旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 � THIS FILE WAS PROVIDED BY � � �袴� �袴� �袴� �袴 �袴� �袴� �袴� �袴� �袴� THE ASTRONOMY AND � � 훤敲 勁暠 勁攷 � 勁� 勁攷 勁攷 훤敲 勁� 袴 SPACE SCIENCES BBS � � 袴暠 � � � 훤� 훤袴 훤暠 � � 袴暠 훤袴 � � (604) 875-6259, Vancouver, BC, Canada � � (1200; 2400 baud) 24 Hours (FidoNet 1:153/719) � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸 THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC Volume 4, Number 7 - February 1993 ########################### TABLE OF CONTENTS ########################### * ASA Membership and Article Submission Information * The Soviets and Venus, Part 1 - Larry Klaes ########################### ASA MEMBERSHIP INFORMATION The Electronic Journal of the Astronomical Society of the Atlantic (EJASA) is published monthly by the Astronomical Society of the Atlantic, Incorporated. The ASA is a non-profit organization dedicated to the advancement of amateur and professional astronomy and space exploration, as well as the social and educational needs of its members. ASA membership application is open to all with an interest in astronomy and space exploration. Members receive the Journal of the ASA (hardcopy sent through United States Mail - Not a duplicate of this Electronic Journal) and the Astronomical League's REFLECTOR magazine. Members may also purchase discount subscriptions to ASTRONOMY and SKY & TELESCOPE magazines. For information on membership, you may contact the Society at any of the following addresses: Astronomical Society of the Atlantic (ASA) c/o Center for High Angular Resolution Astronomy (CHARA) Georgia State University (GSU) Atlanta, Georgia 30303 U.S.A. asa@chara.gsu.edu ASA BBS: (404) 564-9623, 300/1200/2400 Baud. or telephone the Society Recording at (404) 264-0451 to leave your address and/or receive the latest Society news. ASA Officers and Council - President - Eric Greene Vice President - Jeff Elledge Secretary - Ingrid Siegert-Tanghe Treasurer - Mike Burkhead Directors - Becky Long, Tano Scigliano, Bob Vickers Council - Bill Bagnuolo, Michele Bagnuolo, Don Barry, Bill Black, Mike Burkhead, Jeff Elledge, Frank Guyton, Larry Klaes, Ken Poshedly, Jim Rouse, Tano Scigliano, John Stauter, Wess Stuckey, Harry Taylor, Gary Thompson, Cindy Weaver, Bob Vickers ARTICLE SUBMISSIONS Article submissions to the EJASA on astronomy and space exploration are most welcome. Please send your on-line articles in ASCII format to Larry Klaes, EJASA Editor, at the following net addresses or the above Society addresses: klaes@verga.enet.dec.com or - ...!decwrl!verga.enet.dec.com!klaes or - klaes%verga.dec@decwrl.enet.dec.com or - klaes%verga.enet.dec.com@uunet.uu.net You may also use the above addresses for EJASA back issue requests, letters to the editor, and ASA membership information. When sending your article submissions, please be certain to include either a network or regular mail address where you can be reached, a telephone number, and a brief biographical sketch. Back issues of the EJASA are also available from the ASA anonymous FTP site at chara.gsu.edu (131.96.5.29) DISCLAIMER Submissions are welcome for consideration. Articles submitted, unless otherwise stated, become the property of the Astronomical Society of the Atlantic, Incorporated. Though the articles will not be used for profit, they are subject to editing, abridgment, and other changes. Copying or reprinting of the EJASA, in part or in whole, is encouraged, provided clear attribution is made to the Astronomical Society of the Atlantic, the Electronic Journal, and the author(s). Opinions expressed in the EJASA are those of the authors' and not necessarily those of the ASA. This Journal is Copyright (c) 1993 by the Astronomical Society of the Atlantic, Incorporated. THE SOVIETS AND VENUS PART 1 Copyright (c) 1993 by Larry Klaes The author gives permission to any group or individual wishing to distribute this article, so long as proper credit is given and the article is reproduced in its entirety. Revolving around a small yellow star between the celestial paths of a crater-scarred world called Mercury and our blue-white Earth lies the planet known as Venus. Named by the Romans after their goddess of beauty and love for its white brilliance in Earth's night sky, Venus resembles our planet in both size and mass. However, while Venus can come closer to Earth than any other planet in our solar system, the second world from the Sun remained one of the more mysterious places in the Universe before the advent of the Space Age. The relative brightness of Venus is due to the reflection of Sun- light off the planet's enveloping blanket of thick, yellowish clouds. Venus' strange atmosphere was discovered by the Russian scientist Mikhail Vasilievich Lomonosov during a rare transit of the planet across the solar disk in 1761. For two centuries after Lomonosov's revelation, Earth-bound astronomers would find themselves unable to penetrate this dominating feature with their optical telescopes to learn what lay beneath. Wild speculation about Venus arose from the absence of facts to explain the state of this alien world. Through the first half of the Twentieth Century, Venus was populated with everything from primeval swamps crawling with reptilian creatures to boiling oceans of seltzer and oil. Even such 'basic' planetary information as Venus' rate of rotation was unknown because of the continual cloud cover. Estimates on the length of a Venerean day ranged from twenty-four hours to one Venerean year, 224.7 Earth days. Scientists realized that direct measurements were needed to uncover the realities of this moonless world. Rockets and spacecraft capable of reaching other planets were required for the task. Competition for the Cosmos The early years of the Space Age were dominated by two global superpowers, the United States of America and the Soviet Union. Shocked into reality on October 4, 1957 with the launch of the Soviet satellite SPUTNIK 1, these rival nations boldly pushed their ambitions and technologies into the interplanetary realm as part of what was termed the Cold War. By the dawn of the 1960s, the Soviets had taken a considerable lead in this endeavor: Three of their unmanned space probes had already reached Earth's moon, Luna, completing their programmed missions. Other Soviet vehicles, designed to explore the two planets nearest Earth - Venus and Mars - were rapidly being prepared for their destinations. In the Western Hemisphere, the United States had yet to achieve a single fully successful lunar mission with their series of PIONEER probes. As a form of consolation, PIONEER 5, a scaled-back Venus flyby project, was launched from Cape Canaveral in Florida on March 11, 1960 to investigate the interplanetary medium between the orbits of Earth and Venus. The information from such an expedition was considered vital for the planning of spacecraft which would follow PIONEER's charting course all the way to Venus. PIONEER 5 became an amazing success: The solar-powered sphere communicated with Earth until June 26, 36.4 million kilometers (22.5 million miles) from home, a record for that time. The probe confirmed the existence of interplanetary magnetic fields and relayed the sur- prisingly strong effects of various solar forces on the spacecraft. PIONEER bolstered the confidence of both the National Aeronautics and Space Administration (NASA) and the U.S. that they could compete with the Soviets in the exploration of deep space. PIONEER 5 now silently circles the Sun once every 312 days. Soviet Aims for the Goddess of Love On the fourth day of the second month in the year 1961, a rocket of the MOLNIYA class roared from a launch pad at the Tyuratam Space Center - more widely known as the Baikonur Cosmodrome - in a remote region of the Soviet Republic of Kazakhstan. Atop this powerful coni- cal booster was a spacecraft designated by its builders as TYAZHELIY SPUTNIK 4, meaning Heavy Fellow Traveler in Russian. In the West, this craft was called SPUTNIK 7. News of this launch had been kept from most of the world until the mission was well underway. Nearly all Soviet space missions of that era were made government secrets until successful, so that a failure would not be able to disgrace the Soviet Union's appearance in space. Even when a mission did work as planned, it was often that scant information was released about the craft and its purpose. The ensuing Cold War caused both sides to become paranoid about revealing their technological limits to the other. Soviet officials claimed that this new SPUTNIK was only a test of their latest Automatic Interplanetary Station (AIS) for launching spacecraft into higher Earth orbits. Western experts believed it to be the Soviet Union's first attempt to send an unmanned probe to the planet Venus, as this was a prime launch "window" for delivering a spacecraft to that world. Whatever the truth, the vehicle never left its parking orbit. The launch platform and alleged Venus probe even- tually disintegrated on February 26 upon entering Earth's atmosphere. Just one week after the launching of SPUTNIK 7, the Soviets placed yet another Heavy Fellow Traveler, TYAZHELIY SPUTNIK 5 (SPUTNIK 8), into Earth orbit on February 12. Within one day of its insertion into space, a small vehicle emerged from the orbital platform and was sent on its way to the second planet from the Sun. The West's belief that the Soviets were ushering in the era of robotic planetary exploration was thus confirmed. Renamed VENERA 1 ("Venera" is the Russian word for Venus), the first Venus probe acknowledged by the Soviets was a domed, instrument- packed cylinder flanked by two solar panels and a radio antenna shaped like an open umbrella. The entire vehicle weighed 643.5 kilograms (1,418.9 pounds). The primary mission plan for this new breed of spacecraft was stated as a flyby examination of Venus in late May of 1961 at a distance of one hundred thousand kilometers (sixty-two thousand miles). During its flight to the target planet, VENERA 1 would send back data collected on interplanetary gas, dust, magnetic fields, and cosmic rays every five days to its controllers on Earth. The mission proceeded well until February 22. On that day, VENERA 1 was twenty-three million kilometers (fourteen million miles) from Earth and set to relay its next batch of gathered information. Then, unexpectedly, no signals were received at the appointed time. Attempts to pick up the probe's transmissions were made again on March 4 and 5 with the help of the giant Jodrell Bank radio telescope in Great Britain, but without success. VENERA 1 drifted off into heliocentric (solar) orbit, no longer of use to those who lofted it into space. Should VENERA ever be recovered from the depths of interplane- tary space, those who retrieve the Soviet probe will find inside the vehicle a small metal representation of Earth. Sealed within this globe is a commemorative medallion identifying the purpose and national origin of the Venus craft. The placing of such artifacts aboard deep space probes was destined to become a tradition with both the Soviets and the United States. They serve as a means of speaking to those future explorers who would follow, to let them know who and what paved the way into the Universe for humanity. Despite the overall performance of these first two attempts to reach Venus, the VENERA series would eventually become one of the Soviet Union's greatest planetary exploration achievements for the next quarter century. True success, however, would have to wait. In the meantime, the Soviets were content to finish out 1961 with two major victories in one of the most visible areas of their space program. On April 12, cosmonaut Yuri Gagarin became the first human to orbit Earth aboard VOSTOK 1. Nearly four months later, on August 6, VOSTOK 2 played host to Gherman Titov, the first cosmonaut to spend an entire day in space. By comparison, the United States had sent two astronauts on separate fifteen-minute suborbital flights inside the cramped confines of the MERCURY space vehicle in May and July. The U.S. was hard-pressed once again to impress the world with even more spectacular space missions. Failures and Triumph Following the Soviet VENERA missions of early 1961, the next occurrence of a rocket launch window to Venus began in the summer of 1962. These windows are created when Earth and a particular planet are at certain locations in their orbits around the Sun so that the least amount of booster energy can be used to launch the most feasibly massive spacecraft. Such an alignment for Venus and Earth occurs every nineteen months. The United States made the first grasp for Venus in 1962 with their unmanned MARINER 1 spacecraft. Sent skyward from Cape Canaveral on July 22 aboard an ATLAS-AGENA B rocket, the flight at first appeared to be going well. Then, a rocket guidance programming error suddenly caused the booster to deviate from its planned course. With the ATLAS- AGENA heading towards the shipping lanes of the North Atlantic Ocean, the Range Safety Officer (RSO) was forced to destroy the vehicle with a radio command to an explosive device aboard the rocket. A brief rain of metal debris showered the water. The first American spacecraft meant for Venus instead met its end in the icy depths of the Atlantic. One month later, the Soviets made their first Venus launch attempt of the year, but their luck was not much better than America's initial try with MARINER 1. The unnamed vehicle came apart in its Earth parking orbit on August 25 and disintegrated upon entering the atmosphere three days later. Two more Soviet Venus probes were conducted into space on the first and twelfth days of September, but neither craft traveled any further than their brief Earth orbits. These failures made it easy to wonder if the two superpowers' current technologies were truly up to the task of reaching another planet through millions of kilometers of deep space. In the midst of these little-known Soviet attempts, the United States took their second shot at Venus on the night of August 27. MARINER 2, a 203.6-kilogram (448-pound) spacecraft resembling an oil rig with two solar panels and a high-gain radio dish antenna, made its way into interplanetary space on a risk-filled journey to the shrouded world. Four months later, after a mission punctuated by numerous technical and heating problems, MARINER 2 became the first spacecraft to successfully reach another planet while still in commu- nication with Earth. Speeding past the yellow sphere of Venus on December 14 at a distance of 34,827 kilometers (21,648 miles), MARINER's two radiometers scanned the planet for thirty-five minutes. From this brief examination many important discoveries were made. One of the most startling was that Venus' global surface temperature averaged 427 degrees Celsius (800 degrees Fahrenheit), hotter than a conventional kitchen oven. Such intense heat was hundreds of degrees above most scientists' previous temperature estimations. It appeared that Venus' clouds somehow kept heat from the Sun bottled in, much like a green- house allows solar radiation to enter but not to escape. The Venerean clouds floated in an unbroken layer fifty-six to eighty kilometers (thirty-four to forty-eight miles) thick above the planet's baked and arid crust. The dense atmosphere these clouds existed in was thought to exert pressure on Venus' surface twenty to thirty times greater than that of Earth's comparatively thin air at sea level. MARINER 2 also found no evidence for either magnetic fields or radiation belts surrounding Venus as they do about Earth. In less than one hour, MARINER's encounter with the second planet from the Sun disrupted the decades-old theories of humid swamps and oily oceans, along with almost any hope for the existence of Venerean life as humans would recognize it. Venus was more unlike Earth than most astronomers had ever dreamed. The American spacecraft's findings led not only to a radically new view of Earth's nearest planetary neighbor, but also to a rearranging of planetary mission priorities for the United States space program. NASA decided that the Red Planet, Mars, would be the next goal for their unmanned explorers. The conditions on Venus required more extensive study by space vehicles with a technical sophistication which was not readily available in the early 1960s. Mars also appeared to be a far more suitable planet for placing manned expeditions upon in the foreseeable future. The Soviets, meanwhile, pressed on with their missions to Venus. For them, the second world appeared to be an easier spacecraft target to obtain than Mars: Every attempt to reach the Red Planet since 1960 had failed for a variety of mechanical reasons. Many Soviet astronomers were also not entirely convinced of the incredibly harsh environment that had been reported about the veiled planet. Some theorized that the high temperature readings by MARINER 2 may have come from the planet's ionosphere instead of its surface. This view kept alive the hope that the planet might at least harbor simple organisms. Venus still held many secrets to be unlocked. The Darkness Before the Dawn With all the technical troubles encountered by the Soviets from their first Venus and Mars probes, it would have been only logical for the program scientists and technicians to conduct further tests on their planetary vehicles before sending them to those worlds again. A spacecraft launched from Tyuratam into Earth orbit on November 11, 1963, appeared to be the result of such planning. COSMOS 21, so named due in part to a 1962 United Nations treaty demanding that all spacecraft be given some type of official designa- tion, was shuttled into an Earth parking orbit similar to that used by other Soviet craft preparing for planetary destinations. Though no launch windows were open for either Venus or Mars at that time, Wes- tern experts speculated that COSMOS 21 might have been planned for a mission to the vicinity of Venus' solar orbit in a full engineering test of spacecraft systems. If this were the actual scenario, then COSMOS 21 must be considered a failure, as no probe left Earth orbit and the entire vehicle decayed three days later. Whatever the case with COSMOS 21, Soviet scientists apparently felt confident enough to launch another series of Venus probes when the next window opened in February of 1964. Unfortunately, this confidence did not turn into success that year. Two rocket launches, on February 26 and March 4, apparently failed in mid-flight and their payloads were not even given the COSMOS cover nomenclature. Twenty- three days later, a third Venus probe did attain Earth orbit but went no further. COSMOS 27 lasted just one day in space. A fourth and final Soviet try at Venus came the following month. On April 2, the 'barrier' of Earth orbit, which had stopped all Soviet Venus vessels save VENERA 1, was finally breached by ZOND 1, a space- craft with a most non-specific cover name. "Zond" is the Russian word for probe. As with COSMOS, the name was designed to hide the craft's true destination, should it end up succumbing like the previous robotic explorers and thus bring further embarrassment to its creators. Though little was revealed about ZOND 1, it was probably meant to either flyby or impact on Venus in July of 1964, taking measurements of interplanetary space in the process. The ZOND 1 mission proceeded well until after the last communication session on May 14, 1964, when the craft was suddenly fallen by the same fate as VENERA 1 three years earlier: It ceased transmitting to Earth. The Soviets' caution in giving the vehicle a generic name appeared to be a wise move for their prestige after all, though Western space experts were aware of the spacecraft's basic intentions. ZOND 1 was the first and last ZOND mission to Venus. All future ZOND probes would be targeted for missions to Luna and Mars. Soviet space scientists now had another nineteen months to make up for the Venus project failures of 1964. Stranger and Stranger By the middle 1960s, new knowledge about Venus was still being obtained from the vantage of Earth. Various radio telescopes around the globe had penetrated the planet's thick cloud mask and returned to scientists the first radar images of Venus' equatorial regions, indicating a number of mountains and plateaus. As a bonus from these observations, Venus' true rotation rate was finally learned. The information only served to add to the planet's growing reputation for possessing 'bizarre' conditions: One Venerean day (one complete rotation around the planet's axis) equaled 243.1 Earth days, nineteen days longer than its solar year! No other known world in the solar system rotated so slowly. Venus was also discovered to spin on its axis in a retrograde fashion (clockwise as seen over the north pole), opposite to most of the other planets. To a person standing on an 'alternate' Venus - one with skies free of clouds - the Sun would appear to "rise" in the west and "set" on the eastern horizon 116.8 Earth days later. Why Venus behaved in this contrary manner remained a mystery. So Close, Yet Still So Far The year 1965 was a very fruitful one for American lunar and planetary efforts. The last two members of the RANGER series successfully completed their brief photographic missions to Luna, making way for the SURVEYOR fleet of unmanned lunar landers. Deeper into the solar system, MARINER 4 became the first spacecraft to flyby the planet Mars and return to Earth close-up images of its surpri- singly barren and cratered surface. The Soviets, on the other hand, were not accomplishing the showcase space missions they had presented in earlier years. Their numerous attempts to soft land an unmanned vehicle on Earth's moon finished either in solar orbit or as wreckage in the lunar dust. The lone Soviet Mars mission of that year, ZOND 2, suffered a major power drop and ceased communications just four months before its planetary encounter in early August. On the plus side, the robot vehicle ZOND 3 took several dozen images of Luna's hemisphere hidden from Earth in July of 1965, the first such pictures since the Soviet LUNA 3 mission six years earlier. ZOND 3 then headed out to the orbit of Mars for a series of spacecraft system tests in 1966. There was now only one feasible goal left for the Soviet space program to regain some true prestige in the arena of planetary exploration: Venus. The first space probe to be given the official VENERA designation since 1961, VENERA 2 was successfully launched on its way to Venus on November 12, 1965, followed by VENERA 3 four days later. The two probes were the most ambitious Soviet expeditions to the second world from the Sun yet created. VENERA 2 would attempt to flyby Venus in late February of 1966 and return the first close-up images of the planet. VENERA 3 was designed to achieve another space first for the Soviet Union: The actual soft landing of a vehicle on the Venerean surface. The VENERA 3 craft held a ninety-centimeter (35.4-inch) lander capsule weighing 383 kilograms (844 pounds). Once entry into the planet's dense atmosphere had been accomplished, the spherical probe would analyze the surrounding air while descending to the surface dangling beneath a parachute. On the ground, the lander would relay the first direct measurements from Venus' crust back to Earth for the life of its batteries. A third member of the series, possibly a second lander, exploded in its Earth parking orbit on November 23 and decayed sixteen days later. What would have been VENERA 4 was subsequently designated COSMOS 96 and kept out of the public spotlight, like so many other Soviet space failures. VENERA 2 and 3 glided to their alien destination through the first months of 1966, taking measurements of the interplanetary environment along the way. Then, on February 27, just before its closest approach, VENERA 2 reported a rapid increase in temperature and went permanently silent. None of the planned planet images were returned. VENERA 2 sailed past Venus 23,950 kilometers (14,370 miles) from the planet's center to join its fellow spacecraft in heliocentric orbit. Two days later, VENERA 3 arrived on the scene, aimed almost directly for the heart of the veiled world. As the vehicle neared its time to separate the lander from the cylindrical flyby bus, communi- cations were suddenly lost. Apparently the heating problem which had ended the counterpart craft's usefulness also brought about VENERA 3's demise. It is not known if the lander ever broke away from the main bus. It is likely that the entire vessel entered Venus' atmosphere. Though it is also unknown if the probe actually reached the planet's surface or was destroyed from heat friction with the atmosphere, VENERA 3 is generally credited with being the first spacecraft to land on another planet. In commemoration of this event, the probe carried a tradi- tional metal globe of its home world, Earth. The theory that VENERA 2 and 3 succumbed to overheating is not very surprising. Venus averages forty-two million kilometers (twenty- six million miles) closer to the Sun than Earth and receives twice the amount of solar radiation as does our planet. MARINER 2 was almost lost several times during its journey in 1962 due to the Sun's mag- nified heat. Although the VENERAs were kept from completing their main tasks, the probes did prove that the Soviets could at least deliver working spacecraft to the vicinity of Venus. Additionally, Soviet plans for exploring the nearest planet were revealed to be far advanced over contemporary projects from the United States. Testing the Waters In the months after the premature end of the VENERA 2 and 3 mission, the Soviets regained some of their dominance in space exploration. LUNA 9 and 10 became the first vehicles to respec- tively soft land upon and orbit Earth's moon in February and April of 1966, racing ahead of similar American attempts in preparation for placing humans on Luna by 1970. By the close of 1966, two more Soviet lunar orbiters and another lander were to follow. The next launch window to Venus began in June of 1967. Twelve days into the month, a MOLNIYA rocket delivered a spacecraft named VENERA 4 on its way to the Soviets' latest encounter with Venus. Essentially, VENERA 4 was an improved version of the VENERA 3 mission profile. Another possible Venus lander, COSMOS 167, failed to leave the Earth parking orbit it was placed in on June 17 and decayed on the twenty-fifth. Two days after the launch of VENERA 4, the United States also took advantage of the Venerean launch window with its fifth MARINER spacecraft. Originally the backup vehicle for the MARINER 4 Mars probe, the American entry was modified for a mission to the much warmer vicinity of Venus. Though MARINER 5 carried neither cameras nor an entry capsule, the flyby craft was fitted with a number of instruments for making a thorough analysis of the Venerean atmosphere and surrounding environment. The American probe was scheduled to arrive at Venus just one day after VENERA 4, where the two voyagers' data would later be compared. The design of the VENERA 4 lander contained some interesting revelations, not only in the level of current Soviet space technology, but also where Soviet scientists stood in their views on conditions at Venus. One of the more interesting features about the lander capsule was its ability to float in a liquid, in case the capsule encountered a Venerean ocean. VENERA 4 was also built to withstand an atmospheric pressure roughly equivalent to twenty times that of Earth's at sea level, or twenty bars. Despite the information returned five years earlier by MARINER 2 and the subsequent radio telescope scans of the planet, some Soviet scientists remained uncertain as to exactly what lay beneath Venus' cloud layers. Hope sprung eternal for the discovery of a world beyond Earth that was friendly to life, even in rudimentary form. After a single course correction in late July of 1967 to ensure an impact, VENERA 4 reached Venus on October 18. The lander separated from the main spacecraft bus upon arrival, both vehicles aimed into the night side of the planet. The bus was destroyed by the heat from air friction with its fast entry into the Venerean atmosphere, but not before returning valuable information on the conditions surrounding Venus. Among the more important data from the bus were a lack of any detectable radiation belts or magnetic fields. A weak corona of hydrogen particles was found circling ten thousand kilometers (sixteen thousand miles) above the planet. Meanwhile, VENERA 4's lander capsule plowed on into the planet's atmosphere at a speed of ten kilometers (sixteen miles) per second, generating friction heat up to eleven thousand degrees Celsius (19,832 degrees Fahrenheit), twice as hot as the photosphere of the Sun! Thanks to its protective heat shield and sturdy structure, the capsule was able to survive these extremes. Dropping deeper into the thickening soup of Venus' atmosphere, the capsule was slowed to a velocity of three hundred meters (990 feet) per second. At this point, the lander's top cover was ejected and a braking parachute emerged to arrest the craft even further, down to a speed of ten meters (thirty-three feet) per second. Having served its purpose, the braking parachute then made way for the main parachute, which let the capsule drift towards the surface. Instruments snapped into activity and the capsule began taking the first direct atmospheric readings of Venus for ninety-four minutes, until the probe's signals abruptly ceased. At first, Soviet technicians reported that VENERA 4 had trans- mitted all the way to the Venerean surface. Data on the atmosphere indicated it was composed primarily of carbon dioxide, with only traces of oxygen and water vapor. Nitrogen, previously thought to be a major component of Venus' air, could not be detected. Other data seemed to show that the surface air pressure equaled fifteen to twenty-two Earth atmospheres, with an average temperature of 280 degrees Celsius (536 degrees Fahrenheit). The next day, America's MARINER 5 flew by the veiled planet from a distance of just 3,991 kilometers (2,480 miles). For twenty-six minutes the craft's flight path took it behind Venus as viewed from Earth. During this time, MARINER's radio signals cut through the planet's atmosphere on their way to Earth, displaying intricate details in the process. The Data Conflicts Once the MARINER data were received by its mission controllers and properly analyzed, some surprising discoveries were made which were contrary to the information from VENERA 4. According to the American space probe, Venus' surface pressure was far greater than recorded by either its Soviet counterpart or from earlier estimates, being roughly equivalent to seventy-five to one hundred Earth atmospheres. The ground temperature was also much higher, a sizzling 527 degrees Celsius (981 degrees Fahrenheit). MARINER 5 discovered other differences between Venus and Earth: The solar wind was deflected around Venus by its encompassing iono- sphere, rather than by any significant magnetic field as happens with Earth. It appeared that Venus' creeping rotation and possible lack of a liquid iron core were major contributors to the absence of a planetary magnetic field. The mass of Venus was refined to 81.5 percent of Earth's. An object weighing forty-five kilograms (one hundred pounds) on Earth would tip the scales on Venus at forty-one kilograms (ninety-one pounds). The Soviets initially replied to the conflicting data that VENERA 4 must have landed on the summit of a very high mountain, in order to explain the lower pressure and temperature readings from their probe. Eventually, though, it had to be concluded that VENERA 4 did not sur- vive its descent to the surface. The capsule was probably crushed at a height of twenty-seven kilometers (sixteen miles) by the increasing atmospheric pressure, with the top of the craft caving in first. Most likely, VENERA 4 did ultimately reach the planet's crust, but only as so much scrap metal. Venus had taught a hard lesson that its surface pressure and temperature were much higher than originally believed. Although VENERA 4 did not accomplish its main goal of reaching the Venerean surface intact, the on-site atmospheric measurements were priceless to scientists. The high readings of carbon dioxide found by the VENERA probe gave the initial clues as to why Venus is so alarm- ingly hot. This colorless gas is excellent at trapping the radiation received from the Sun and keeping it from escaping the planet back into space. However, carbon dioxide alone could not hold in such intense heat for long. More missions would be needed to learn what the other key ingredients were. One could not call the VENERA 4 mission a failure, despite its premature demise. The very fact that the Soviets had attempted to land a vehicle on another planet just ten years after they had placed the first satellite into Earth orbit was an astounding accomplishment in its own right. Most importantly, VENERA 4's tandem investigation of Venus with MARINER 5 gave their parent nations a good indication of how much valuable information could be learned about space through mutual cooperation. The Final Steps Since the launch window of 1961, the Soviet Union had not passed up a single attempt at a mission to Venus. The window of 1969 was to be no exception. However, enough had been learned about the shrouded world in those eight years to prove that Venus was quite hostile to an invading spacecraft from Earth. Any future expeditions to Venus had to be fortified against crushing pressures and melting temperatures, amongst a host of unknown factors. The relatively short period since the 1967 Venus launch window did not allow the Soviets enough time to develop a vehicle that would be tough enough. Instead, they opted to send one more mission with their existing VENERAs to venture further into the planet's dense atmosphere before the inevitably destructive end above Venus' broiling surface. A VENERA which could survive on Venus' rocky face would have to wait for the next window. Just seven months before the United States would deliver the first astronauts to the surface of Earth's moon with the historic flight of APOLLO 11, the two latest entries in the Soviet exploration of Venus were launched into deep space. VENERA 5 lifted off from Tyuratam on January 5, 1969, followed by VENERA 6 five days later. For the first time, a multiple Soviet Venus probe mission did not lose any known spacecraft members during launch or in Earth orbit. This success would not be duplicated again until 1975. After one mid-course correction each during their five-month interplanetary journeys, VENERA 5 and 6 arrived at Venus just one day apart. On May 16, VENERA 5 injected its lander capsule into Venus' atmosphere. The capsule plunged in at a greater speed than did VENERA 4's lander two years earlier. These newest VENERA capsules were given some modifications against the planet's harsh environment. Among the changes were smaller parachutes, which helped the landers drop faster towards the Venerean surface. VENERA 5 returned atmospheric data to Earth for fifty-three minutes, descending for thirty-six kilometers (twenty-two miles) until being flattened by the surrounding pressure just twenty-four to twenty-six kilometers (fourteen to sixteen miles) above the hot landscape. The VENERA 5 data was extrapolated to indicate that the surface temperature and pressure beneath the spacecraft's descent path was 530 degrees Celsius (986 degrees Fahrenheit) and 140 Earth atmospheres, respectively. The capsule also carried a photometer device to examine the amount of light below Venus' clouds. One light reading of twenty-five watts per square meter was recorded just four minutes before the lander ceased transmitting. VENERA 6 came upon the scene the next day, releasing its capsule from the main bus some twenty-five thousand kilometers (fifteen thou- sand miles) from Venus. The VENERA 6 lander lasted for fifty-one minutes in the dark of the planet's night side, eventually collapsing just as its twin probe did, but at an improved altitude of between ten and twelve kilometers (six and eight miles) from the ground. Though the atmospheric constituents relayed by both landers generally agreed with the data from VENERA 4, traces of nitrogen were detected this time. The temperature and pressure readings returned by VENERA 6 were puzzling, however. The robot's measurements seemed to indicate that the crust below was just four hundred degrees Celsius (752 degrees Fahrenheit) warm and pressed down by an atmosphere only sixty times greater than Earth's, much lower than previous readings. For a while Soviet scientists tried the same "high mountain" excuse for the contrasting information that they used with the VENERA 4 lander data. This hypothesis was soon rejected in favor of the possibility that VENERA 6 had suffered some sort of instrument malfunction during its operation, thus the inconsistent readings. Later explorations of Venus have since shown that the region the two Soviet probes were aimed for, Tinatin Planitia, lies just below the planet's mean radius, discrediting the high mountain hypothesis. The Surface at Last Nineteen Seventy was a golden year for the Soviet Union and their growing space program. In Earth orbit, the cosmonaut crew of SOYUZ 9 broke the two-week manned space endurance record held by the crew of America's GEMINI 7 since 1965. Earth's moon was the location of several more major Soviet accomplishments: On September 24, LUNA 16 returned to its home world with the first lunar soil samples taken by an automated probe. Two months later, LUNA 17 carried the first unmanned rover, LUNOKHOD 1, to the lunar surface. The multi-wheeled robot spent the next year exploring the Sea of Rains. The shining planet Venus was also remembered during that year. On August 17 and 22, two MOLNIYA boosters placed identical payloads into Earth orbit. The first one went on to the second planet from the Sun and became known as VENERA 7. The second payload failed to leave the vicinity and was called COSMOS 359, where it remained until atmosphere entry on November 6, 1970. VENERA 7 was the hardiest of the Soviet Venus probes yet built. Its creators wanted this vessel to land on the planet's surface in working order. As a result, the spacecraft became much heavier than its predecessors. The entry capsule alone weighed about five hundred kilograms (1,100 pounds), due to modifications based on information supplied by VENERAs 4 through 6. The VENERA 7 lander could withstand temperatures up to 540 degrees Celsius (1,004 degrees Fahrenheit) and pressures equal to 180 bars for at least ninety minutes. The egg-shaped capsule was to be kept cooled at minus eight degrees Celsius (17.6 degrees Fahrenheit) by a refrigeration system in the main bus until its release at the planet, to guard against Venus' intense heat for as long as possible. A smaller parachute was made to quicken the capsule's fall through the turgid Venerean air. Shock absorbers were added to cushion the impact with the alien soil. There were fewer external openings and more insulation on the small vehicle, and its instrument compartment was hermetically sealed. VENERA 7 performed two mid-course corrections during its flight through space - another first in the Soviet Venus program - before arriving at the veiled planet on December 15, 1970. Unlike the earlier VENERA entry profiles, the VENERA 7 lander did not break from the main bus until both craft were entering the atmosphere, probably to extend the capsule's cooling period. Sixty kilometers (thirty-six miles) above the planet, the vessel's main parachute popped free and the probe began transmitting informa- tion about the thick night air around it. Then, thirty-five minutes later, VENERA 7 suddenly went silent. Without any warning, something had apparently destroyed the capsule. Soviet controllers back on Earth were shocked. They had thought for certain that this time every possible contingency about Venus had been accounted for with room to spare. Fortunately the controllers had kept tracking and recording the mission even after the apparent signal loss. Several weeks later, a very pleasant discovery was made during a search through the recording tapes: VENERA 7 had reached the Venerean crust intact and continued to send data for twenty-three minutes from the southwestern section of Tinatin Planitia. It seems the capsule had somehow been knocked over upon landing, causing its transmitter antenna to point in an unfavorable direction. The lander's signal strength was only one percent of what it was during the descent through the atmosphere. The lander's transmissions became almost indistinguishable from the regular background radio noise. While it may not have been very graceful, VENERA 7 had achieved yet another victory for the Soviet Union: The first successful landing of a functioning vehicle on another planet. In addition to its historical accomplishment, VENERA 7 confirmed the numerous analyses of Venus' environment from previous Soviet and American explorations during its brief lifetime. The temperature at Tinatin Planitia was reported to be 475 degrees Celsius (887 degrees Fahrenheit), give or take twenty degrees. A bare chunk of lead placed on the planet would melt. Air pressure ninety times greater than Earth's at sea level (give or take fifteen atmospheres) engulfed the small probe. Existing on Venus was equivalent to being 990 meters (3,300 feet) under the oceans of Earth, only much warmer and drier. No other member of the terrestrial family of planets held such high surface temperatures and pressures. The second planet from the Sun, once thought to be a goddess of beauty from its brilliant appearance in Earth's night sky, was finally revealed to be a world more like the fire and brimstone vision of Hell from Christianity. Instead of invoking fear, however, there was now even greater curiosity and will to learn why a planet so similar to Earth in many fundamental ways could also be so radically different at the same time. Bibliography - Burgess, Eric, VENUS: AN ERRANT TWIN, Columbia University Press, New York, 1985 Burrows, William E., EXPLORING SPACE: VOYAGES IN THE SOLAR SYSTEM AND BEYOND, Random House, Inc., New York, 1990 Davies, Merton E., and Bruce C. Murray, THE VIEW FROM SPACE: PHOTOGRAPHIC EXPLORATION OF THE PLANETS, Columbia University Press, New York, 1971 Gatland, Kenneth, THE ILLUSTRATED ENCYCLOPEDIA OF SPACE TECHNOLOGY, Salamander Books, New York, 1989 Gatland, Kenneth, ROBOT EXPLORERS, Blandford Press Ltd., London, Macmillan Company, New York, 1972 Hart, Douglas, THE ENCYCLOPEDIA OF SOVIET SPACECRAFT, Exeter Books, New York, 1987 Johnson, Nicholas L., HANDBOOK OF SOVIET LUNAR AND PLANETARY EXPLORATION, American Astronautical Society, Univelt, Inc., San Diego, California, 1979 Newlan, Irl, FIRST TO VENUS: THE STORY OF MARINER 2, McGraw-Hill Book Company, Inc., New York, 1963 Nicks, Oran W., FAR TRAVELERS: THE EXPLORING MACHINES, NASA SP-480, Washington, D.C., 1985 Sagan, Carl, and Jonathan Norton Leonard, PLANETS, Life Science Library, Time, Inc., New York, 1966 Shelton, William, SOVIET SPACE EXPLORATION: THE FIRST DECADE, Washington Square Press, Inc., New York, 1968 Smith, Arthur, PLANETARY EXPLORATION: THIRTY YEARS OF UNMANNED SPACE PROBES, Patrick Stephens, Ltd., Wellingborough, Northamp- tonshire, England, 1988 Stoiko, Michael, SOVIET ROCKETRY: PAST, PRESENT, AND FUTURE, Holt, Rinehart, and Winston, New York, 1970 VOYAGE THROUGH THE UNIVERSE: THE NEAR PLANETS, By the Editors of Time-Life Books, Inc., Alexandria, Virginia, 1990 Wilson, Andrew, JANE'S SOLAR SYSTEM LOG, Jane's Publishing, Inc., New York, 1987 About the Author - Larry Klaes, EJASA Editor, is the recipient of the ASA's 1990 Meritorious Service Award for his work as Editor of the EJASA since its founding in August of 1989. Larry also teaches a course on Basic Astronomy at the Concord-Carlisle Adult and Community Education Program in Massachusetts. Larry is the author of the following EJASA articles: "The One Dream Man: Robert H. Goddard, Rocket Pioneer" - August 1989 "Stopping Space and Light Pollution" - September 1989 "The Rocky Soviet Road to Mars" - October 1989 "Astronomy and the Family" - May 1991 THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC February 1993 - Vol. 4, No. 7 Copyright (c) 1993 - ASA -END OF FILE- ----------