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The Compton Gamma Ray Observatory

The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

Gehrels, N.↗

Space astronomy and upper atmospheric sounding

The discoveries and activities of the Space Science Program are reported. Results of studies are presented for the following areas: gamma and x-ray astronomy, optical geophysics and solar wind, infrared astronomy, radio astronomy, and rocket spectroscopy. Lists of publications, talks, and conferences are included.

Friedman, H.↗

Apollo 16 preliminary science report

Ever since Galileo's telescope made the rugged lunar surface more clearly visible (in 1610), men have strived to learn more about the origin and history of the Earth's big natural satellite, and never has so much progress been made as in the last few years. The fifth manned lunar landing was in a highlands area, quite different from the sites visited previously, and the discoveries there now seem certain to result in significant improvements in the hypotheses of lunar scientists. Much of the Moon's surface is similar to the Descartes Highlands that the Apollo 16 astronauts examined. From this highly productive mission, more photographs were obtained than on any previous Apollo flight, a greater amount of time was spent outside the lunar module, a greater weight of scientific equipment landed on the Moon, and a record weight of scientific samples was brought back to laboratories on Earth. The network of automatic scientific stations at work on the Moon was extended into a new area and has since detected a moonquake caused by the largest meteoroid impact that has yet been recorded. Additional experiments on the surface and in flight also were successfully performed on this mission for the enlightenment of students of natural phenomena. The Apollo 16 astronauts observed, and scientists studying material they collected have subsequently deduced, that this landing site differed surprisingly from earlier expectations. Future generations consequently may benefit from better concepts of the operation of the solar system and events throughout the physical universe than have hitherto been possible. This volume is but one of a series of NASA Special Publications being issued promptly to document potentially significant discoveries in the course of the Apollo Program, thereby possibly increasing their usefulness to scientists grappling with problems that have long perplexed mankind.

NASA Editorial Review Board↗

Automatic discovery of optimal classes

A criterion, based on Bayes' theorem, is described that defines the optimal set of classes (a classification) for a given set of examples. This criterion is transformed into an equivalent minimum message length criterion with an intuitive information interpretation. This criterion does not require that the number of classes be specified in advance, this is determined by the data. The minimum message length criterion includes the message length required to describe the classes, so there is a built in bias against adding new classes unless they lead to a reduction in the message length required to describe the data. Unfortunately, the search space of possible classifications is too large to search exhaustively, so heuristic search methods, such as simulated annealing, are applied. Tutored learning and probabilistic prediction in particular cases are an important indirect result of optimal class discovery. Extensions to the basic class induction program include the ability to combine category and real value data, hierarchical classes, independent classifications and deciding for each class which attributes are relevant.

Cheeseman, Peter↗

Demonstrating damage tolerance of composite airframes

Commercial transport aircraft operating in the United States are certified by the Federal Aviation Authority to be damage tolerant. On 28 April 1988, Aloha Airlines Flight 243, a Boeing 727-200 airplane, suffered an explosive decompression of the fuselage but landed safely. This event provides very strong justification for the damage tolerant design criteria. The likely cause of the explosive decompression was the linkup of numerous small fatigue cracks that initiated at adjacent fastener holes in the lap splice joint at the side of the body. Actually, the design should have limited the damage size to less than two frame spacings (about 40 inches), but this type of 'multi-site damage' was not originally taken into account. This cracking pattern developed only in the high-time airplanes (many flights). After discovery in the fleet, a stringent inspection program using eddy current techniques was inaugurated to discover these cracks before they linked up. Because of concerns about safety and the maintenance burden, the lap-splice joints of these high-time airplanes are being modified to remove cracks and prevent new cracking; newer designs account for 'multi-site damage'.

Poe, Clarence C., Jr.↗

Observational Search for Cometary Aging Processes

The scientific objectives of this study were (i) to search for physical differences in the behavior of the dynamically new comets (those which are entering the solar system for the first time from the Oort cloud) and the periodic comets, and (ii) to interpret these differences, if any, in terms of the physical and chemical nature of the comets and the evolutionary histories of the two comet groups. Because outer solar system comets may be direct remnants of the planetary formation processes, it is clear that the understanding of both the physical characteristics of these bodies at the edge of the planet forming zone and of their activity at large heliocentric distances, r, will ultimately provide constraints on the planetary formation process both in our Solar System and in extra-solar planetary systems. A combination of new solar system models which suggest that the protoplanetary disk was relatively massive and as a consequence comets could form at large distances from the sun (e.g. from the Uranus-Neptune region to the vicinity of the Kuiper belt), observations of activity in comets at large r, and laboratory experiments on low temperature volatile condensation, are dramatically changing our understanding of the chemical'and physical conditions in the early solar nebula. In order to understand the physical processes driving the apparent large r activity, and to address the question of possible physical and chemical differences between periodic, non-periodic and Oort comets, the PI has been undertaking a long-term study of the behavior of a significant sample of these comets (approximately 50) over a wide range of r to watch the development, disappearance and changing morphology of the dust coma. The ultimate goal is to search for systematic physical differences between the comet classes by modelling the coma growth in terms of volatile-driven activity. The systematic observations for this have been ongoing since 1986, and have been obtained over the course of approximately 300 nights using the telescopes on Mauna Kea, Kitt Peak, Cerro Tololo, the European Southern Observatory, and several other large aperture facilities. A greater than 2 TB database of broad band comet images has been obtained which follows the systematic development and fading of the cometary coma for the comets in the database. The results to date, indicate that there is a substantial difference in the brightness and the amount of dust as a function of r between the two comet classes. In addition to this major finding, the program has been responsible for several exciting discoveries, including: the P/Halley outburst at r = 14.3 AU, the discovery of Chiron's coma and modelling and observations of the gravitationally bound component, observational evidence that activity continues out beyond r = 17 AU for many dynamically new comets

Meech, Karen J.↗

Lunar and Planetary Information Bulletin

The articles in this issue cover the end of the Galileo mission to Jupiter, educational outreach programs, and news on planetary science, including discoveries and updates on Mars missions. This issue also features brief book reviews, and a calender listing conferences for 2003.

Schenk, Paul M.↗

Brake Failure from Residual Magnetism in the Mars Exploration Rover Lander Petal Actuator

In January 2004, two Mars Exploration Rover spacecraft arrived at Mars. Each safely delivered an identical rover to the Martian surface in a tetrahedral lander encased in airbags. Upon landing, the airbags deflated and three Lander Petal Actuators opened the three deployable Lander side petals enabling the rover to exit the Lander. Approximately nine weeks prior to the scheduled launch of the first spacecraft, one of these mission-critical Lander Petal Actuators exhibited a brake stuck-open failure during its final flight stow at Kennedy Space Center. Residual magnetism was the definitive conclusion from the failure investigation. Although residual magnetism was recognized as an issue in the design, the lack of an appropriately specified lower bound on brake drop-out voltage inhibited the discovery of this problem earlier in the program. In addition, the brakes had more unit-to-unit variation in drop-out voltage than expected, likely due to a larger than expected variation in the magnetic properties of the 15-5 PH stainless steel brake plates. Failure analysis and subsequent rework of two other Lander Petal Actuators with marginal brakes was completed in three weeks, causing no impact to the launch date.

Jandura, Louise↗

Vibroacoustic Response of the NASA ACTS Spacecraft Antenna to Launch Acoustic Excitation

The Advanced Communications Technology Satellite was an experimental NASA satellite launched from the Space Shuttle Discovery. As part of the ground test program, the satellite s large, parabolic reflector antennas were exposed to a reverberant acoustic loading to simulate the launch acoustics in the Shuttle payload bay. This paper describes the modelling and analysis of the dynamic response of these large, composite spacecraft antenna structure subjected to a diffuse acoustic field excitation. Due to the broad frequency range of the excitation, different models were created to make predictions in the various frequency regimes of interest: a statistical energy analysis (SEA) model to capture the high frequency response and a hybrid finite element-statistical energy (hybrid FE-SEA) model for the low to mid-frequency responses. The strengths and limitations of each of the analytical techniques are discussed. The predictions are then compared to the measured acoustic test data and to a boundary element (BEM) model to evaluate the performance of the hybrid techniques.

Larko, Jeffrey M.↗

Titan Saturn System Mission

Titan is a high priority for exploration, as recommended by NASA's 2006 Solar System Exploration (SSE) Roadmap. NASA's 2003 National Research Council (NRC) Decadal Survey and ESA's Cosmic Vision Program Themes. Recent revolutionary Cassini-Huygens discoveries have dramatically escalated interest in Titan as the next scientific target in the outer solar system. This study demonstrates that an exciting Titan Saturn System Mission (TSSM) that explores two worlds of intense astrobiological interest can be initiated now as a single NASA/ESA collaboration.

Titan Saturn System Mission (TSSM)↗

The Space Shuttle as an educational tool

The paper discusses the impact of the Space Transportation System (STS) and the Space Shuttle on the science educational community and gives an overview of past space education programs. Construction of four flight 'Orbiters' (Columbia, Challenger, Discovery, and Atlantis) is being planned, with each Orbiter containing an External Tank (ET) to power the Orbiter's main engines, and two solid rocket boosters (SRB). Each Orbiter can carry a crew of seven, has a cargo bay for 65,000 lb of satellites and scientific equipment, and has an average flight duration of up to 7 days. NASA educational programs reviewed are the Skylab Student Program, the 'Getaway Special' Program, and the Shuttle Student Involvement Project for Secondary Schools (SSIP-S), as well as ESA programs including the Educational Physics Experiments in Spacelab and the Access to Spacelab for Young Europeans Program. A 'Classroom in Space' and 'Space University' have been proposed for the future.

David, L. W.↗

Commercial opportunities in bioseparations and physiological testing aboard Space Station Freedom

The Center for Cell Research (CCR) is a NASA Center for the Commercial Development of Space which has as its main goal encouraging industry-driven biomedical/biotechnology space projects. Space Station Freedom (SSF) will provide long duration, crew-tended microgravity environments which will enhance the opportunities for commercial biomedical/biotechnology projects in bioseparations and physiological testing. The CCR bioseparations program, known as USCEPS (for United States Commercial Electrophoresis Program in Space), is developing access for American industry to continuous-flow electrophoresis aboard SSF. In space, considerable scale-up of continuous free-flow electrophoresis is possible for cells, sub cellular particles, proteins, growth factors, and other biological products. The lack of sedemination and buoyancy-driven convection flow enhances purity of separations and the amount of material processed/time. Through the CCR's physiological testing program, commercial organizations will have access aboard SSF to physiological systems experiments (PSE's); the Penn State Biomodule; and telemicroscopy. Physiological systems experiments involve the use of live animals for pharmaceutical product testing and discovery research. The Penn State Biomodule is a computer-controlled mini lab useful for projects involving live cells or tissues and macro molecular assembly studies, including protein crystallization. Telemicroscopy will enable staff on Earth to manipulate and monitor microscopic specimens on SSF for product development and discovery research or for medical diagnosis of astronaut health problems. Space-based product processing, testing, development, and discovery research using USCEPS and CCR's physiological testing program offer new routes to improved health on Earth. Direct crew involvement-in biomedical/biotechnology projects aboard SSF will enable better experimental outcomes. The current data base shows that there is reason for considerable optimism regarding what the CCDS program and the biomedical/biotechnology industry can expect to gain from a permanent manned presence in space.

Hymer, W. C.↗

Systems Integration, Analysis and Modeling Support to the HEDS Technology/Commercialization Initiative (HTCI)

In response to a recommendation from OMB, NASA's Fiscal Year 2001 budget included a new program within the HEDS (Human Exploration and Development of Space) Enterprise called HEDS Technology/ Commercialization Initiative (HTCI). HTCI had three overarching goals: to support REDS analysis and planning for safe, affordable and effective future programs and projects that advance human exploration, scientific discovery, and the commercial development of space; to pursue research, development, and validation of breakthrough technologies and highly innovative systems concepts; and to advance die creation of strong partnerships within NASA, with U.S. industry and universities, and internationally. As part of its contracted effort, SAIC was to write a report contribution, describing die results of its task activities, to a final HTCI report prepared by MSFC. Unfortunately, government cancellation of the HTCI program in the summer of 2001 curtailed all efforts on the program including die Final HTCI report. In the absence of that report, SAIC has issued this final report in an attempt to document some of the technical material it produced. The report contains SAIC presentations for both HTCI workshops; a set of roadmap charts for the Systems Analysis, Integration and Modeling; and charts showing the evolution of the current TITAN modeling architecture.

Feingold, Harvey↗

STS-60 Space Shuttle mission report

The STS-60 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Redesigned Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the sixtieth flight of the Space Shuttle Program and eighteenth flight of the Orbiter vehicle Discovery (OV-103). In addition to the Orbiter, the flight vehicle consisted of an ET designated at ET-61 (Block 10); three SSME's which were designated as serial numbers 2012, 2034, and 2032 in positions 1, 2, and 3, respectively; and two SRB's which were designated BI-062. The RSRM's that were installed in each SRB were designated as 360L035A (lightweight) for the left SRB, and 360Q035B (quarterweight) for the right SRB. This STS-60 Space Shuttle Program Mission Report fulfills the Space Shuttle Program requirement as documented in NSTS 07700, Volume VIII, Appendix E. That document requires that each major organizational element supporting the Program report the results of its hardware evaluation and mission performance plus identify all related in-flight anomalies. The primary objectives of the STS-60 mission were to deploy and retrieve the Wake Shield Facility-1 (WSF-1), and to activate the Spacehab-2 payload and perform on-orbit experiments. Secondary objectives of this flight were to activate and command the Capillary Pumped Loop/Orbital Debris Radar Calibration Spheres/Breman Satellite Experiment/Getaway Special (GAS) Bridge Assembly (CAPL/ODERACS/BREMSAT/GBA) payload, the Auroral Photography Experiment-B (APE-B), and the Shuttle Amateur Radio Experiment-II (SAREX-II).

Fricke, Robert W., Jr.↗

RHSEG and Subdue: Background and Preliminary Approach for Combining these Technologies for Enhanced Image Data Analysis, Mining and Knowledge Discovery

Under a project recently selected for funding by NASA's Science Mission Directorate under the Applied Information Systems Research (AISR) program, Tilton and Cook will design and implement the integration of the Subdue graph based knowledge discovery system, developed at the University of Texas Arlington and Washington State University, with image segmentation hierarchies produced by the RHSEG software, developed at NASA GSFC, and perform pilot demonstration studies of data analysis, mining and knowledge discovery on NASA data. Subdue represents a method for discovering substructures in structural databases. Subdue is devised for general-purpose automated discovery, concept learning, and hierarchical clustering, with or without domain knowledge. Subdue was developed by Cook and her colleague, Lawrence B. Holder. For Subdue to be effective in finding patterns in imagery data, the data must be abstracted up from the pixel domain. An appropriate abstraction of imagery data is a segmentation hierarchy: a set of several segmentations of the same image at different levels of detail in which the segmentations at coarser levels of detail can be produced from simple merges of regions at finer levels of detail. The RHSEG program, a recursive approximation to a Hierarchical Segmentation approach (HSEG), can produce segmentation hierarchies quickly and effectively for a wide variety of images. RHSEG and HSEG were developed at NASA GSFC by Tilton. In this presentation we provide background on the RHSEG and Subdue technologies and present a preliminary analysis on how RHSEG and Subdue may be combined to enhance image data analysis, mining and knowledge discovery.

Tilton, James C.↗

STS-114: Discovery Flight Day 7 Post MMT Meeting

Wayne Hale Space Shuttle Deputy Program Manager, and Chuck Campbell Subsystem Engineer in Aerothermodynamics are seen in this post mission management teem briefing on this seventh day of space flight. Wayne Hale begins with talking about how the International Space Station has been resupplied with its necessities, and that the Control Moment Gyroscope (CSG) has been replaced. Hale expresses his concern about the health of the Space Shuttle Discovery with the two protruding gap fillers present, and the aerothermodynamics surrounding the gap fillers. These concerns led to the conclusion to have spacewalker Stephen Robinson remove the gap fillers during EVA-3. Campbell shows a video of the protruding gap filler aft of Nose Landing Gear Door (NLGD). Campbell and Hale answer questions from the news media about the risks of performing this spacewalk, boundary layer transitions, flight safety, inspections, and temperature concerns.

Source record↗

STS-114: Discovery Launch Readiness Press Conference

Michael Griffin, NASA Administrator; Wayne Hale, Space Shuttle Deputy Program Manager; Mike Wetmore, Director of Shuttle Processing; and 1st Lieutenant Mindy Chavez, Launch Weather Officer-United States Air Force 45th Weather Squadron are in attendance for this STS-114 Discovery launch readiness press conference. The discussion begins with Wayne Hale bringing to the table a low level sensor device for everyone to view. He talks in detail about all of the extensive tests that were performed on these sensors and the completion of these ambient tests. Chavez presents her weather forecast for the launch day of July 26th 2005. Michael Griffin and Wayne Hale answer questions from the news media pertaining to the sensors and launch readiness. The video ends with footage of Pilot Jim Kelly and Commander Eileen Collins conducting test flights in a Shuttle Training Aircraft (STA) that simulates Space Shuttle landing.

Source record↗