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A Publication of THE PLANET: rvSOCIETV

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Board of Directors FROIVI THE CARL SAGAN BRUCE MURRAY EDITOR President Vice President Director, Laboratory for Planetary Professor of Planetary Studies, Cornell University Science, California Institute of Technology LOUIS FRIEDMAN Executive Director JOSEPH RYAN Q 'Melveny & Myers MICHAEL COLLINS Apollo 11 astronaut STEVEN SPIELBERG director and producer THOMAS O. PAINE former Administrator, NASA HENRY J. TANNER lanetary missions---each one ranking Aims High-at Mars-The club of plan­ Chairman, National financial consultant Commission on Space P among the most ambitious projects et-exploring nations was once limited to Board of Advisors ever undertaken-begin with a glimmer­ the Soviet Union and the United States.

DIANE ACKERMAN JOHN M. LOGSDON ing image of what might be possible. It is Now Japan and the European Space poet and author Director, Space Policy Institute, George Washington University the nature of these undertakings that they Agency have also launched missions to ISAAC ASIMOV author HANS MARK cannot be accomplished by an individual other worlds. And ESA is looking toward Chancel/or. RICHARD BERENDZEN University of Texas System alone, however inspired he or she might that most seductive of planets, Mars. educator and astrophysicist JAMES MICHENER be. The ideas that enable us to explore the Page 16-A Little Warmth Against the JACOUES BLAMONT author Chief Scientist, Centre National d'Etudes Spatia/es, MARVI N MINSKY planets can only be rendered real by enti­ Big Chill-Scientists once conceived of France Toshiba Professor of Media Arts and Sciences, Massachusetts ties we call "space agencies"-such as comets within the Oort Cloud as primor­ RAY BRADBURY Institute of Technology poet and author NASA in the US, Glavkosmos in the dial bodies perfectly preserved since our PHI LIP MORR ISON ARTHUR C. CLARKE {nsfilute Professor, Massachusetts USSR, the Institute of Space and Astro­ solar system's birth. But recent research author Institute of Technology CORNELIS DE JAGER nautical Science in Japan and the Euro­ hints that these comets, under influences PAUL NEWMAN Professor of Space Research, The Astronomical Institute at actor pean Space Agency-bureaucracies creat­ from the galactic environment, may not Utrecht, The Netherlands JUN NISH IMURA ed to turn dreams into reality. In this be pristine. FRANK DRAKE Director-General, Institute of Space Professor of Astronomy and and Astronautical Sciences, Japan Planetary Report we look at ideas soon to Page 18-Can NASA Still Do the Astrophysics, University of California at Santa Cruz BERNARD M. OLIVER Chief, SET! Program, reach fruition, at imaginative concepts for Job?-From the media darling of the LEE A. DUBRIDGE NASNAmes Research Center former presidential the future, and at NASA, the agency that, 1960s and 1970s to the embattled bureau­ science advisor SALLY RIDE Director, California Space Institute, although recently beset with problems, cracy of the 1980s, the American space JOHN GARDNER University of California, San Diego founder, Common Cause and former astronaut still looks forward to an expanding future agency has traveled a difficult road. With MARC GARNEAU ROALD Z. SAGDEEV on the Moon and Mars. perhaps its greatest challenge still before Canadian astronaut former Director, Institute for Space Research, Page 3-Members' Dialogue-The it-the Space Exploration Initiative that GEORGIY GOLITSYN Academy of Sciences of the USSR Institute of Atmospheric Physics, Academy of Sciences of the USSR HARR ISON H. SCHM ITI Planetary Society's position on astronomi­ would send humans back to the Moon and former US Senator, NM THEODORE M. HESBURGH and Apollo 17 astronaut cal observatories on the Moon and how on to Mars-we asked six NASA veter­ President Emeritus, University of Notre Dame S. ROSS TAYLOR storms rotate have caught the attention of ans for their views of the agency's past SH IRLEY M. HUFSTEDLER Professorial Fellow, Australian our members. and future. educator and jurist National University, Canberra GARRY E. HUNT LEWIS THOMAS Page 4-The Mars Balloon Relay­ Page 24-World Watch-Missions to space scientist, Chancellor, Memorial Sloan United Kingdom Kertering Cancer Center NASA's Mars Observer, scheduled to the Moon are engaging the attention of SERGEI KAPITSA JAMES VAN ALLEN reach Mars in 1993, will carry a radio re­ scientists and engineers, and the American Institute for Physical Problems, Professor of Physics, Academy of Sciences of the USSR University of Iowa lay to aid communication with the Sovi­ space community is organizing to plan the et-French Mars Balloon probe on the implementation of President Bush's Space The Planetary Report (ISSN 0736-3680) is published six times yearly at the editorial offices of The Planetary Society, 65 North Catalina Avenue, Mars '94 mission. (The Mars Balloon will Exploration Initiative. Pasadena, CA 91106, (818) 793-5100. It is available to members of The Planetary Society. Annual dues in the US or Canada are $25 US dollars fly with a guide-rope designed by The Page 25-The Planetary Society's Fam­ or $30 Canadian . Dues outside the US or Canada are $35 (US). Planetary Society.) This small step in in­ ily Grows-We welcome distinguished Editor, CHARLENE M. ANDERSON Technical Editor, JAMES D . BURKE ternational cooperation began as a brain­ new additions to the Society'S -Boards of Assistant Editor, DONNA STEVENS Copy Editor, KARL STULL storm in the mind of Jacques Blamont, Directors and Advisors. Art Director, BARBARA SMITH Society Advisor. Page 26-News & Reviews-This Au­ Viewpoints expressed in columns or editorials are those of the authors and do not necessarily represent positions of The Planetary Society, its officers Page 9-The Key to Mars, Titan and gust, Magellan will enter orbit about or advisors. © 1990 by The Planetary Society. In Canada: Second Class Mail Registration Number 9567 Beyond?--Our exploration of the planets Venus. Clark Chapman comments on is limited primarily by our skills in what we expect to learn from it. COVER: The Space Race ofthe 1960s spawned a robust, propulsion. With bigger rockets, better Page 27-Society Notes-Honors, match­ energetic agency to conduct the American space pro­ gram. NASA launched a series of human missions, work­ fuels and faster spacecraft, humans and ing gifts and tips on correspondence with ing its way, step by step, to the Moon. On June 3, 1965, Gemini astronaut Edward H. White II became the first their robots could range throughout the the Society are among this issue's topics. American to "walk" in space, while his orbital compan­ solar system. Engineer Robert Zubrin de­ Page 28-Q & A-Can we predict aster­ ion, James A. McDivitt, remained inside the two-man cap­ sule. (Cosmonaut Alexei Leonov was the first human to scribes a type of propulsion-almost oid impacts? Why is there an asteroid "walk" in space.) The Gemini program served as a bridge within our grasp-that could enormously belt? How did the dinosaurs die? Find between the Mercury program, which sent the original seven American astronauts into space, and the Apollo advance our exploratory capabilities. some possible answers in this column. program, which would send three-man crews to their lu­ Page 14-European Space Agency - Charlene M. Anderson, Editor nar des.tination. Photograph: Johnson Space Center, NASA NEWS BRIEFS

During the International Space Year of 1992 (an international effort to focus As administrators of a membership organization, The Planetary Society's Directors space studies on global change), Canada and staff care about and are influenced by our members' opinions, suggestions will produce the Global Change Ency­ and ideas about the future of the space program and of our Society. We encourage clopedia. The encyclopedia will not be a members to write us and create a dialogue on topics such as the space station, the book but will consist of computer disks, lunar outpost, the exploration of Mars and the search for extraterrestrial life. designed for personal computers with Send your letters to: Members' Dialogue, The Planetary Society, 65 N. Catalina color monitors. The encyclopedia will Avenue, Pasadena, CA 91106. combine and correlate diverse sets of measurements-global and regional­ The NASA photo on page four of the January/February Planetary Report is radically from a variety of satellite and ground­ wrong. The spiral rain bands feeding the tropical stonn are spiralling the opposite based studies, updating and adding to way for a low pressure system in the northern hemisphere. I suspect that the photo the data on a regular basis. was reproduced from a slide that was copied backwards or perhaps this stonn was in "This will be the first atlas of the the southern hemisphere. world to show animated land and sea You are correct in stating that cyclones (or low pressure systems) occur in all plan­ changes over an extended period of etary atmospheres. What makes these photos so interesting is that similar atmospheric time," says Wesley T. Huntress Jr. of fluid dynamics can be deduced from such photos of different atmospheres. By study­ NASA's Earth Science and Applications ing planet Earth, we can extend our knowledge of distant planets by correlation, Division. because many of the same physical concepts are applicable. The really exciting aspect -from Science News of such comparisons is the awesome magnitudes of planetary atmospheric motions. What you call a stonn in the caption of this photo would be a howling vortex of sev­ eral greater orders of magnitude on a larger and faster rotating planet. The real beauty In late February, Pioneer 11 crossed the here is that good estimates can be made of those fierce winds by the connections used orbit of Neptune and became the fourth by atmospheric scientists who study planetary atmospheres. spacecraft (along with Pioneer 10 and The thrust of this particular issue is quite practical-study Earth to gather the facts Voyagers 1 and 2) to leave the solar on planets and study planets to reinforce the lessons needed for living on Earth. system. JOEL CURTIS, Juneau, Alaska Launched in 1973, Pioneer 11 contin­ ues to return good data. In three years it Yes, the photo got flopped in production. Seen from above, cyclonic storms rotate will become difficult to operate the radio counterclockwise in the northern hemisphere and clockwise in the southern. Yours is transmitter and scientific instruments simultaneously, says NASA project the most interesting of several letters and calls we received on the subject--evidence manager Richard Fimmel. However, that our readers pay attention, and a strong incentive for us to pay attention to every technical adjustments may extend the step in publishing The Planetary Report. -James D. Burke, Technical Editor craft's life through 1995. Pioneer 10, with its stronger power supply, may Although the concept of a lunar observatory has been widely discussed for years, it return data through the year 2000, does not appear to have had the active support of The Planetary Society, which is which would extend its original 30- surprising because a lunar observatory would create an unequalled opportunity to month design life to 28 years. advance research in planetary science as well as other areas of astronomy. -from NASA Ames Research Center Early in the next century, radio telescopes on the Moon's far side could search for sigrrs of extraterrestrial intelligence without interference from terrestrial radio sources. The most distant planets of our own solar system could be studied regularly Minor setbacks plagued the Hubble at a level of detail comparable to that obtained by planetary probes. The study of Space Telescope after its release from other solar systems would enable us to better understand our own. Optical arrays on the shuttle Discovery on April 25. the lunar surface could image the nearer stars and provide infonnation about their Problems with the aperture cover and planets. Ultimately, optical arrays might be developed that could produce fairly then the solar panels were eventually detailed images of such distant planets themselves. remedied. However, a partial loss of What a misfortune it would be if The Planetary Society, preoccupied by its pursuit maneuverability in one antenna, due to of other objectives, failed to provide effective support for the project that, more than a distended cable, will be overcome by any other that might be undertaken during our lifetimes, would expand our under­ rewriting antenna software. standing of the universe and of our place in it. With an expected life of 15 years, the DAVID L. BARRETT, Wisdom, Texas Hubble Space Telescope has a 94.5- inch primary mirror with a finish so The Planetary Society is interested in lunar astronomical facilities and we have main­ smooth that if Earth's surface had been tained close liaison with the several scientific committees studying the possibilities. molded to the same specifications, the Astronomy, astrophysics and radio observatories are now under study. In order to tallest peak would be five inches above evaluate the merits of a specific proposal we will need information on its cost as well sea level. Such amazing engineering as alternate methods of reaching the same astronomical goals, such as ground-based precision will enable astronomers to or Earth-orbiting observatories. Other people propose Moon mining for theftrst study light from sources nearly 14 bil­ lunar site. We will continue to monitor the progress of these ideas, and whenftrm lion light years away. proposals are made, we will report on them. -Louis D. Friedman, Executive Director -from the New York Times 3 by Jacques Blamont

Question: What's the main requirement than the density of Earth's atmosphere amount. for taking part in the exploration of at an altitude of 35 kilometers (22 One of the scarcest and most pre­ Mars? miles), so the balloon has to be light cious resources is energy. Aboard the Answer: Exciting work in the labora­ and large. Light means that the fabric balloon all the energy comes from the tory, in the field, in the test facilities, must be thin, and thus the overall size batteries: Within the allotted mass bud­ on the launch pad, at the receiving sta­ of the balloon is severely limited. Large get, it is not possible to carry more than tions and in front of the computer, and means that, notwithstanding these con­ 3 kilograms (7 pounds) of batteries, a fine blend of theory, perspiration and straints, the volume cannot be less than which could at best provide 1 kilowatt experiment. several thousand cubic meters for the hour for the total duration of the bal­ Wrong. The real answer is: sitting on balloon to sustain itself, even without loon mission. The expected lifetime of committees ad nauseam. the payload. Since there are limits to the Mars Balloon is about 10 days. how much we can practically transport The greatest energy consumer is the to Mars, it was obvious from the start radio transmitter, which sends out the n March 1986, engineers of the that the overall mass carried by the bal­ data collected by the balloon. Since the Babakin Center, which builds the loon could not exceed 20 to 25 kilo­ power required to send data directly to I spacecraft for the planetary program grams (44 to 55 pounds). Earth would be enormous, signals from of the USS,R Academy of Sciences, The present design envisions a 15 the balloon have to be picked up by a suggested that a balloon could be in­ kilogram (33 pound) gondola that the satellite orbiting Mars and relayed to cluded in the next Soviet mission to balloon carries aloft; hanging 100 me­ Earth. Mars, as a follow-on to their successful ters (300 feet) below the balloon is a use of balloons in Venus' atmosphere 13.5 kilogram (30 pound) guide-rope, Data Bottleneck (see the January/February 1987 Plane­ part of which touches the ground at The Venus balloons deployed by the So­ tary Report). night. Component responsibilities are viets in 1986 did indeed transmit direct­ When I heard about it from my friend divided as follows: The Soviets are re­ ly to Earth but at an exceedingly slow Slava Linkin of the USSR Space Re­ sponsible for balloon inflation, the rate: for 300 seconds out of every half search Institute, I proposed building a French for making the balloon, the So­ hour they sent 4 bits per second to the balloon that could lift off in the morn­ viets for making the gondola and the largest and most sensitive antennae ing (as the Sun heated the atmospheric French for making the guide-rope (with available on Earth. One picture-500 by gases within the balloon), fly during the the help of The Planetary Society). 500 pixels (picture elements)---contains day only and sit on the ground at night What the balloon could do was clear 2 million bits; transmitting one such pic­ (see the May/June 1987 Planetary Re­ from the start: It could gather data need­ ture directly to Earth would take three port). Initially, this system needed two ed to engineer future landings of rovers days of uninterrupted reception. balloons; since then an in-depth study and various other packages on the mar­ Therefore we planned from the start by the French space agency CNES tian surface. At that time the United that a Soviet satellite would be avail­ (Centre National d'Etudes Spatiales) States and the Soviet Union both envi­ able for relaying the data. The orbit has shown that the same flight profile sioned missions to Mars that would cul­ would be eccentric (highly elliptical) can be achieved with a single bal­ minate in sample returns. As part of a with its apogee, or farthest point, be­ loon-and that is the present design to precursor mission, the balloon could tween 10,000 and 20,000 kilometers be put aboard the Soviet/French mis­ take zillions of high-resolution pictures, (6,000 to 12,000 miles) from the sur­ sionMars '94. measure infrared reflectance of rocks face of Mars. (The orbit's eccentricity is After a Franco-Soviet workshop on and, using electromagnetic waves, necessary to synchronize it with Earth's the shores of the Black Sea in Sep­ sound the subsurface to a depth of one rotation so that the spacecraft can be in tember 1986, the proposal gelled into kilometer (0.6 mile). Able to travel position to communicate with the Sovi­ an agreement and both sides started to more than a thousand kilometers during et tracking station.) The relay could re­ study in earnest what a martian balloon its mission, the balloon could explore ceive signals from the balloon for only could be and do. many sites. one hour twice per day at an average A main design premise of today's distance of around 10,000 kilometers. A Very Light, Very Large Balloon planetary missions is that resources are Under such conditions the balloon's What the balloon could be was not easy limited to what you bring from Earth. electrical power supply could manage a to decide: God did not create the atmo­ For instance, the balloon carries a limit­ transmission rate of 16 kilobits per sec­ sphere of Mars to be flown in by human ed mass of buoyant gas, and we have ond. That translates to-assuming the contraptions. The atmospheric density had to design the balloon to survive and best possible case-about 60 pictures at ground level is, at best, no greater fly as long as possible on that fixed per day. (continued on page 7) 5

n I

(continued from page 5) of May 1987 at the Jet Propulsion Labo­ to "see" Mars Observer twice each day, Suppose we want our camera to re­ ratory (JPL) in Pasadena, California. in the afternoon and in the early morn­ solve.features as small as 10 centimeters The first task given to the group was to ing. (4 inches) so that we can document a assess, urgently, what improvements From orbit to orbit, the shortest dis­ landing site for a future Mars rover. Ev­ could be made to the payload of the tance between Mars Observer and a ery picture (500 by 500 pixels) will Mars Observer. The launch of Mars ground station could be anywhere be­ show us a patch of martian surface mea­ Observer, a NASA mission to study the tween 360 kilometers (if directly over­ suring 50 by 50 meters (160 by 160 climatology and surface geology of the head) and 900 kilometers (600 miles) feet). Given these conditions, one day's Red Planet (and well known to members -much less than the average 10,000 transmitted data would cover an area of of The Planetary Society, who supported kilometers between the Mars Balloon and only 1,000 by 300 meters (3,000 by it massively through its vicissitudes), the Soviet Mars '94 spacecraft. Thus we 1,000 feet). had just been postponed for budgetary would use far less of the Mars Balloon's Remember, the point of sending the reasons from 1990 to 1992. Therefore, battery power for transmitting if we Mars Balloon is to get zillions of high­ in 1987, there was a little time available placed a relay on Mars Observer, and for resolution pictures. But with a bottle­ for some slight modifications. the same power we would get much more neck in the relaying of picture data back On May 22, during a splinter group data. to Earth, the outlook was dim. Some­ meeting, my mind wandered some­ I immediately consulted a few knowl­ thing had to be done. where outside the room and an idea edgeable friends in the working group suddenly struck me: Mars Observer and was unanimously encouraged to My Mind Wandered . .. would be placed on a circular orbit, think more deeply about this fledgling At the end of 1986, NASA created a timed in such a way that the spacecraft idea. After some homework, I found working ' group under the chairmanship would always cross the martian equator that a small antenna placed on the Mars of the world-renowned Mars expert at two o'clock in the morning and two Observer could provide a data retrieval Michael Carr of the US Geological Sur­ 0' clock in the afternoon, at the constant rate as high as 160 kilobits per second, vey to help define the scientific objec­ altitude of 360 kilometers (230 miles). compared to 16 kilobits per second for tives of a possible Mars Rover/Sample That meant that any station on the mar­ the Soviet spacecraft. As I faxed to the Return mission. I was appointed a mem­ tian surface, whether fixed or slowly working group chairman: "Since the ber of this group, which met at the end moving like the balloon, would be able balloon mission is power limited, the 7 first guess seems to indicate that the gondola transmitter that did not exist 1,000 seconds--depends on the relative presence of a receiver on Mars Observ­ yet even in concept. That was Novem­ positions of the balloon and the space­ er would be of great benefit to the bal­ ber 1987. craft. loon mission and also to the small per­ The balloon gondola first empties its manent stations we want to propose to Behind Closed Doors 32-megabit memory of the data collect­ the Soviets." In the December 21, 1987 issue of Avi­ ed since the last pass; then it sends im­ At the next meeting of the working ation Week I saw this headline with ages of what it is seeing at that moment, group-<>n June 29 in Houston, Texas­ pleasure: "Soviets Propose Relay Role providing of course the pass is taking I presented the concept, suggesting for Mars Observer Mission." Accom­ place during daylight. During the night that it could be raised at the upcoming panied by a painting of the Mars Bal­ pass, no pictures are taken in real time. first meeting of the US/USSR coopera­ loon by Michael Carroll (commissioned We have included in the balloon cam­ tive agreement group (established that by The Planetary Report), the article era a compression procedure that multi­ year for cooperation between the two said: "The Reagan Administration and plies the number of pictures tenfold; by nations in planetary and other science NASA are seriously studying the Mars relaying data through both the available endeavors). Observer proposal, which could lead to spacecraft, American and Soviet, we ex­ It was then that I learned that the data a low-cost but significant US/Soviet pect to obtain about a thousand pictures system of Mars Observer was "all cooperative effort doubling or tripling per day of balloon life. booked up." To solve this problem, I the amount of low-altitude imagery of The importance of the Mars Observ­ suggested sending the balloon's data Mars that could be transmitted from the er relay to the balloon mission cannot stream through the Mars Observer cam­ Soviet/French mission, set for launch in be overestimated. Very recently, it has era (MOC) and storing it in the MOC 1994." been agreed that the small Soviet sta­ memory. With proper formatting of the A cloud of secrecy had descended tions placed on the martian surface dur­ balloon data, the MOC data system from the Top: There was no hint of the ing the Mars '94 mission will also use would not distinguish these data from progress of the relay idea through the the Mars Observer relay. its own, and no change to the spacecraft Government of the United States; no hardware would be required. Without third partner, and especially no minis­ Everybody Is Happy this trick, the proposal would have cule froggies, would be admitted to the From a political point of view, the Mars stopped there. august assembly of the superpowers Balloon relay is palatable to both sides discussing their business on a strictly since it has high visibility as coopera­ More Meetings bilateral basis. tion yet does not create a lot of technol­ The idea of the relay was received en­ Let us not follow the tortuous itin­ ogy-interface problems for them to thusiastically and included at the top of erary of the idea through the bureau­ solve. It is French equipment integrated the list of recommended modifications cratic maze. It took about one year for into the spacecraft by French engineers. to Mars Observer. NASA Headquarters the decision to be reached: The French CNES is happy to participate since the reacted immediately, initiating a prelim­ space agency CNES, acting as a sub­ relay improves the scientific value of inary study. The concept survived the contractor to the Soviets (and paying for the balloon mission, and also because it study, and from a technical point of the entire system), agreed to provide the continues the French space agency's view looked better and better. relay to JPL. The bilateral agreements tradition of working actively toward a Now I had to scale a high mountain: are still not signed, even though the rapprochement of the major space pow­ convincing the American, the Soviet equipment is being built in Toulouse by ers. NASA is happy because American and the French space agencies to accept the French company Alcatel-Espace, scientists and engineers will have im­ the idea of an American facility as a which is under contract to CNES. mediate and direct access to data need­ major subsystem of a Soviet mission. ed for the future exploration of the Red Perestroika had not yet been accepted 1,000 Pictures a Day Planet. The US agency is paying for the as a political fact. The Mars Balloon relay system, as it is mechanical interface between the Slava Linkin, as a delegate in the implemented now, draws upon expe­ spacecraft and the relay antenna. USSR cooperation group, agreed to rience with the EOLE project, which I Everybody is happy about the Mars raise the issue as a Soviet proposal: The proposed to CNES in 1963 and which Observer relay--cheap and sanitized. I Mars '94 project would provide a re­ flew successfully as a US/French study was proud to fmd it as an individualized ceiver for inclusion in the Mars Ob­ of Earth's atmosphere in 1971. CNES item in President Bush's 1991 NASA server mission. The US satellite would launched 500 balloons designed to float budget, a $2 million project alongside arrive at Mars in 1993, perform its tasks at an altitude of about 20 kilometers other items with price tags in the hun­ and then serve as a relay for the balloon (60,000 feet) and take atmospheric dreds of millions of dollars. There must launched in the martian atmosphere by readings; then a French spacecraft, be a reason. the Soviet spacecraft. launched by a NASA Scout rocket, re­ All I need hope for now is that all the Now the relay proposal was in the layed the meteorological data obtained partners will still be alive in October hands of others-I was "out of the by the balloons. 1995, when the Mars Balloon is sched­ loop," but still had the technical work to The operational outline is similar for uled to begin its cross-country trek on do. I have a painful recollection of sit­ Mars: the French box on Mars Observ­ Mars. ting one day in the Space Research In­ er sends a signal that triggers the elec­ stitute, just myself and Andre Ribes, a tronic package aboard the balloon, Jacques Blamont, Professor of Physics bright engineer from CNES' Toulouse which replies to Mars Observer at 128 at the University of Paris and Chief Space Center, writing the specifications kilobits per second. The duration of the Scientist at CNES, has been a Plane­ B for a system receiving signals from a transmission-from 300 seconds to tary Society Advisor since 1981. The Key to Mars, TItan and Beyond? Nuclear Rockets Using Indigenous Propellants

by Robert M. Zubrin

ack in the 1960s, when NASA last was serious about launching a human mission to explore Mars, a program was initiated to de­ velop a new kind of rocket engine.B A "classical" rocket works by burning a chemical propellant and di­ recting the exhaust gases out through a nozzle, thus providing thrust to drive the rocket (see the March/April 1990 Planetary Report for more background on rocketry). This new engine, called NERVA (Nuclear Engine for Rocket Vehicle Appli­ cations), was to have an exhaust velocity twice that of the best possi­ ble chemical engines. The increase in exhaust velocity was a big step forward in preparation for a human mission to Mars, cutting the mass required for such a mission to less than half. The principle was simple enough: Using a nuclear reactor, heat hydro­ gen to high temperature and exhaust it out a rocket nozzle. And it worked. More than 20 NERVA engines were built and successfully ground-tested with power levels between 40 and 4,000 megawatts, thrust levels up to 100,000 kilograms (200,000 pounds) and the desired ultra-high exhaust Early visions of spacecraft to carry humans to the planets bore little resemblance to the eminently functional velocities. A flight test model of but awkward-looking craft that have carried us to Earth orbit and the Moon. As exemplified in this Mars land­ ing craft painted by Chesley Bonestell. sleek winged rockets carried out the space exploration imagined in the NERVA was being prepared when, 1940s and 1950s. (The 1954 film The Conquest of Space cinematizeiJ this view of a glider landing on a martian in 1972, the whole program was desert.) If future human explorers use advanced propulsion systems such as those described in this article, cancelled after the Nixon administra­ sleek winged rockets may yet become reality. Painling: Chesley Boneslell, coullesy Space All Inlernalional tion eliminated NASA's post-Apollo plans for human exploration of Mars. Today, as we once again think of openirig up the Red Planet, it makes make use of any gas as propellant, of the mission while increasing its sense to re-examine NERVA techno­ including gases found naturally on capability. logy. In addition, there is a way to use extraterrestrial bodies. Therefore, if nuclear engines-not examined dur­ we design a spacecraft that can refuel NIMF: Hopping Around on Mars ing the NERVA program-that can itself on Mars, rather than carrying The atmosphere on Mars is 95 per­ radically benefit space exploration: round-trip fuel from Earth, we will cent carbon dioxide (C02), Ordinari~ In principle at least, these engines can drastically reduce the mass and cost ly, nobody would consider CO an 2 9 r------~------

ideal propellant for a nuclear engine. While such an approach can reduce would only need to carry enough for This gas can only achieve an exhaust the mass of a piloted Mars mission, a one-way hop. velocity of 2.75 kilometers per sec­ the problem is that the energy required At some point the need to carry ond (km/s) when superheated to for such chemical synthesis (about round-trip propellant becomes too 3,000 kelvins in a nuclear engine, 100 times greater than required for burdensome. The CO/02 chemical which compares rather poorly to the simply acquiring CO2) implies a pow- hopper has an exploratory range of 4.5 km/s performance only about 1,300 kilo­ available from a good meters (800 miles) chemical engine using liq- from base camp, and uid hydrogen/oxygen, or the methane/02 hopper the 9.0 km/s in a hydro- Key Terms can go as far as 2,200 gen-fueled NERVA. kilometers (l,400 On the other hand, all miles) before turning Nuclear engine: an engine that uses a nuclear reac­ that martian CO2 is there back. When returning for the taking. At the tem­ tor to heat a single chemical substance~such as hydro­ to base, the chemical peratures that prevail on gen, water or carbon dioxide~to produce hot exhaust vehicle must land pre­ Mars, CO2 can be liquefied gas for rocket thrust. For example, if water were the pro­ cisely on target: If it simply by compressing it pellant. such an engine would be essentially a flying lands a few miles off to about 100 pounds per steam kettle. course, there is a risk it square inch, or six to seven may never be refueled, Exhaust velocity: the speed of propellant gas as it is times Earth's sea level at­ as transporting large fired out of a rocket nozzle. We want the highest possible mospheric pressure. A quantities of chemical landing vehicle of 40 met­ exhaust velocities because the greater the exhaust veloci­ propellant from the ric tons sitting on the sur­ ty, the less propellant is required to attain the desired ve­ base over the rough face of Mars would easily hicle velocity. Less propellant, of course, means less mass martian terrain may be able to fuel itself for a to carry on the mission. prove impossible. flight into orbit in about Thrust: the force with which a rocket engine pushes on five days. The pump used the spacecraft; measured in pounds or newtons (1 pound Water Power Carbon dioxide may to compress CO2 for fuel of thrust =4.45 newtons). Vehicles traveling in deep would need only 100 kilo­ not be the only NIMF space can get by with very little thrust, but a vehicle like watts (134 horsepower), propellant available on produced by running the the NIMF, which takes off from a planetary surface, must Mars. Many scientists 2,000 megawatt engine re­ have thrust greater than its weight if it is to get off the believe that Mars pos­ actor at very low power. ground. sesses large quantities In half that time, this Power: measured in megawatts, the power of a of water in the form of

CO2 hopper could fuel rocket engine is proportional to the product of thrust permafrost or even ice itself for a suborbital hop times exhaust velocity. The NIMF engine needs about covered by a few feet of some thousands of kilo­ 2,000 megawatts of power. of sand~after all, the meters (or, if it is a winged planet seems once to Bipropellants: two chemicals, such as hydrogen and craft, supersonic flight for have had flowing oxygen, that are combined and burned to produce hot similar distances). Such a rivers. craft would then land and exhaust gases for rocket thrust. If water is accessible, refuel itself again, thus giv­ Kelvin: the scale of temperature that begins at abso­ it could make an attrac­ ing astronauts unlimited lute zero, the temperature at which molecules are almost tive NIMF propellant, mobility for planetary ex­ "stationary." We use the Kelvin scale because it reflects yielding an exhaust ploration. I call this vehicle the energy content of a gas, which is proportional to its velocity of 3.4 km/s. a NIMF, for Nuclear rocket temperature in kelvins. Subtract 273 from the temperature This level of perfor­ using Indigenous Martian in kelvins to obtain the equivalent in degrees Celsius. mance is good enough Fuel. to allow a piloted NIMF vehicle to ascend from Chemical vs. Nuclear the surface of Mars and It has been proposed that propel itself directly chemically fueled Mars back to low Earth orbit landing and ascent vehi- (LEO). A robotic NIMF cles and hoppers could also use in- er source that is too large to travel could probably do this with CO2 pro­ . digenous propellants. For example, with the vehicle. Thus a convention­ pellant, if we stretch the engineering martian CO2 could be split into CO ally fueled craft would need a base a bit. (carbon monoxide) and O2 (molecular camp with a large power supply and If water is available on the martian oxygen) bipropellants. Or, if water is chemical-engineering infrastructure. moon Phobos, a NIMF could travel to available, methane (CH4) could be For any sortie from the base camp it Earth orbit and then back to Phobos synthesized and burned with oxygen would have to carry enough propel­ (or Mars), without any additional pro­ 10 in a rocket combustion chamber. lant for the round trip. The NIMF pellant from Earth. NASA is current- l ly studying the concept of breaking tation, and a small ascent vehicle. requires about six launches of a down Phobos water into propellants The reason for using a detachable heavy-lift vehicle to deliver 700 or that would allow a chemical vehicle lander, rather than landing the entire more metric tons to LEO, as well as to perform the same maneuver. [The spacecraft, is to minimize mass: Any an extended and expensive effort in environmental consequences of min- mass lowered to the planet surface assembling the six payloads in orbit. ing Phobos or other solar system will require fuel to return to space, Another advantage of a NIMF bodies still need to be assessed. See and that ascent-fuel means additional mission is that the science return will "Phobos- A Surface Mine or an In- mass. Furthermore, if this fuel has to be much greater: Instead of being ternational Park," September/October be transported from Earth, still more limited to the single landing site of a 1988 Planetary Report.] But the ener- fuel, and mass, are required to get to conventional mission, the NIMF will gy needed to break water into hydro- Mars in the first place. The total mass be able to visit dozens of locales. gen and oxygen and then refrigerate and cost of the mission multiply. Furthermore, when it returns from them to liquefying temperatures for With the advent of NIMF, any Mars, the NIMF can be "parked" in use as fuels is 500 times that required mass landed on Mars can be lifted to LEO and reused. To send the next to melt the ice into water as propel- orbit using propellant readily avail- Mars mission will thus require only 60 lant for the NIMF (and the technolog- able on the ground. Thus we can metric tons to be lifted to LEO (100 ical complexity of the equipment abandon the concept of detachable metric tons less the 40 metric tons of needed for chemical processing and landers and orbiting mother ships the NIMF). With cheap, repeatable refrigeration would be considerable). altogether, and instead land the entire access to Mars, we'll be on the way spacecraft, living quarters and all, on toward settlement of the Red Planet. Nuclear Byproducts the planet surface. If the NIMF and There's no such thing as a free lunch the interplanetary vessel are one and On to Titan even for a system with the simplicity the same, then all that need be left in Mars is not the only potential port of and versatility of NIMF. One chal- orbit is an automated propulsion unit call for nuclear rockets using indige- lenge to overcome in development of with fuel and supplies for the return nous propellants. Water ice exists in nuclear engines arises from the fact trip to Earth. nearly pure form on Jupiter's moons

that CO2 or water, when heated to Under the conventional thinking, Europa, Ganymede and Callisto; on very high temperatures, will become a piloted Mars mission requires that Saturn's moons Enceladus, Tethys, an oxidizer and severely corrode the two complete sets of living quarters Rhea and Dione; and on Uranus' carbide fuel elements developed in be driven to Mars, one for the orbiting moons Ariel, Umbriel, Oberon and the early NERVA program. We will mother ship and one to be abandoned Titania. Along the way, ice may also have to develop new types of fuel on the surface. By eliminating the be found on the asteroid Ceres and on elements for the NIMF, probably of extra set of living quarters, as well as several Trojan asteroids (which are uranium-thorium oxide (whose melt- the landing/ascent vehicle and asso- clustered 60 degrees ahead and 60 ing point is 3,300 kelvins) surrounded ciated propellant, a NIMF mission degrees behind Jupiter as they orbit by a layer of oxide of nonfissionable can cut the total mass of a Mars trip the Sun), as well as in the cores of material (this layer will prevent by a factor of three. comets. Thus there are numerous radioactive products from migrating bases from which water-fueled NIMF into the propellant exhaust). To Mars in One Launch spacecraft might carry out the explo- On the issue of nuclear safety, I In fact, a complete Mars mission can ration of the solar system. A winged should note that because they would be started from LEO with a mass of automated NIMF using atmospheric

operate at high power only for short about 100 metric tons if we use a 3- CO2 as propellant could conceivably periods, NIMF engines would typi- person/40-metric-ton NIMF space- explore Venus' surface, collecting , cally contain about one millionth the craft, which is conveyed from Earth ground samples and performing radioactive material of today's civil- orbit to Mars orbit (and Mars orbit to low-level aerial reconnaissance from ian nuclear power reactors. This small Earth orbit) by a hydrogen-fed every part of the planet and then quantity is easy to shield effectively NERVA "tug." Delivering this entire returning to orbit. and, in case of mishap, represents no mass to LEO is within the capability But to my way of thinking, the significant threat to the martian envi- of the proposed NASA launcher most exciting target of all for post- ronment. Shuttle Z or the Defense Department's Mars NIMF missions is Titan, Sat- Advanced Launch System, not to urn's largest moon, a world whose Mother Ship Syndrome mention the already flown and tested nitrogen and methane atmosphere, , The NIMF concept, in addition to Soviet Energia. (For more on these postulated hydrocarbon lakes and making it easy to get around on Mars, launch vehicles and Mars mission lift oceans, and continents of rock and makes,possible a drastic reduction in requirements, see articles by Ivan water ice contain in great abundance the mass and cost of a Mars mission. Bekey, Jerry Grey and Saunders all the elements needed for the origin Since the days of the Apollo program, Kramer in the March/April 1990 of life. Indeed, many scientists think it has been axiomatic that a piloted Planetary Report.) that the chemistry of Titan may planetary mission requires a combi- In other words, we can accomplish resemble in certain respects that of nation of an orbiting mother ship (con- a piloted Mars mission in a single Earth during the period when life be- taining long-term living quarters), a launch. This is in sharp contrast to gan. But Titan is frozen in time by the landing craft providing surface habi- the conventional approach, which slow rate of chemical reactions in a 11 low-temperature environment. While A mission that could penetrate Titan's life may never have evolved on Titan, clouds, perform a low-level aerial humans may one day use some of its reconnaissance and bring back samples billions of tons of readily accessible from Titan's air, land, sea and sub­ carbon, nitrogen, oxygen and hydro­ marine regions would be of immense gen, together with such "imports" as scientific interest. A NIMF can ac­ reactor-generated heat (converted to complish such a mission. electricity at 80 percent efficiency with the aid of Titan's very low tem­ Aviator's Paradise perature), seeds and a few breeding What I propose is a small automated pairs of livestock, to create a huge NIMF Titan Explorer (NIFTE) with agricultural base within an artificial foldout wings and a NERVA engine. biosphere. [The idea of transforming The NIFTE-with a dry mass of eight Titan into a world useful to human metric tons (including a scientific industry is controversial. Some feel it payload of two metric tons) plus its might be important to preserve this ten metric tons of hydrogen propellant planet-sized laboratory on the origin when fully fueled--could be lifted to of life in its pristine state.] LEO by a Titan 4 or the space shuttle. Because of its thick, cloudy atmo­ The hydrogen propellant would power sphere, Titan's surface is not visible a four-year course to Titan, where the from space; the Voyager cameras NIFTE would use the atmosphere for returned only images of a fuzzy, braking, open its wings and commence orange ball. Many essential facts slow-moving, air-breathing aerody­ about this world remain mysterious. namic flight.

RIGHT: One of the many exciting missions beyond Mars made possible by NIMF technology is the exploration of Saturn's largest moon, Titan. After a four-year flight from Earth, the automated spacecraft called NIFTE unfolds its modest-sized wings, taking advantage of Titan's high atmospheric density and low gravity to perform a low-altitude, low-speed recon­ naissance of the entire satellite. To collect samples for scientific study, the NIFTE releases small, tilt-rotor aircraft that can land and takeoff from solid ground or ocean and can even explore submarine regions. Its exploration completed, the NIFTE fills its tanks with liquid methane from Titan's atmosphere and rockets back to Earth with a massive science return from this mysterious cloud-covered world. Painting: John Tieleman, Martin Marietta Astronautics

RIGHT: In a surface­ hopping configuration, the NIMF vehicle might have its para­ chute compartment on top with the control deck and habitation deck below. In the midsection of the craft CO2 compressors sit atop the main propel­ lant tank, and under­ neath is a nuclear reactor, surrounded by a secondary, donut­ shaped propellant tank for extra shielding. Painting: Robert Murray, Martin Marietta Astronautics

12 Titan, with one-seventh Earth's empty hydrogen tanks would contain gravity and four and a half times up to 64 metric tons. The refueled Earth's atmospheric density, is an NIFfE could then make round trips aviation paradise: A NIFTE flying at to the surface of every other satur­ 90 kilometers per hour (55 miles per nian satellite except Mimas (which hour) would require a wing area of would be out of range), or it could only 20 square meters (70 square make a rapid (two-year) return to feet) to remain airborne. (A human Earth. standing on the surface of Titan Thus, in a single mission, we could could strap on wings and fly like a explore Titan and prospect Saturn's bird.) As the NIFTE cruises along, it other moons and, even more impor­ could dispatch smaU electric-powered tant, test and prove a transportation aircraft (which could take the form of system that will enable humans to mini-helicopters, tilt-rotor seaplanes, venture to the saturnian system. dirigibles or even flying submersibles) Worlds await human explorers­ to retrieve samples from Titan's land Mars, Jupiter's moon Ganymede, and sea. Titan, even Neptune's Triton. Nuclear With its exploration of Titan rockets using indigenous propellants complete, the NIFfE would fill its can open up the entire solar system propellant tanks with methane from to humanity. the atmosphere. In the NERVA-type nuclear engine, methane is a high­ Robert M. Zubrin is Senior Engineer performing propellant (exhaust at Martin Marietta Corporation's velocity 5.4 km/s), and the NIFTE's Astronautics Division.

LEFT: The rocketplane version of a NIMF could attain supersonic (Mach 3 to 51 aerodynamic flight with modest wing area, even in Mars' thin abnosphere. MVinged flight allows for greater exploratory freedom and flexibility; this craft would also be able to propel itsell out of the abnosphere to orbit. Painting: Roben Murray. Martin Marietta Aslronautics

13 1 ------:---....,

by Agustin F. Chicarro

uring the last quarter century, robotic spacecraft have taught us much about Mars. Although it is Dgeologically less evolved than our world, Mars is far more Earth-like than any other planet in our solar system. Mars has evolved over the past few billion years as internal pressures deformed its crust, volcan­ ism reshaped its face, and meteorites and comets bat­ tered its surface. Still, Mars is the most Earth-like plan­ APPROXIMATE et, with an ancient environment that seems to have PENETRATION been even still more Earth-like. Therefore, Mars is an obvious target for us in the search for present or extinct DEPTH IN lifeforms. SOFT SOIL The European Space Agency (ESA) has formed a APPROXIMATE team to study outstanding questions about the nature of PENETRATION Mars and to determine how European space scientists DEPTH IN and engineers might contribute to their resolution. We HARD SOIL recently published the results of our investigation, enti­ tled Mission to Mars: Report of the Mars Exploration Study Team. Here are some of our conclusions:

Scientific Objectives: The future international explo­ ration of Mars must address major scientific questions, such as: -What is the present internal structure, composition and geologic activity of the planet? -Why has the northern hemisphere been more geo­ logically active than the southern hemisphere, which retains more scars of ancient cratering episodes? -What is the chronology of its tectonic phases in which internal forces deformed the crust? -What are the most common minerals in martian rocks? -How has the martian atmosphere changed? -What is the present distribution of surface and sub- surface water? -When did liquid water flow on the surface of Mars? -How closely did early Mars resemble Earth when life appeared on our planet about 3.8 billion years ago? -Are there sediments on Mars containing organic compounds or fossils?

Strategy: After analyzing the key scientific issues, ESA has identified three possible areas of European participation in the exploration of Mars. Several strong . requirements shaped our study, including the need for a major and novel scientific return; use of state-of-the­ art technology, now available or under development in Europe, to maximize scientific return within limited financial resources; and adaptability to American and Soviet missions to Mars now planned for the near 14 future. Network Science: An array of small surface stations, including two surface penetrators (Figure 1) and a cluster of three mini-probes (Figure 2), would define a seismological network. After taking atmospheric mea­ surements during their descent, these small stations would land at scientifically interesting sites (Figure 3). They would be designed to operate for one martian year. The returned data would help define the planet's structure, its mineral and chemical composition and its surface meteorology. This network would be part of a precursor mission to a Mars Rover/Sample Return effort and to human exploration. Rover Science: A complex sample-acquisition subsystem, including an intelligent robotic arm, would be placed on board a rover from another space agency (Figure 4). The subsystem would be capable of stereo­ vision as well as handling and sampling rocks and soil. It would analyze chemical and mineralogical samples, study subsurface structures, perform biological experi­ ments and take atmospheric measurements in several locations within its area of mobility. This sampling subsystem could contribute to a Mars Rover/Sample Return mission. Orbiter Science: A facility on board an orbiting spacecraft would acquire very detailed images, provide radar altimetry and subsurface sounding, help identify the mineralogical and chemical composition of surface features or study atmospheric processes. This orbital facility would include an advanced imager, a micro­ wave radar instrument or a lidar (a laser atmospheric sounder), and would have scientific potential for any surveillance mission to Mars. The technology could be adapted to many mission scenarios.

International Cooperation: Any of these areas of possible European participation would represent a major and independent contribution to future interna­ tional missions to Mars; some would complement the already scheduled American Mars Observer and the Soviet Mars' 94 missions. ESA is now conducting in­ depth technical and scientific assessment studies, with emphasis on the network mission. Following the coop­ erative path initiated by Cassini (a joint US-European mission to the Saturn system), such participation in international planetary missions stands as a sensible and viable approach for Europe to take its proper place in the exploration of the solar system in the next decade and beyond.

Agustin F Chicarro is Study Scientist for Mars Explo­ ration at the European Space Agency. 15 ------

The Evolution of Comets in the Dort Cloud

by S. Alan Stern tretching over one thousand times cometary material really is, and how as far from the Sun as Pluto, a vast much they have been modified during Ssphere of comets called the Oort their long stay in the Oort Cloud. Cloud surrounds our solar system. This frozen reservoir likely contains over a Radiation Damage trillion icy comets ejected from the plan­ The first indication that comets evolve in etary region as the giant planets formed the Oort Cloud came in the early 1980s some 4.6 billion years ago. when researchers, including Yugoslavian In 1950 Jan Oort published a land­ astronomer I. G. Draganic, Fred Whip­ mark paper deducing this cloud and de­ ple of Harvard, Louis Lanzerotti of Bell scribing its origin. Until just a few years Laboratories and Robert E. Johnson of ago, scientists believed that comets had the University of Vuginia, began calcu­ been peifectly preserved since their exile lating the radiation dose comets receive to the Oort Cloud. On first inspection, in the cloud. They found that cometary this idea seems reasonable. After all, surfaces are likely to be heavily dam­ during the four-billion-year night be­ aged by cosmic rays, very high energy tween their ejection from the planetary particles that can penetrate many meters region to today, comets experienced am­ into comets. Using measurements of flux bient temperature only a few degrees of cosmic rays in space, they calculated above absolute zero (minus 273 degrees that cometary surfaces may have been Celsius), far too cold for any chemical hit by tens of trillions of cosmic rays per evolution to take place. Compared to square centimeter over the age of the so­ temperatures in the Oort Cloud, condi­ lar system. These particles disrupt mo­ greatly over time. tions on Triton-a relatively sweltering lecular bonds, ionize atoms and mole­ Computer models that simulate the minus 236 degrees Celsius-would cules, and induce chemical reactions variation in sticking and erosion rates as seem to be a veritable Miami Beach! along their paths. the Sun orbits the center of the galaxy To understand the significance plane­ The next indication that Oort Cloud indicate that between 60 and 600 grams tary scientists place on comets, we must comets change came as a result of my (2 and 20 ounces) of material may have know a bit about what they are. The own research. Late in 1985, I began to been lost from each square centimeter Giotto and Vega probes to Halley's examine whether the Oort Cloud's inti­ of cometary surface. Thus, if comets Comet showed that comets are rich in mate relationship with the surrounding have surface densities similar to water frozen water, carbon dioxide and other galactic environment might modify ice, several meters of material may ices, mixed with dust particles, much as comets. Far from being empty, the space have been stripped away. If their densi­ predicted by Harvard astronomer Fred between the comets is instead filled by a ties are more like snow, tens of meters Whipple's "dirty snowball" model. (See current of gas and dust that we call the may have been lost during their stay in the July/August 1985 Planetary Report.) interstellar medium. the Oort Cloud. In any case, this ero­ Having been stored in the deep freeze of Owing to the solar system's motion sion may erase much or all of the radia­ the Oort Cloud, well out of the warmth around the galaxy, these gases and dust tion damage that cometary surfaces ex­ of the planetary region, comets are likely flow through the Oort Cloud at typical perience. to be nearly unchanged relics of the so­ speeds of 20 to 30 kilometers per second lar system's birth. This makes them an (l0 to 20 miles per second). Although Getting Heated Up important target for scientific study and some interstellar gas molecules stick to In 1987, astrophysicist Mike Shull of the spacecraft exploration. Indeed, NASA is cometary surfaces, collisions with mi­ University of Colorado and I began to now preparing the Comet Rendezvous­ croscopic interstellar grains slowly but study the thermal effects that passing Asteroid Flyby (CRAF) mission for a continually sandblast away cometary stars have on comets in the cloud. Stars 1995 launch and a rendezvous in 2000 surfaces. This erosion is much more effi­ have long been known to penetrate the with comet Kopff, a former Oort Cloud cient than the build-up of gas molecules, Oort Cloud regularly. Indeed, Oort him­ denizen perturbed into the planetary re­ and the net effect is to strip away self recognized errant stars as a major in­ gion. comets' outermost layers while they are fluence on comets' orbits around the With so much effort being invested in in the Oort Cloud. Because the interstel­ Sun. Over time about 6,000 stars have understanding these frozen messengers lar medium contains some regions that probably passed through or near the Oort from the genesis of our solar system, it are rarefied and others that are more Cloud. Shull and I constructed a com­ 16 is important to ask just how pristine dense, this sandblasting effect varies puter model of the encounters between stars and the Oort Cloud to determine Galactic Influences this work. During its two-year-long ren­ how much heating each comet has re­ Heating from passing stars and super­ dezvous, CRAF will fly in formation ceived from passing stars. novae may have leached out the most with comet Kopff, while sensors on the We found that the great majority of easily evaporated cometary constituents spacecraft and in a penetrator probe de­ stars heat the comets very little. Most and generated complex chemical reac­ termine the comet's mass, composition stars, being only about as luminous as tions in the comets' surface layers. If and surface properties. Later, perhaps as our Sun, simply cannot heat much of the estimates of the conductivity of cometary early as 2010, a joint NASA/European cloud to interesting temperatures when ices are accurate, the effects of passing Space Agency mission known as Rosetta they pass by. However, occasionally, a stars and supernovae may have penetrat­ is intended to return samples from a very bright O-type star (several hundred ed tens of meters below the cometary comet to laboratories on Earth. thousand times as luminous as our Sun) surfaces. As we prepare to send CRAF and Ros­ will pass through or near the cloud, sub­ Together, cosmic rays, interstellar etta to comets, we now realize that in ad­ stantially raiSing the temperature of all grain erosion and stellar heating have dition to learning about the origin of our the comets. By carefully modeling the driven Oort Cloud cometary surfaces to solar system, we will also learn about the encounter rates of various stellar types, evolve significantly. These evolutionary galactic environment through which the we estimated that most Oort Cloud influences are inevitable in the galactic Sun has traveled. We also now recognize comets should have been heated at least environment. By neglecting these influ­ that truly pristine material from the solar once by a passing luminous star to a tem­ ences and calculating the evolutionary system's formation is probably buried perature near minus 250 degrees Celsius. history of comets solely on the Sun's in­ many meters below cometary surfaces. Because the stars pass by so slowly, we fluence, early researchers failed to appre­ As with many things in planetary found that these heating events, though ciate some subtle but important effects. science, our view of the Oort Cloud has rare, each last many thousands of years. Rather than being the perfectly pre­ grown richer and more complex with We also found that nearby supernova serving icebox we once thought it was, time. And our understanding of the en­ detonations, which sometimes approach the Oort Cloud is now perhaps best de­ vironment in which comets-and our a billion times the energy output of the scribed as an icebox whose door is left Earth-reside has also grown more Sun, could heat all the comets in the ajar from time to time. As such, the outer interesting. cloud. This probably happened on sever­ layers of comets, though still the best al occasions, raising temperatures for a preserved relics of solar system forma­ Alan Stern is a planetary scientist at the few weeks to minus 240 degrees Celsius. tion, are likely to have ripened a bit over University of Colorado, Boulder. He likes Probably one supernova has raised tem­ the last 4.6 billion years. to fly, ski and raise his family. peratures as high as minus 220 degrees. Exploring spacecraft will soon test 17 Projects Mercul')' and Apollo predominate in memofles of the space program of the 1960s, but in butween NASA~ lirst tentative human flights in­ to space and the voyages to the Moon came Project Gemini. These missions, which carried crews of two astronauts into Ealth omit, saw the first Ameri­ can spacewalk and dock­ ing in omit Docking skills would be vitally impor­ tant to the Apollo mis­ sions, in which the lunar module would separate from the command cap­ sule, land on the Moon and return the astronauts to the capsule. Here, as­ tronauts in Gemini 6 pho­ toglaphed the Gemini 7 capsule a5Jhey plepared to lendezvous in space. Photograph: NASA

he United States' space program is Exploration Initiative-during cele­ management and restricted new hiring going through a critical period. brations marking the triumph of Apollo to "fresh outs," people immediately out THaving passed the 20th anniver­ 11. In the 20 years since Annstrong and of college. The average age of NASA's sary of the Moon landing, the National Aldrin walked on the Moon, the once top management gradually climbed. Aeronautics and Space Administration bold, aggressive agency matured into a Many career employees stayed beyond (NASA) is now in transition. The veter­ government bureaucracy. normal retirement age, in large part be­ ans who have staffed the agency since While all long-lived organizations cause they were dedicated to the agen­ the glory days of Apollo are retiring in evolve, several developments have cy's mission. large numbers and the reins are being made the changes at NASA particularly Then came new policies making gov­ passed to a new generation. rapid and significant. ernment employment less attractive, At the same time, NASA faces a new Budget limitations, personnel ceil­ followed by the Challenger tragedy in challenge. President Bush chose signifi­ ings and top policy decisions in the 1986. After the disaster the retirement cantly to present his vision of the future 1970s worked against younger employ­ rate at NASA jumped up significantly. 18 in space-now known as the Space ees' advancement to middle and upper Since then there has been a steady out- flow of knowledge and experience from "more optimistic than he has been in the agency. some time" because he believes the If NASA is to rise to the President's space program is on the threshold of a challenges-to culminate in a human major resurgence. Donald Hearth con­ mission to Mars-it must possess the curs: "I see a growing recognition in energy, creativity and drive that sent hu­ Washington, DC that space exploration mans to the Moon over 20 years ago. To is part of the national agenda and that it gain a better perspective on the agency, is time to get on with doing meaningful we talked to several NASA veterans in things in space." two sets of interviews, with the second While Gentry Lee expresses opti­ set following up on two key develop­ mism about the future of the human ments: the appointment of Admiral space program, he is considerably less Richard Truly as NASA Administrator sanguine about the prospects for space and the announcement of the Space Ex­ science in the presence of possible cost " ploration Initiative. overruns on piloted space efforts. Six former NASA officials who have At the other end of the spectrum, made major contributions to the plane­ Norm Ness characterizes his view as tary research program gave us their "pessimistic, in the context that I am a views on the status and the future of the well-informed optimist." US space program: -Philip Culbertson, past Associate NASA Strengths Deputy Administrator, General Manager When asked what they considered and Associate Administrator for Plan­ NASA's major strength, the group gave ning and Policy, now an aerospace con­ a variety of answers. sultant; According to Phil Culbertson, it is the - Donald Hearth, who served as Direc­ agency's ability to tackle "very large, tor of the Planetary Program at NASA very tough systems problems." He adds: Headquarters, Deputy Director of God­ "The state of the art in the analysis, de­ dard Space Flight Center and Director sign, fabrication and operation of ex­ of Langley Research Center and now tremely complex systems owes much to teaches at the University of Colorado at NASA." Similarly, Hans Mark responds Boulder; that it is NASA's ability "to plan and ex­ -Gentry Lee, Mission Operations ecute complicated programs." Manager for Viking, who also served in "NASA has always been the organi­ the Solar System Exploration Office and zation that takes on the 'impossible' as­ on the Ride Committee, and who is now signments-landing on the Moon, land­ writing science fiction novels with ing on Mars and building the shuttle Arthur C. Clarke; - and carries them out in a very visible -Hans Mark, formerly Director of the fashion," Young says. Ames Research Center and Deputy Ad­ In Lee's view, however, NASA's fun­ ministrator of NASA, now Chancellor damental strength has been its "ability of the University of Texas System and a to excite the imagination of its employ­ Planetary Society Advisor; ees and industry associates. This has -Norman Ness, who established and brought immense dedication and caused headed the Goddard Space Flight Cen­ people to put in 60- to 80-hour work ter's Laboratory for Extraterrestrial weeks." Physics before becoming president of At the same time, Ness considers the Bartol Research Institute at the Uni­ NASA's greatest strength to be its her­ versity of Delaware; itage: "It has epitomized in many of its -Thomas Young, Mission Director on projects what is best about the United Viking, Director of the Planetary Pro­ States as a society. Give it a well-de­ gram, Deputy Director of Ames Re­ fined goal. Give it adequate resources. search Center and Director of the God­ Assign the best people to it. And let dard Space Flight Center before going them do their specialties." to work for Martin Marietta Corpora­ tion, of which he is now President. Concerns While their views differed consider­ At the same time, some of the NASA ably, many common themes emerged. veterans expressed serious reservations on several fronts: that the US space pro­ Cautious Optimism gram as a whole has lacked an adequate Most profess at least cautious optimism sense of direction, although President about the future of the space program. Bush's initiative has the potential to For example, Tom Young says he is change things; that NASA hasn't aged LEFT: Sunsets in space became familiar vistas even to those who never left the ground as astronauts and cosmonauts captured on film evocative images like this. taken on December 6. 1965 during the Gemini 7 mission. Such perspectives of Earth are perhaps the most enduring legacy of the early space program. Image: Johnson Space CeIJter. NASA

BELOW: In 1970. a human explorer meets the robot that blazed the lunar trail for him. as an Apollo 12 astronaut examines Surveyor 3. During the 1960s both the United States and the Soviet Union launched a series of spacecraft to investigate the Moon. NASA sent Rangers and Surveyors while the USSR launched Lunas andZonds. Photograph: Johnson Space Center. NASA

well; and that the agency has been ad­ concerns that space science tends to lose NASA officials repeatedly make the versely affected by a growing spirit of out relative to other agency priorities, mistake of trying to justify elements of risk aversion within US society as a such as developing the space shuttle the piloted program, such as the space whole. and, more recently, constructing the station, on scientific grounds. "The jus­ Gentry Lee expresses doubt about the space station. tification [for the space station] is not agency's priorities. NASA's "natural Hearth, however, fears that this inter­ space science or microgravity experi­ tendency," he believes, is to ignore sci­ nal argument has damaged the program ments. The only reason for the space ence unless externally motivated. "We as a whole: "One of my concerns has station is to serve as a zero-gravity labo­ need competitive tension to keep us ac­ been with us since the Apollo program. ratory for human beings to determine if tive in space," he says. Thus the recent It is the seeming inability of policy mak­ we can send men into deep space," he Soviet failures in the Phobos missions to ers, and NASA, and the external com­ says. Mars are cause for some misgiving. If munities involved in space- including the Soviets reduce their planetary pro­ the scientific community-to recognize Aging gram, he is wOfl'Bd that the US program that there are two distinct elements of When asked what changes they have no­ might be scaled back as well. the program with two different con­ ticed in NASA during the years they "It's not fair to say that the US has stituencies. " worked there, several of the veterans abandoned space science. It is simply One aspect of the problem, he says, is commented on the way the agency has that planetary research is such a low pri­ that the constituency for the robotic pro­ aged. ority with the press and with top NASA gram tends to treat the division of the "NASA is getting old. It is caught in management that any major budget space budget as a zero-sum game, in an aging process which it struggles to crunch in the future could totally wipe it which you win by imposing a loss on try to turn around," Culbertson says. out," Lee asserts. the other player. What they don't seem According to Hearth, this problem is Such comments reflect a continuing to understand is that "the manned pro­ partly self-inflicted. "The average age of debate on the proper priorities within the gram has the 'sex appeal' with the pub­ people at NASA today, as compared space program. Our interview subjects, lic that enables NASA to market the with 1962, is so dramatically different and many other members of the space space program as a whole." that it is scary. Today, those with the 20 science community, have long-standing At the same time, Hearth objects that corporate memory are in their 50s and LEFT: During the 1970s NASA operated an orbiting space station where astronauts lived and studied the space around them and the Earth below them. In this image taken in February 1974 during the Skylab 4 mission, an infrared camera looks back at Cape Canaveral (upper right), its point of launch. There has been no NASA space sta- tion since then. Pholograph: Johnson Space Cenle" NASA

BELOW: The Pioneer missions to Jupiter and Saturn, and the Voyagers that followed them to the outer solar system, were spawned during a "Golden Age" of planetary exploration made possible by the race to the Moon. Pioneer 11 flew by Jupiter on December 12, 1974, giving us a perspective and detail impossible from telescopes on Earth. Pholograph: Ames Research Cenle" NASA

really close to retirement. And the finan­ While Young sees progress being the NASA veterans list other side effects cial incentives today are for them to get made on this front, several of the others of the agency's aging process. One is a out. There are a lot of good young peo­ do not. weakening of the engineering capabili­ ple, but the age distribution is definitely "NASA's charter is to do something ties of several of the NASA centers. bimodal. So an important question is fundamentally important, something "Today some of the field centers are so how to get past this gap." that can resuscitate the human spirit. bereft of in-house technical expertise While Young agrees that passing the However, NASA has ossified as an or­ that they can't attend project meetings torch to a new generation is a major ganization. It has been rewarding medi­ unless their contractors are available. challenge, he is more optimistic than ocrity rather than merit. There has been You can't be smart managers and smart some of the others. "There has been a no advancement for young people. buyers if you can't read and understand lot of turnover. A number of people who Someone needs to reinvigorate the agen­ technical specifications," says Ness. have led the progrhlll have left. The real cy from the bottom," Lee says. "I don't know what all the causes are, challenge is to bring in new people to Ness, too, has seen an "increasing but the symptoms are slowly made deci­ lead the program over the next decade. cerebral calcification, a growing mental­ sions, conservatively made decisions, However, I see that happening," he says. ity of assured success and an increasing­ heavy-handed overview on the part of There is general agreement on what ly bureaucratic agency that began Congress and a diffusion of authority must be done to rectify this problem. spending more and more time concerned and responsibility within the administra­ "People went to work at NASA because with paper pushing." tion," Culbertson summarizes. of their pride in the agency. That comes Since "paperwork has become more from leadership and programs. We must important than engineering," projects Growing Risk Aversion give them the tools of competitive take longer and cost more, Ness asserts. As Culbertson's comment suggests, sev­ salaries, support and prestige," Young "Enclaves of power have been set up eral of the veterans perceive the agency argues. The veterans point out that top and the number of checks and balances, as becoming progressively less willing NASA talent can make two to four the number of hoops that people have to to take risks. "NASA is not simply times as much money working for jump through, have increased consider­ afraid of failure, it has allowed that fear aerospace companies as they can work­ ably." to dominate its decision making. In part, ing for the agency. In addition to a growing bureaucracy, NASA is the victim of its own success. 21 one else to do the job. But to tie his hands with a myriad of directives and restrictions is a lousy way to produce a creative and productive civil space pro­ gram. "Also, there are so many review pro­ cesses set up now. There are boards set up at the drop of the hat reporting to ev­ In July 1975NASA erybody up to the President to help flflWthfllastApollo, NASA figure out what to do. lin Earth orbitltl mis­ "For example, the President approved sion to randezvous and dock with a So­ the space station in principle in 1984. viet Soyuz space­ Now, five years later, we've spent about craft. Tlte compet;­ $800 million defining and re-defining tion hfltwflfln the two superpowfllS, which that program. It's had more people on stllrted with thfl race committees reviewing it than the num­ to the Moon, ended ber of people working on it." with the twu contes­ tltnts OIbiting their Young has observed the same trend. hume world tugeth­ "There is now a much higher degree of el. Here the Soyuz oversight by Congress and others now, drifts uutside the window 01 the Apollo as opposed to the past. NASA officials CIlPSU/e. must spend much more time dealing Photograp/t: Johlls«l Space CeI1tetrNASA with this oversight. It is part of the stretch-out and interruption in the devel­ opment of our space transportation sys­ tem. It is part of the country moving to­ ward a more risk-averse society."

An Ideal NASA The view that NASA should remain pre­ The public and the press got to the point If you analyze it, we're probably doing eminently a research and development that they just couldn't imagine that better today than we were 20 years ago." agency was voiced by most of those in­ NASA could faiL So when failure came, Donald Hearth adds "a note of cau­ terviewed. "NASA's role should be the whole roof fell in," Culbertson con­ tion, based on my own experience in leadership in technical areas, doing tinues. NASA." The criticism the agency re­ things that others cannot. It is important Ness explains this increasing risk ceived for underestimating the costs and to focus priorities on those things NASA aversion as part of a larger process: "As complexity of the space shuttle and the is unique at: the advancement of aero­ the costs [of spacecraft] went up, every­ space station programs, and for the loss nautical technology, scientific and tech­ body became concerned. If you had a of Challenger, he feels, has made NASA nological aspects of planetary explo­ failure it was going to be very bad news. even more conservative than before. ration, and man-in-space," Young says. People were also consolidating all of the Hearth worries that the ambitious If NASA is to retain its focus on ex­ experiments on these large observatories scope of President Bush's space initia­ ploration, the agency must face up to so one failure would affect many, many tive might induce the agency "to make what may be a difficult decision. "The more experiments than it had in the past commitments it can't meet," because big question that NASA faces internally when you had lots of small spacecraft." meeting them would require a greater is to what degree should it 'retain opera­ However, Young sees this trend as willingness to take risks. "This could tions responsibility in contrast to devel­ one that is being imposed upon the exacerbate the problem of underestimat- opment responsibility. In the long term, agency by society at large. "As a coun­ . ing cost and complexity. One has to be that must be solved because at a time in try we're becoming more risk averse, as careful in how one responds to high­ the late '90s when we are operating both illustrated by the response to the Chal­ technology projects." the shuttle and the space station and two lenger disaster, to Three Mile Island and or three big observatories, well beyond Chernobyl [nuclear reactor accidents]. Increased External Oversight 50 percent of NASA's budget and man­ We may be losing our appetite for risk­ Another problem for NASA is increased power will be operational," Young ex­ taking because we consider the costs to external oversight. Culbertson com­ plains. be too high. It is a current that NASA ments: Culbertson would like to change the might succumb to." "Congress is trying to play too great a collegial fashion in which space policy role in the program. They are trying to decisions are currently made: "I would Objection and Caution make technical decisions. They are try­ like to see a departure from this posture Hans Mark strongly disagrees with ing to dictate actions to an unbelievable we seem to have gotten into in the last those who feel that NASA has lost its level of detaiL If the President, with the few years where there are a bunch of de­ edge in recent years. "I think you are consent of Congress, appoints an Ad­ partments involved in different pieces of getting some 'great old days' nostalgia ministrator and 22,000 people to do the space and they are all co-equal and from those you are interviewing. You job and they don't like the way he does solve all problems on a congenial ba­ 22 need to talk to people who aren't jaded. it, they should fire him and find some- sis." This is a problem, he says, because r------~------~

NASA, which has the biggest budget for a long time." However, Culbertson human mission to Mars-are "exactly devoted to civilian space, is not equal to admits to "mixed feelings": He believes right." other departments, which are headed by that Truly will be a very good Adminis­ Ness demurs: "The study is very in­ individuals at the cabinet level, such as trator but worries that the agency may complete and to make any comment at the Secretary of Commerce and the Sec­ become more conservative and less will­ this stage of the game is inappropriate." retary of Transportation. "The NASA ing to take risks. He adds: "There were no guidelines pro­ Administrator is not an equal at the Hearth believes that Truly will do vided by the White House. The agency table. So it is hard for him to play poker well in implementing the ongoing pro­ had to essentially fabricate the charge by in that game," Culbertson argues. gram but doubts that he can make a ma­ the President based upon his very gener­ Instead, Culbertson thinks that NASA jor difference. President Bush's initia­ al remarks." should be the US's lead agency in civil tive will be a major challenge to the new l Culbertson is pleased yet cautious in space. "I believe the NASA Administra­ Administrator. "At this point in our na­ his enthusiasm for the initiative. "It has tor should have two roles: He should be tion's history, I'm not sure that Admiral re-energized NASA right now. The the senior among equals of all the agen­ Truly or any recent Administrator can question is does it have a chance at life? cy and department heads, including make a difference. The situation is not Will it survive the administration re­ those who carry the title of Secretary, in analogous to the situation in 1962. Any views, will it survive the congressional determining what our civil space policy Administrator would have trouble con­ reviews, will it survive the budgetary re­ should be. He should also manage the vincing Congress and the people [to take views? If it does, it will put a vitality in organization charged with the responsi­ on the Space Exploration Initiative]." NASA that will be reminiscent of the vi­ bility of carrying it out." tality that NASA had in the mid- '60s." Space Exploration Initiative Hearth sums it up: The Space Explo­ New Administrator, New Hope If the NASA veterans interviewed share ration Initiative "is going to be a very The NASA veterans' responses to Presi­ a new optimism about the agency's fu­ tough sell." dent Bush's appointment of Admiral ture, it is because of the plan President With a new Administrator at the helm Richard Truly as NASA Administrator Bush put forward on the 20th anniver­ and a presidential administration that is ranged from enthusiastic applause to sary of Apollo 11. Most feel that, after willing to put space exploration on its qualified delight. Most feel that he will years of no leadership from the White agenda, things seem to be looking up for make a positive difference to the agen­ House, a President has finally put forth a NASA. President Bush has re-estab­ cy. "He's first class," Culbertson says. vision that NASA can follow. lished a National Space Council, headed Truly is the first astronaut to rise to "I'm much more optimistic than I was by Vice President Quayle, to further de­ agency Administrator, and Culbertson before the President's speech. The final fine US space policy. The glory days of believes "the big difference is that Dick analysis depends on how the implement­ Apollo may be gone, but there are posi­ has straightforward, practical experience ing organization-NASA-reacts to tive signs for the future. in space that we haven't had in NASA what the President has said," Gentry Lee "Hopefully, Congress and the admin­ states. "It should be a call for NASA to istration will understand that the space reinvigorate itself," he adds, "and get agency is like a thoroughbred: You have out the old weight, to get new, young, to give it its head if you are to get the enthusiastic people with dreams in their most out of it," Young entreats. The Viking milsion til Mars romaillB the most ambitious robotic spat:e eyes." milsfon elf8f launcllflll. It waS co".. Hans Mark feels the stepping stones David F Salisbury is a veteran science ceiftflll in the fS6l1s ami /'fIBcIled its laid out by the President-first, a space writer currently working for the Univer­ llestillation in 1976. This paoorama was t:empillld ffom images taken by station, then a lunar outpost, finally a sity of California at Santa Barbara. Viking Lander Zfrom its station on lItopia Pla"itia. M/mIic: MarrlJa/e-lllmnister; WBsbington IlnivlJtSi!y in St Louis by Louis D. Friedman

WASHINGTON, DC-A Lunar Ob­ spectrometer that has been in controlled ety should feel gratified to see this new server has been proposed in NASA's storage since 1972. If placed in a low, direction for US space policy, advocat­ FY 1991 budget. Scheduled for launch polar lunar orbit, this instrument might ed by our organization since 1983. in 1996, Lunar Observer will go into a detect cold-trapped ices. (See the In addition to the guidelines, Quayle near-polar orbit of the Moon and pro­ March/April 1989 Planetary Report.) A sent a letter to NASA directing the vide a large and varied data set, includ­ different private venture, by a group at agency to conduct further studies on ing the first maps of the entire lunar MIT, wants to send robotic micro­ human exploration and to search out­ surface. Of particular interest is the in­ rovers (5-pound walkers) to the Moon side the NASA space community for vestigation of lunar polar regions, via a small rocket. more innovative approaches. The ob­ which some scientists speculate may jective in seeking new approaches is to harbor frozen water in permanently WASHINGTON, DC-As a result of put humans on the Moon and on Mars, shadowed areas. On the rest of the studies conducted under the aegis of the perhaps at lower cost, perhaps with Moon, where sunlight strikes the sur­ National Space Council (chaired by less demanding mission requirements face at least part of the time, frozen Vice President Quayle, reporting to and perhaps with near-term milestones. water could not survive the heat from President Bush), the White House has The search for innovation has caused the Sun. issued a set of guidelines for the Moon­ NASA to cast a wider net in looking This mission will be the second, after Mars initiative presented by President for new technological ideas and con­ Mars Observer (scheduled for launch Bush on July 20, 1989 in a speech com­ cepts. in 1992), in the Observer series of memorating the 20th anniversary of the NASA has reorganized its program spacecraft, built by adapting the design Apollo Moon landing. The new nam€ office to deal with SEI. The Office of of Earth-orbiting satellites with new for the program, which was known for Exploration has been merged into the sensors and instruments. a while as the Human Exploration Ini­ Office of Aeronautics and Space Tech­ The US/USSR joint working group tiative, is the Space Exploration Initia­ nology, now called the Office of Aero­ on planetary exploration, which has al­ tive or SEI. nautics and Exploration Technology. ready set up effective bilateral coopera­ The presidential guidelines describe, This new office is headed by Associate tion on Mars Observer (see "The Mars in the words of one NASA official, "a Administrator Arnold Aldridge. In ad­ Balloon Relay" by Jacques Blamont in general science and technology pro­ dition, plans call for the appointment of this issue), is investigating possibilities gram." The guidelines assert that it will a deputy to Aldridge to head the explo­ for Soviet participation on the Lunar be at least two years before any deci­ ration studies. A new Deputy Adminis­ Observer mission as well. A proposed sion is announced as to what the pro­ trator will report directly to NASA Ad­ Soviet "sub-satellite," working in con­ gram content and "architecture" will ministrator Richard Truly to coordinate cert with the American orbiter, would be. In the meantime Moon and Mars all the agency's activities in support of provide valuable data characterizing the missions, human and robotic, are to be the SEI. Moon's gravitational field. studied. The National Research Council of Meanwhile Japanese space scientists In addition to NASA, the Depart­ the National Academy of Sciences con­ are studying a lunar orbiter of their own ment of Energy and the Department of ducted a review of the NASA 90-day for possible launch in the mid-1990s. Defense are to be strongly involved in report (so called because it was present­ Japan's Institute of Space and Astro­ SEI, while the National Space Council ed three months after President Bush nautical Science (IS AS) flew MUSES­ coordinates the activities of these three announced the Moon-Mars initiative) A, a systems-testing mission around the agencies. Both departments can call on and generally supported the level, if not Moon in March of this year. the talents of national laboratories and the breadth, of the technical work done The Space Studies Institute (SSI) of think tanks to contribute to civilian by NASA in that study. In what is sure Princeton, New Jersey, a privately space exploration. to be a controversial and important funded group promoting the discovery Not mentioned in the presidential finding, the council urged that greater and use of extraterrestrial resources, guidelines is international cooperation. attention be paid to nuclear power and commercial space development and hu­ However, on March 30 the White nuclear propulsion, saying that nuclear man settlements off-Earth, has an­ House announced that the US would energy was essential for future human nounced plans to develop a lunar orbiter seek international cooperation in the exploration of the solar system. using a left-over Apollo instrument as SEI, citing the USSR as a possible part­ its primary science payload. NASA ner as well as Europe, Canada and Louis D. Friedman is the Executive Di­ 24 plans to release to SSI a gamma-ray Japan. Members of The Planetary Soci- rector o/The Planetary Society. New- Directors and Advisors Join Our Boards by Charlene M. Anderson

ilmmaker Steven Spielberg and Apollo 11 astronaut Marc Garneau-In October 1984, on board the space Michael Collins have joined The Planetary Society's shuttle Challenger, Marc Garneau became the first F Board of Directors, deepening the talent and vision Canadian astronaut to fly in space. He received a doctor­ of the Society'S governing body. We've also expanded our ate in electrical engineering from the Imperial College of Board of Advisors, welcoming five international members Science and Technology in London. He has served in the who will help broaden our influence around the world. Canadian Navy with expertise in communications and Our new international Advisors include: Canadian electronic equipment and systems. In January 1986, he astronaut Marc Garneau, Soviet atmospheric scientist was promoted to captain. Dr. Garneau now provides tech­ Georgiy Golitsyn, Soviet physicist Sergei Kapitsa, nical and program support to the Canadian space agency Japanese space leader Jun Nishimura and Australian and is helping to prepare experiments to fly on board the space scientist S. Ross Taylor. shuttle during future Canadian missions. "We are honored to have such an outstanding group of world citizens become part of The Planetary Society's Georgiy Golitsyn--Georgiy Golitsyn is the Director of official family," says Society President Carl Sagan. "Our the Soviet Academy of Sciences' Institute for Atmospher­ two new directors, Michael Collins and Steven Spielberg, ic Physics. He has served on the governing Presidium of have helped broaden our perspective beyond the Earth to the Academy, one of the most prestigious positions a So­ the boundless possibilities in space. Their insight and ex­ viet scientist can hold. Academician Golitsyn works pri­ pertise will help expand the Society'S horizons in impor­ marily on the physics of planetary atmospheres and has tant new directions." contributed to understanding the possible effects of green­ house gases and nuclear winter on Earth's environment. Steven Spielberg- Steven Spielberg is possibly the most successful filmmaker of all time. In 1983 he gave Sergei Kapitsa-As host of the most popular Soviet the Society $100,000 to begin building META television program about science, Sergei Kapitsa is one (Megachannel Extraterrestrial Assay), the most powerful of the best-known scientists in the USSR. He is an Asso­ radio search for extraterrestrial intelligence now operat­ ciate of the USSR's Institute for Physical Problems, Pro­ ing on Earth. META has been operating continuously fessor of the Moscow Physicotechnical Institute and from Harvard University's Oak Ridge Radio Observato­ President of the USSR Physical Society. During The ry since 1985, when in a special ceremony Mr. Spielberg Planetary Society'S 1987 "Together to Mars?" space­ switched it on. Later this year, META II will begin scan­ bridge between Soviet and American scientists (later a ning the skies from our new site in Argentina, giving us PBS television special), Dr. Kapitsa shared the duties of full coverage of the sky. (See the January/February 1989 moderator with Society Carl Sagan. Planetary Report.) Mr. Spielberg has directed or produced 7 of the 20 Jun Nishimura- Jun Nishimura is Director-General of most-watched films of all time. His credits include ET the Institute of Space and Astronautical Science (ISAS), the Extra-Terrestrial, the three Indiana Jones films, the space agency for Japan's scientific missions. ISAS Jaws and Close Encounters of the Third Kind. In 1987 recently sent a spacecraft into lunar orbit, making Japan he received the prestigious Irving G. Thalberg Award the third nation, after the Soviet Union and the United from the Academy of Motion Picture Arts and Sciences. States, to explore the Moon. Professor Nishimura's research specialties include cosmic rays, space physics Michael Collins-The Apollo 11 mission to the Moon and scientific ballooning. marks the zenith of human exploratory endeavors. As Apollo 11 command module pilot, Michael Collins orbited s. Ross Taylor- S. Ross Taylor is a Professorial Fel­ the Moon as Neil Armstrong and Buzz Aldrin left their low at the Research School of Earth Sciences at the Aus­ footprints in the lunar soil. Mr. Collins is the first astro­ tralian National University in Canberra. He also works as naut to join our Board of Directors, and the rare perspec­ a visiting scientist at the Lunar and Planetary Institute in tive he brings to our deliberations will be invaluable to Houston, where he is a Principal Investigator for lunar The Planetary Society's progress. samples. Dr. Taylor is an Honorary Fellow of the Geolog­ Mr. Collins' distinguished career of public service has ical Society of London and in 1988 received the Norman included service as an Air Force test pilot, Assistant L. Bowen Award of the American Geophysical Union for Secretary of State for Public Affairs and Director of the "important contributions to our understanding of the ori­ National Air and Space Museum. He now works as an in­ gins and early history of Earth and Moon." dependent consultant, writing and lecturing about aerospace issues. Mr. Collins' new book, On to Mars, is Charlene M. Anderson is Director of Publications for soon to be published. The Planetary Society. 25 in implementing VRM (Venus Radar Mapper, "son of VOIR," now called Magellan). During the interim, the Soviet Venera 15 and 16 missions produced good radar maps of the northern part of Venus beginning in 1983, resolving features down to 1 to 2 kilometers. Ground-based radar, from Puerto Rico's giant Areci­ bo dish, has managed I kilometer resolution in some locations on Venus. The geologists have been studying these radar data-whetting their appetites for Magellan-and practicing their interpretational skills by Clark R. Chapman on side-looking radar images of familiar terrains on Earth. Soon there will be a flood of data from Magellan, if all goes well. The maps will be at better resolution than any previous data set, but the leap will be nothing so enormous as we have been used to with landscapes from Voyager. At least as important as the improved or more than a decade, only one American plan­ clarity of the maps will be that most of Venus will be etary mission has brought us new views of other mapped, uniformly, rather than just small pieces of it. F worlds-Voyager. Its final planetary encounter, with Neptune last August, is now past. So our eyes tum Become Venus Literate toward two recently launched spacecraft, Galileo and What scientific issues about Venus as a planet will Magellan. Magellan's prime mission will soon be upon Magellan address? I recommend two recent articles to us: It arrives at Venus in August. Magellan is very un­ introduce readers to the perplexing questions about like Voyager, and we should get used to its differences. Venus that pfanetary geophysicists have been wrestling While Voyager is a complex spacecraft, carrying nu­ with. The easier article to read ("Venus: The Hellish merous esoteric scientific instruments, many of its re­ Place Next Door") appeared in the March issue of As­ markable discoveries were made with a fairly ordinary tronomy magazine. R. Stephen Saunders, the Project camera system. At the risk of oversimplifying, one Scientist for Magellan, has written a picturesque, easy­ could say that all Voyager did was carry a slow-scan to-understand description of the basic issues in venu­ video camera to unimaginably distant parts of our so­ sian geology and geophysics. lar system, snap a large number of pictures and radio For readers willing to tolerate a terse, much more them back to Earth. technical article, there is a tour de force on the same

> Magellan's goal is very different, and so is its tech­ subject in the March 9 Science, written by the UCLA nology. To begin with, this is not our sole opportunity geophysicist William Kaula ("Venus: A Contrast in to study the surface of Venus. Moreover, the problem in Evolution to Earth"). With much clarity, Kaula offers learning about our sister planet is not that it is so far the "big picture" on why Venus and Earth are so differ­ away but that its surface is hidden beneath optically ent from each other, before he bogs down in some very impenetrable clouds. There are no clear days, or even technical discussions of global geophysics. partly cloudy ones, on Venus. So sending a TV camera Both Kaula and Saunders are geophysicists by train­ over to Venus would do geologists little good. (Such ing, so they spend little time on the "runaway green­ cameras have studied its atmosphere, from Earth-based house effect," which is the most common topic of com­ telescopes as well as from spacecraft, such as Mariner parisons of Venus with Earth. Instead they ask why 10, the Pioneer Venus orbiter and-most recently­ does Venus lack a system of global plate tectonics such Galileo.) as dominates the geology of our own planet (although Magellan will use the modem technology of side­ there are intriguing exceptions in Venus' Aphrodite looking radar to see through the clouds and map the province), how thick is the crust, how does Venus get surface of Venus. This technique is much more com­ rid of its internal heat, is there active volcanism and plex than TV imaging. Indeed, the main limit to how what kind of erosion operates on Venus, among other well Magellan can map Venus is computer power for geological and geophysical questions that Magellan image reconstruction back here on Earth. Trying as will illuminate if not answer. hard as they can, the Magellan Project people will It is fitting, as NASA turns a major focus toward the probably fall far behind the spacecraft as they try to new agenda of Mission to Planet Earth, that Magel/an convert the massive quantity of data into visualizable will provide us with a rich set of data about a planet "maps" of Venus. Then geologists will have to unlearn that should be the most Earth-like but in many ways is the intuitive ways in which they habitually interpret or­ hellishly different. That difference is unsettling. We dinary photographs of Earth and other planets. While need to learn why Venus is the way it is so we never the radar maps will look something like photographs, make mistakes that could send our own green planet they will really be quite different. along a similar course of evolution. But the ge010gists have been preparing for the Mag­ ellan data for years-too many years, in fact, as fund­ Clark R. Chapman is a Senior Scientist at the Plane­ ing cutbacks in the early 1980s caused cancellation of tary Science Institute in Tucson, Arizona, a division of 26 the Venus Orbiting Imaging Radar (VOIR) and delays Science Applications International Corporation. l I

SOCIETY ADVISOR and Venus," the Society'S cial, economic and policy until you tell us. MARVIN MINSKY HONORED educational program on en­ strategies for robotic and hu­ • When ordering gift Marvin Minsky, a pioneer in vironmental issues. - LDF man missions to Mars. The memberships, be sure to in­ the field of artificial intelli­ Society is sponsoring a pub­ clude your name and address gence, has been named the TEAMING UP WITH NSTA lic event the evening of June as well as the recipient's winner of this year's Japan Society President Carl Sagan 6. For further details, contact name and address. Gift mem­ Prize. The award honors and Soviet Academician Case for Mars Event, c/o the berships must be paid before Minsky, co-founder of MIT's Roald Sagdeev, speaking on Society. -SL we can put the names on file. Artificial Intelligence Labo­ "Exploring Other Worlds and • Donations to special ratory, for work over four Protecting This One: The ALDRIN IN AUSTRALIA funds are restricted by law decades that has centered on Connection," drew a sold­ The Society will host a spe­ and may not be used toward the question of how to orga­ out, spill-over crowd at the cial event in Australia fea­ your membership dues. nize the "brain" of a comput­ Regency Ballroom of the turing Apollo 11 astronaut • Put your membership er so that it can improve its Hyatt Regency Hotel in At­ Buzz Aldrin on August 25. number on all correspon­ own performance, "learning" lanta, April 6, at the National The Society, in cooperation dence (and on your check from experience as people do. Science Teachers Associa­ with the National Space So­ when renewing member­ A mathematician by train­ tion annual conference. (Au­ ciety, will present a lecture ship). This number is printed ing, Minsky is one of the few dio tapes of this event will by Aldrin at the Australian on your membership card scholars who are members of soon be available for pur­ Space Conference in Sydney. and above your name on both the National Academy chase by Society members.) With over 1,400 members, your Planetary Report mail­ of Sciences and the National The Planetary Society will Australia has the largest ing label. ---Sue Pratt, Mem­ Academy of Engineering. He continue its working relation­ concentration of Planetary bership Correspondent joined the Society'S Board of ship with NSTA at their con­ Society supporters outside Advisors in January 1988. vention next year in Houston, the United States and Cana­ WIll YOUR EMPI.OYER The Japan Prize, presented where the Society will spon­ da. Volunteer groups are ac­ MATCH YOUR GIFT? by the Emperor, was estab­ sor seminars, lectures, tours tive in several regions of the Hundreds of companies in lished in 1985 to recognize and workshops. The 1991 country, and the Society the US will match their em­ achievements in science that NSTA meeting will include a hopes to enlist more volun­ ployees' gifts to The Plane­ promote peace and prosperi­ special Planetary Society teers through special meet­ tary Society, doubling your ty. -Louis D . Friedman, day, highlighted by a ple­ ings to be held in Sydney donation to our many pro­ Executive Director nary-session address by Carl and Melbourne this August. grams. If you would like Sagan and special programs For more information on more information on match­ ABE GOMEl JOINS NEW on the exploration of Mars, these volunteer meetings and ing-gift programs, please MIllENNIUM COMMITTEE Society scholarships, the the Buzz Aldrin events, write check with your company's Abe Gomel of Montreal, 1992 International Space to Australia Volunteer Meet­ personnel department, or owner of Liberty Yogurt, has Year and the Society'S Dud­ ings, c/o the Society. ---SL write to Matching Gift Infor­ joined the New Millennium ley Wright International Stu­ mation, c/o the Society. -Lu Committee, a select group of dent Contest, which is being MEMBERSHIP DEPT. TIPS Coffing, Financial Manager contributors organized to administered in the US by You can help us deliver bet­ fund annual scholarships and NSTA. -Susan Lendroth, ter service by remembering special Planetary Society Manager of Events and Com­ these tips: projects. munications • Renew early. We send Our mailing address: Mr. Gomel, a member of out renewal notices four and The Planetary Society the Society since 1982, is CASE FOR MARS IV a half months in advance to 65 N. Catalina Avenue committed to the ideal that The international Case for conserve Society resources Pasadena, CA 91106 everyone can become in­ Mars IV conference, to be and make delivery more effi­ volved in the adventure of held June 4 to 8, 1990 at the cient. General calls: planetary exploration, and he University of Colorado in • Send us a change of ad­ (818) 793-5100 believes that involvement Boulder, will consider the dress card when you move. Sales calls ONLY: begins with education. He potential for human habita­ The post office won't for­ (818) 793-1675 has directed his initial dona­ tion of Mars and will cover ward or return magazines, so tion to "Sister Worlds: Earth scientific, technological, so- we won't know you've moved 27 Thinking about impact craters made bility and plan are not great now. Even of the asteroid belt is the only place me wonder if observatories could de­ now, human preparations (except in where a fairly wide band of orbits can tect a large approaching object before Japan) for the earthquakes that are cer­ be stable. It's stable there because the it struck Earth. Could we have a tain to occur (we just don't know gap between Mars and Jupiter is unusu­ warning? when) are lamentably inadequate. The ally wide relative to the sizes of their -William H. Matzke, St. Paul, Min­ asteroid threat, although potentially orbits. In fact, there would be plenty of nesota more destructive, is much more remote. room for an extra planet in this gap. -JAMES D. BURKE, Jet Propulsion Between other pairs of planets, nearly Yes, we could. However, no such Laboratory any small body would experience grav­ search system is yet in operation. As itational pulls that would soon (on a more and more small Earth-crossing Why is there an asteroid belt between cosmic time scale) destabilize its orbit asteroids are discovered by existing as­ the orbits of Mars and Jupiter and not by driving it across the planetary orbits. tronomical searches (see "The Asteroid anywhere else in the solar system? A deeper reading of your question Project Shows Results" in the Jan­ -Stacey A. Maxwell, Syracuse, New requires us to consider the formation uary/February 1986 Planetary Report), York processes that led to the wide interval a "protective" search may eventually between Jupiter and Mars and populat­ begin. However, the chances of having Given the positions and masses of the ed it with small objects, or asteroids. r adequate warning and an action capa- planets in the solar system, the location The planets grew from a nebula of gas and small bodies around the Sun. Cur­ rent thinking suggests that once Jupiter grew large enough by gravitational ac­ cretion of small bodies, gases collapsed onto it, quickly creating the giant plan­ et. Then Jupiter's gravity was strong enough to scatter other growing planets through what is now the asteroid belt, resulting in collisions that aborted plan­ et growth in that region. Wliat we now see there are partially formed and bro­ Solar system ken planets. objects plow­ ing into Earth The asteriod belt is not the only part can, depend­ of the solar system populated with ingontheir size, wreak small bodies. Beyond the outer planets aI/manner lies the Gort Cloud of comets (icy as­ ofhavoc. Manhattan teroids). Near Earth, thousands of little Island might bodies are traveling in orbits that are look like this if a small com­ unstable over geologic time; in fact, etal}' nucleus some of these occasionally hit Earth. A were to crash down into its zone inside Mercury's orbit would al­ cemer. low for fairly stable orbits, but we don't know whether any small objects are there, or even whether formation of solid bodies was possible so close to the Sun. -RICHARD GREENBERG, Univer­ sity of Arizona INCOMING FAST EJECTA

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Planetary Society Background Papers - For those who can't attend the specialist conferences or read the arcane journals in which issues and ideas in planetary science are aired, The Planetary Society is beginning a Background Paper series. Offered in a low-cost booklet format, this series will keep interested members informed and involved.

Planets and Politics: Mission to Planet Earth - Reflections on the Presidential by John L. McLucas Moon-Mars Initiative - The Chairman of the NASA Advisory Council describes the global scale of by Carl Sagan environmental questions we face today and In August 1989, JPL staffers gathered to hear traces the efforts of International Space Carl Sagan, Distinguished Visiting Scientist, Year organizers toward coordinating deliver an address in response to President planet-wide studies of Earth. 32 pages Bush's announcement of a renewed program $3.00 #702 of exploration. 32 pages $3.00 #701 ORDER PRICE liN 230 Voyager 1 Saturn Encounter NUMBER Books US DOLLARS) (40 slides with sound cassette) $ 15.00 231 Voyager 2 Saturn Encounter 114 Cosmic Catastrophes 523 Galileo T-Shirt - (40 slides with sound cassette) $ 15.00 by Clark R. 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Artist Paul Hudson and his wife Colette live on their farm in the Cascade Mountains of Washington, where they are engaged in design work for the new Space Exploration Initiative.

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