MARSBUGS: The Electronic Astrobiology Newsletter Volume 7, Number 19, 22 May 2000. Editors: Dr. David J. Thomas, Biology and Chemistry Division, Lyon College, Batesville, AR 72503-2317, USA. dthomas@lyon.edu Dr. Julian A. Hiscox, School of Animal and Microbial Sciences, University of Reading, Reading, RG6 6AJ, United Kingdom. J.A.Hiscox@reading.ac.uk Marsbugs is published on a weekly to quarterly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editors, except for specific articles, in which instance copyright exists with the author/authors. While we cannot copyright our mailing list, our readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing list. The editors do not condone "spamming" of our subscribers. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editors. E-mail subscriptions are free, and may be obtained by contacting either of the editors. Article contributions are welcome, and should be submitted to either of the two editors. Contributions should include a short biographical statement about the author(s) along with the author(s)' correspondence address. Subscribers are advised to make appropriate inquiries before joining societies, ordering goods etc. Back issues and Adobe Acrobat PDF files suitable for printing may be obtained from the official Marsbugs web page at http://www.lyon.edu/webdata/users/dthomas/marsbugs/marsbugs.html. The purpose of this newsletter is to provide a channel of information for scientists, educators and other persons interested in exobiology and related fields. This newsletter is not intended to replace peer- reviewed journals, but to supplement them. We, the editors, envision Marsbugs as a medium in which people can informally present ideas for investigation, questions about exobiology, and announcements of upcoming events. Astrobiology is still a relatively young field, and new ideas may come from the most unexpected places. Subjects may include, but are not limited to: exobiology and astrobiology (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis and terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. --------------------------------------------------------------------- CONTENTS 1) PUBLIC INVITED TO BROWSE 20,000 NEW ADDITIONS TO MARS PHOTO GALLERY JPL release 2) EQUATORIAL WATER MAY HAVE PROVIDED MEANS OF SURVIVAL FOR EARLY LIFE By Janet Wong 3) "DEATH OF THE DINOSAURS" NEW PLANETARIUM SHOW AT GRIFFITH OBSERVATORY PREMIERES WEDNESDAY, MAY 24, 2000 Griffith Observatory release 4) MARTIAN METEORITES MAY HAVE REACTED WITH LIQUID WATER ON MARS INTERMITTENTLY DURING THE PAST 650 MILLION YEARS By G. Geoffrey Taylor 5) RARE MARS METEORITE DISCOVERED IN MIDDLE EAST By Richard Stenger 6) SETI@HOME, UC BERKELEY'S SEARCH FOR EXTRATERRESTRIAL LIFE, CELEBRATES FIRST ANNIVERSARY, IS NAMED FINALIST IN COMPUTERWORLD SMITHSONIAN AWARDS University of California-Berkeley release 7) CASSINI WEEKLY SIGNIFICANT EVENTS JPL release 8) GALILEO MILLENNIUM MISSION STATUS JPL release 9) THIS WEEK ON GALILEO JPL release 10) MARS GLOBAL SURVEYOR STATUS REPORT JPL release 11) STARDUST STATUS REPORT JPL release --------------------------------------------------------------------- PUBLIC INVITED TO BROWSE 20,000 NEW ADDITIONS TO MARS PHOTO GALLERY JPL release 22 May 2000 More than 20,000 images of the planet Mars taken by NASA's Mars Global Surveyor spacecraft are now available in a web-based photo album--the single largest one-time release of images for any planet in the history of solar system exploration. The "picture postcard" scenes in the new images reveal the Red Planet, often said to be the most Earth-like planet, as an alien, bizarre and puzzling world. "These are exciting times for Mars scientists and this release of images is in my opinion something unprecedented in the Mars science business," said Dr. Ken Edgett, staff scientist at Malin Space Science Systems, San Diego, CA. "People everywhere with Internet access will be able to take their own personal journey of exploration and discover Mars via these pictures. They can experience them the same way that Mars Global Surveyor scientists do--one at a time, no captions or explanations, just 'Here it is. What does it show me?'" The archive of images now covers one Mars year (687 Earth days), beginning in September 1997 with pictures taken during the aerobraking phase and extending through August 1999 when Global Surveyor was well into its mapping mission. Many of the pictures have such high resolution that objects on the surface the size of a school bus can be seen. According to the imaging team, placing these images within NASA's Planetary Data System for archiving is an important step in the Mars Global Surveyor mission that permits scientists and the public to examine the original data and make discoveries "for themselves." "Putting these data into perspective is very difficult. We have focused on 'themes.' Layers on the martian surface are the biggest 'theme' or 'finding' of the imaging investigation so far. To a geologist, layers record history and they are the most geologically important, profound thing we have seen," said Dr. Michael Malin, principal investigator for the camera system at Malin Space Science Systems. "We see layers in the walls of canyons, craters, and troughs. We see layers in the both the north and south polar regions. We see them in the craters on top of volcanoes, we see them in pits at the bottoms of impact craters, we see them virtually everywhere that some process has exposed the subsurface so that we can see it from above." "Seeing Mars up close through the narrow angle camera has been a humbling experience. We often find surfaces for which there are no obvious analogs on Earth, like certain ridges that look like dunes. Our terrestrial geologic experience seems, at times, to fail us," Edgett said. "Perhaps it is because water is the dominant force of erosion on Earth, even in the driest desert regions. But on Mars that force of change may have been something else, like wind. The ridges seen in places like the Valles Marineris floors are strange. They aren't dunes because they occur too close together, their crests are too sharp, their slopes too symmetrical. They often appear to be a specific layer of material that has undergone erosion--we just wish we knew what processes are involved that cause this kind of erosion." The camera system uses a "push-broom" technique that systematically builds up pictures of the surface directly below one line at a time as the spacecraft orbits Mars. The wide-angle lens provides a complete low-resolution global map of the planet every day showing surface features and clouds at a resolution of about 7.5 kilometers (4.6 miles). The narrow-angle telescope takes close-up pictures of small areas with a resolution of about 1.5 meters (about 5 feet). Because of the extremely high data volume of the high-resolution images, controllers cannot use this mode continuously. Instead, they painstakingly plan which areas they want to target. The archive of images can be found at http://www.msss.com/moc_gallery/ A subset of the images can be seen at the following URLs: http://photojournal/cgi-bin/PIADBSearch.pl?NewReleases http://www.msss.com/mars_images/moc/may_2000/ http://mars.jpl.nasa.gov/mgs Mars Global Surveyor was launched on November 7, 1996 and arrived at Mars on September 12, 1997. The spacecraft has made more than 5,000 orbits of Mars and has been systematically mapping the Red Planet since March 1999. Mars Global Surveyor is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. The camera system was built and is operated by Malin Space Science Systems, San Diego, CA. JPL's industrial partner is Lockheed Martin Astronautics, Denver, CO, which developed and operates the spacecraft. JPL is a division of the California Institute of Technology, Pasadena, CA. --------------------------------------------------------------------- EQUATORIAL WATER MAY HAVE PROVIDED MEANS OF SURVIVAL FOR EARLY LIFE By Janet Wong University of Toronto release 24 May 2000 The precursor of modern animals may have been able to survive a Snowball Earth era that occurred some 600 million years ago because of a belt of open water along the equator, suggests scientists from the University of Toronto and Texas A&M University. This was a time considered critical in the evolutionary development of multi-celled animals and therefore the most important interval for biological evolution in general. In a paper to be published in the May 25 edition of Nature, U of T physics professor Richard Peltier and Texas A&M oceanographers William Hyde, Thomas Crowley and Steven Baum note that the late Proterozoic era (600-800 million years ago) was the most important period of evolution for multi-cellular creatures. However, this period was also a time in Earth's history that has come to be referred to as the Snowball Earth. At that time, the planet was thought to be completely ice-covered. Geological and paleomagnetic evidence indicates that for alternating periods, the Earth was completely covered by ice sheets over the continents and sea ice over the oceans, followed by sudden warming trends that melted the ice. "If the suface of the planet was covered by ice, the question arises as to how early life managed to survive under such environmental stress," says Peltier. To find an answer, the scientists employed several different models of the climate systems and ran detailed computer simulations of the climate thought to have been characteristic of that time. To simulate the Snowball Earth, they reduced the amount of sunlight reaching the Earth--to account for the fact that the sun was about six per cent less luminous than it is now--and varied the concentration of atmospheric carbon dioxide within the range expected for that time. In most of the simulations, their analysis revealed the presence of a belt of open water near the equator when the general circulation of the ocean was taken into account. "It is this open water that may have provided a refuge for multi-celled animals when the rest of the Earth was covered by ice and snow," Peltier explains. The findings of this research are critical to understanding how early life evolved, he states. "This could help clarify how multi-celled animals managed not only stay alive, but to thrive given the Earth's harsh conditions. The extreme climates may even have exerted pressure on these animals to evolve and adapt, possibly leading to the rapid development of new forms of animals and their movement into new, unpopulated habitats when the Earth exited the snowball state. It was during the warm Cambrian era--immediately following the late Proterozoic--in which life proliferated." The late Proterozoic period was also a time when the supercontinents Rodinia and Pannotia formed and subsequently rifted and disassembled. Located over the south rotational pole in the position of present-day Antarctica, these supercontinents were made up of the current land masses of Africa, South America, Antarctica, Australia, Greenland, Laurentia and parts of Asia. According to Peltier, the entry of the Earth into the snowball state required not only the weak sun and atmospheric carbon dioxide levels not significantly higher than present-day, but also this high degree of polar continentality. Funding for this research came from the Natural Sciences and Engineering Research Council of Canada and the National Science Foundation in the U.S. --------------------------------------------------------------------- "DEATH OF THE DINOSAURS" NEW PLANETARIUM SHOW AT GRIFFITH OBSERVATORY PREMIERES WEDNESDAY, MAY 24, 2000 Griffith Observatory release 23 May 2000 One of greatest scientific mysteries of all time--what happened to the dinosaurs--was solved when it was realized that a giant asteroid or comet clobbered Earth 65 million years ago. The impact and the destruction caused by worldwide tidal waves, grass and forest fires, and clouds that blocked sunlight for years, caused the extinction of many of the worlds species--including the dinosaurs. The disappearance of previously successful species paved the way for the rise of mammals--and eventually us--in the age that followed. This impact demonstrated in a dramatic way how the earth (and our human destiny) is connected to the rest of the solar system. "Death of the Dinosaurs," the new live multi-media planetarium show at Griffith Observatory, uses the Zeiss star projector to show how comets and asteroids can strike our planet and what happens when one does. We've recently come to appreciate that such impacts are not things that used to happen long ago, and that our earth remains vulnerable. The show provides an updated assessment of the risk from asteroid and comet impacts today, and it concludes with the latest thinking on answers to the question, "What do we do to defend our planet to prevent a similar catastrophe from happening to us?" "Death of the Dinosaurs" is presented Tuesday through Sunday at 3:00 PM and 7:30 PM, with additional shows at 4:30 PM on Saturdays and Sundays, beginning tomorrow, Wednesday, May 24. There are no planetarium shows on Mondays. For additional information on Griffith Observatory programs and activities, please call (323) 664-1191 for a recorded message or visit the Observatory's web site at http://www.GriffithObservatory.org. --------------------------------------------------------------------- MARTIAN METEORITES MAY HAVE REACTED WITH LIQUID WATER ON MARS INTERMITTENTLY DURING THE PAST 650 MILLION YEARS By G. Geoffrey Taylor Planetary Science Research Discoveries 24 May 2000 Two studies shed light on the nature and timing of alteration by water of rocks from Mars. One is an experimental study of the alteration of a rock similar to martian meteorites, conducted by Leslie Baker, Deborah Agenbroad, and Scott Wood (University of Idaho). They exposed crushed pieces of terrestrial lava flows to water at 23°C and 75°C and normal atmospheric pressure, and to hot water at 200°C to 400°C and a pressure 1000 times normal atmospheric to see what minerals would form. On the basis of a detailed comparison between the experimental products and the martian meteorites Baker and colleagues conclude that the rocks from which martian meteorites derived were intermittently exposed to water or water vapor; they were not exposed for a long time to large volumes of water. In an independent study, a team led by Tim Swindle (University of Arizona) tried to determine the time of formation of a reddish-brown alteration product in the martian meteorite Lafayette. This meteorite appears to have formed from magma 1.3 billion years ago, but the rusty-looking weathering product, a mixture of clay minerals, iron oxide, and iron hydride, formed long after the original rock had crystallized. Although the precise time is not pinned down, their measurements indicate formation during the past 650 million years. Taken together, these studies suggest that water flowed intermittently on the surface of Mars during the past 650 million years. Get the full story at http://www.soest.hawaii.edu/PSRdiscoveries/May00/wetMars.html --------------------------------------------------------------------- RARE MARS METEORITE DISCOVERED IN MIDDLE EAST By Richard Stenger CNN Interactive 25 May 2000 A meteorite hunter combing the deserts of Oman found a stone thought to have originated on Mars. Of the 20,000 known meteorite discoveries, the brownish gray stone is only the 15th identified as coming from the red planet, scientists said this week. "We're convinced it's from Mars," University of Tennessee geochemist Lawrence Taylor said. He analyzed samples of the Oman find with Mikhail Nazarov, a Russian colleague from the Vernadsky Institute in Moscow. The rock has chemical similarities to a Mars meteorite found in Antarctica in 1984, which some NASA researchers said exhibits fossilized signs of microscopic life. Called the Dhofar 019, the 1,056-gram (37-ounce) stone seems to be made of martian basalt. It was picked up in the Dhofar region of the Sultanate of Oman, which occupies the eastern corner of the Arabian Peninsula. Get the full story at http://www.cnn.com/2000/TECH/space/05/25/mars.meteorite/index.html --------------------------------------------------------------------- SETI@HOME, UC BERKELEY'S SEARCH FOR EXTRATERRESTRIAL LIFE, CELEBRATES FIRST ANNIVERSARY, IS NAMED FINALIST IN COMPUTERWORLD SMITHSONIAN AWARDS University of California-Berkeley release 26 May 2000 The University of California, Berkeley's SETI@home project, which just breezed past its first anniversary with more than 2 million subscribers looking for intelligent signals from space, is one of five finalists in the science category of the 2000 Computerworld Smithsonian Awards. The awards are given each year to visionary projects and people in 10 separate categories, ranging from science and technology to arts and entertainment. The winner in each category will be announced June 5 at an awards ceremony in Washington, DC. SETI@home was launched May 17, 1999. Within 48 hours, some 200,000 people had downloaded the software to participate in UC Berkeley's search for extraterrestrial intelligence (SETI). The software acts like a screen saver, launching when the computer is idle to analyze a chunk of data in search of intelligent radio signals from space. Once the analysis is complete, the computer connects to the internet, returns the analyzed data and retrieves a new chunk of data to chew on. In the past year, users of the SETI@home software have contributed more than 280,000 years of free computing time. A group at Sun Microsystems, dubbed SETI@sun, contributed more than 520 years. Sun has been one of SETI@home's major sponsors, donating the server computers that send out work units to subscribers. The other major sponsors are the Planetary Society, which provided early seed money, and the University of California's Digital Media Innovation Program. "Thanks to people around the world, we have built our planet's largest supercomputer," said project scientist Dan Werthimer. "We seem to have benefited from an obvious public fascination with everything related to the Search for Extraterrestrial Intelligence (SETI), UFOs and the X-Files," said project director David Anderson. Werthimer and UC Berkeley colleagues operate several ongoing SETI projects, including the 21-year-old SERENDIP project (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations), whose newest instrument, SERENDIP IV, provides the data for SETI@home. The project was designed in part as an experiment in "distributed computing"--a way of breaking down a problem requiring lots of computation into small chunks that can be done by many small computers distributed anywhere in the world. The SETI@home project is the first distributed computing project to allow the general public the opportunity to participate in important research. To date, the peak signals plucked from the data have all been terrestrial radio pollution rather than extraterrestrial messages. The search has only begun, though. "Right now, Earthlings are just getting in the game," Werthimer said. "In the past 20 years we have made great progress, from being able to scan 100 radio bands at once to scanning 100 million. If we can improve the technology in the next 20 years by a factor of a million or a billion, then we'll have a good chance of detecting another civilization's radio signals, if they're out there." As more data comes in on more and more frequencies, distributed computing allows the team to keep pace. Computers will continue to get faster, users will upgrade, and SETI@home gets faster analysis without having to invest in a supercomputer. "The good news is, we're limited by computing power, and that's always getting better," Werthimer said. To improve the search, Werthimer also is exploring the option of collecting data from a radio telescope in the southern hemisphere. This would complement the northern sky data coming from the Arecibo radio telescope in Puerto Rico. Nevertheless, Anderson said the current phase of the project is scheduled to wind down in a year's time, primarily because the Arecibo telescope will have scanned the same area of the sky three to four times, which is sufficient for now. Once that data has been analyzed for pulsed, radar-like signals as well as continuous beacons, little more information can be squeezed from it. Assuming Anderson and Werthimer can raise additional money--SETI@home operation now costs about $400,000 per year--they hope to extend the project indefinitely with data from improved instruments or other areas of the sky. "It's clear that there are lots of users who are desperate to continue looking for intelligent life in the universe," Anderson said. The project was launched three years ago with the Planetary Society, in cooperation with Paramount Pictures, providing $100,000 for development of the publicly available software. Sun Microsystems also donated computing equipment, and the University of California provided matching funds of $180,000 from its Digital Media Innovation Program. Other sponsors include Fuji Film Computer Products, Quantum Corp., Informix and The SETI Institute. Contact information David Anderson, project director, is at (510) 845-9854 or davea@ssl.berkeley.edu. Dan Werthimer, project scientist, is at (510) 642-6997 or danw@ssl.berkeley.edu. The SETI@home web site is http://setiathome.berkeley.edu/. --------------------------------------------------------------------- CASSINI WEEKLY SIGNIFICANT EVENTS JPL release 18-24 May 2000 The most recent spacecraft telemetry data was acquired from the Goldstone tracking station on Wednesday, 5/24. The Cassini spacecraft is in an excellent state of health and is operating normally. Activities this week include the first time use in the background sequence of the new 82.95k and 22.12k telemetry modes. The Backup ALF Injection Loader (BAIL) and Engine Gimbal Actuator (EGA) portions of Periodic Engineering Maintenance were executed. The Reaction Wheel Assembly (RWA) portion was replaced by an RWA friction test, followed by transition to RWA control. Real time commands were sent to update flight software for the Cosmic Dust Analyzer (CDA), Composite Infrared Spectrometer (CIRS), Radio and Plasma Wave Science (RPWS), and Ultraviolet Imaging Spectrograph (UVIS) instruments. The speed of the spacecraft can be viewed on the "Where is Cassini Now?" web page at http://www.jpl.nasa.gov/cassini/today/. A joint Cassini-RPWS/Galileo Conjunction Experiment was performed. This conjunction, like the one in February, provided the opportunity to observe Jovian radio emissions in a stereoscopic sense. Both the Cassini and Galileo spacecraft were very nearly aligned relative to Jupiter. Using the small, but finite differences in viewing angle offers the possibility of understanding some of the beaming characteristics of Jovian radio emissions. One of our team members led an effort to do a similar experiment during Instrument Checkout 1 (ICO1) and the Earth flyby using Cassini and Wind (a spacecraft in Earth orbit). Those results have now been accepted by the Journal of Geophysical Research (apparently the first Cassini science paper to be published). They report that Jovian decametric arcs have a beam width of 1.5 ± 0.5 degrees and that those radio emissions associated with the moon Io sweep around Jupiter with the rotation rate of Io and not that of Jupiter. The Cassini observations during this interval look very good and Jupiter was quite active in the radio frequencies monitored. Galileo data was properly recorded and will be available for analysis in a month or so. A strategy meeting for Trajectory Correction Maneuver 14 (TCM 14) was held and established the schedule and overall design strategy for this maneuver. TCM 14 will be a main engine maneuver of about 0.5 meter per second and will execute on June 14. A telecon was held to discuss possible science observations during the Saturn Orbit Insertion time period. This interval will provide the highest resolution remote sensing data of the rings for the entire mission and will provide unique data on Saturn's magnetosphere as well. The plan to provide Science-data-over-the-Internet to remote sites during ICO2 is ready. RPWS and Magnetospheric Imaging Instrument (MIMI) teams are set to use this mode. Other instrument teams are verifying their ability to accept data in this mode and should be ready by the end of this week. System Engineering and Mission Support & Services Office team members met to discuss the criteria for final transition from the Central Database (CDB) to Distributed Object Manager (DOM) as the Cassini file repository. DOM has been in operational use since January and the flight team is currently comfortable with its use. --------------------------------------------------------------------- GALILEO MILLENNIUM MISSION STATUS JPL release 22 May 2000 NASA's Galileo spacecraft has successfully flown past the largest moon in our solar system--Ganymede, which orbits around Jupiter. Galileo dipped to 809 kilometers (503 miles) above the surface early Saturday, May 20. This was the spacecraft's first flyby of Ganymede since May 7, 1997. "It's great that things went so smoothly," said Galileo Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory. "The team was ready for any problems, but they got to relax on this one. We're really looking forward to the new pictures and learning more about this largest of all moons." At 4:00 AM PDT, mission controllers at JPL received the signal indicating that the flyby took place. The spacecraft's camera and other instruments were set to capture the flyby with images and other observations. If all goes as planned, the data will be transmitted to Earth over the next several months for processing and analysis. To fly by Ganymede, Galileo had to approach Jupiter's powerful radiation belts. Not surprisingly, the radiation, which can affect spacecraft instruments, components and systems, did cause two main resets of Galileo's main computer. Onboard software correctly diagnosed this as a false indication, and went ahead with the Ganymede encounter unaffected. "It appears that this workhorse spacecraft has done it again," Erickson said. Galileo has already survived three times the radiation it was designed to withstand. Ganymede is even larger than Mars and Mercury. Its surface is a mixture of clean, white ice and dirty, dark ice, with varied geological formations, including craters, basins, grooves and rough mountain areas. Additional information about the Galileo mission is available at http://galileo.jpl.nasa.gov. Galileo was launched from the Space Shuttle Atlantis on October 18, 1989. After a long journey to Jupiter, Galileo began orbiting the huge planet and its moons on December 7, 1995, and successfully completed its two-year primary mission on December 16, 1997. That was followed by a two-year extended mission which concluded in December 1999, and Galileo is now continuing its studies under yet another extension, called the Galileo Millennium Mission. JPL, a division of the California Institute of Technology in Pasadena, CA, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. --------------------------------------------------------------------- THIS WEEK ON GALILEO JPL release 22-28 May 2000 Jupiter continues to dominate Galileo's observation schedule on Monday as instruments focus on the planet's aurora and its atmosphere, including the Great Red Spot. The spacecraft makes its closest approach to Callisto at 4:39 PM PDT [see Note 1] Monday at a range of 331,000 kilometers (206,000 miles). The first three observations of the week are spectral scans of Jupiter's bright limb, performed by the Near-Infrared Mapping Spectrometer (NIMS). Like observations performed on Sunday, May 21, these scans will be used to provide scientists with data on the bulge created at Jupiter's equator as Jupiter rotates once every 10 hours. NIMS follows these observations with a series of 10 spectral scans of Jupiter's north polar region. The series consists of 10-minute samples separated by 60 minutes, and is designed to capture auroral activity. Interspersed with the aurora observations are three global observations performed by NIMS and three Great Red Spot observations performed by the Solid-State Imaging camera (SSI). Taken together, the global observations performed by NIMS will map a substantial proportion of the complete range of longitudes of the planet. The Great Red Spot observations performed by SSI will provide scientists with high spatial and time resolution images of this storm, which is over 400 years old. Similar observations were taken at the beginning of Galileo's orbital tour in June 1996, so scientists will be able to observe long-term changes in the characteristics of the Great Red Spot. The Great Red Spot is so large that the Earth fits two times across it! A brief interlude from Jupiter is afforded to SSI to obtain a set of global images of Europa through four different color filters. The images will fill in a gap in existing global color coverage between 120 and 230 degrees longitude. Five more Jovian equatorial bulge observations are then performed by NIMS. The first three occur on Monday night, with the remaining two performed on Tuesday morning. Next, SSI takes a set of global images through different color filters that capture Europa while eclipsed from the Sun by Jupiter. The observation should help scientists search for auroral glows in Europa's tenuous atmosphere. These glows would be produced by the interaction of atmospheric gases with Jupiter's magnetosphere, and may produce current flow between Europa and Jupiter. The geometry and timing of this observation are superior to those of similar observations taken earlier in the mission. SSI's eclipse observation brings to a close the bulk of this encounter's observing. In previous encounters, playback of recorded data was initiated at this point. But Galileo is not yet finished collecting data. The Fields and Particles instruments will continue observing for nearly one month. This will allow them to extend their typical survey of the inner magnetosphere (performed at each encounter) through the outer magnetosphere, and through the transition from inside Jupiter's vast magnetosphere into the solar wind. Some data will be returned in realtime and some will be placed on the tape recorder for return after the conclusion of the survey. The survey is interrupted once during the remainder of the week. On Wednesday, the spacecraft will perform a flight path adjustment, if needed. Note 1. Pacific Daylight Time (PDT) is 7 hours behind Greenwich Mean Time (GMT). The time when an event occurs at the spacecraft is known as Spacecraft Event Time (SCET). The time at which radio signals reach Earth indicating that an event has occurred is known as Earth Received Time (ERT). Currently, it takes Galileo's radio signals 50 minutes to travel between the spacecraft and Earth. For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page at one of the following URL's: http://galileo.jpl.nasa.gov http://www.jpl.nasa.gov/galileo --------------------------------------------------------------------- MARS GLOBAL SURVEYOR STATUS REPORT JPL release 24 May 2000 Launch / Days since Launch = Nov 7, 1996 / 1295 days Start of Mapping / Days since Start of Mapping = April 1, 1999 / 419 days Total Mapping Orbits = 5418 Total Orbits = 7021 Recent events The spacecraft continues to operate nominally in performing the beta- supplement daily recording and transmission of science data. The following background sequences executed successfully: mm038 from 00- 132 (5/11/00) through 00-135 (5/14/00); mm039 from 00-136 (5/15/00) through 00-138 (5/17/00); mm040 from 00-139 (5/18/00) through 00-142 (5/21/00); and mm041 from 00-143 (5/22/00) through 00-145 (5/24/00). The mm042 sequence was successfully uplinked on 00-144 (5/23/00) and will begin executing on 00-146 (5/25/00). Three science experiment campaigns took place during the past two weeks. They were Bistatic Radar, MOLA Off-NADIR Polar Scans, and Radio Science Occultation Egress Scans. Commands for the Bistatic Radar experiment were included in the mm038 sequence as part of DOY 135 activities. Commands for the MOLA Off-NADIR Polar Scans composed the mz051 mini-sequence. They executed over 11 consecutive orbits on DOY 138 and DOY 139. Finally, MGS performed Radio Science Occultation Egress Scans on DOY 141,142, and 143 according to the mz052 mini-sequence. Overall, spacecraft performance during all experiments was nominal. The following paragraphs provide additional information regarding AACS performance. In the MOLA experiment, we used the same CSA offset quaternions as the previous two polar opportunities. The SARBES (Starex reset) command was eliminated from this sequence and replaced with a general memory load of high rate gyro bias estimates and a separate software command to load the high rate steady state gyro biases. We also retained the divided North and South Pole slews implemented with the last MOLA polar opportunity. We are happy to report that the Starex problems observed in previous MOLA polar experiments have disappeared. Starex performance was completely, totally, and utterly nominal. Slew performance was superb, as it was for the previous polar experiments. For the first time during a Radio Science Occultation Egress experiment, we used an Off-NADIR pointing scheme. AACS performance proved nominal, comparing well with predicts. Again, Starex performed superbly, converging in 10 stars. We successfully used the same method of gyro bias loading in the Radio Science experiment that we used in the MOLA Polar Scan experiment. Preliminary results indicate that the science teams received useful data during these experiments. Therefore, we plan to use the same spacecraft pointing and sequence development techniques for future MOLA and Radio Science experiments. Spacecraft health All subsystems report nominal health. Uplinks There have been 28 uplinks to the spacecraft during the last two weeks, including new star catalogs and ephemeris files, instrument command loads, and the background sequences cited above. Total command files radiated to the spacecraft since launch is 4666. Upcoming events Normal beta-supplement sequences are planned between now and Solar Conjunction. We are in the final stages of Solar Conjunction planning. The mm050 sequence will cover the Solar Conjunction period between 6/21/00 and 7/12/00. --------------------------------------------------------------------- STARDUST STATUS REPORT JPL release 26 May 2000 Ms. Aimee Whalen, Stardust Opportunity Manager, and Mr. Robert Ryan, Stardust Mission Manager, received NASA awards for there distinguished work on Stardust. The Stardust Team at JPL and at Lockheed Martin Astronautics in Denver also received NASA group achievement awards. There were six Deep Space Network (DSN) tracking passes during the past week. All subsystems onboard the spacecraft are performing normally. Trajectory Correction Maneuver 3 (TCM 3) was completed with the engine firing for 72 seconds to impart a velocity change of about 2 meters/second. This maneuver was performed to fine tune the spacecraft's trajectory for an Earth flyby next January. This Earth flyby will give the spacecraft a gravity assist to intercept the orbit of Comet Wild 2. The maneuver was performed flawlessly. The Stardust Opportunity Manager was moderator of the Women in Science Panel Discussion, involving and honoring prominent nation women in science, with the Cheyenne Wyoming community and public school children. The Cheyenne Public School District and the National Weather Service sponsored these discussions. A Stardust display was set up in the Denver Museum of Natural History and a presentation was given to the Director and staff of the Space Science Institute in Denver Colorado. Discussions were initiated with the Fiske Planetarium in Denver to provide them with a Stardust display. A presentation on Stardust was given at the European Geophysical Society (EGS) XXV Symposium in Nice, France. For more information on the Stardust mission--the first ever comet sample return mission--please visit the Stardust home page at http://stardust.jpl.nasa.gov. --------------------------------------------------------------------- End Marsbugs, Volume 7, Number 20.