot of impact. Do not think of space as something separate from Earth and its concerns: We live on a planet in space, and if we ruin not only our world but the environment around it, then where can we go to live? Phil Karn of Warren, New Jersey, writes: Instead of just cleaning up space debris, I would advocate the following preventive approaches: 1. An international treaty prohibiting deliberate collisions between or explosions of objects in Earth orbit above a certain altitude, say 500 kilometers (300 miles). This would include both Soviet and American Strategic Defense Initiative (SDI) and ASAT tests. Much existing orbital debris is the result of Soviet ASAT tests. The reduction of space debris is only one of many reasons that a complete ban on all ASAT testing would be to our mutual advantage. 2. An international treaty requiring launch agencies to vent excess liquid fuel from spent upper stages to render them incapable of exploding. Much existing orbital debris has come from upper stages that explode some time after deploying their payloads. This can happen in a cryogenic stage when the fuel vaporizes (e.g., the ARIANE third stage that launched the SPOT-1 satellite) or it can happen in a hypergolic stage when the fuel and/or oxidizer corrode through the bulkhead and mix (e.g., some DELTA second stages). I believe that most launchers now vent as standard operating procedure, so it should not be much of a burden to make this a formal requirement. 3. International guidelines for the design of orbital missions missions such that the fewest possible non-payload objects are deployed in long-lived orbits. This would consist of several aspects: a. The use of short-lived transfer orbits whenever possible. For example, a standard ARIANE geostationary transfer orbit has a perigee of about 200 kilometers (120 miles). Spent ARIANE third stages generally last in this orbit for a few years or so. Intermediate Earth orbits with "direct ascent" launches are the real problem, since the upper stage goes into the same orbit as the payload. If at all possible, spent stages should be designed to de-orbit themselves after deploying their payloads. b. Methods to control the amount of debris generated in long-lived orbits, with emphasis on payload deployment operations. Clamp bands, springs, fasteners, explosive bolt cutters and the like should be captive, i.e., they should be tethered so that they do not go floating off on their own after separation. This is already standard procedure on most Western launches; it should be an international requirement. c. Integrity standards for external coatings on all objects deployed in long-lived orbits. The white paint used on DELTA upper stages has been traced as the cause of some small craters found on Space Shuttle windows. A CHALLENGER mission in 1983 displayed this most dramatically, when the astronauts on board found one window with a circular crack in it, as if the window had been hit with a rifle bullet that did not quite penetrate. The main problem is not intact payloads. The real problem, first, is with the numerous small fragments in long-lived orbits. These are not easily reached from a vehicle such as the Shuttle. Debris, large or small, that is in a typical Shuttle orbit (about 300 kilometers/180 miles) re-enters within a few months anyway, so there is not much point in going up to get it. Second, there are so many small bits of debris, in so many different orbits, that even if you could reach them with the Shuttle you would have to expend enormous amounts of fuel chasing them all. Third, the Shuttle itself generates a significant amount of debris through such things as waste dumps and loose parts. This would largely offset whatever debris it could pick up. I remember seeing the first on-orbit television transmission of the payload bay sent to Earth during the Space Shuttle COLUMBIA mission Space Transportation System 1 (STS-1); clearly visible was a small piece of loose hardware spinning across the field of view, off into the blackness. THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC September 1989 - Vol. 1, No. 2. Copyright (c) 1989 - ASA -- 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