MARSBUGS: The Electronic Astrobiology Newsletter Volume 6, Number 25, 18 August 1999. Editors: Dr. David J. Thomas, Biology and Chemistry Division, Lyon College, Batesville, AR 72503-2317, USA. Marsbugs@aol.com or 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 out of 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) SPACEDEV OFFERS COMMERCIAL MARS AND LUNAR MISSIONS SpaceDev release 2) CASSINI SUCCESSFULLY COMPLETES FLYBY OF EARTH JPL release 3) NASA TO HOST HOUSTON CONFERENCE EXPLORING COMMERCIAL INTEREST IN SPACE STATION LIVING QUARTERS NASA release 99-94 4) MARS SURVEYOR 98 MISSION STATUS JPL release 5) MARS GLOBAL SURVEYOR STATUS REPORT JPL release 6) STARDUST STATUS REPORT JPL release 7) THE NEXT NINE DAYS ON GALILEO JPL release 8) GALILEO EUROPA MISSION STATUS JPL releases 9) NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke ---------------------------------------------------------------- SPACEDEV OFFERS COMMERCIAL MARS AND LUNAR MISSIONS SpaceDev release 16 August 1999 SpaceDev Inc. announced Friday it is offering low-cost Mars probe-carrier missions as a commercial product, starting with the 2003 Mars launch opportunity. SpaceDev is also offering lunar orbiters and derivatives of its newly revised Near Earth Asteroid Prospector (NEAP) mission for sale as turnkey commercial products. Such commercial deep-space missions are a first for the industry. SpaceDev Chairman and Chief Executive Officer Jim Benson made the announcement in Boulder at the annual convention of the Mars Society. "We are now offering to deliver small payloads on Mars-entry trajectories for a fixed price of about $24 million. The estimated NASA procurement cost for a similar mission is thought to be significantly higher than the SpaceDev fixed price, perhaps twice as much," Benson said during his remarks at the conference, later adding that "savings of comparable magnitude are possible with SpaceDev's turn-key lunar and asteroid missions." SpaceDev missions, unlike government-sponsored missions, will be insured against the risk of launch-vehicle failure and catastrophic failures during mission operations. SpaceDev has been working with its space-insurance broker, industry leader International Space Brokers (ISB), to define the required coverage. Mars missions During his presentation, Benson detailed that the $24M charge for the Mars probe-carrier mission was the total mission cost minus customer-provided payload costs. Such missions, designed to release one to three entry probes into the Martian atmosphere, would launch at the earliest between November 2002 and May 2003, arriving at the Red Planet in late 2003. Subsequent mission opportunities arise in 2005, 2007, 2009, etc., consistent with recurring Earth-to-Mars launch periods. Benson challenged the Mars Society to identify and finance just such a mission. "You say things aren't happening fast enough with NASA's current Mars Exploration Program. Then decide what you want to send to Mars, get a sponsor, and just do it! Inner planet missions like this one can now be done for about the cost of a private jet or mega-yacht," he said. Lunar missions For $20M SpaceDev will sell clients a lunar orbiter mission accommodating up to four payloads -- scientific instruments, advanced technologies such as the newly developing Interplanetary Internet, a Web server or other experiments. Payloads could be fixed to or ejectable from the main vehicle. With the relatively close lunar distances, very high data rates are achievable from the Moon, including real-time, high- definition TV broadcasts of lunar surface fly-overs and multiple earthrises. MicroNEAP mission and derivatives SpaceDev's recent success in identifying low-cost spacecraft design approaches and in developing a range of modular microspacecraft concepts led the company to evolve its two-year- old Near Earth Asteroid Prospector (NEAP) spacecraft design into a smaller, simpler MicroNEAP. "We are in the business of producing low-cost, multi-use, modular spacecraft that can be sent to any destination in the inner solar system. NEAP--as the MicroNEAP implementation is a seamless addition to our growing, fixed-price space-mission product line," said Benson. NEAP is to be launched in late 2001 for a rendezvous with the near-Earth asteroid Nereus in mid-2002. SpaceDev has already negotiated a contract for one paying NEAP payload and has an agreement with the University of Arizona for delivery of an advanced imaging spectrometer instrument. SpaceDev's commercial deep-space missions utilize a spacecraft bus (chassis) design derived from the intensive Mars mission and system definition effort completed by a SpaceDev-led team in March this year under a contract with JPL. SpaceDev's Mars Micromissions Bus Feasibility Study sought to validate earlier JPL findings that selected Mars missions are possible for less than $50M each using microspacecraft. Key to this low-cost approach is that the microspacecraft be launched as secondary payloads on the European Ariane 5 launch vehicle. Total mass of the bus, payload(s) and propellant at launch is approximately 200 kg. JPL followed these studies in June with a competitive procurement for the first NASA Mars Micromission--either a carrier bus delivering the proposed Mars Airplane or a communications and navigation orbiter--arriving at Mars in December 2003. Industry proposals are currently being evaluated by JPL. The SpaceDev-led team elected not to bid on that procurement. Benson summarized his remarks to the Mars Society by saying, "The key element to SpaceDev's business plan is to offer deep- space missions as complete commercial products, all the way from Mercury to Mars if the market so demands. For years NASA has been encouraging the private sector to step up to the space- commercialization plate. We have, and we intend to hit home runs. Any country, consortium or sufficiently wealthy individual in the world can now afford to buy their own deep- space mission. The idea of focused, inexpensive deep-space missions as a commercial product is as revolutionary today as personal computers were only twenty years ago." SpaceDev (www.spacedev.com), a two-year-old, 70-person company based in Poway, in northern San Diego County, is the world's first commercial space exploration and development company. Co- located in new Poway facilities are SpaceDev's corporate offices, its wholly owned subsidiary Integrated Space Systems (ISS, www.spaceinc.com) and the firm's Space Missions Division. The company's other wholly owned subsidiary, Space Innovations Limited (SIL, www.sil.com), is in Newbury, England. ---------------------------------------------------------------- CASSINI SUCCESSFULLY COMPLETES FLYBY OF EARTH JPL release 17 August 1999 Earthlings bid farewell to the Cassini spacecraft tonight as the Saturn-bound mission successfully completed a highly accurate pass of Earth at 8:28 PM Pacific Daylight Time (03:28 Universal Time August 18). The flyby gave Cassini a 5.5-kilometer-per- second (about 12,000-mile-per-hour) boost in speed, sending the spacecraft on toward the ringed planet more than 1 billion kilometers (almost one billion miles) away. Engineers at NASA's Jet Propulsion Laboratory confirmed that the spacecraft flew past Earth at an altitude of about 1,171 kilometers (727 miles), passing most closely above the eastern South Pacific at -23.5 degrees latitude and 231.5 degrees longitude. Cassini may have been visible from small islands in that area, such as Pitcairn Island or Easter Island. The spacecraft remains in excellent health as it continues along its seven-year-long journey to Saturn. Having completed its cruise among the inner planets, Cassini's future now resides in the cold, dark realm of the outer planets. The spacecraft will pass by Jupiter on December 30, 2000; the giant planet's gravity will bend Cassini's flight path to put it on course for arrival into orbit around Saturn on July 1, 2004. Cassini's mission is to study Saturn, its moons, elaborate rings, and its magnetic and radiation environment for four years. Cassini will also deliver the European Space Agency's Huygens probe to parachute to the surface of Saturn's moon Titan. Titan is of special interest partly because of its many Earthlike characteristics, including a mostly nitrogen atmosphere and the presence of organic molecules in the atmosphere and on its surface. Lakes or seas of ethane and methane may exist on its surface. The Cassini/Huygens program is a joint endeavor of NASA, the European Space Agency and the Italian Space Agency. The Cassini orbiter, built by NASA, and the Huygens probe, provided by the European Space Agency (ESA), were mated together and launched as a single package from Cape Canaveral, Florida, on October 15, 1997. The Italian Space Agency provided Cassini's dish-shaped high-gain antenna for the mission. At Saturn, the Huygens probe will detach from Cassini to parachute to the surface of Titan on November 30, 2004. Nine of Cassini's 12 science instruments were turned on to make observations of the Earth/Moon system. Scientific and engineering data from the Earth flyby will be transmitted by Cassini to receiving stations of NASA's Deep Space Network over coming days. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA. JPL is a division of the California Institute of Technology. More information about the Cassini mission is available at http://www.jpl.nasa.gov/cassini. ---------------------------------------------------------------- NASA TO HOST HOUSTON CONFERENCE EXPLORING COMMERCIAL INTEREST IN SPACE STATION LIVING QUARTERS NASA release 99-94 17 August 1999 NASA has invited private industry to Houston from August 24 to 26 to participate in a conference that will explore potential commercial interest in a government and industry partnership to build the crew habitation module for the International Space Station. NASA needs a crew-quarters module that will house at least four crewmembers. The module should also include bedrooms, a kitchen, a pantry, a dining and meeting area, videoconferencing and entertainment equipment, windows, storage space, exercise equipment and a medical examination room. "NASA is dedicated to the commercial use of space and fostering private enterprise on the new frontier," said Dan Tam, Special Assistant to the NASA Administrator for Commercialization. "This invitation is one way for us to actively pursue the ideas that businesses may have for using a living area in space for profit-driven motives. On Earth, it has been demonstrated time and time again that with market support, private industry can do a better job than the government. We expect the same will be true in space." The Habitation Module Commercialization Conference will be held at the Nassau Bay Hilton and Marina Hotel, 3000 NASA Road 1, Houston. The conference will explore the formation of a commercial consortium that would own, use and maintain all or part of the module. NASA would be one of many module users and customers of the consortium. Current station plans specify that the module be a traditional metallic design similar to other International Space Station modules. A more recent NASA concept has proposed an innovative, space fabric version of the living quarters module. At this conference, participants will consider existing designs and new ideas for the module. Innovative concepts for enhanced habitation capabilities benefiting both NASA and commercial partners are especially sought. The habitation module will be launched from the Space Shuttle and attached to the station in November 2004. In addition to aerospace industries, NASA is hoping to attract other businesses and investors to spur innovation in the commercial use of space. These non-aerospace companies may have ideas related to sponsorship, space tourism, entertainment, advertising, education or technology development. This activity will serve as a pathfinder for other commercial uses of the International Space Station and commercial involvement in other NASA programs. "We really want this conference to be a brainstorming session with businesses and investors of all kinds and hope it leads to a business relationship between NASA and a commercial consortium. NASA is open to any and all ideas that are of benefit to both private enterprise and the government," Tam said. News media are invited to attend the full sessions of the conference. More information and registration information is available on the Internet at http://technology.jsc.nasa.gov/habconference. ---------------------------------------------------------------- MARS SURVEYOR 98 MISSION STATUS JPL release 11 August 1999 Mars Climate Orbiter (MCO) The MCO spacecraft continues to perform well in cruise, with no scheduled activities during the past week. The flight team conducted its first Operational Readiness Test (ORT) on Tuesday and Wednesday (August 10-11), in preparation for Mars Orbit Insertion (MOI) and the Period Reduction Maneuver (PRM) next month. In addition, evaluation of telemetry from the solar array gimbal drive following Trajectory Correction Maneuver #3 (TCM-3) on July 25 continues, in preparation for an in-flight checkout of the two-axis drive to verify its integrity. Command preparation for the in-flight checkout is underway, targeting for transmission to the spacecraft on Wednesday, August 18. Mars Climate Orbiter is 43 days from mars orbit insertion. Mars Polar Lander (MPL) Mars Polar Lander experienced a quiet week in flight, given the flight team's focus on the MOI/PRM ORT. The Entry/Descent/Landing (EDL) system test effort is well underway now in the MPL simulator facility in Denver. The EDL test team is approximately 1/3 through a set of 24 test cases slated for execution, covering a range of nominal, off-nominal, and fault scenarios. For more information on the Mars Surveyor 98 mission, please visit our web site at http://mars.jpl.nasa.gov/msp98. ---------------------------------------------------------------- MARS GLOBAL SURVEYOR STATUS REPORT JPL release 12 August 1999 Launch / Days since Launch = Nov 7, 1996 / 1009 days Start of Mapping / Days since Start of Mapping = April 1, 1999 / 133 days Last Orbit Covered by this Report = 1918 Total Orbits = 3600 Total Mapping Orbits = 1918 Recent events The mm006 sequence is currently executing the daily science data collection and return and will continue execution through August 25. OTM-3 was successfully executed on Wed Aug 11 at 17:38:05 UTC. The OTM was designed to target a 50-km ground track repeat cycle. Preliminary Navigation team orbit determination analysis performed following the burn predicts a 50.4 km ground track repeat cycle. All spacecraft subsystems performed nominally during and after the burn. On the orbit following the OTM, autonomous solar array tracking was terminated and the three part per orbit Solar Array motion command sequences were successfully initiated. Based on tests performed recently on the spacecraft, it is believed that this will significantly reduce the microphonics noise seen in the Thermal Emission Spectrometer (TES) instrument data. Work continues on the development of a Magnetometer (MAG) calibration sequence to be executed on the spacecraft August 31. This test is comprised of a series of solar array motions on the night side of the orbit that will be used to more fully characterize the magnetic signature of the spacecraft. The source of the "tiny gaps" that have regularly occurred in the high rate mapping telemetry appears to have been isolated. A series of operational changes were made with the DSN stations on Aug 10, 11, and 12 with regards to activation of the command and ranging channels, that have effectively eliminated the gaps in the telemetry. HGA anomaly The HGA gimbal is currently operational with full redundancy on side-A. The fault protection threshold for HGA stuck gimbal is at 25 seconds (50 counts). Spacecraft health All subsystems continue to report nominal status. Power reports that our excess energy has dropped from an average of 460 W-hrs per orbit to about 400 W-hrs with the initiation of the new solar array tracking scheme. The three-move solar array tracking scheme will be used until August 2000, at which time autonomous tracking of the sun must resume in order to meet energy requirements as we approach aphelion. Uplinks There have been 15 uplinks to the spacecraft during the last week, including new star catalog and ephemeris files, and instrument command loads. Total command files radiated to the spacecraft since launch is 3845. Upcoming events 1) MM007 sequence development starts Friday Aug 13. 2) MAG calibration on Aug 31. ---------------------------------------------------------------- STARDUST STATUS REPORT JPL release 13 August 1999 The Deep Space Network communication window on August 10 showed Stardust to be operating and communicating normally. The Anomaly Investigation Team has found the apparent cause of the two recent safing events. An error from the Sun sensor caused the Payload and Attitude Control Interface (PACI) board to reset, as it should. Not all of the PACI interrupts were reset properly, however, due to a software problem. As a result the star camera was unable to communicate through the PACI board. This quite properly caused the spacecraft to place itself in a safe state, which did reset everything. The PACI sequence of events has been reproduced on the ground in the Spacecraft Test Laboratory. The anomaly team is developing responses to prevent recurrences of this situation. The Cometary Interstellar Dust Analyzer (CIDA) team held their week-long annual meeting this week with attendance from Lockheed Martin Astronautics (LMA) and JPL. Major items of discussion included uplink and downlink protocols and data analysis and archiving. Spacecraft cruise sequence eight (SC008) will begin on August 16. The Stardust Teachers Workshop is being held at JPL next week running from August 16-19. 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. ---------------------------------------------------------------- THE NEXT NINE DAYS ON GALILEO JPL release 14-22 August 1999 Galileo concludes the eleventh encounter of the Galileo Europa Mission on Saturday, August 14, at 3 PM PDT [see Note 1]. The remaining encounter activities include the close flyby of Jupiter's moon Callisto, an observation by the Radio Science team and one by the Ultraviolet Spectrometer. Following the encounter, the spaceraft begins playing back data acquired during the previous several days and stored on its onboard tape recorder. Data playback is interrupted once during this week. On Thursday, August 19, the spacecraft performs a small flight path correction. Back here on Earth, flight team members are in the process of analyzing engineering data to determine the cause of four spacecraft anomalies seen during the encounter. Preliminary theories implicate Jupiter's intense radiation environment as the primary culprit. Onboard fault protection software was successful in keeping encounter operations going, although during one incident the spacecraft's tape recorder temporarily stopped recording. This error resulted in the truncation of the Fields and Particles Io Torus and Perijove recording, the loss of two Europa observations by the Near Infrared Mapping Spectrometer, and the loss of the Plasma Wave instrument's observation of Chorus emissions (Chorus emissions are created when plasma is accelerated due to wave-particle interactions within Jupiter's magnetosphere). The close flyby of Callisto occurs early on August 14, at 1:31 PDT and a distance of 2296 kilometers (1427 miles). The flyby will reduce the spacecraft's Perijove distance, or closest distance to Jupiter for a given orbit, from 7.3 Jupiter radii (523,000 kilometers, 325,000 miles) to 6.5 Jupiter radii (465,000 kilometers, 289,000 miles). The change in Perijove distance is not seen until Galileo's next encounter, however, because the Callisto flyby has occurred after this encounter's Perijove passage. During the Callisto flyby, the spacecraft passes behind the moon as seen from the Sun and the Earth. As the spacecraft flies behind the moon, its radio signal will be weakened and refracted by Callisto's tenuous atmosphere. Back on Earth, the Radio Science team will measure these changes, which will allow scientists to study the structure of Callisto's atmosphere. Galileo's last observation for this encounter is performed by the Ultraviolet Spectrometer. The observation looks at Ganymede while it is eclipsed from the Sun by Jupiter and hopes to capture auroral activity in action. This week's playback schedule includes observations made by the Solid-State Imaging camera and the Near-Infrared Mapping Spectrometer, but first on the schedule is the return of a recording performed by the Fields and Particles instruments. The recording was performed for six hours as the spacecraft flew through the Io torus and Perijove. The measurements will contribute to the study of the dynamic processes that occur within these regions. The Solid-State Imaging camera returns 16 observations this week. The first five contain images of Io, two others capture views of Amalthea, and the remaining nine look at Jupiter. The first four Io observations are part of a campaign designed to monitor volcanic plume activity on the moon. The remaining observation provides data on the size and shape of the volcanic moon. The camera's observations of Amalthea will enhance studies of the shape of this inner moon. They will provide the best spatial resolution ever obtained of the moon (up to 8.5 kilometers, 5.3 miles, per picture element). Finally, the camera's observations of Jupiter are part of an extensive campaign designed to enable scientists to study the dynamics of cloud motion in Jupiter's atmosphere. The campaign includes examining nine different locations on Jupiter's globe and five different atmospheric features. This week's data return returns 9 of 34 total observations performed during the encounter. The Near-Infrared Mapping Spectrometer fills the remaining time available in this week's playback plan. The observation returns measurements of a white oval in Jupiter's atmosphere. White ovals are long-lived storms that form between two adjacent zonal jet streams. Note 1. All times listed correspond to the Pacific Time zone (currently daylight time) and spacecraft event time. Radio signals indicating that an event has occurred on the spacecraft reach the Earth 33 to 50 minutes later, depending on the time of year. Currently, Pacific Daylight Time (PDT) is 7 hours behind Greenwich Meridian Time (GMT), and it takes radio signals 38 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 http://www.jpl.nasa.gov/galileo. ---------------------------------------------------------------- GALILEO EUROPA MISSION STATUS JPL releases 13 August 1999 Today Galileo embarks on the third of four days of encounter operations. Jupiter and Io are the main targets of today's observations, which are performed primarily by the Solid-State Imaging camera and Ultraviolet Spectrometer. In addition to the observations with the Jovian system, the camera also obtains some data to calibrate one of its filters by looking at Saturn and its moon Titan! Today's activity is dominated by an extensive series of observations (or campaign) performed by the Solid State Imaging camera and the Ultraviolet Spectrometer. This campaign looks at nine different locations on Jupiter and obtains measurements of five different types of features of Jupiter's atmosphere. These data are designed to enable scientists to study the dynamics of cloud motion in Jupiter's atmosphere. The two instruments account for a total of 43 observations, 34 by the Solid-State Imaging camera and 9 by the Ultraviolet Spectrometer. The features observed in this campaign are a hot spot, a region know for the appearance of lightening, a region in Jupiter's north equatorial belt, a region at high northern latitudes, and a region near Jupiter's north pole. In addition to observations of particular regions in the Jovian atmosphere, the Ultraviolet Spectrometer performs two other types of observations. In the first type of observation, the Spectrometer obtains measurements that will help to determine how minor components of the atmosphere are involved in the dynamics of the upper atmosphere. In the second type of observation, the Spectrometer looks at auroral activity near Jupiter's south pole. The observation is designed to provide scientists with a view into the interaction of Jupiter's upper atmosphere with Jupiter's magnetosphere. Six observations related to Io are performed today, five by the Solid-State Imaging camera and one by the Ultraviolet Spectrometer. The camera observations are the second half of a ten-observation campaign designed to monitor volcanic plume activity on Io. Attempts will be made to compare the volcanic activity seen in these images to measurements of the Io torus taken by the Fields and Particles instruments. The Ultraviolet Spectrometer observation does not look at Io directly, but rather makes measurements of the Io torus. The torus is a region of relatively dense plasma (which originates at Io) and is characterized by intense radiation activity and strong magnetic and electric fields. The plasma is believed to be constantly replenished by the volcanic activity on Io. This observation will allow scientists to keep track of signficant changes in the characteristics of the torus. 16 August 1999 NASA's Galileo spacecraft survived an unexpected whopper dose of radiation--the strongest it has experienced since its closest- ever approach to Jupiter in 1995--before completing the third in a series of flybys of Jupiter's moon Callisto. The radiation bombardment occurred as Galileo headed toward its Callisto encounter, when the spacecraft flew within 452,000 kilometers (281,000 miles) of Jupiter's cloud tops at 3:59 a.m. Pacific Daylight Time on Thursday, August 12. "We anticipated the spacecraft's star scanner would detect about 300 to 400 pulse counts of radiation, so imagine our surprise when the instruments showed Galileo had flown through 1,400 pulse counts!" said Galileo Project Manager Jim Erickson. "Then again, that's why we're exploring Jupiter and its moons--to discover these unusual phenomena." The cause of the outburst is unknown, but several factors may have played a role. First, at the time the spacecraft was near its close approach to Jupiter and its high radiation environment. Second, it was also near a "plasma sheet," crossing, an area brimming with charged particles trapped in a thin disc that rotates with Jupiter's magnetic field. In addition, it took place one week after the largest heat output since 1986 from Jupiter's volcanic moon Io. The Io heat output was measured by ground-based infrared telescopes and may coincide with an increase in volcanic activity. The radiation level endured by Galileo during this flyby was many times higher than the levels engineers expect the spacecraft will encounter during its flybys of Jupiter's volcanic moon Io in October and November. "This was a great dress rehearsal for the Io encounters," said Erickson. "We've been wondering how the spacecraft might hold up when it gets close to Io. This latest brush with radiation makes us think that the odds of survival may be fairly good." The radiation exposure did have its tense moments. It appears the radiation triggered four spacecraft faults, but all of them were handled correctly by onboard software. The radiation apparently triggered a computer reset of the non-spinning portion of the spacecraft three times--on Thursday, August 12 at 6:07 AM PDT, at 10:29 AM PDT, and at 5 PM PDT. Because the onboard tape recorder was in use during the first reset, the recording was disrupted temporarily. This resulted in the loss of a few observations--one from the instruments that study magnetic fields and charged particles and two by the near infrared mapping spectrometer. The radiation apparently caused one other anomaly at 8:21 AM PDT on August 12, when a spin detector, used as a backup monitor of the spacecraft's spin rate, experienced a hardware glitch. Onboard fault protection software disabled the faulty detector. After Galileo passed beyond the high radiation zone and corrected its faults, the spacecraft went on to fly by Callisto at an altitude of 2,299 kilometers (1,429 miles) on Saturday, August 14, at 1:31 AM PDT. The flyby included experiments involving changes in the spacecraft's signal as it passed behind Callisto (as seen from Earth). During that period, Galileo's radio signal was weakened by Callisto's tenuous atmosphere. By studying these changes, scientists can learn more about the structure of the atmosphere. Galileo has begun transmitting to Earth pictures and other science information gathered during the flyby and stored on its onboard tape recorder. On Thursday, August 19, the recorder will be paused so the spacecraft can make a minor flight path adjustment to position it for its next scheduled Callisto flyby on September 16. Galileo's instruments are gathering valuable science information during the Callisto flybys, but the primary purpose is to lower Galileo's orbit to prepare for the two close flybys of Io. The Io encounters will provide the closest-ever look at the most volcanic body in our solar system. Galileo has been orbiting Jupiter and its moons since December 1997. The spacecraft is more than halfway through a two-year extended Galileo Europa Mission, a follow-on to the primary mission that ended in December 1997. JPL, a division of the California Institute of Technology, Pasadena, CA, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. ---------------------------------------------------------------- NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke 16 August 1999 The following new images taken by the Mars Global Surveyor spacecraft are now available. A Typical Martian Scene: Boulders and Slopes in a Crater in Aeolis The images reside on the Mars Global Surveyor web site at http://mars.jpl.nasa.gov/mgs/msss/camera/images/index.html. The image captions are appended below. Mars Global Surveyor was launched in November 1996 and has been in Mars orbit since September 1997. It began its primary mapping mission on March 8, 1999. Mars Global Surveyor is the first mission in a long-term program of Mars exploration known as the Mars Surveyor Program that is managed by JPL for NASA's Office of Space Science, Washington, DC. Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Mars Global Surveyor Mars Orbiter Camera A Typical Martian Scene: Boulders and Slopes in a Crater in Aeolis MGS MOC Release #MOC2-173, 16 August 1999 The Mars Orbiter Camera (MOC) was designed to be able to see objects the size of automobiles and small buildings on the martian surface. Of course, the Mars Global Surveyor science teams do not expect to find buildings and automobiles...but boulders, instead. These pictures show a typical MOC scene in the martian equatorial cratered highlands. The picture on the left (above) is a MOC wide-angle context frame, showing the location of the high-resolution image on the right. The high resolution image exhibits slopes and valleys that occur within an ancient impact crater that is about 33 kilometers (20.5 miles) across, located at 6.5°S, 218.8°W in the Aeolis region of Mars. The high-resolution view shows smooth, mantled surfaces, as well as bare, rocky surfaces. The bare surfaces are typically located on slopes. Small rounded knobs--particularly in the upper left corner of the image--are boulders. A few boulders have rolled down the slopes and are deposited in the valleys. The high-resolution image covers a very small area--only 3 km wide by 4.2 km tall (1.9 miles by 2.6 miles). Both images were obtained at the same time, and both are illuminated by sunlight from the left. North is toward the upper right. ---------------------------------------------------------------- End Marsbugs Vol. 6, No. 25.