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Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: JPL Recruits Two Experts To Help Hunt For New Planets and Life Привет всем! Вот, свалилось из Internet... MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov Contact: Jane Platt FOR IMMEDIATE RELEASE March 5, 1998 JPL RECRUITS TWO EXPERTS TO HELP HUNT FOR NEW PLANETS AND LIFE Two newly-arrived scientists at NASA's Jet Propulsion Laboratory will play a key role in the search for planets around other stars and the hunt for life beyond Earth. The appointments highlight a new JPL initiative to unite scientists from various disciplines, such as biology and astronomy, to study the evolution of planets and life in the universe. Dr. Didier Queloz, a Swiss astronomer who co-discovered the first known planet around a star similar to our Sun, is a distinguished visiting scientist at JPL for the next year and a half. Dr. Kenneth Nealson has joined JPL as a senior researcher in astrobiology, a new field whose goal is to understand how planets and life co-evolve. While at JPL, Queloz will continue his search for planets and help the Lab develop sophisticated search technologies. His work will benefit NASA's Origins Program, a series of planned missions to study the formation of galaxies, stars, planets and life. The program has gained momentum from discoveries by Queloz and, subsequently, other astronomers, of several planets orbiting stars beyond our Sun. Many scientists believe this raises the odds that an Earth-like planet exists with suitable conditions for life. Queloz, a Swiss citizen, received his degree in physics in 1990 from the University of Geneva and worked on his doctoral thesis at Geneva Observatory with Professor Michel Mayor from 1991 to 1995. Using the French Elodie telescope in Haute Provence, France, they looked for signs of a Doppler shift in nearby stars. As a star moves closer and then farther away from Earth, the star's color shifts from red to blue. By detecting this motion, astronomers can infer that the star is being tugged by gravity from an orbiting planet. "Back then, these experiments were considered a bit nutty," recalled Queloz. When Queloz and Mayor first detected a Doppler shift from the star 51 Pegasus, Queloz said their first reaction was, "We'd better check our instruments." Even after they verified the instruments' accuracy, Queloz and Mayor spent several weeks monitoring 51 Pegasus to confirm the discovery. In July of 1995, they were confident enough to buy a large cake and hold a celebration party in the south of France for family and friends. Queloz and Mayor formally announced their discovery, a Jupiter-sized planet orbiting 51 Pegasus, at an October 1995 scientific meeting in Florence, Italy. Queloz has received several honors, including the Swiss Society for Physics' Balzers Award, the Bioastronomy Medal from the International Astronomical Union, Commission 51, and a Best Thesis in Science honor from a Swiss corporation, Vacheron Constantin. Queloz is continuing his hunt for new planets with the Elodie telescope and its twin, Coralie, a Swiss telescope in La Silla, Chile. But he and other astronomers face great challenges in finding new and better ways to detect planets more like Earth. Current techniques allow only for the detection of giant, Jupiter-sized planets, which are considered unlikely candidates for life. While at JPL, Queloz will share his planet-finding experience with engineers who are designing more advanced technologies. Queloz is using a testbed interferometer at Caltech's Palomar Observatory to run tests on stars and prepare for an observing program. This work will help pave the way for other Origins projects, including the W.M. Keck Observatory interferometer in Hawaii, the Space Interferometry Mission, and the Terrestrial Planet Finder, all being planned by NASA. Interferometry combines and processes light from several telescopes to simulate a much larger telescope, and holds great promise as a tool in the search for Earth-sized planets. "I'd like to play a role in future exploration by helping to define interferometry techniques," Queloz said. During his stay at JPL, Queloz is living in Pasadena with his wife and their two children. Until very recently, an astronomer like Queloz would have had little if any interaction with a biological scientist like Dr. Kenneth Nealson. But various disciplines, such as astronomy, geology, biology and chemistry, are joining forces to study the development of life on Earth and the prospects of life elsewhere. Therefore, the work of scientists like Nealson and Queloz is converging to form a broad, interdisciplinary approach. "After all," said Nealson, "life is not a simple system and no science operates in a vacuum. Younger students are studying several disciplines to gain a more comprehensive view." Nealson is part of this new wave of scientific training, as a geobiology teacher and faculty associate in Caltech's geology and planetary sciences division. At JPL, a division of Caltech, Nealson has been appointed to head a new astrobiology unit. Nealson said over the next few years, his astrobiology group will develop an understanding of the way life and planets have evolved, and will define the signatures of life. "Not many foolhardy souls have ventured into this area," Nealson said. "After all, how can you find life if you don't know what you're looking for? This is a very, very important problem to be solved because right now we're not sure how to distinguish life from non-life. Our goal is to develop tools to make that distinction clearly." In recent years, microbiologists have made startling discoveries about the hardiness of life on Earth, studying living organisms in thermal vents, acid lakes and other unlikely environments. Nealson pointed out, "This has opened the eyes of scientists to the notion that life could exist under seemingly inhospitable conditions on other planets." Astrobiologists will also study changes in Earth's chemical composition over billions of years. They will then apply this knowledge to other planets to look for "chemical signatures" that might indicate that life has existed or could exist there. Nealson said astrobiology will be useful for numerous space missions, including the Mars sample return mission, scheduled to bring back Martian rocks in the middle of the next decade. Astrobiology will also benefit the Origins Program's Terrestrial Planet Finder, which will look for Earth-like planets around other stars and hunt for signs of life-sustaining chemicals. Nealson said astrobiological studies may prove valuable in the study of Jupiter's moon, Europa, which may have liquid oceans under its frozen surface. This icy moon is currently being studied by NASA's Galileo Europa Mission, and a new Europa Orbiter has a planned launch in 2003. Originally from West Liberty, Iowa, Nealson got his bachelor of science degree in biochemistry in 1965 from the University of Chicago. He earned his Ph.D. in microbiology from the University of Chicago and did postdoctoral studies at Harvard University. Nealson taught at Scripps Institution of Oceanography, San Diego, CA, and at the Center for Great Lakes Studies, University of Wisconsin, Milwaukee, WI. His honors include the Guggenheim Fellowship for Sabbatical Leave in 1981, and an appointment as an elected fellow in the American Academy of Microbiology, which he received in November 1993. Nealson and his wife live in South Pasadena, CA. ##### Hа сегодня все, пока! =SANA=

Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: * SpaceNews 09-Mar-98 * Привет всем! Вот, свалилось из Internet... SB NEWS @ AMSAT $SPC0309 * SpaceNews 09-Mar-98 * BID: $SPC0309 ========= SpaceNews ========= MONDAY MARCH 9, 1998 SpaceNews originates at KD2BD in Wall Township, New Jersey, USA. It is published every week and is made available for non-commercial use. * HAM RADIO AND AMSAT FEATURED IN NY TIMES * AMSAT-NA Executive Vice President Keith Baker, KB1SF, has reported that AMSAT is included in a feature article about Amateur Radio and the Internet in the Thursday, March 5th edition of the New York Times newspaper. The article, written by John Verity, a New York Times feature writer, is contained in a recently added section of the paper called "Circuits". The story examines the links between the Amateur Radio hobby and the Internet, and how Amateur Radio and AMSAT have both expanded and exploited those links over the years. The AMSAT-NA Web Site http://www.amsat.org was included along with others as a source of information on the amateur radio satellites. "Mr. Verity and I spent a few hours on the telephone talking about the continuing magic of Amateur Radio and what AMSAT has done to spark new ways of telecommunication over the years", said Keith. Keith is shown operating on the satellites from his "shack" in one of the two photos included with the story. Keith reports that Mr. Verity was quite impressed with the ease with which we regularly communicate through our fleet of AMSAT satellites. "He was most impressed with the fact that we can, for example, communicate via one of our MICROSATS using nothing more sophisticated than a low powered hand-held radio and a flexible antenna," said Keith. "The carpenter's rule antenna material we regularly use aboard our satellites also caught his attention," he said. Says Keith, "Needless to say, this story is great publicity for AMSAT and for Amateur Radio as a whole. If it sparks enough interest in just one youngster to become a Ham then it was well worth the effort!" [Info via the AMSAT-NA News Service] * MIR APRS EXPERIMENT * The MIREX (Mir International Amateur Radio Experiment) team would like to announce an Automatic Packet/Positioning Reporting System (APRS) test that is scheduled for 10-Mar-98 beginning at 1455 UTC and lasting through 1651 UTC. APRS stations will be allowed to use the Digital Repeater (R0MIR) on the Russian Mir Packet Station during the period of this experiment, which will cover approximately 99% of the USA on two orbits of Mir. MIREX hopes that schools will be able to take part in the experiment by logging into one of the APRS Web sites (www.aprs.net) to track APRS beacons across the US. Hams are also encouraged to set up packet stations at schools to allow students and educators to witness the experiment first-hand. The Mir PMS frequency is currently 145.985 FM simplex. The Mir Digital Repeater callsign is R0MIR. After 10-Mar-98 @ 1651 UTC, APRS should NOT be used via Mir. A recent 2-line Keplerian data set for use in tracking Mir follows: Mir 1 16609U 86017A 98063.08565753 .00008828 00000-0 10311-3 0 3011 2 16609 51.6575 217.9855 0005337 84.5056 275.6535 15.62474297687614 [Info via Dr. Dave Larsen, N6CO] * EVIDENCE OF ICE DISCOVERED ON MOON * There is a high probability that water ice exists at both the north and south poles of the Moon, according to initial scientific data returned by NASA's Lunar Prospector. Just two months after the launch of the cylindrical spacecraft, mission scientists have solid evidence of the existence of lunar water ice, including estimates of its volume, location and distribution. "We are elated at the performance of the spacecraft and its scientific payload, as well as the resulting quality and magnitude of information about the Moon that we already have been able to extract," said Dr. Alan Binder, Lunar Prospector Principal Investigator from the Lunar Research Institute, Gilroy, CA. The presence of water ice at both lunar poles is strongly indicated by data from the spacecraft's neutron spectrometer instrument, according to mission scientists. Graphs of data ratios from the neutron spectrometer "reveal distinctive 3.4 percent and 2.2 percent dips in the relevant curves over the northern and southern polar regions, respectively," Binder said. This is the kind of data 'signature' one would expect to find if water ice is present." However, the Moon's water ice is not concentrated in polar ice sheets, mission scientists cautioned. "While the evidence of water ice is quite strong, the water 'signal' itself is relatively weak," said Dr. William Feldman, co-investigator and spectrometer specialist at the Department of Energy's Los Alamos National Laboratory, NM. "Our data are consistent with the presence of water ice in very low concentrations across a significant number of craters." Using models based on other Lunar Prospector data, Binder and Feldman predict that water ice is confined to the polar regions and exists at only a 0.3 percent to 1 percent mixing ratio in combination with the Moon's rocky soil, or regolith. Assuming a water ice depth of about a foot and a half (0.5 meters), the depth to which the neutron spectrometer's signal can penetrate, Binder and Feldman estimate that the data are equivalent to an overall range of 11 million to 330 million tons (10-300 million metric tons) of lunar water ice, depending upon the assumptions of the model used. This quantity is dispersed over 3,600 to 18,000 square miles (10,000-50,000 square kilometers) of water ice-bearing deposits across the northern pole, and an additional 1,800 to 7,200 square miles (5,000-20,000 square kilometers) across the southern polar region. Furthermore, twice as much of the water ice mixture was detected by Lunar Prospector at the Moon's north pole as at the south. "This finding by Lunar Prospector is primarily of scientific interest at this time, with implications for the rate and importance of cometary impacts in the history and evolution of the Solar System," said Dr. Wesley Huntress, NASA Associate Administrator for Space Science. "A cost-effective method to mine the water crystals from within this large volume of soil would have to be developed if it were to become a real resource for drinking water or as the basic components of rocket fuel to support any future human explorers." Lunar Prospector is scheduled to continue its current primary data gathering mission at an altitude of 62 miles (100 kilometers) for a period of ten more months. At that time, the spacecraft will be put into an orbit as low as six miles (10 kilometers) so that its suite of science instruments can collect data at much finer resolution in support of more detailed scientific studies. In addition, surface composition and structure information developed from data returned by the spacecraft's Gamma Ray Spectrometer instrument will be a crucial aspect of additional analysis of the polar water ice finding over the coming months. [Info via NASA Press Release 98-38] * FEEDBACK/INPUT WELCOMED * Comments and input for SpaceNews should be directed to the editor (John, KD2BD) via any of the paths listed below: WWW : http://www.njin.net/~magliaco/ PACKET : KD2BD @ KS4HR.NJ.USA.NA INTERNET : kd2bd@amsat.org, magliaco@email.njin.net SATELLITE : AMSAT-OSCAR-16, LUSAT-OSCAR-19, KITSAT-OSCAR-25 <<=- SpaceNews: The first amateur newsletter read in space! -=>> <<=- Serving the planet for 10 years -=>> /EX -=-=-=-=-=-=-=-=-=-=-=-=- John A. Magliacane, KD2BD -=-=-=-=-=-=-=-=-=-=-=-=- Internet : kd2bd@amsat.org | Voice : +1.732.224.2948 Satellite : OSCAR-16, OSCAR-19 | Morse : -.- -.. ..--- -... -.. Packet : KD2BD @ KS4HR.NJ.USA.NA | WWW : http://www.njin.net/~magliaco/ Video : 426.250 MHz/439.250 MHz | FAX : +1.732.224.2060 -=-=-=-=-=-=-=-=- Hiroshima '45, Chernobyl '86, Windows '95 -=-=-=-=-=-=-=-=- Hа сегодня все, пока! =SANA=

Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: Clues To Possible Life On Europa May Lie Buried In Antarctic Ice Привет всем! Вот, свалилось из Internet... Marshall Space Flight Center Press Release Clues to possible life on Europa may lie buried in Antarctic ice March 5, 1998: More than a century ago, science fiction pioneer Jules Verne wrote about people swept "Off on a Comet" and into space where they lived more or less happily ever after. Verne's 1877 book (also published as "Hector Servadac") was a bit fanciful, but it had an element of truth: life may have hitchhiked across the solar system. The proof may be found at the ends of the Earth. This week, American and Russian scientists are examining deep ice from the Antarctic and hoping to find clues that fungi, bacteria, and even diatoms could survive conditions in icy solar system bodies. This would help make the South Pole one of the first destinations for the growing field of astrobiology. "It's possible to say that ancient impacts of asteroids on the [Antarctica] Earth could have ejected soil, rocks, and seawater containing terrestrial microorganisms into space, and that they may have made it to other places in the solar system," explained Richard Hoover at NASA's Marshall Space Flight Center. Hoover is an X-ray astronomer who is also is internationally known for his work on diatoms and a firm believer that living microorganisms locked in ice have a chance of remaining viable for long periods in outer space. The debate over whether the Antarctic Allan Hills meteorites brought life from Mars (or were contaminated by life on Earth) is the best known case. Hoover said that other evidence abounds, including asteroids striking the Earth or Mars and blasting materials into space, the survival of streptococcus bacteria on the Surveyor 3 moon lander, and the survival of microorganisms inside Antarctic ice. The possibilities expanded this week when NASA released new images and data that Europa, one of Jupiter's larger moons, slush and perhaps liquid water near the surface. That raises the intriguing possibility that Europa may harbor life. Discoveries on the Earth over the last few years show that life thrives or can be preserved in a range of "hostile" conditions, from volcanic vents deep in ocean trenches, to ice more than 400,000 years old, to Siberian permafrost more than 5 million years old. This week, Hoover and Dr. S. S. Abyzov of Russia's Institute of Microbiology of the Russian Academy of Sciences in Moscow are examining ancient ice drilled at Russia's Vostok (East) Station about 1,000 km (1,600 mi) from the South Pole. Eventually, they hope to examine water taken from inside a lake - liquid, not ice - discovered under Vostok Station in 1996. The first samples being examined are from 386 meters (1,266 ft) down; the deepest in this set is from 1,249 meters (4,097 ft). Samples from as deep as 3,610 meters (11,840 ft) are on their way from Vostok to the Institute of Microbiology. Abyzov says that portions will be brought to Marshall later this year. Russian scientists have been drilling at Vostok since 1974. In 1996, seismic and other tools revealed the lake's presence in 1996. Lake Vostok is overlaid by about 3,710 meters (12,169 ft) of ice and may be 500,000 to 1 million years old. Since the discovery, drilling has gone slowly while procedures are worked out to keep it pristine. No one has seen or sampled the lake - the deepest ice sample is from 100 meters (328 feet) above the liquid surface - nor is anyone sure why it is liquid, hence the scientific curiosity. (Check below for links to stories about Lake Vostok.) While Lake Vostok holds clues about life on Earth, it also is a good model for conditions on Europa (the image links to the latest news from Europa). The lake is about 48 by 224 km (30 by 140 mi) in size - about the size of Lake Ontario - and 484 meters (1,600 ft) deep. Recent data indicate that it has about 50 meters (165 ft) of sediment at the bottom. "Recent research [shows] that extremely severe conditions of cosmic environments do not exclude the possibility that microorganisms may exist in anabiotic states at high altitudes in interplanetary space," Abyzov wrote in a recent paper. The only way to resolve the question is to use the Antarctic as a model for conditions in comets, the Martian ice caps, and other icy moons orbiting Jupiter and Saturn. At Vostok station in 1975, Abyzov discovered bacteria, fungi, diatoms, and other microorganisms which were blown to Antarctica by winds from lower latitudes. The numbers of the organisms at different depths, and thus different ages of the ice, change with major climate changes on the Earth. Thus, the ice also serves as a time capsule, preserving specimens of life as far back as 500,000 years. This offers the potential for studying how genetic material changes over the centuries. Abyzov brought his samples to Marshall to use the Environmental Scanning Electron Microscope, or ESEM, a relatively new tool that Marshall uses to analyze how materials fail and break. It was originally designed to analyze biological specimens in their natural environment, without coating them in gold to make them reflective. And that's ideal for observing whatever is in the ice. It also uses an X-ray scan to analyze the elements in a target, an important step in determining whether an object is organic. The ice specimens will be analyzed at Marshall over the next week, then Abyzov will go to the Jet Propulsion Laboratory to work with another colleague with different analytical tools. Check back in a few days for a follow-up story on what the ESEM finds. Hа сегодня все, пока! =SANA=

Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: Lunar Ice: Privat Company's Mission-In-Progress Could Lead To Sample R Subject: Lunar Ice: Privat Company's Mission-In-Progress Could Lead To Sample R Привет всем! Вот, свалилось из Internet... CONTACT: Beth Elliott 516/579-1249 Direct eelliott@appliedspace.com For Immediate Release LUNAR ICE: PRIVATE COMPANY'S MISSION-IN-PROGRESS COULD LEAD TO RETURN OF SAMPLES Applied Space Resources, Inc.'s current engineering work for a September 2000 Lunar Sample Return Mission will provide framework for polar exploration Bethpage, NY - 03/06/98 - As NASA announced the Lunar Prospector's discovery of polar ice on the Moon, Applied Space Resources, Inc. (ASR) of Long Island, New York said the robotic sample return mission it is currently engineering will provide a proof of concept for low-cost commercial lunar sample retrieval missions. ASR's lunar sample return mission, the Lunar Retriever, will retrieve lunar rock and soil to sell both to research organizations and, through commercial channels, to the general public. ASR expects to launch Lunar Retriever by September 2000, the 30th anniversary of Luna 16, the first robotic sample return mission to soft land on the moon. "Based on the spacecraft designed for the Lunar Retriever mission, a follow-on mission to retrieve lunar soil and ice samples could be launched within six to twelve months after the initial mission at a cost well under $100 million," says Denise Norris, ASR's CEO. When passed, the Commercial Space Act of 1997 will specifically instruct NASA to look to private companies like ASR to develop the In Situ Resource Utilization (ISRU) technology critical to its plans for future space exploration and colonization. And technology for using the newly-discovered lunar ice would give space exploration an immense boost. Water is critical to human life support, and can also be separated into its chemical components of hydrogen and oxygen: oxygen for breathing, and combinations of hydrogen and oxygen for rocket fuel. But the cost of lifting the thousands of gallons of water into low Earth orbit alone, much less transporting it from there to the Moon, would be prohibitive. The Lunar Prospector data suggests there is an immense amount of water on the Moon in the form of ice mixed in with lunar soil. But before space explorers can make use of the water, scientists and engineers will have to figure out how best to extract it from the lunar soil, in which it is sparsely scattered. The Lunar Prospector's investigators, Dr. Alan Binder of the Lunar Research Institute in Gilroy, California and Dr. William Feldman of the Los Alamos National Laboratory in New Mexico, say the data suggests that water ice is confined to the polar regions and exists at only a 0.3 percent to 1 percent mixing ratio in combination with the rocky lunar soil. Jay Manifold, ASR's Vice President of Research and Development, says, "The key to ISRU development, including research on how to extract and use lunar ice, is putting samples of lunar resources in the hands of scientists on Earth. ASR's goal is to use existing technologies to deliver spacecraft to any destination with precision, and return resources and information with equal precision, for a profit. Our Lunar Retriever, for example, will use the same Lockheed-Martin Athena 2 rocket as the Lunar Prospector. A mission to collect samples of lunar polar ice, and return them in cryogenic storage, would be a logical next step for us." ASR's principals stress the importance of entrepreneurs to opening near-Earth space to the resource development that will make possible fulfilling NASA's exploration goals. ASR will make its services available to private and public concerns alike, but will take no subsidies. "Humankind will only benefit from the resources of space when they are developed by private enterprises such as ours," says Denise Norris. "We intend to use our knowledge, creativity, hard work and business vision to demonstrate the viability of market-driven space missions. We will not go to the public asking them to send us into space. We will go into space first, then come to the public with something to offer: the productive utilization of the vast resources of near-Earth space." More information about Applied Space Resources and its Lunar Retriever mission can be found at the ASR web site, http://www.appliedspace.com. # # # Hа сегодня все, пока! =SANA=

Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: New Model Explains Venusian Land Forms Привет всем! Вот, свалилось из Internet... Washington University in St. Louis New Model Explains Venusian Land Forms March 5, 1998 Because Earth and Venus have nearly the same size, scientists long have called them planetary twins. But scientists theorize the processes that form the geological features of the planets are different. Earth forms its continents and physical features and sheds its interior heat by plate tectonics. Though Venus might be expected to do the same, its surface shows scant evidence for plate tectonics, and planetary researchers long have debated, often heatedly, just what the corresponding process is on our sister planet. Now a new model of Venus, derived largely from the highly successful Magellan Mission early in this decade, shows that two of the planet's most predominant features, crustal plateaus and volcanic rises, were formed by a mechanism similar to hot spot plumes, a process still active on Earth today and evident in the Hawaiian Islands. Hotspots are thermal plumes of hot rock originating deep within the Earth and rising buoyantly upward over millions of years. They eventually surface in dramatic, lava-spewing displays geologists call flood basalts. The new interpretation comes from the mapping of very subtle geological faults on the surfaces of the crustal plateaus, and was published March 6, 1998, in Science magazine. Roger J. Phillips, Ph.D., professor of earth and planetary sciences at Washington University in St. Louis, and his colleague Vicki L. Hansen, Ph.D., professor of geological sciences at Southern Methodist University in Dallas, analyzed recent data and hypothesize that a thickening of the Venusian lithosphere, the outer strong shell of a rocky planet, approximately one billion years ago largely shut down the creation of crustal plateaus and led to the formation of volcanic rises instead. Phillips and Hansen suggest that the thickening occurred rapidly in geological time, in 100 to 200 million years. The thickening prevented the plumes from melting substantially and creating new crustal material to form crustal plateaus. Volcanic rises form when there is not massive melting in the plumes. Phillips and Hansen estimate the Venusian lithosphere is about 60 miles thick today, compared with about 24 miles thick at the end of the 'thin lid' era, which they suggest lasted up until about one billion years ago. "To maintain the thin lithosphere you have to have some sort of recycling going on, which on Earth is plate tectonics, but that's not the case with Venus over the past billion years," said Phillips. "Our calculations also show that you get plenty of plains volcanism during the thin lid era, almost an embarrassment of riches, with formation going on almost constantly up to the point where the lithosphere thickens.." That conclusion clashes with another popular planetary theory that holds that plains formation was an abrupt episode on Venus. Phillips said the lack of water on Venus no doubt contributed to the formation of the thickened lithosphere. "The rocks are stronger on Venus probably because of a lack of water," he said. " It probably got to the point where the stresses induced by the interior just couldn't break the strong rocks, and the process of lithospheric recycling, which maintained the thin lid, just quit. "Water is the basic difference between Venus and Earth in this context Water makes the lithosphere of Earth relatively weak, and lack of water makes this structure relatively strong on Venus. Whether you have recycling of the lithosphere into the mantle comes down to a competition between how strong the lithosphere is and how much force from the convecting mantle can be applied to break the lithosphere. This competition basically operates differently on the two planets." Because the Phillips and Hansen model indicates a recycling process during the thin lid era, it's conceivable that Venus was using plate tectonics during its geological heyday. "Prior to the thickening of the lithosphere, Venus could have had plate tectonics, as far as we're concerned," Phillips said. "There was some kind of lithospheric recycling. It may have been plate tectonics or something else, but it was there." The model also couples the climate and interior evolution of Venus, the planet that suffers from the runaway greenhouse effect to give a present-day surface temperature of nearly 900 degrees Fahrenheit. All of the volcanism that went on during the early years of the planet pumped so-called greenhouse gases sulfur dioxide and carbon dioxide in the Venusian atmosphere, so that the surface temperature was even hotter then. "The gases increased the greenhouse effect, which in turn raised surface temperatures, and that in turn led to more interior melting, which resulted in more greenhouse gases being released," Phillips said. "There is a very tight coupling between climate evolution and interior evolution on Venus over much of its history, and that is something we're just beginning to take seriously on Earth. ### Contact: Tony Fitzpatrick p72245tf@wuvmd.wustl.edu (314) 935-5272 Washington University in St. Louis Hа сегодня все, пока! =SANA=

Дата: 10 марта 1998 (1998-03-10) От: Alexander Bondugin Тема: Mars Surveyor 98 Update - March 6, 1998 Привет всем! Вот, свалилось из Internet... Mars Surveyor 98 Project Status Report March 6, 1998 John McNamee Mars Surveyor 98 Project Manager Orbiter and lander integration and test activities are proceeding on schedule with no significant problems. Orbiter electromagnetic compatibility testing is in process and will be completed next week. Mechanical integration of the lander to the cruise configuration is in process. The lander vehicle will be encapsulated within the aeroshell on Mar 9. The lander spacecraft in full cruise configuration will be transported to the acoustics lab at Lockheed Martin on Mar 18. The Thermal and Evolved Gas Analyzer (TEGA) flight instrument integration is complete. Testing and calibration of the TEGA is in process at the University of Arizona. For more information on the Mars Surveyor 98 mission, please visit this website: http://mars.jpl.nasa.gov/msp98/ Hа сегодня все, пока! =SANA=

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