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Дата: 03 февраля 1998 (1998-02-03) От: Alexander Bondugin Тема: Cassini Update - January 30, 1998 Привет всем! Вот, свалилось из Internet... Cassini Significant Event Report For Week Ending 01/30/98 MSO Significant Events input for week of Friday 01/23 through Thursday 01/29: Spacecraft Status: The Cassini spacecraft is presently traveling at a speed of approximately 120,000 kilometers/hour (~75,000 mph) and has traveled approximately 260 million kilometers (~163 million miles) since launch last October 15. The most recent Spacecraft status is from the DSN tracking pass on Thursday, 01/29, over Goldstone. The Cassini spacecraft is in an excellent state of health and is operating nominally, with the C6 sequence executing onboard. Inertial attitude control is being maintained using the spacecraft's hydrazine thrusters (RCS system). The spacecraft continues flying in a High Gain Antenna-to-Sun attitude. It will maintain the HGA-to-Sun attitude, except for planned trajectory correction maneuvers, for the first 14 months of flight. Communication with Earth during early cruise is via one of the spacecraft's two low-gain antennas; the antenna selected depends on the relative geometry of the Sun, Earth and the spacecraft. The downlink telemetry rate is presently 40 bps. Spacecraft Activity Summary: From Friday, 01/23, through Saturday, 01/24, there were no changes in spacecraft configuration. On Sunday, 01/25, the Off-Sun Time Constraint was set for the C6 sequence. This limit, based on the range from the spacecraft to the sun, is adjusted approximately every two months, for thermal reasons, as Cassini travels along its interplanetary trajectory. From Monday, 01/26, through Tuesday, 01/27, there were no changes in spacecraft configuration. On Wednesday, 01/28, the Solid State Recorder (SSR) record and playback pointers were reset, according to plan. This housekeeping activity, done approximately weekly, maximizes the amount of time that recorded engineering data is available for playback to the ground should an anomaly occur on the spacecraft. On Thursday, 01/29, the Articulated Reaction Wheel Mechanism (ARWM) was unlatched successfully, according to plan. The Articulated Reaction Wheel is a spare device which can be aligned with the appropriate spacecraft axis, should it be needed to replace a failed prime unit later in the mission. (Thrusters, rather than reaction wheels, are used during early cruise for controlling spacecraft attitude.) Also on Thursday, the spacecraft's active vector was updated in the Inertial Vector Table. This housekeeping activity, which updates the vectors between the spacecraft and the Sun, Earth, and other bodies, is performed every few months. Upcoming spacecraft events: Events for the week of 01/30 through 02/05 include: a reset of the SSR pointers (02/03), and an SSR Flight Software Partition maintenance activity (02/02 and 02/03). DSN Coverage: For the next month or so, there will be an increase in DSN coverage for Navigation purposes, as the second and third Trajectory Correction Maneuvers (TCMs) approach. Over the past week Cassini had 4 track periods (01/22, 01/25,01/27, 01/28). In the coming week there will be 8 DSN passes, Friday to Saturday (01/30-01/31), 3 additional passes on Saturday, (01/31), Monday, (02/02), Tuesday, (02/03), Wednesday, (02/04), and Thursday (02/05). Hа сегодня все, пока! =SANA=

Дата: 03 февраля 1998 (1998-02-03) От: Alexander Bondugin Тема: Mars Surveyor 98 Update - February 1, 1998 Привет всем! Вот, свалилось из Internet... 1998 MARS SURVEYOR PROJECT STATUS REPORT FEBRUARY 1, 1998 John McNamee Mars Surveyor 98 Project Manager The 1998 Mars Surveyor orbiter is 312 days from launch and the lander is 335 days from launch (as of 2/1/98). The following provides a summary description of the current Project status as of February 1, 1998. Orbiter Integration and Test The orbiter spacecraft has been fully assembled and checked out functionally. Major tests successfully completed include the Deep Space Network (DSN) Compatibility Test, the Bus Functional Test (BFT), Mission System Test #1 (MST #1), and the modal survey. Descriptions of the Bus Functional Test and the Mission System Test are included on the attachment. The Pressure Modulator InfraRed Radiometer (PMIRR) flight instrument is integrated and all interfaces and functionality have been verified. The Mars Color Imager (MARCI) electrical interface unit (i.e., electrical equivalent camera less optics) is integrated and interfaces are verified. The flight camera is on schedule for integration in February prior to thermal vacuum testing. The refurbishment of the orbiter flight processor and power distribution and drive unit ATLO Test Units is complete and all orbiter electronics are in their final flight configuration. The orbiter is in the Reverberant Acoustics Lab (RAL) at Lockheed Martin in Denver and is being prepared for acoustic testing. The current schedule for the orbiter is: 2/17/98 - Start Acoustic Test 2/26/98 - Start ElectroMagnetic Interference/Compatibility Tests (EMI/EMC) 4/3/98 - Start Thermal Vacuum Testing 9/3/98 - Ship to Kennedy Space Center (KSC) 12/10/98 - Launch The schedule maintains 71 days of margin prior to shipment and 20 days of margin at KSC. Significant mass margin for the orbiter exists with essentially all elements weighed. Recent orbit insertion analyses indicate that by utilizing just a portion of the expected margin at launch to further fill the hydrazine and ox tanks will allow the orbiter to insert directly into a 15 hour or shorter period orbit. This provides significant margin against aerobraking uncertainties and increases the probability that the orbiter will be in place to support the lander at lander arrival. Lander Integration and Test The lander spacecraft is fully integrated electrically and all interfaces have been verified. Major tests successfully completed include the Deep Space Network (DSN) Compatibility Test and the Bus Functional Test (BFT). In addition, the lander to orbiter UHF relay was tested successfully using both spacecraft in the high bay at LMA. Installation of the lander science payload is in process. The flight Lidar, Meteorology package, Surface Stereo Imager, Robotic Arm, and Robotic Arm Camera, have been installed on the spacecraft and functional testing is in progress. The flight Mars Descent Imager will be installed next week and the flight Thermal and Evolved Gas Analyzer experiment will be installed in June prior to landed configuration Thermal Balance testing. The lander is in the high bay facility at Lockheed Martin and will be moved to the Reverberant Acoustics Lab in March for the start of environmental testing. The current schedule for the lander is: 3/21/98 - Start Acoustic Test 3/31/98 - Start EMI/EMC Tests 5/4/98 - Start Cruise Thermal Vacuum Test 6/23/98 - Start Landed Thermal Balance Test 10/14/98 - Ship lander to KSC 1/3/99 - Launch The current lander schedule maintains 41 days of margin prior to shipment with 20 days of margin at KSC. Significant mass margin for the lander exists with full tanks and most elements weighed. In all likelihood the lander will be well below the maximum design mass providing significant margin against launch vehicle performance shortfalls, entry heating limits, parachute deployment limits, and landing site elevation uncertainties. Bus Functional Test The purpose of the Bus Functional Test (BFT) is to verify the end-to-end core command and control functionality in an integrated vehicle configuration. The major parts of the test include complete testing of uplink and downlink command and data capability (data rates, file sizes, etc.), non-volatile memory read and write functionality, and test of the Command and Data Handling Module Interface Card (C-MIC) functions which control heartbeat, fault recovery, and vehicle state. Also, end-to-end phasing of the Attitude Control Subsystem from sensor inputs through actuator commands is tested in a quasi-closed loop manner. The BFT is conducted on both A&B sides of the hardware. Some miscellaneous functions also will be verified as part of the BFT, including voltage drop verification throughout the longest harness cable run, launch event detection logic, and critical command aliveness functions to be used in later tests. The BFT represents a major milestone in the integration and test phase of development. Mission System Test The Mission System Tests (MST), which consist of the System Aliveness Test (SAT), the Mission Profile Test (MPT), and Sequence Verification Test (SVT), are run before and after each environmental test and after the spacecraft is shipped to KSC. The SAT is a standard, multiple use test that will be run as the first part of each MST. It's purpose is to demonstrate continuity of the electrical signal and power paths, meaning that all components are operational and able to receive commands and send telemetry. The significance of this first SAT is in demonstrating that the spacecraft has achieved a fully integrated system of software and hardware and to establish the baseline data for subsequent runs of the SAT. Unlike earlier subsystem level tests on the spacecraft, this end to end test was performed without the aid of ground support equipment and thereby establishes a higher level of verification of the hardware / software interfaces. Orbiter MST #1 also includes a limited mission profile test (MPT). For more information on the Mars Surveyor 98 program, please visit the Mars Surveyor 98 home page: http://mars.jpl.nasa.gov/msp98/ Hа сегодня все, пока! =SANA=

Дата: 03 февраля 1998 (1998-02-03) От: Alexander Bondugin Тема: Cambridge Conference Digest - February 2, 1998 [1/2] Привет всем! Вот, свалилось из Internet... CAMBRIDGE CONFERENCE DIGEST, 02/02/98 (1) RAMPINO'S NEW PAPER ON THE SHIVA HYPOTHESIS (2) LOOKING AT ASTEROID 1620 GEOGRAPHER (3) THE NUMBER DENSITY OF MAIN-BELT ASTEROIDS (1) RAMPINO'S NEW PAPER ON THE SHIVA HYPOTHESIS From: Michael Rampino <rampin@is3.nyu.edu> wrote: Benny: Here is a summary of the Shiva article: The Shiva Hypothesis: Impacts, Mass Extinctions, and the Galaxy Michael R. Rampino NASA, Goddard Institute for Space Studies New York, NY 10025 and New York University New York, NY 10003 The discovery by Walter and Luis Alvarez and their colleagues at the University of California at Berkeley of anomalous concentrations of the rare element iridium in a thin clay layer at at the Cretaceous/Tertiary (K/T) boundary in a rock outcrop near the town of Gubbio, Italy, almost twenty years ago, triggered an upheaval in the geological sciences. The intervening years have seen a remarkable confirmation of the Alvarez group's hypothesis that the unusual traces of iridium were the fingerprint of dust created by the collision of a huge asteroid or comet with the Earth, and that the occurrence of the tell-tale clay layer at the precise time that the dinosaurs and some 75% of life on the planet disappeared was no mere coincidence. This proposal culminated in the discovery of a giant 65-million year old impact crater in the Yucatan, widespread evidence of massive tsunami in the Caribbean/Gulf of Mexico region at the same time, and spectacular deposits derived from storms of rock debris blasted out of the crater that were investigated during recent Planetary Society expeditions to Belize in Central America. The convergence of evidence for impact at the Cretaceous/Tertiary (K/T) boundary has led to renewed interest in mass extinctions and a recognition of their importance as a major driving force in the evolution of life on Earth. The K/T mass extinction is but one of a number of mass extinction events recorded in the fossil record, and in fact was not the most severe. Could impacts be responsible for the recurrent mass extinctions seen in the geologic record? A few years ago such a suggestion would have seemed far-fetched, but recent evidence is converging on the conclusion that mass extinctions coincided with comet or asteroid impacts, and that periodic comet showers, triggered by the Solar System's motions through the Milky Way Galaxy may provide a general theory to explain impact-related mass extinctions. The cyclic extinctions are followed by explosive evolution of the surviving species that re-filled the many life niches emptied by the global catastrophe, so we have named this idea the "Shiva Hypothesis", after the Hindu deity of cyclic destruction and renewal. One of the most intriguing findings in the study of extinctions has been that of a possible cycle of these mass die offs. Analyses of the extinction record by Dave Raup and Jack Sepkoski revealed an underlying cycle of about 26 million years in the mass extinctions of the last 250 million years (the best-dated part of the record), and recent work on an improved and better dated extinction data base with Bruce Haggerty at NYU reveals that a cycle of 26 to 30 million years persisted through the entire 540 million year record. Raup and Sepkoski's original findings prompted Richard Stothers of NASA's Goddard Institute for Space Studies and me, and independently Walter Alvarez and Rich Muller at Berkeley, to analyze the record of impact craters, and we detected a similar cycle in the occurrence of large impacts on the Earth. Furthermore, it seems that clusters of craters of similar ages are closely correlated with the mass extinction episodes. These results suggest that many impact events on Earth were part of a periodic, most likely from showers of comets, leading to periodic mass extinctions. If a 26 or 30 million year periodicity in mass extinctions and impacts is real, then it may be related to a known astronomical cycle-the motion of the Solar System up-and-down through the plane of the disk-shaped Milky Way Galaxy. Astrophysicists have determined that the Solar System revolves around the center of the Galaxy about once every 220 million years, and as it does so the Solar System bobs up and down like a horse on a carrousel through the dense, central portion of the galactic disk. In this cycle, the Sun and planets pass through the dense region packed with stars and clouds of interstellar gas and dust every 26 to 30 million years. Stothers and I first suggested that passage of the Solar System through the galactic plane could lead to gravitational disturbance of some of the trillions of comets that orbit the Sun in the so-called Oort Cloud, resulting in periodic showers of comets in the inner Solar System. Recent work by astrophysicist John Matese and colleagues at the University of Southwestern Louisiana has confirmed that the pull of the combined mass of the material in the galactic disk is sufficient to induce a hail of comets during our passage though the central plane. Like Shiva, the Hindu Destroyer/Creator, the cyclic impacts bring an end to one world, and allow the beginning of a new one. With the Chicxulub impact 65 million years ago, the Mesozoic world, populated by giant dinosaurs and flying reptiles, gave way to the modern world of mammals and birds. This cycle of doom has relevance to the present-day impact hazard, as the Solar System passed through the Galaxy's central plane in the last few million years, and by some accounts a barrage of comets recently dislodged from the Oort Cloud should be approaching the planets now. A few impact/extinction events may be out of phase with the 30 million year galactic cycle, but it is expected that some comet and asteroid impacts would occur independently of the periodic perturbation of Oort Cloud comets. These exciting new findings from astronomy, geology, and the history of life point to a general theory relating mass extinctions, and perhaps other geologic events, to the impacts of large comets and asteroids on the Earth. In this view, mass extinctions of life occur as discrete pulses, marked by abrupt mass mortality on land and in the oceans, decimation of plant life, major environmental perturbations shown by changes in carbon isotopes, and climatic changes shown by oxygen-isotope shifts. The mass extinctions are commonly followed by a period of rapid evolution of surviving species, with newcomers filling the many niches abandoned en-masse by the victims of global disaster. In a growing number of cases, the times of mass extinction have been found to be marked by evidence of great asteroid or comet impacts, in the form of large, dated impact craters, and widespread layers rich in iridium, shocked minerals, and glassy microtektites. It may be that all of the major, and many of the minor, breaks in the geologic record were caused by impacts of objects of various sizes. The underlying periodicity of about 30 million years that seems to pervade the record of these events may well be related to showers of comets from the Oort Cloud triggered as the Solar System passes through the galactic plane. Thus the impact hypothesis of mass extinctions, which began with study of a thin clay layer at Gubbio, has grown in theoretical and observational support, culminating in an important unifying concept in the earth sciences. Michael R. Rampino Earth & Environmental Science Program New York University 100 Washington Square East New York, NY 10003 (212) 998-3743 Office Phone (212) 995-3820 Office Fax (212) 242-0929 Home Phone (212) 255-2739 Home Fax Hа сегодня все, пока! =SANA=

Дата: 03 февраля 1998 (1998-02-03) От: Alexander Bondugin Тема: Cambridge Conference Digest - February 2, 1998 [2/2] Привет всем! Вот, свалилось из Internet... (2) LOOKING AT ASTEROID 1620 GEOGRAPHER V.V. Prokofeva*), L.G. Karachkina and V.P. Tarashchuk: Investigations of oscillations in the brightness of Asteroid 1620 geographer during its approach to the Earth in 1994. ASTRONOMY LETTERS-A JOURNAL OF ASTRONOMY AND SPACE ASTROPHYSICS, 1997, Vol.23, No.6, pp.758-767 *) UKRAINIAN ACADEMY OF SCIENCE, CRIMEAN ASTROPHYS OBSERV, P-O NAUCHNYI, UA-334413 CRIMEA,UKRAINE Comprehensive investigations were conducted of Asteroid 1620 Geographer during its approach to the Earth in 1994. A frequency analysis of fine photometric effects and oscillations in its brightness was performed using data from a catalog of photometric observations of asteroids. This analysis confirms the monolithic nature of the very elongated body of the asteroid. In addition to the known rotation period of the asteroid, periods of 0(d).8 and 2(d).8 are detected, as well as multiples of these periods. The observed periodicity suggests that the first of these periods is associated with free precession of the rotation axis of the asteroid, while the second is due to forced precession with precession angle 3 degrees +/- 1 degrees. The free precession could have arisen either during the formation of the asteroid or during a collision with another body. The presence of forced precession and the fact that Geographer is associated with a meteor shower is consistent with the possible existence of modest-sized companions. Copyright 1998, Institute for Scientific Information Inc. (2) DID COSMIC IMPACT HIT EARLY CHINESE? S.L. Guo*), W. Huang, X.H. Hao and B.L. Chen: Fission track dating of ancient man site in Baise, China, and its significances in space research, paleomagnetism and stratigraphy. RADIATION MEASUREMENTS, 1997, Vol.28, No.1-6 SISI, pp.565-570 *) INSTITUE OF ATOMIC ENERGY, POB 275 96, BEIJING 102413, PEOPLES REPUBLIC OF CHINA A large number of artifacts (stone tools) have been discovered in Baise (Bose), Guangxi, China in recent years. They show that ancient man were living in the south of China during very ancient times. During excavation, tektites were discovered in the same layer of deposits as the stone tools. The structure of the layers of deposits in this site was never disturbed, which is the evidence that the stone tools were left behind by the ancient man at the time when the tektites fell on the earth, which were slowly covered over by layers of deposits. Fission track dating has been carried out on tektites. The age of the tektites is 0.732 +/- 0.039 Ma, which is also the age of the ancient man in Baise, Guangxi, China. The annealing degree of spontaneous fission tracks in the tektite was investigated by measuring track diameters. A correction of age for track fading has been made by track diameter technique. According to current understanding, tektites were formed by the impact of falling asteroids or comets on the earth's surface. The dating shows that a big impact occurred on the earth 0.732 Ma ago. The coincidence of the age of the tektites with the age of geomagnetic polarity reversal (similar to 0.73 Ma) from the Matuyama Epoch to the Brunhes Epoch proposes a plausible explanation that the possible cause of the geomagnetic polarity reversal is due to the big impact of space objects falling onto the earth. The result of the dating also set up a standard for inferring the ages of the deposits in South China as well as in South-East Asia where laterite (red soil) deposits exist in the entire region. Copyright 1998, Institute for Scientific Information Inc. (3) THE NUMBER DENSITY OF MAIN-BELT ASTEROIDS C.I. Lagerkvist and J.S.V. Lagerros: The number density of main-belt asteroids. ASTRONOMISCHE NACHRICHTEN, 1997, Vol.318, No.6, pp.391-393 ASTRONOMICAL OBSERVATORY, BOX 515, S-75120 UPPSALA, SWEDEN In this paper we have studied how the number density of asteroids varies as a function of the mean distance from the sun. Copyright 1998, Institute for Scientific Information Inc. THE CAMBRIDGE-CONFERENCE NETWORK The Cambridge-Conference List is a scholarly electronic network organised by Dr Benny J Peiser at Liverpool John Moores University, United Kingdom. It is the aim of this international network to disseminate the latest information and research findings related to i) geological and historical neo-catastrophism, ii) NEO research and the hazards to civilisation due to comets and asteroids, and iii) the development of a planetary civilisation capable of protecting itself against cosmic disasters. For further information about this network and how to subscribe, please contact Benny J Peiser <b.j.peiser@livjm.ac.uk>. Information circulated on the Cambridge-Conference Network is for scholarly and educational use only. The attached information may not be copied or reproduced for any other purposes without prior permission of the copyright holders. Hа сегодня все, пока! =SANA=

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