264
264
May 21, 2011
05/11
by
Regler, Hans; Ruede, Ulric
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Finding the optimal position for the individual cells (also called functional modules) on the chip surface is an important and difficult step in the design of integrated circuits. This paper deals with the problem of relative placement, that is the minimization of a quadratic functional with a large, sparse, positive definite system matrix. The basic optimization problem must be augmented by constraints to inhibit solutions where cells overlap. Besides classical iterative methods, based on...
Topics: FRAGMENTATION, MANEUVERABLE SPACECRAFT, SOVIET SPACECRAFT, SPACECRAFT BREAKUP, EXPLOSIVE DEVICES,...
Problem Definition: A simulation that accounts for all the data items affecting the trajectory as the Time of Closest Approach (TCA) nears is needed to improve event characterization.
Topics: NASA Technical Reports Server (NTRS), SIMULATION, TRAJECTORIES, SPACE DEBRIS, PARABOLIC REFLECTORS,...
Since 1963 more than 900 spacecraft and more than 200 launch vehicle upper stages have been inserted into the vicinity of the geosynchronous regime. Equally important, more than 300 spacecraft have been maneuvered into disposal orbits at mission termination to alleviate unnecessary congestion in the finite GEO region. However, the number of GEO satellites continues to grow, and evidence exists of a substantial small debris population. In addition, the operational modes of an increasing number...
Topics: NASA Technical Reports Server (NTRS), GEOSYNCHRONOUS ORBITS, SPACE DEBRIS, HAZARDS, ECCENTRIC...
On 6 Dec. 1991 Kosmos 2163, a maneuverable Soviet spacecraft which had been in orbit for 58 days, experienced a major breakup at an altitude of approximately 210 km. Although numerous pieces of debris were created, the fragments decayed rapidly leaving no long-term impact on the near-Earth environment. The assessed cause of the event is the deliberate detonation of an explosive device. Details of this event are presented.
Topics: NASA Technical Reports Server (NTRS), FRAGMENTATION, MANEUVERABLE SPACECRAFT, SOVIET SPACECRAFT,...
232
232
Jun 9, 2011
06/11
by
Dearden, Richard; Meuleau, Nicholas; Washington, Richard; Feng, Zhengzh
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We describe an approach for exploiting structure in Markov Decision Processes with continuous state variables. At each step of the dynamic programming, the state space is dynamically partitioned into regions where the value function is the same throughout the region. We first describe the algorithm for piecewise constant representations. We then extend it to piecewise linear representations, using techniques from POMDPs to represent and reason about linear surfaces efficiently. We show that for...
Topics: SOFTWARE ENGINEERING, PROGRAM VERIFICATION (COMPUTERS), CHALLENGER (ORBITER), BUILDINGS, SPACECRAFT...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, DMSP SATELLITES, METEOROLOGICAL SATELLITES,...
This viewgraph presentation reviews the debris that is in orbit, and reduction of the orbital debris. Specifically, attention is paid to the reduction of orbital debris from launch vehicle stages after the launch.
Topics: NASA Technical Reports Server (NTRS), LAUNCH VEHICLES, SPACE DEBRIS, SPACECRAFT BREAKUP, SPACECRAFT...
Many satellite breakups occur as a result of an explosion of stored energy on-board spacecraft or rocket-bodies. These breakups generate a cloud of tens or possibly hundreds of thousands of debris fragments which may pose a transient elevated threat to spaceflight crews and vehicles. Satellite breakups pose a unique threat because the majority of the debris fragments are too small to be tracked from the ground. The United States Human Spaceflight Program is currently implementing a risk...
Topics: NASA Technical Reports Server (NTRS), SPACECRAFT BREAKUP, EXPLOSIONS, FRAGMENTS, DEBRIS, RISK,...
In recent years, emphasis has shifted from national efforts to control the space debris population to international ones. Here, too, great progress has been made, most notably by the Inter-Agency Space Debris Coordination Committee (IADC) and the Committee on the Peaceful Uses of Outer Space (COPUOS) of the United Nations. Today, a firm international consensus is rapidly building on the principal space debris mitigation measures. The IADC is an association of the space agencies of ten countries...
Topics: NASA Technical Reports Server (NTRS), INTERNATIONAL COOPERATION, POLICIES, SPACE DEBRIS,...
Recent analyses on the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resource, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of its effectiveness must be...
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, EARTH ORBITAL ENVIRONMENTS, LOW EARTH ORBITS,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, IMPACT DAMAGE, COLLISIONS, SPACECRAFT BREAKUP,...
This presentation reviews the international and NASA interests in Space Situational Awareness (SSA) and space debris as it affects space flight safety. The international interesrt has increased since the collision of the Iridium and Cosmos satellites in 2009. The United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS) has commenced a multi-year effort to review the long-term sustainability of outer space activities.
Topics: NASA Technical Reports Server (NTRS), COLLISIONS, SPACE DEBRIS, NEAR EARTH OBJECTS, INTERNATIONAL...
This bulletin contains articles from the Orbital Debris Program office. This issue's articles are: "Orbital Debris Success Story --A Decade in the Making", "Old and New Satellite Breakups Identified," "Update on Three Major Debris Clouds," and "MMOD Inspection of the HST Bay 5 Multi-Layer Insulation Panel" about micrometeoroid and orbital debris (MMOD) inspection of the Hubble Space Telescope (HST) insulation panel. A project review is also included...
Topics: NASA Technical Reports Server (NTRS), MICROMETEOROIDS, SPACE DEBRIS, NASA PROGRAMS, INSPECTION,...
For public safety reasons, the Compton Gamma Ray Observatory (CGRO) was intentionally deorbited on June 4, 2000. This deorbit was NASA's first intentional controlled deorbit of a satellite, and more will come including the eventual deorbit of the International Space Station. To maximize public safety, satellite deorbit planning requires conservative estimates of the debris footprint size and location. These estimates are needed to properly design a deorbit sequence that places the debris...
Topics: NASA Technical Reports Server (NTRS), SPACECRAFT BREAKUP, SPACECRAFT REENTRY, ESTIMATING, REENTRY...
Analysis of amateur video of the early reentry phases of the Columbia accident is discussed. With poor video quality and little theoretical guidance, the analysis team estimated mass and acceleration ranges for the debris shedding events observed in the video. Camera calibration and optical performance issues are also described.
Topics: NASA Technical Reports Server (NTRS), DEBRIS, IMAGING TECHNIQUES, REENTRY, COLUMBIA (ORBITER),...
No abstract available
Topics: NASA Technical Reports Server (NTRS), MICROMETEOROIDS, SPACE DEBRIS, SHIELDING, RISK ASSESSMENT,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, EARTH ORBITAL ENVIRONMENTS, SPACECRAFT BREAKUP,...
On 1 May 1991, the Nimbus 6 second stage Delta Rocket Body experienced a major breakup at an altitude of approximately 1,100 km. There were numerous pieces left in long-lived orbits, adding to the long-term hazard in this orbital regime already present from previous Delta Rocket Body explosions. The assessed cause of the event is an accidental explosion of the Delta second stage by documented processes experienced by other similar Delta second stages. Various aspects of the event are discussed.
Topics: NASA Technical Reports Server (NTRS), ACCIDENT INVESTIGATION, FRAGMENTATION, NIMBUS 6 SATELLITE,...
Since 1964 at least 56 spacecraft and two launch vehicle upper stages have been deliberately fragmented while in Earth orbit. Many of these events have had no long-lasting effects on the near-Earth space environment, but one represents the most devastating satellite breakup in history that will pose hazards to operational spacecraft in low Earth orbit for decades to come. International space debris mitigation guidelines now call for avoiding the creation of long-lived debris from intentional...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE ENVIRONMENTS, FRAGMENTATION, LAUNCH VEHICLES, EARTH...
No abstract available
Topics: NASA Technical Reports Server (NTRS), LESSONS LEARNED, SPACE FLIGHT, SPACE DEBRIS, INTERNATIONAL...
This issue of the Orbital Debris Quarterly contains articles on the congressional hearing that was held on orbital debris and space traffic; the update received by the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) on the collision of the Iridium 33 and Cosmos 2251 satellites; the micrometeoroid and orbital debris (MMOD) inspection of the Hubble Space Telescope Wide Field Planetary Camera; an analysis of the reentry survivability of the Global Precipitation Measurement...
Topics: NASA Technical Reports Server (NTRS), LOW EARTH ORBITS, MICROMETEOROIDS, SPACE DEBRIS, SPACECRAFT...
As the Space Shuttle Program comes to an end, it is important that the lessons learned from the Columbia accident be captured and understood by those who will be developing future aerospace programs and supporting current programs. Aeromedical lessons learned from the Accident were presented at AsMA in 2005. This Panel will update that information, closeout the lessons learned, provide additional information on the accident and provide suggestions for the future. To set the stage, an overview...
Topics: NASA Technical Reports Server (NTRS), ACCIDENT INVESTIGATION, AEROSPACE MEDICINE, LESSONS LEARNED,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), LOW EARTH ORBITS, SPACE DEBRIS, EARTH ORBITAL ENVIRONMENTS,...
This viewgraph presentation reviews the rationale for disposal of Low Earth Orbit (LEO) satelites and other spacecraft after the operational lifetime for the space craft and launch vehicle stages. It also reviews the National and International Space Debris Mitigation Guidelines, LEO Spacecraft Disposals, and the LEO Launch Vehicle Stage Disposals. Several examples of space craft disposals or passivation are given.
Topics: NASA Technical Reports Server (NTRS), DISPOSAL, LOW EARTH ORBITS, SPACE DEBRIS, SPACECRAFT BREAKUP,...
The purpose of this project is to provide a process for loan of Columbia debris to qualified researchers and technical educators to: (1) Aid in advanced spacecraft design and flight safety development (2) Advance the study of hypersonic re-entry to enhance ground safety. (3) Train and instruct accident investigators and (4) Establish an enduring legacy for Space Shuttle Columbia and her crew.
Topics: NASA Technical Reports Server (NTRS), DEBRIS, SPACECRAFT DESIGN, SPACECRAFT BREAKUP, COLUMBIA...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, SPACE FLIGHT, EARTH ORBITAL ENVIRONMENTS, LOW...
There is a need for more faithful simulation of space debris impacts on various space vehicles. Space debris impact velocities can range up to 14 km/sec and conventional two-stage light gas guns with moderately heavy saboted projectiles are limited to launch velocities of 7-8 km/sec. Any increases obtained in the launch velocities will result in more faithful simulations of debris impacts. It would also be valuable to reduce the maximum gun and projectile base pressures and the gun barrel...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, SPACE DEBRIS, PROJECTILES, IMPACT...
Orbital debris scientists from major international space agencies, including JAXA and NASA, have worked together to predict the trend of the future environment. A summary presentation was given to the United Nations in February 2013. The orbital debris population in LEO will continue to increase. Catastrophic collisions will continue to occur every 5 to 9 years center dot To limit the growth of the future debris population and to better protect future spacecraft, active debris removal, should...
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, LOW EARTH ORBITS, EARTH ORBITAL ENVIRONMENTS,...
Orbital debris is any man-made object in orbit about the Earth that no longer serves a useful purpose
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, SPACECRAFT BREAKUP, MATHEMATICAL MODELS, EARTH...
The Compton Gamma Ray Observatory (CGRO) controlled re-entry operation was successfully conducted in June of 2000. The surviving parts of the spacecraft landed in the Pacific Ocean within the nominal impact target zone. The design of the maneuvers to control the trajectory to accomplish this re-entry presented several challenges. These challenges included the timing and duration of the maneuvers, propellant management, post-maneuver state determination, collision avoidance with other...
Topics: NASA Technical Reports Server (NTRS), REENTRY TRAJECTORIES, TRAJECTORY CONTROL, SPACECRAFT...
279
279
Sep 20, 2010
09/10
by
Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Taylor, Peter R
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The bond dissociation energies (D sub e) of C2H2, C2H4, C2H6, N2, N2H2, and N2H4 are studied at various levels of correlation treatment. The convergence of D sub e with respect to the one particle basis is studied at the single reference modified coupled-pair functional (MCPF) level. At all levels of correlation treatment, the errors in the bond dissociation energies increase with the degree of multiple bond character. The multireference configuration interaction (MRCI) D sub e values,...
Topics: CLEANING, MODULES, PARKING ORBITS, POSITION (LOCATION), REFUELING, SPACE SHUTTLES, SPACECRAFT...
This slide presentation reviews the surviability and vulnerability of the International Space Station (ISS) from the threat posed by meteoroid and orbital debris. The topics include: (1) Space station natural and induced environments (2) Meteoroid and orbital debris threat definition (3) Requirement definition (4) Assessment methods (5) Shield development and (6) Component vulnerability
Topics: NASA Technical Reports Server (NTRS), INTERNATIONAL SPACE STATION, METEOROID HAZARDS,...
To replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoD and NASA breakup models: DebriSat is intended to be representative of modern LEO satellites. Major design decisions were reviewed and approved by Aerospace subject matter experts from different disciplines. DebriSat includes 7 major subsystems. Attitude determination and control system (ADCS), command and data handling (C&DH), electrical...
Topics: NASA Technical Reports Server (NTRS), HYPERVELOCITY IMPACT, SPACE DEBRIS, FRAGMENTATION, IMPACT...
This slide presentation reviews the requirement and issues around removal of debris from the earth orbital environment. The 10 questions discussed are: 1. Which region (LEO/MEO/GEO) has the fastest projected growth rate and the highest collision activities? 2. Can the commonly-adopted mitigation measures stabilize the future environment? 3. What are the objectives of active debris removal (ADR)? 4. How can effective ADR target selection criteria to stabilize the future LEO environment be...
Topics: NASA Technical Reports Server (NTRS), EARTH ORBITAL ENVIRONMENTS, SPACE DEBRIS, REMOVAL, LOW EARTH...
Of the 4 recent major breakup events, the FY-1C ASAT test and the collision between Iridium 33 and Cosmos 2251 generated the most long-term impact to the environment. About half of the fragments will still remain in orbit at least 20 years after the breakup. The A/M distribution of the Cosmos 2251 fragments is well-described by the NASA Breakup Model. Satellites made of modern materials (such as Iridium 33), equipped with large solar panels, or covered with large MLI layers (such as FY-1C) may...
Topics: NASA Technical Reports Server (NTRS), COLLISIONS, LOW EARTH ORBITS, SPACECRAFT BREAKUP, DEBRIS,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, REMOVAL, DISPOSAL, LOW EARTH ORBITS, EARTH...
This viewgraph presentation gives an overview of the investigation into the breakup of the Space Shuttle Columbia, and addresses the importance of a failure analysis strategy for the investigation of the Columbia accident. The main focus of the presentation is on the usefulness of electron microscopy for analyzing slag deposits from the tiles and reinforced carbon-carbon (RCC) wing panels of the Columbia orbiter.
Topics: NASA Technical Reports Server (NTRS), ELECTRON MICROSCOPY, COLUMBIA (ORBITER), SPACECRAFT BREAKUP,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, MATHEMATICAL MODELS, EARTH ORBITAL...
Since the dawn of the Space Age more than 50 years ago, humans have been launching objects into the space environment faster than they have been removed by active means or natural decay. This has led to a proliferation of debris -- derelict satellites, discarded rocket upper stages, and pieces from satellite breakups -- in Earth orbit, especially in well-used orbital regimes. This talk will summarize the current knowledge of the debris environment and describe plans to address the challenges...
Topics: NASA Technical Reports Server (NTRS), EARTH ORBITS, SHIELDING, SPACE DEBRIS, REMOVAL, DISPOSAL,...
The passivation of spacecraft and launch vehicle orbital stages at end-of-mission has been a principal space debris mitigation measure world-wide since the 1980 s. Space vehicle passivation includes the removal of stored energies, especially those associated with propulsion and electrical power systems. Prior to 2007 the breakup of non-functioning, non-passivated space vehicles was the major source of hazardous debris in Earth orbit. The United Nations and the Inter-Agency Space Debris...
Topics: NASA Technical Reports Server (NTRS), PASSIVITY, SPACECRAFT BREAKUP, SPACE DEBRIS, LOW EARTH...
Although differences exist between building software systems and building physical structures such as bridges and rockets, enough similarities exist that software engineers can learn lessons from failures in traditional engineering disciplines. This paper draws lessons from two well-known failures the collapse of the Tacoma Narrows Bridge in 1940 and the destruction of the space shuttle Challenger in 1986 and applies these lessons to software system development. The following specific...
Topics: NASA Technical Reports Server (NTRS), SOFTWARE ENGINEERING, PROGRAM VERIFICATION (COMPUTERS),...
The beginning of the year 2013 marks the sixth anniversary of the destruction of the Fengyun-1C (FY-1C) weather satellite as the result of an anti-satellite test conducted by China in January 2007 and the fourth anniversary of the accidental collision between Cosmos 2251 and the operational Iridium 33 in February 2009. These two events represent the worst satellite breakups in history. A total of 5579 fragments have been cataloged by the U.S. Space Surveillance Network (SSN), and almost 5000 of...
Topics: NASA Technical Reports Server (NTRS), SPACECRAFT BREAKUP, CATALOGS (PUBLICATIONS), COLLISIONS,...
The collision between Iridium 33 and Cosmos 2251 in 2009 signaled the potential onset of the collision cascade effect, commonly known as the "Kessler Syndrome", in the low Earth orbit (LEO) region. Recent numerical simulations have shown that the 10 cm and larger debris population in LEO will continue to increase even with a good implementation of the commonly-adopted mitigation measures. This increase is driven by collisions involving large and massive intacts, i.e., rocket bodies...
Topics: NASA Technical Reports Server (NTRS), LOW EARTH ORBITS, RISK, SPACE DEBRIS, SPACECRAFT BREAKUP,...
Since the first serious satellite fragmentation occurred in Jun. 1961, and instantaneously increased the total Earth satellite population by more than 400 percent, the issue of space operations within the finite region of space around the Earth has been the subject of increasing interest and concern. The prolific satellite fragmentations of the 1970's and the marked increase in the number of fragmentations in the 1980's served to widen international research into the characteristics and...
Topics: NASA Technical Reports Server (NTRS), ARTIFICIAL SATELLITES, EARTH ORBITAL ENVIRONMENTS, EARTH...
The Compton Gamma Ray Observatory (CGRO) controlled re-entry operation was successfully conducted in June of 2000. The surviving parts of the spacecraft landed in the Pacific Ocean within the predicted footprint. The design of the maneuvers to control the trajectory to accomplish this re-entry presented several challenges. These challenges included timing and duration of the maneuvers, fuel management, post maneuver position knowledge, collision avoidance with other spacecraft, accounting for...
Topics: NASA Technical Reports Server (NTRS), GAMMA RAY OBSERVATORY, REENTRY TRAJECTORIES, SPACECRAFT...
Collision with orbital debris is a hazard of growing concern as historically accepted practices and procedures have allowed man-made objects to accumulate in orbit. To limit future debris generation, NASA Management Instruction (NMI) 1700.8, 'Policy to Limit Orbital Debris Generation,' was issued in April of 1993. The NMI requires each program to conduct a formal assessment of the potential to generate orbital debris. This document serves as a companion to NMI 1700.08 and provides each NASA...
Topics: NASA Technical Reports Server (NTRS), SPACE DEBRIS, SAFETY, COLLISIONS, LOW EARTH ORBITS, RISK,...
This slide presentation reviews the modeling activities for modeling of the long-term debris environment, the updated assessments of the environment, and the necessity to model the effectiveness of the technologies aimed at the removal of orbital debris. The model being used is named a LEO to GEO environment debris (LEGEND). It is a high fidelity three dimensional numerical simulation model with the capability to treat objects individually. It uses a Monte Carlo approach and a collision...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, EARTH ORBITAL ENVIRONMENTS, SPACE DEBRIS, THREE...
No abstract available
Topics: NASA Technical Reports Server (NTRS), ACCIDENT INVESTIGATION, LESSONS LEARNED, COLUMBIA (ORBITER),...
This paper presents the aeromedical lessons learned from the Space Shuttle Columbia Accident Investigation. The contents include: 1) Introduction and Mission Response Team (MRT); 2) Primary Disaster Field Office (DFO); 3) Mishap Investigation Team (MIT); 4) Kennedy Space Center (KSC) Mishap Response Plan; 5) Armed Forces Institute of Pathology (AFIP); and 6) STS-107 Crew Surgeon.
Topics: NASA Technical Reports Server (NTRS), ACCIDENT INVESTIGATION, AEROSPACE MEDICINE, LESSONS LEARNED,...
Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, SPACE DEBRIS, EARTH ORBITAL...
