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) ROVER SIMULATES PLANETARY EXPLORATION IN FIELD TRIALS NASA release 00-39AR 2) STUDENTS TAKE THE LEASH AS FIDO HEADS BACK TO THE DESERT JPL release 3) JPL SEEKS EDUCATORS FOR SPACE TEACHING FELLOWSHIPS JPL release 4) SPECIAL AIRCRAFT READY TO TAKE OFF WITH SPACE EXPERIMENTS IN PHYSICS AND BIOLOGY ESA press release 33-2000 5) NEXT FIVE DAYS ON GALILEO JPL release 6) GALILEO--COUNTDOWN TO GANYMEDE By Ron Baalke 7) TODAY ON GALILEO JPL releases 8) MARS GLOBAL SURVEYOR STATUS REPORT JPL release 9) STARDUST STATUS REPORT JPL release --------------------------------------------------------------------- ROVER SIMULATES PLANETARY EXPLORATION IN FIELD TRIALS NASA release 00-39AR 16 May 2000 NASA is deploying a prototype planetary rover named K9 in the Nevada desert this week as part of an ongoing field test program designed to simulate robotic exploration on other planets. During the joint field operation between NASA Ames Research Center, Moffett Field, CA, and the Jet Propulsion Laboratory (JPL), Pasadena, CA, K9 will act as a "scout" for JPL's rover, called FIDO. K9 will assist FIDO by searching ahead for the best candidate rocks for it to sample. Planning of the rover's actions will be supported by a suite of software tools called Viz, which were developed at Ames by the Autonomy and Robotics group, a branch of Ames' Computational Sciences Division. Viz uses images from stereo cameras on-board K9 to create a photo-realistic 3D model of the surrounding environment. This model is displayed as a virtual-reality environment within which scientists and rover operators travel, measuring distances and object sizes, to choose the best sampling sites and routes. "We've developed a systems-oriented approach with the ability to quickly bring diverse robotics technologies, advanced instrument designs, and a close knit science and engineering operations team together in a realistic field test," said Dr. Nicola Muscettola, lead of Ames' autonomy and robotics group. "The FIDO-K9 project is a terrific design tool for advancing NASA capabilities and dramatically reducing risk during future exploration missions." "This type of trial has never been done before. We are learning many new things about robotic exploration," said Maria Bualat, project manager for K9. The main purpose of the test is to simulate using multiple cooperating robots in planetary exploration. The test also exposes the Athena science team, a group of researchers from several universities selected for the next Mars rover mission, to Ames' science visualization technologies. "This will allow the team to evaluate these technologies, recommend changes and improvements, and have better capabilities when their missions occur," explained Bualat. "This field test illustrates how two robots can work together to maximize the effectiveness and science return for a planetary exploration mission," said Dr. Carol Stoker, Ames chief scientist for the test. "In this test, K9 is exploring for interesting things, while FIDO is performing detailed analysis," she said. During the tests, the FIDO science and engineering teams are kept sequestered in the mission control room at JPL's Planetary Robotics Laboratory while the two rovers explore the site, whose location is being kept secret." The teams only see the site through the eyes of the rovers just like it would be on a planet like Mars," said Stoker. The science and engineering teams "see" the remote field site through the rover's instruments by collecting black and white and color panoramic images, near infrared spectra and close-up measurements at the site, she said. FIDO and K9 are each about the size of a St. Bernard. K9 weighs about 90 pounds and is 33 inches wide, 41 inches long, and 22 inches high. The rover moves at an average speed of 200 meters (less than one mile) per hour over smooth terrain. During the tests, K9 is powered both by solar panels and by rechargeable batteries. K9 is about twice the size of Mars Pathfinder's "sojourner" rover and is capable of performing tasks without much human help. K9 was named for the robotic assistant in the British science fiction television series "Dr. Who." Its chassis was built at the Jet Propulsion Laboratory to be mechanically identical to FIDO. Its electronics, avionics, and instruments were built at NASA Ames. "Our engineering team designed K9's electronics to consume very little power and to enable remote control of the robot's power subsystems," said Bualat. "This allows our autonomy software to selectively manage resources and power systems on and off, depending on the type of operations we are performing." K9 is controlled through the "Virtual Dashboard," a graphical user interface designed and built at Ames that lets the rover operator send single commands or build and up-link a sequence of commands. Command sequences are up-linked to the robot over a satellite and executed autonomously by K9's on-board executive software. The Dashboard automatically generates web pages, which let scientists view sequence logs and down-linked images in real time. --------------------------------------------------------------------- STUDENTS TAKE THE LEASH AS FIDO HEADS BACK TO THE DESERT JPL release 16 May 2000 Several groups of high school students will take the controls of NASA's prototype Mars rover, the Field Integrated Design and Operations (FIDO) rover, this week as part of ongoing field tests designed to simulate robotic driving conditions on the red planet. "This year, we are focusing the rover tests on controlling FIDO as if it were on Mars," said Dr. Eric Baumgartner, systems engineer for FIDO rover development at NASA's Jet Propulsion Laboratory, Pasadena, CA. "The science and engineering teams are sequestered in the mission control room at JPL's Planetary Robotics Laboratory while the rover is in a geologically interesting site in an extremely remote portion of central Nevada. The teams will only see the site through the eyes of the rover." As part of the formal engineering tests, two days have been set aside for student participation. The student groups are located at their schools around the country in Ithaca, NY; Birmingham, AL; St. Louis, MO; and Flagstaff, AZ. In addition, a group of students from Copenhagen, Denmark will be in the JPL mission control room for their portion of the test drive. The students will use the same tools as the engineers and will view rover telemetry and develop their own command sequences for communicating with the rover. Each student group is responsible for creating and executing a part of the sequence that controls the rover's return to the vicinity of a simulated lander. "The students have a real role helping us complete a very complicated rover field test. We are providing an exciting venue for motivated high school students to apply verbal, written, mathematical, and computer skills to solve real problems involving simulated surface operations," said Dr. Raymond Arvidson, a geologist from Washington University, St. Louis, and mission director for the field tests. FIDO is about the size of a St. Bernard. It weighs about 70 kilograms (150 pounds) and is approximately 85 centimeters (about 33 inches) wide, 105 centimeters (41 inches) long, and 55 centimeters (22 inches) high. The rover moves at an average speed of about 200 meters an hour (about one-tenth of a mile per hour) over smooth terrain, using its onboard stereo vision systems to detect and avoid obstacles "on-the-fly." During these tests, FIDO is powered both by solar panels that cover the top of the rover and by replaceable, rechargeable batteries. FIDO is about twice the size of Mars Pathfinder's Sojourner rover and is more capable of performing its job without frequent human help. The FIDO science and engineering teams are exploring the remote field site through the eyes of the rover by collecting black-and-white and color panoramic images, near- infrared spectra, and close-up measurements at the site in an attempt to characterize the area's geology and geologic history. During a portion of the field test, FIDO is being joined by K9, a rover under development at NASA's Ames Research Center, Moffett Field, Calif. During the joint field operation, K9 will act as a "scout" by moving ahead of FIDO in search of rocks that are the best candidates for core sampling. K9 is controlled from JPL using Ames' "Virtual Dashboard," a graphical user interface that lets the rover operator send commands to K9, which executes them using onboard executive software. The planning of K9's command sequences is supported by a suite of software tools called Viz, developed at Ames by the Autonomy and Robotics Area. Viz uses images from stereo cameras onboard K9 to create a realistic 3D model of the surrounding environment. During the trial, this model will be displayed as a virtual reality environment that allows the scientists and rover operators to travel around the area, measuring distances and object sizes, in order to recommend the best sampling sites and traverse routes. "This field trial is a 'proof of concept' of a successful multi-rover experiment," said Dr. Nicola Muscettola, Autonomy and Robotics Area Lead at Ames. Like FIDO, K9 is controlled from JPL's mission control center. The FIDO rover is a test bed for future missions, including the proposed Mars Mobile Lander that is currently under study for a possible launch in 2003. "FIDO's development began in 1998 as a way to integrate and test new robotic technologies for future Mars rover missions," says Dr. Paul Schenker, who leads the FIDO project at JPL. "A major strength of this work has been its rapid prototyping, science-driven style. We've developed a systems-oriented approach with the ability to quickly bring diverse robotics technologies, advanced science instrument designs, and a close knit science and engineering operations team together in realistic field tests. FIDO has become a terrific design tool for advancing NASA's capabilities and reducing risk for future Mars missions." Pictures of FIDO in the field can be retrieved at http://www.jpl.nasa.gov/pictures/tech/fido/. JPL manages the FIDO mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology. --------------------------------------------------------------------- JPL SEEKS EDUCATORS FOR SPACE TEACHING FELLOWSHIPS JPL release 16 May 2000 Educators in the United States with an interest in teaching about space are invited to apply for approximately 20 new Solar System Educator fellowships. Selected educators will attend the Solar System Educator Program Institute held at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA, from August 2 to 5, 2000. All Solar System Educators will agree to lead educator workshops in their home states, reaching a minimum of 100 teachers per year. The designated educators will have the opportunity to partner with the Space Grant Consortia in their states to help them meet the training workshop requirements. Implemented by NASA in 1989, the Space Grant Consortia is a network of universities that contributes to the nation's science enterprise by funding research, education and public service projects. The goal of the Solar System Educator program is to inspire America's students, create learning opportunities and enlighten inquisitive minds by engaging them in the planetary exploration efforts conducted by JPL. The program is managed for JPL by Space Explorers Inc. and the Virginia Space Grant Consortium. However, the heart of the program is a nationwide network of highly motivated educators who lead teaching workshops for their fellow educators throughout the country. Solar System Educators are comprised of current K-12 educators and others from the informal education community (museums, science centers, planetariums, etc.) with a strong background in teaching science or math and experience in teacher training. Solar System Educators receive training at a four-day, all-expenses paid institute at JPL, and throughout the year via the Internet. More information and an online application form are available at http://www.ssep.org/apply. For more information, contact Eric Brunsell, Space Explorers, Inc. at (920) 339-4600 or via email eric@space-explorers.com. NASA/JPL missions participating in the institute include the Cassini mission to Saturn, the Stardust and Deep Impact comet missions, the Galileo mission to Jupiter, the Mars Exploration Program, the Outer Planets/Solar Probe program and the Deep Space Network of ground- based antennas that communicate with spacecraft. The Solar System Educators Program is an element of NASA's Office of Space Science Education and Public Outreach Program, NASA Headquarters, Washington, DC. --------------------------------------------------------------------- SPECIAL AIRCRAFT READY TO TAKE OFF WITH SPACE EXPERIMENTS IN PHYSICS AND BIOLOGY ESA press release 33-2000 19 May 2000 On 23 May, the "Zero-g" Airbus A-300 will take off from Bordeaux- Mérignac airport in France on the first of a four-day campaign of parabolic flights designed to carry out experiments in weightlessness and test instruments and equipment before they are used in real space flight. During the 28th parabolic flight campaign organized by the European Space Agency (ESA), experiments to be conducted on board sounding rockets and, later, on board the International Space Station, will be prepared. This campaign will focus on physical sciences and biology. Twelve experiments proposed by international teams of investigators, and the testing of crew support apparatus, will be performed between 23 and 26 May on the specially adapted Airbus A-300 "Zero-g". Parabolic flights are practically the only means on Earth of reproducing weightlessness with human operators on board. During a parabolic flight, the "Zero-g" Airbus pilot--flying at an altitude of approximately 6000 meters, usually in a specially reserved air- corridor above the Gulf of Gascogne--first performs a nose-up maneuver to put the aircraft into a steep climb (7600 m). This generates an acceleration of 1.8 g (1.8 times the acceleration of gravity on the ground) for about 20 seconds. Then the pilot reduces engine thrust to almost zero, injecting the aircraft into a parabola. The plane continues to climb until it reaches the apex of the parabola (8500 m), then it starts descending. This condition lasts for about 20 seconds, during which the passengers in the cabin float in the weightlessness resulting from the free fall of the aircraft. When the angle below the horizontal reaches 45°, the pilot accelerates again and pulls up the aircraft to return to steady horizontal flight. These maneuvers are repeated 30 times per flight. The 27 previous campaigns that ESA has conducted since 1984 have produced a total of more than 2.650 parabolas and almost 15 hours of weightlessness, the equivalent of flying around the Earth (in low Earth orbit) nearly 10 times. A total of 360 experiments have been carried out so far. Some of the experiments being tested during this parabolic flight campaign will later be flown on sounding rockets. Using sounding rockets from its test range in Kiruna, Sweden, ESA has been running flight campaigns with Texus since 1977 (6 minutes of absence of gravity), with Maser since 1987 (6 minutes) and with Maxus since 1991 (12.5 minutes). With Europe and its international partners now building the International Space Station, where research will be carried out for the next 15 years, parabolic flights are also crucial to the preparation of experiments, equipment and astronauts and allow scientists to have their experiments tested before they are actually flown on a space mission. Over the next four years, ESA will be running two parabolic campaigns a year. Scientists are regularly invited to submit experiment proposals for review and selection by peers. Those [scientists] whose experiments are selected are given the opportunity to participate in an ESA parabolic flight campaign. A list of the experiments and scientists involved in the 28th campaign is attached. The subsequent ESA parabolic flight campaign (the 29th) is scheduled for November 2000 and will feature a mix of experiments in life and physical sciences, mainly focusing on physiological and medical experiments. Further information on ESA parabolic flights can be found on ESA's special parabolic flight internet pages at http://www.estec.esa.int/spaceflight/parabolic. For further information contact: Vladimir Pletser ESA/ESTEC, Microgravity Payloads Division Directorate of Manned Spaceflight and Microgravity Tel: + 31.71.565.33.16 Fax: +31.71.565. 31.41 Anna Brück ESA/ESTEC Coordination Office Directorate of Manned Spaceflight and Microgravity Tel: +31.71.565.5445 Fax : +31.71.565.5441 For further information on ESA, visit our web site at http://www.esa.int. Experiments and scientists involved in the 28th ESA parabolic flight campaign: "Hydrodynamics of wet foams" by Dr. B. Kronberg (Institute for Surface Chemistry, Stockholm, S) and Dr. M. Adler (University of Marne la Vallée, Paris, F). Will study different types of foams and will test a new method of forming foams by injecting C02 in different liquids. The technique of foam generation cannot be tested on the ground as foams are transient and collapse rapidly in 1g conditions. "Interfacial turbulence in evaporating liquids" by Professor J.C. Legros and Dr. P. Colinet (University of Brussels, B). Will study the three-dimensional temperature field in an evaporating liquid (ethanol) caused by turbulent motions at the liquid-gas interface, known as Marangoni convection (after the name of an Italian scientist who studied interfacial phenomena between gas and liquids at the end of the 19th century). Technical aspects of these two experiments are being attended to by the Swedish Space Corporation, which is in charge of the preparation of the Maxus and Maser sounding rocket flights. "Vibrational phenomena in inhomogeneous media" by Dr. P. Evesque (CNRS, Ecole Centrale, Paris, F), Dr. D. Beysens (CEA, Grenoble, F) and Dr. Y. Garrabos (CNRS, Pessac, F). Will investigate the effect of vibrations in weightlessness on inhomogeneities in two-phase fluids and granular matter. This is one of the experiments recommended to fly in the Fluid Science Laboratory currently being developed for ESA's Columbus Laboratory. "Liquid diffusion model experiments with the shear cell technique" by Professor G. Frohberg, Dr. A. Griesche (Berlin Technical University, D) and Dr. G. Matthiak (DLR, Köln, D). Continues a previous experiment flown on the Russian satellite Foton-12. Diffusion is the main process in metallurgy and crystal growth. The diffusion coefficient of liquids is difficult to measure on the ground due to other mass transport phenomena resulting from gravity-induced natural convection. "Study of synthesis of carbon species in microgravity" proposed by Professor J. P. Issi, Dr. J. C. Charlier and Dr. J. M. Beuken (University of Louvain, B). Will investigate the synthesis of new forms of carbon, such as fullerenes, nanotubes and diamonds, by applying a strong electric discharge between two graphite electrodes. Similar experiments were conducted previously during parabolic flights and showed that the process of obtaining these different carbon forms could be improved to some extent. "Recrystallisation of tungsten filament" by Dr. R. Van Wijk and P. Dona (Philips Eindhoven, NL). Will study aspects of processing tungsten filaments to improve the performance of new lamps. This is one of the first experiments conducted directly by an industrial company in weightlessness, and shows the potential of applied research and development in microgravity. "Laminar diffusion flames representative of fires in microgravity environments" by Professor P. Joulain (CNRS, Poitiers, F) and Dr. J. L. Torero (University of Maryland, USA). Continues a series of combustion experiments conducted during previous parabolic flight campaigns, sounding rocket flights and drop towers. The final experiment goal is to provide the scientific background necessary for the evaluation of material flammability in microgravity, enabling the risk of fire on board manned space vehicles to be reduced. "Real-time physiological and molecular biological measurements of osteoblast-like cells under microgravity using fluorescence techniques" by Professor D. Jones (University of Marburg, D) and Professor Vander Sloten (University of Leuven, B). Will investigate bone cells stimulated mechanically in microgravity. Osteoblasts are responsible for the regeneration of bone tissues while osteoclasts are responsible for resorption of used bone tissues. The results will help to shed light on the mechanisms of bone resorption and regeneration, which are not yet fully understood. "Effects of gravity at biomolecular level" by Professor P. Vanni (University of Florence, I). Will investigate whether microgravity can affect enzyme reactions, complementing a previous experiment on a sounding rocket in 1996. "Lipoxygenase activity in microgravity" by Dr. M. Maccarone and Professor A. Finazzi-Agro (University of Rome, I) with the support of Profs G. A. Veldink and J. F. G. Vliegenhart (University of Utrecht, NL). Will investigate the role of microgravity in enzyme catalysis reactions, as enzymes play important regulatory roles in all living cells, in both plants and animals. These two experiments (9 and 10) will use the EMEC (Effect of Microgravity on Enzyme Catalysis) module already flown on the Maser 7 sounding rocket in 1996, specially refurbished for this parabolic flight campaign by the firm Officine Galileo (I). "Postural control in flatfish" by Professor A. Berthoz (CNRS, Collčge de France, Paris, F). Will study the behavior of flat fishes swimming in a large pressurized aquarium. This experiment is related to the study of the inner ear vestibular system and complements previous investigations to bring more information on the central mechanisms of imbalance compensation, postural balance and asymmetries in the gravistatic system, thought to be the cause of space sickness. This is an experiment proposed by CNES that will fly in an ESA campaign in the framework of an experiment exchange agreement. "Testing of the Mirsupio crew support pouch" by engineers of ESA's European Astronaut Centre. Mirsupio is an improved multi-function wearable equipment pouch worn around the waist to support the astronaut in his daily life in orbit. An initial version of this pouch was flown on the Mir Space Station during the Perseus mission with ESA astronaut J. P. Haigneré. --------------------------------------------------------------------- NEXT FIVE DAYS ON GALILEO JPL release 15-19 May 2000 Galileo emerges from a period of unreliable communications this week, only a few days prior to a close flyby of Ganymede. Of the Galilean moons, Ganymede is third closest in distance from Jupiter, preceded by Io and Europa, and followed by Callisto. This flyby is the third of the Galileo Millenium Mission, an extension of Galileo's tour of the Jovian system. It is the second such extension, following both the primary mission, which ended in December 1997, and the Galileo Europa Mission, which concluded in December 1999. Galileo resumes normal operations late Tuesday night. For a few weeks prior to Tuesday, the orbital motion of the Earth and Jupiter brought the Sun between the two, creating radio interference and making reliable communications between the spacecraft and Earth impossible. This geometric situation is known as superior solar conjunction. As the spacecraft emerges from behind the Sun, the Sun's effect on its radio signal will gradually decrease to the point where communications can again be trusted. If this situation sounds familiar, it is because it has occurred approximately every 13 months while the spacecraft has been in orbit around Jupiter. The Ganymede flyby is scheduled to occur Saturday morning at 3:10 AM PDT [see Note 1]. Radio signals indicating that the flyby has occurred, however, won't reach Earth until 50 minutes later, or at 4:00 AM. PDT, which is denoted as Earth Received Time (ERT). The time difference is caused by the fact that Earth is approximately 6 astronomical units (898 million kilometers, or 558 million miles; 1 astronomical unit is equal to the average distance between the Earth and the Sun) from the spacecraft and it will take radio signals just under 50 minutes to travel between the two. Radio signals travel at a speed of 300,000 kilometers per second (186,000 miles per second), just under 670 million miles per hour. This is Galileo's fifth return to Ganymede, and its second closest. The spacecraft's previous close flyby of Ganymede occurred in May 1997, but its closest was in September 1996 with an altitude of 262 kilometers (163 miles). During the upcoming flyby, the spacecraft will pass within 808 kilometers (502 miles) of Ganymede's surface. That is about the same as the distance between San Diego and San Francisco. Galileo's flyby of Ganymede again places the spacecraft at risk of being affected by Jupiter's intense radiation belts. This risk is only slightly less than during recent Io encounters as the spacecraft won't be passing as deep into the belts as during those encounters, Galileo's instruments have already survived three times the radiation they were originally designed to withstand. Any passage through the Jupiter system adds to the total radiation dose experienced by the spacecraft. Mission planners believe this risk is well worth the promise of new scientific information. Events leading up to this weekend's high activity period are geared primarily toward spacecraft preparation. Late Tuesday night, the spacecraft will perform standard maintenance on its propulsion systems. On Wednesday, the spacecraft will perform standard maintenance on its onboard tape recorder. The tape recorder is a key component that allows Galileo to store its valuable science data for later transmission to Earth. Finally, on Friday, the spacecraft will perform a small flight path adjustment, if deemed necessary by flight controllers. The first science activities also start Thursday night when the Fields and Particles instruments begin a month-long survey of Jupiter's magnetosphere. In most orbits, this survey is performed only in the inner portions of the Jovian magnetosphere, in order to study its variation and to provide context for any recorded high- resolution observations. The current survey, however, will span the entire range from the inner to outer regions of the magnetosphere, and the transition from inside Jupiter's vast magnetic bubble out into the solar wind. The Fields and Particles instruments are comprised of the Dust Detector, Energetic Particle Detector, Heavy Ion Counter, Magnetometer, Plasma Detector, and Plasma Wave instrument. Late Friday night, Galileo's radio signal will begin to pass through Jupiter's atmosphere on its way to Earth. Within minutes, the spacecraft will pass behind Jupiter as seen from the Earth, completely blocking its radio signal from reaching Earth. About 40 minutes later, the spacecraft will emerge from behind Jupiter and communications are restored. During this passage, Galileo's radio signal is weakened and refracted by Jupiter's atmosphere. The changes in the signal will be measured by radio scientists here on Earth, which will allow them to gain more knowledge of the structure and electron density of Jupiter's upper atmosphere. Note 1. Pacific Daylight Time (PDT) is 7 hours behind Greenwich Mean Time (GMT). 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 --------------------------------------------------------------------- GALILEO--COUNTDOWN TO GANYMEDE By Ron Baalke 18 May 2000 It is now 1 day, 13 hours to the Galileo spacecraft's next encounter with Jupiter moon Ganymede. A special Countdown to Io home page is now available on the Galileo Home Page at http://www.jpl.nasa.gov/galileo/countdown/ Launched in October 1989, Galileo entered orbit around Jupiter in December 1995. The next encounter for Galileo is scheduled for Ganymede on May 20, 2000. Referred to as Ganymede 28, since this will occur on the 28th orbit since Galileo entered orbit around Jupiter, this encounter will be Galileo's fifth flyby of Ganymede. With a diameter of 5,262 km, Ganymede is the largest satellite in the solar system. In fact, Ganymede is larger than Mercury and Pluto, and three-quarters the size of Mars. Galileo will pass by Ganymede at a distance of 808 kilometers in the upcoming encounter. Highlights of the Countdown to Ganymede home page: * A virtual flyby of Ganymede with computer-generated approach images of Jupiter and Ganymede displayed at the top of the home page. These images are all updated every 5 minutes in sync with the actual flyby by the spacecraft. * Latest Galileo status reports reporting on the Ganymede 28 encounter. * Fact sheets and Europa, Callisto and Io. * Voyager 1 & 2 images of Callisto, Ganymede, Europa and Io. * Hubble Space Telescope images of the Galilean satellites. * Pioneer 10 & 11 images of Callisto, Ganymede, Europa and Io. --------------------------------------------------------------------- TODAY ON GALILEO JPL releases 20 May 2000 A full day lies ahead for Galileo as its instruments perform observations of Ganymede, Europa, Jupiter and the Jovian magnetosphere. The spacecraft flies over the surface of Ganymede at 3:10 AM PDT today [see Note 1] at an altitude of 808 kilometers (502 miles) and a speed of 11.3 kilometers per second (7.0 miles per second, or 25,200 miles per hour). Galileo also makes its closest approach to Europa, Jupiter and Io at 2:29 PM, 9:53 PM, and 11:40 PM PDT, at ranges of 595,000 kilometers (370,000 miles), 479,000 kilometers (298,000 miles), and 380,000 kilometers (236,000 miles), respectively. During the Ganymede flyby, the spacecraft will pass behind this largest of the Galilean moons as seen from the Earth and Sun. The solar occultation is uneventful as Galileo does not use solar power to operate. However, Galileo's transmissions to Earth will pass through Ganymede's tenuous atmosphere (as they did yesterday with Jupiter's atmosphere) as the spacecraft moves behind the icy moon, until they are completely blocked from reaching Earth. About 30 minutes later, the spacecraft will emerge from behind Ganymede and communications will be restored. As with yesterday's Jupiter occultation, during this passage, Galileo's radio signal is weakened and refracted by the tenuous atmosphere. The changes in the signal are again measured by radio scientists to learn more about the structure and electron density of Ganymede's tenuous atmosphere. The Fields and Particles instruments also take advantage of the flyby to perform a 60-minute high-resolution recording of the plasma, dust, and electric and magnetic fields surrounding Ganymede. Ganymede is the only planetary moon known to have its own internally-generated magnetic field, and thus, its own magnetosphere. During the recording, Galileo hopes to actually penetrate magnetic field lines that both originate and close on Ganymede's surface. This will allow scientists to obtain a far more complete understanding of how the magnetic fields and magnetospheres of both Ganymede and Jupiter interact with one another. The first remote sensing observation of the day is performed by the Photopolarimeter Radiometer (PPR) as it takes high-resolution thermal measurements of Ganymede's surface. Remote sensing observations occur both during the 60-minute Fields and Particles recording, and afterwards as the spacecraft moves away from Ganymede. Next, the Plasma Wave instrument (PWS) performs an observation dedicated to the detection of chorus emissions within Ganymede's magnetosphere. A chorus signal is seen in the electromagnetic fields measured by PWS when plasma is being accelerated by a particularly efficient type of wave-particle interaction. By detecting and analyzing chorus emissions, scientists hope to understand more about how Ganymede's unique magnetosphere operates. The PWS observation is followed by a series of five observations of Ganymede performed by the Solid-State Imaging camera (SSI). The observations are designed to provide scientists with information regarding questions of how different features and terrains come to exist on Ganymede's surface. The regions examined in these mosaics are believed to have been created by processes internal to Ganymede. However, are the processes volcanic, tectonic, or from some other mechanism? This observation set may help answer the question. The first mosaic of images captures smooth bright terrain and possibly sheltered grooved terrain. The second looks at a transition region between bright and dark terrain. Yet another mosaic contains pristine dark terrain, believed to be the oldest type of terrain on Ganymede. The fourth observation captures another region of smooth bright terrain containing bands with a smooth, 'plank-like' appearance. Finally, the last mosaic of images captures a caldera- like feature. The Near-Infrared Mapping Spectrometer (NIMS) takes the next observation of Ganymede. In it, NIMS obtains a spectral scan of a dark crater, surrounding ice, and background dark regions. The scan will allow scientists to determine if there are any differences in the composition of these different types of terrains. Then, SSI returns to the observation schedule with five mosaics centered at the locations of the high-resolution mosaics taken earlier, but covering a much wider area of the surface. These images will provide the geologic context for the high-resolution samples. In addition, the motion of the spacecraft along its flight path will allow stereo images to be produced by combining data from the two sets of images. NIMS takes another look at Ganymede by performing a scan just off of the moon's limb. The observation should allow scientists to gain more knowledge on the characteristics of Ganymede's tenuous atmosphere. SSI then takes another image of Ganymede, this time of enigmatic smooth dark terrain with a wispy appearance to it. Then, NIMS performs a spectral scan of the Perrine region of Ganymede's surface. Again, the scan will provide scientists with much desired information about the composition of the region. PPR is next on the observation plan. In an observation of Ganymede's dayside, PPR gathers information on the thermal properties of the surface in the presence of daylight. PPR continues in the observation spotlight by shifting attention from Ganymede and initiating a series of polarimetry observations of Europa. Polarimetry measurements allow scientists to learn about surface texture and small-scale surface properties. For the remainder of the day, PPR makes nine observations of Europa at different solar phase angles. Interspersed with these observations are two observations performed by NIMS. The first is a return to Ganymede and is designed to provide a high-resolution spectral map of Ganymede's entire disk. This global map can then be used for global scale comparisons of Ganymede to the other Galilean satellites. The second observation is a distant view of Europa while the moon is in Jupiter's shadow. A very low signal is expected, but detection of an elevated signal would suggest the presence of anomolously warm regions of the surface, due to either unusual surface materials, or the presence of recent ice-volcanic activity on Europa. The last two observations of the day turn their attention to Jupiter's atmosphere. Both performed by PPR, they are designed to capture polarimetry measurements of the atmosphere, which will provide scientists with information on the structure and temperature of its upper levels. 21 May 2000 The focus of Galileo's encounter turns away from Ganymede and Europa today, and toward observations of Jupiter, Jupiter's rings and Io. Observing activities are interrupted once today while the spacecraft performs a standard gyroscope performance test and a test to slew its scan platform. The Photopolarimeter Radiometer (PPR) is first to observe this morning, taking data for a thermal map of the recently-merged white ovals in Jupiter's atmosphere. White ovals are storms that occur between two adjacent zonal jet streams, and have lasted for decades. However, two of them have merged within the past few months to create a single storm. Next, PPR performs two scans of Jupiter's limb. These observations are designed to detect upwellings in Jupiter's atmosphere. The Near-Infrared Mapping Spectrometer (NIMS) continues observation of Jupiter with a spectral scan of its North Equatorial Belt. The NIMS observation is performed in realtime, which means that the data are not stored on the spacecraft's tape recorder, but rather are directly transmitted to Earth after processing and packaging. The Plasma Wave instrument (PWS) performs the next observation in conjunction with instruments on the Cassini spacecraft. The Cassini spacecraft is approaching Jupiter enroute to arrival at Saturn in 2004. Cassini will pass closest to Jupiter in December 2000, where it will perform more coordinated observations with Galileo. The current joint observation is designed to study the properties of radio-frequency emissions from Jupiter. NIMS returns to observing Jupiter's atmosphere with a spectral scan of the North Temperate Zone. This observation is again performed in realtime. PPR is next to observe, but this time the target is Io. In a pair of observations taken at different solar phase angles, PPR will obtain data on the texture and small-scale properties of Io's surface. The Solid-State Imaging camera (SSI) shifts attention to another target by capturing a few images of Jupiter's rings. The images will be taken at relatively high resolution, low solar phase angle, and high tilt angle. They will provide scientists with better determinations of the size and distribution of ring particles, both within Jupiter's main ring, and at its inner edge. The images will also attempt to detect wavelike features in the main ring and undulations in the ring's outer boundary, which would be important for understanding how the rings are maintained by the small inner satellites. NIMS wraps up the observing day with six more observations. The first four are realtime scans of Jupiter's North Equatorial Belt and North Temperate Zone. For the last two observations, NIMS performs spectral scans of Jupiter's bright limb. The scans will be used to provide scientists with data on the equatorial bulge created by Jupiter's rotation. 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 20 May 2000 Launch / Days since Launch = Nov 7, 1996 / 1281 days Start of Mapping / Days since Start of Mapping = April 1, 1999 / 405 days Total Mapping Orbits = 5250 Total Orbits = 6853 Recent events The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm036 sequence executed successfully from 00-125 (5/4/00) through 00- 128 (5/7/00). The mm037 sequence also successfully executed from 00- 129 (5/8/00) through 00-131 (5/10/00). The mm038 sequence was successfully uplinked on 00-130 (5/9/00) and will begin execution on 00-132 (5/11/00). Spacecraft health All subsystems are reporting nominal health. Uplinks There have been 16 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm037 and mm038 sequences. Total command files radiated to the spacecraft since launch is 4638. Upcoming events A bistatic radar experiment, in which the Spacecraft signal will be reflected off the martian surface to Earth, is in final development and will execute on May 14. The commands to perform this experiment have been incorporated into the mm039 sequence, which is scheduled to be uplinked on 00-134 (5/13/00) The next monthly MOLA off-nadir polar scan mini-sequence (mz051) is also in final development and will execute over 12 consecutive orbits beginning on May 17. The implementation of the first Radio Science occultation egress scans, replacing the previous fixed-HGA periods for obtaining occultation egress data, is also in development at this time and is scheduled for execution on 5/20-5/22/00. --------------------------------------------------------------------- STARDUST STATUS REPORT JPL release 19 May 2000 There were five Deep Space Network (DSN) tracking passes during the past week. All subsystems onboard the spacecraft are performing normally. The third of three spacecraft activities to support Doppler data measurements was performed. The DSN station successfully locked onto the spacecraft signal and obtained two-way Doppler data. At the conclusion of the tracking pass the DSN station tracked the carrier signal as the spacecraft return to its nominal cruise sun pointed attitude. The Navigation team is analyzing the data to determine the effect of the forces due to the thruster firings by observing the Doppler shift. Flight sequence SC018 was successfully transmitted to the spacecraft and will go active next week. The remainder of the DSN passes was used for tracking purposes to support the Trajectory Correction Maneuver (TCM 3) on May 24. Preparations for TCM 3 are continuing. The estimated size of TCM 3 is 2 meters/second or a burn time of 77 seconds. The command files for the Navigation Camera images have been developed and is being tested in the System Test Laboratory. 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 19