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All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

A Distributed Approach to High-Rate Delay Tolerant Networking Within a Virtualized Environment

The High-Rate Delay Tolerant Networking (HDTN) project has taken a distributed service-based approach to the development of a highly efficient delay tolerant networking (DTN) implementation. Through the analysis of many DTN implementations, system and mission requirements as well as the DTN protocol specifications, HDTN has worked to infuse modern computing technologies into the NASA approach to interplanetary networking. The initial use case of the HDTN software runs on a hypervisor representative of the International Space Station (ISS) DTN Gateway. In this scenario, multiple emulated payloads will send science data through HDTN to a mission operations center. HDTN will provide store and forward capability as well as network flow management. This paper discusses the infusion path of cognitive networking technologies in the NASA SCaN networks using the DTN architecture and protocols as the basis for cognitive routing and network management capabilities. HDTN has been developing the Bundle Protocol encoding and decoding mechanisms and messaging framework that can be used as the basis for integrating DTN with various learning and decision-making processes. The concepts of distributed computing, network virtualization, software defined networking and delay tolerant networking are basic building blocks which will further the development of cognitive networking. In addition to discussion of the HDTN software development and testing, this paper examines the role that each of these technologies play in the evolution of the current state of space networking into an intelligent network of networks.

Delay Tolerant Networking↗
NASA NTRSDate not supplied

A Distributed Approach to High-Rate Delay Tolerant Networking Within a Virtualized Environment

The High-Rate Delay Tolerant Networking (HDTN) project has taken a distributed service-based approach to the development of a highly efficient delay tolerant networking (DTN) implementation. Through the analysis of many DTN implementations, system and mission requirements as well as the DTN protocol specifications, HDTN has worked to infuse modern computing technologies into the NASA approach to interplanetary networking. The initial use case of the HDTN software runs on a hypervisor representative of the International Space Station (ISS) DTN Gateway. In this scenario, multiple emulated payloads will send science data through HDTN to a mission operations center. HDTN will provide store and forward capability as well as network flow management. This paper discusses the infusion path of cognitive networking technologies in the NASA Space Communications and Navigation (SCaN) networks using the DTN architecture and protocols as the basis for cognitive routing and network management capabilities. HDTN has been developing the Bundle Protocol encoding and decoding mechanisms and messaging framework that can be used as the basis for integrating DTN with various learning and decision-making processes. The concepts of distributed computing, network virtualization, software defined networking and delay tolerant networking are basic building blocks which will further the development of cognitive networking. In addition to discussion of the HDTN software development and testing, this paper examines the role that each of these technologies play in the evolution of the current state of space networking into an intelligent network of networks.

Rachel Mary Dudukovich↗
NASA NTRSDate not supplied

Advances in Design Capabilities for Planetary Missions from the NASA Entry Systems Modeling and Instrumentation Portfolio

The Entry Systems Modeling project (ESM) is supported by both the NASA Space Technology and the Science Mission Directorates and focuses on developing simulation tools and validated models for characterizing the performance of entry systems tailored to planetary destinations across the Solar System. ESM is organized into six technical capability areas that together address all relevant factors related to spacecraft entry, as well as some aspects of descent: Thermal Protection System (TPS) Materials; Aerothermodynamics; Entry & Descent Vehicle Dynamics; Guidance, Navigation, and Control; Vehicle Systems Analysis; and Advanced Tools and Numerical Methods. Development within the capability areas is undertaken explicitly with a focus on transition and infusion to science missions, human exploration missions, and commercial space activities. The present talk details developments that specifically impact science missions, including simulation tool capabilities that aid in mission design and model development to understand entry system performance at a given destination. Examples of the successful infusion and transition of such project outcomes to science missions also are provided. Several simulation tool development efforts within ESM have resulted in new design capabilities for missions. One such outcome is improved toolsets for mission trajectory and concept of operations design. Specifically, an initiative to couple a leading tool for entry, ascent/descent, and orbital trajectory optimization (Program to Optimize Simulated Trajectories II or POST2) to those used within the Agency for interplanetary trajectory optimization (Copernicus and Monte) has made substantial progress, with the outcomes to date promising to allow efficient trajectory optimization across mission phases. Additionally, toolchains for the evaluation of vehicle performance during entry and descent have been developed that allow assessment of multi-dimensional aeroheating on detailed vehicle geometries, characterization of deployment and inflation of parachutes, and assessment of vehicle dynamic stability during descent. These capabilities are achieved by coupling diverse sets of physics together – material response, computational fluid dynamics, radiation, and vehicle dynamics – to suitably describe complex entry and descent phenomena. Several model development and validation efforts for specific destinations and entry regimes also are underway within the ESM project. For instance, new experimental capabilities to validate radiation models at low densities/high altitudes recently have been established with project support, specifically the Low-Density Shock Tube (LDST) at the NASA Ames Research Center Electric Arc Shock Tube (EAST) facility. The LDST is being leveraged to develop improved models of shock layer kinetics and radiation in Titan atmospheres, while future studies will be conducted in the LDST and the existing high velocity shock tube to provide validation data for radiation models of Venus, Ice Giants, and Mars atmospheres. Models describing the aerothermal and thermo-structural performance of Thermal Protection System (TPS) materials has been another focus, with multiscale modeling activities on-going for the two leading TPS materials applicable to a range of entry conditions and science missions: the Phenolic-Impregnated Carbon Ablator (PICA) and woven materials like 3D Mid-Density Carbon Phenolic (3MDCP). A continual effort is made to infuse and transition outcomes from ESM simulation tool and model development activities into relevant science missions. Significant progress has been made on this front, with missions such as Dragonfly, DAVINCI, and Mars Missions benefitting from project outcomes. The groundwork also is being laid to provide insights into forward looking missions to Gas/Ice Giants as well as for potential sample returns.

Justin Haskins↗
NASA NTRS1988

Trajectory design for the Comet Rendezvous Asteroid Flyby 1995-1996 opportunities

Recent reprogramming of NASA's Comet Rendezvous Asteroid Flyby (CRAF) mission has motivated an examination of the comet rendezvous opportunities available with launch dates in 1995 and 1996. Various interplanetary transfer modes have been investigated including direct, Delta V-earth-gravity- assist and Venus/earth gravity assist trajectories. Optimal trajectories have been generated and their performance assessed for a spacecraft using a chemical propulsion system and the upgraded Titan/Centaur launch vehicle. Of the viable options available, a new CRAF baseline mission has been selected. One important result of the present study is that while there are comet rendezvous trajectories with launch dates throughout the next decade, 1997 marks the beginning of a hiatus of opportunities with short flight times to the comet targets which promise the greatest potential science return.

Myers, Mark R.↗
NASA NTRS1972

Nonlinear estimation theory applied to orbit determination

The development of an approximate nonlinear filter using the Martingale theory and appropriate smoothing properties is considered. Both the first order and the second order moments were estimated. The filter developed can be classified as a modified Gaussian second order filter. Its performance was evaluated in a simulated study of the problem of estimating the state of an interplanetary space vehicle during both a simulated Jupiter flyby and a simulated Jupiter orbiter mission. In addition to the modified Gaussian second order filter, the modified truncated second order filter was also evaluated in the simulated study. Results obtained with each of these filters were compared with numerical results obtained with the extended Kalman filter and the performance of each filter is determined by comparison with the actual estimation errors. The simulations were designed to determine the effects of the second order terms in the dynamic state relations, the observation state relations, and the Kalman gain compensation term. It is shown that the Kalman gain-compensated filter which includes only the Kalman gain compensation term is superior to all of the other filters.

Choe, C. Y.↗
NASA NTRS1976

Physical processes in comets

The paper discusses physical processes in comets which involve solar and nuclear radial forces that affect the motions of gases and icy grains, gas-phase chemistry very close to the nuclei of large comets near the sun, sublimation of icy grains, dissociation of parent molecules into radicals and of radicals into atoms, and ionization by sunlight and collisions. The composition and dimensions of nuclei are examined along with variations in intrinsic brightness, the nature of volatiles, gas production rates in the coma, characteristics of icy grains in the coma, and the structure of streamers, ion tails, and dust tails. The structure of the coma is described in detail on the basis of spectroscopic observations of several comets. The origin of comets is briefly reviewed together with the relation of comets to earth, the interplanetary complex, and the interstellar medium. Desirable future observations are noted, especially by space missions to comets.

Whipple, F. L.↗
NASA NTRS1978

Optical detection of local interstellar particles during an out-of-ecliptic mission

A proposed NASA/ESA 'out of ecliptic' mission for placing limits on the brightness of the interstellar (IS) relative to the interplanetary (IP) component of zodiacal light is discussed. The brightness integral used to estimate the monochromatic is introduced, and it is explained that, although the interstellar contribution is below the limit of detectability for earth-based measurements, sunwards viewing from a spacecraft located at a distance of 1 AU would be able to detect the IS component. The color difference between the IS and IP components is considered in an analysis of the upper limit of IS component detectability.

Greenberg, J. M.↗
NASA NTRS1980

The Goddard program of gamma ray transient astronomy

Gamma ray burst studies are reviewed. The past results, present status and future expectations are outlined regarding endeavors using experiments on balloons, IMP-6 and -7, OGO-3, ISEE-1 and -3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma ray transient, detected on 1979 March 5.

Cline, T. L.↗
NASA NTRS1981

The Goddard program of gamma-ray transient astronomy

The Goddard program of gamma-ray burst studies is briefly reviewed. The past results, present status and future expectations are outlined regarding our endeavors using experiments on balloons. IMP-6 and IMP-7, OGO-3, ISEE-1 and ISEE-3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma-ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma-ray transient, detected on 5 March, 1979.

Cline, T. L.↗
NASA NTRS1986

The solar radio corona: Manifestations of energetic electrons

Radio observations are powerful tools which are complementary to the space missions devoted to the physics of the flares, of the corona, or of the interplanetary medium. To undertake this task two multifrequency radioheliographs presently exist: the Nancay instrument (the multifrequency facility will be in operation by the end of 1985) observes the middle corona at decimeter-meter wavelengths, and the Clark Lake radioheliograph, operating at decameter wavelengths, is the only one in the world to have the ability of observing the outer corona above the disk.

Pick, M.↗
NASA NTRS1990

Equilibrium radiative heating tables for aerobraking in the Martian atmosphere

Studies currently underway for Mars missions often envision the use of aerobraking for orbital capture at Mars. These missions generally involve blunt-nosed vehicles to dissipate the excess energy of the interplanetary transfer. Radiative heating may be of importance in these blunt-body flows because of the highly energetic shock layer around the blunt nose. In addition, the Martian atmosphere contains CO2, whose dissociation products are known to include strong radiators. An inviscid, equilibrium, stagnation point, radiation-coupled flow-field code has been developed for investigating blunt-body atmospheric entry. The method has been compared with ground-based and flight data for air, and reasonable agreement has been found. In the present work, the method was applied to a matrix of conditions in the Martian atmosphere. These conditions encompass most trajectories of interest for Mars exploration spacecraft. The predicted equilibrium radiative heating to the stagnation point of the vehicle is presented.

Hartung, Lin C.↗
NASA NTRS1990

The scientific mission of Ulysses

The major aims of the Ulysses' scientific investigations of the heliosphere at all latitudes are described. Missions goals include the assessment of the global three-dimensional properties of the interplanetary magnetic field and solar wind, the study of the composition of the solar wind plasma at different heliographic latitudes, and the study of the acceleration of energetic particles in solar flares. Waves, shocks and other discontinuities in the solar wind will be investigated through sampling of various plasma conditions, and interplanetary dust and cosmic rays will be analyzed. Other important goals include the search for gamma-ray-burst sources and for low-frequency gravitational waves by using the spacecraft's radio communication link. Achievement of the Ulysses' solar pole trajectory, which will utilize both launch vehicle thrust and gravitational pull, is also described.

Wenzel, K.-P.↗
NASA NTRS1992

The magnetic field investigation on the Ulysses mission - Instrumentation and preliminary scientific results

A fundamental feature of the heliosphere is the three-dimensional structure of the interplanetary magnetic field. The magnetic field investigation on Ulysses, the first space probe to explore the out-of-ecliptic and polar heliosphere, aims at determining the large-scale features and gradients of the field, as well as the heliolatitude dependence of interplanetary phenomena so far only observed near the ecliptic plane. The Ulysses magnetometer uses two sensors, one a Vector Helium Magnetometer, the other a Fluxgate Magnetometer. Onboard data processing yields measurements of the magnetic field vector with a time resolution up to 2 vectors/second and a sensitivity of about 10 pT. Since the switch-on of the instrument in flight on 25 October 1990, a steady stream of observations has been made, indicating that at this phase of the solar cycle the field is generally disturbed: several shock waves and a large number of discontinuities have been observed, as well as several periods with apparently intense wave activity. The paper gives a brief summary of the scientific objectives of the investigation, followed by a detailed description of the instrument and its characteristics. Examples of wave bursts, interplanetary shocks and crossings of the heliospheric current sheet are given to illustrate the observations made with the instrument.

Balogh, A.↗
NASA NTRS1992

The Ulysses mission - In-ecliptic phase

Coordinated data analyses from the initial in-ecliptic phase of the Ulysses mission are presented with special attention given to measurements of particles and fields in interplanetary space. The collection of papers presents the results of observations of large solar flares and effects related to solar wind, and some results are synopsized. The charged-particle instrumentation on the spacecraft is shown to have good dynamic range and energy coverage as demonstrated by a sample proton-energy spectrum.

Wenzel, K.-P.↗
NASA NTRS1993

Effect of Earth and Mars departure delays on human missions to Mars

This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

Desai, Prasun N.↗
NASA NTRS1995

Effect of Departure Delays on Manned Mars Mission Selection

This study determines the effect on the initial mass in low Earth orbit (IMLEO) of delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep-space maneuver (DSM) is considered in order to alleviate the IMLEO penalties. Three different classes of missions are analyzed, using chemical and nuclear thermal propulsion systems in the 2000-2025 time frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction-class missions have the highest IMLEO penalties, upwards of 432.4 and 1977.3 metric tons (mt), respectively. Conjunction-class missions, on the other hand, tend to be insensitive to Mars and Earth delays, having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties than chemical propulsion. The use of a DSM does not significantly reduce the penalties. The results of this study can enable mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design of a Mars transfer vehicle.

Desai, Prasun N.↗
NASA NTRS2000

The Transition from Spacecraft Development Ot Flight Operation: Human Factor Considerations

In the field of aeronautics and astronautics, a paradigm shift has been witnessed by those in academia, research and development, and private industry. Long development life cycles and the budgets to support such programs and projects has given way to aggressive task schedules and leaner resources to draw from all the while challenging assigned individuals to create and produce improved products of processes. however, this "faster, better, cheaper" concept cannot merely be applied to the design, development, and test of complex systems such as earth-orbiting of interplanetary robotic spacecraft. Full advantage is not possible without due consideration and application to mission operations planning and flight operations, Equally as important as the flight system, the mission operations system consisting of qualified personnel, ground hardware and software tools, and verified and validated operational processes, should also be regarded as a complex system requiring personnel to draw upon formal education, training, related experiences, and heuristic reasoning in engineering an effective and efficient system. Unquestionably, qualified personnel are the most important elements of a mission operations system. This paper examines the experiences of the Deep Space I Project, the first in a series of new technology in-flight validation missions sponsored by the United States National Aeronautics and Space Administration (NASA), specifically, in developing a subsystems analysis and technology validation team comprised of former spacecraft development personnel. Human factor considerations are investigated from initial concept/vision formulation; through operational process development; personnel test and training; to initial uplink product development and test support. Emphasis has been placed on challenges and applied or recommended solutions, so as to provide opportunities for future programs and projects to address and disposition potential issues and concerns as early as possible to reap the benefits associated with learning from other's past experiences.

Basilio, Ralph R.↗