NASA's International Research Articles

Physics of a Spinning Object Cyclic Inversion at an Orbital Flight

The opening up of space flights is going on with physical discoveries. One of them was a spinning object cyclic inversion revealed on the MIR space station classified in 1985. Later, the NASA International Space Station openly showed the same effect. This physical effect was an object of stare studying by physicists and mathematicians. They developed only approximated and numerical models on the level of assumptions. The inversion of the spinning objects in the condition of free flight is the subject of gyroscope theory. The mass of the spinning object at the orbital flight generates the system of the interrelated inertial torques that results from the action of the inertial torques produced by the curvilinear motion of the object around the earth. This system of the torques acting on the spinning object at an orbital flight manifests its cyclic inversions, which is the gyroscopic effects. The theory of the gyroscopic effects describes the method of application of the system of the inertial torques, the physics of all gyroscopic effects that manifested by any rotating objects under any condition of their motions.

Bidirectional DC-DC Converter Systems: Sustaining Power Component Design Methodology to Achieve Critical Power Conditioning

Converting interchangeable loads and sources on committed power interconnect is becoming more commonplace in the art of switch-mode power design. Simple, robust schemes have ended up serving in strategically important applications such as those in the dc bus system of NASA's International Space Station and in the more familiar world of automotive hybrid electric vehicles [1], [2]. As more diverse sources of energy lend themselves to economical and efficient conversion into electricity, the need to streamline the delivery of electrical power from one dc potential to another becomes more apparent. Switched-mode power conversion is a well-established means of achieving high-efficiency dc regulation. It has been found that making adaptations to a proprietary switched-mode resonant topology results in the achievement of a reliable, high-performance bidirectional converter (BDC). The flexibility BDCs offer in numerous applications brings significant economic and operational outcomes.

Waypoints for Evaluating Big Science*

AbstractAs illustrated by the articles in this volume, there are considerable gaps in the measurement of research productivity/innovation for programs enabled by large initial and ongoing infrastructure investments. Such programs include NASA's International Space Station, DOE's National Ignition Facility, NSF's Polar Program, and CERN's Large Hadron Collider. The enormous sums spent on these projects are often justified by predictions about their contributions to knowledge, the economy, or innovation. But at virtually any point in the lifecycle of a Big Science program, it is not easy to explain to the public, elected officials, and scientists whose proposals were rejected why the program is a compelling investment, given that all of the aforementioned benefits will emerge only over time—if at all.

The RapidScat Ocean Winds Scatterometer: A Radar System Engineering Perspective

The NASA International Space Station (ISS)-RapidScat scatterometer operated on board the ISS from October 2014 into August 2016. It was developed using a combination of new subsystems and spare SeaWinds scatterometer engineering model subsystems to interface with the ISS. Using commercial (nonflight-qualified) parts in the new assemblies, developing RapidScat required a relatively small budget and short time schedule (just over two years). This article describes RapidScat's development from the perspective of radar system engineering, particularly in relation to performance requirements and testing.

Applying social network analysis to validate mass collaboration innovation drivers: An empirical study of NASA's International Space Apps Challenge

The authors model the user innovation networks of NASA's International Space Apps Challenges and use social network analysis to empirically investigate the existence and impact of three drivers of innovation. These drivers are competition, social interaction, and network vitality. We empirically prove that competitive intensity exists as a driver of innovation in our networks, and is an indicator of innovation success, while the drivers of social interaction intensity and network vitality do not.

The influence of social movements on space astronomy policy: The cases of “Hubble Huggers”, JWST's “Science Warriors” and the ISEE-3 “Reboot Team”

Public engagement (PE) initiatives can lead to a long term public support of science. However most of the real impact of PE initiatives within the context of long-term science policy is not completely understood. An examination of the National Aeronautics and Space Administration's (NASA) and European Space Agency's (ESA) Hubble Space Telescope, James Webb Space Telescope, and NASA's International Sun/Earth Explorer 3 reveal how large grassroots movements led by citizen scientists and space aficionados can have profound effects on public policy. We explore the role and relevance of public grassroots movements in the policy of space astronomy initiatives, present some recent cases which illustrate policy decisions involving broader interest groups, and consider new avenues of PE including crowdfunding and crowdsourcing.

Atmospheric Electric Propulsion Mission Performance Tool

The amount of available propellant limits low-Earth orbit satellite lifetime due to the necessity of drag makeup. An electric propulsion device that uses in situ ions as propellants is considered as an alternative method for satellite drag makeup. This work presents a tool that consists of a one-dimensional thruster mathematical model integrated with the NASA International Reference Ionosphere to provide ion and neutral species densities for an electrostatic electric propulsion approach. This mathematical model predicts thrust, drag, and thruster power. The thrust-to-drag ratio and thruster power are averaged over the entire mission duration of one year and compared with various circular orbits and satellite configurations: 300–1000 km orbit altitude, 0–60 deg orbit inclination, low to high solar activity, satellite frontal area, 1–10 kV acceleration voltage, and total grid area. The Satellite Tool Kit provides orbit propagation. An average thrust-to-drag ratio greater than one is achievable for many thruster and orbit configurations considered in this analysis, at power levels less than 90 W. Most satellite missions at altitudes of less than 400 km may fall into the region in which the thrust-to-drag ratio is less than one. Thrust-to-drag ratio values of less than one will still benefit satellites by extending mission lifetimes for months or years with average power requirements less than 100 W.

Using Social Network Analysis to Investigate the Potential of Innovation Networks: Lessons Learned from NASA's International Space Apps Challenge

This research analyzes the affiliated multipartite social networks of hackathon style mass collaboration events. Using social network analysis we model the innovation networks for NASA's International Space Apps Challenge and use social network analysis to understand the structure of and relationships within the modeled networks. Using metrics such as degree, degree distribution, degree correlations, and density, the resulting models and study answer questions like: can social network statistics act as indicators of innovation performance within a network and which statistics provide insight to the likelihood of innovation performance? We address these research questions by building the affiliation networks for the 2012 and 2013 NASA International Space Apps Challenges and applying Gnyawali and Srivastava's conceptual model on cluster and network effects against these real-world networks to empirically prove the likelihood of innovation.

The Glacier and Land Ice Surface Topography Interferometer: An Airborne Proof-of-Concept Demonstration of High-Precision Ka-Band Single-Pass Elevation Mapping

As part of the NASA International Polar Year activities, a Ka-band cross-track interferometric synthetic aperture radar (SAR) recently demonstrated high-precision elevation swath mapping capability. This proof-of-concept instrument was achieved by interfacing two Ka-band slotted-waveguide antennas in a cross-track geometry and Ka-band electronics with the Jet Propulsion Laboratory's L-band uninhabited aerial vehicle SAR. Deployed on the NASA Gulfstream III, initial engineering flights in March and April 2009 marked the first airborne demonstration of single-pass cross-track interferometry at Ka-band. Results of a preliminary interferometric assessment indicate height precisions that, for a 3 m × 3 m posting, range from 30 cm in the near range to 3 m in the far range and greater than 5 km of swath over the urban areas imaged. The engineering flights were followed by a comprehensive campaign to Greenland in May 2009 for ice-surface topography mapping assessment. Toward that end, coordinated flights with the NASA Wallops Airborne Topographic Mapper lidar were conducted in addition to establishing ground calibration sites at both the Summit Station of the National Science Foundation and the Swiss Camp of the Cooperative Institute for Research in the Environmental Sciences. Comparisons of the radar-derived elevation measurements with both in situ and lidar data are planned for a subsequent paper; however, at this stage, a single data example over rugged ice cover produced a swath up to 7 km with the desired height precision as estimated from interferometric correlation data. While a systematic calibration, including assessment and modeling of biases, due to penetration of the electromagnetic waves into the snow cover has not yet been addressed, these initial results indicate that we will exceed our system requirements.

New technology innovations with potential for space applications

Human exploration and development of space is being pursued by spacefaring nations to explore, use, and enable the development of space and expand the human experience there. The goals include: increasing human knowledge of nature's processes using the space environment; exploring and settling the solar system; achieving routine space travel; and enriching life on Earth through living and working in space. A crucial aspect of future space missions is the development of infrastructure to optimize safety, productivity, and costs. A major component of mission execution is operations management. NASA's International Space Station is providing extensive experience in both infrastructure and operations. In view of this, a vigorously organized approach is needed to implement successful space-, planet-, and ground-based research and operations that entails wise and efficient use of technical and human resources.Many revolutionary technologies being pursued by researchers and technologists may be vital in making space missions safe, reliable, cost-effective, and productive. These include: ionic polymer–metal composite technology; solid-state lasers; time-domain sensors and communication systems; high-temperature superconductivity; nanotechnology; variable specific impulse magneto plasma rocket; fuzzy logic; wavelet technology; and neural networks. An overview of some of these will be presented, along with their application to space missions.

7.3.2 Measurements for the Safety and Mission Assurance of the International Space Station

AbstractEffective and efficient programmatic decisions are required throughout the design, development, and operation of the International Space Station (ISS), which involves sixteen countries, over one million pounds of flight hardware, and an on‐orbit assembly process spanning six years. Paramount to the success of the ISS, are the safety and mission assurance (S&MA) aspects of the program. Various S&MA products, such as critical items (CILs), safety nonconformances, and problem reports, all provide an individual assessment of the program's risk throughout the design, development, and operation phases of the ISS life cycle. However, until recently, no method existed for measuring the overall S&MA risk of NASA programs. The NASA International Space Station Program's Safety and Mission Assurance/Program Risk Office (S&MA/PR) has developed such a metric.

4.1.4 System Engineering in an Integrated Product Team Organization

AbstractThis paper presents a discussion of the functions of a system engineering organization in an integrated product team (IPT) setting. IPTs are being adapted widely as a more efficient means for accomplishing large product developments. Recent examples include the US Air Force F‐22 fighter program. Additionally, when management difficulties plagued NASA's Space Station Freedom program, NASA responded by implementing an IPT management structure for the program.A brief review of classical system engineering functions as described by government and academic texts and a resultant synopsis are followed by a brief review of the IPT organizational schema. Subsequent discussion presents a paradigm for system engineering within an IPT setting, and describes the similarity in function of the analysis and integration teams (AITs) within an IPT versus classical systems engineering functions. A conclusion is supported that by controlling the scope of the system engineering task, the function of AITs is comparable to that of classical system engineering organizations. Finally, system engineering within NASA's International Space Station Alpha (ISSA) program is presented as example of a system engineering application within an IPT setting.

Auroral x-ray imaging from high- and low-Earth orbit

Observations of bremsstrahlung x rays emitted by energetic electrons impacting the Earth's atmosphere can be used for remotely sensing the morphology, intensity, and energy spectra of electron precipitation from the magnetosphere. The utility of the technique is derived from the broad energy range of observable x rays (2 to > 100 KeV), the simple emission process, the large x-ray mean free path in the atmosphere, and negligible background. Two auroral x-ray imagers, developed for future spaceflights, are discussed. The Polar Ionospheric X-Ray Imaging Experiment is scheduled for launch on the NASA International Solar-Terrestrial Physics/Global Geospace Science program POLAR satellite in 1994. The POLAR orbit, with an apogee and perigee of 9 and 1.8 R[sub e] (Earth radii), respectively, affords the opportunity to image the aurora from a high altitude above the north pole continuously for several hours. The Magnetospheric Atmospheric X-Ray Imaging Experiment (MAXIE) was launched aboard the NOAA-I satellite on August 8, 1993. The 800-km polar orbit passes over both the northern and southern auroral zones every 101 min. MAXIE will be capable of obtaining multiple images of the same auroral region during a single satellite orbit. The experimental approaches used to exploit these very different orbits for remotemore » sensing of the Earth's auroral zones are emphasized.« less

Satellite observations and instrumentation for measuring energetic neutral atoms

Direct measurements of energetic neutral atoms (ENA) and ions have been obtained with the cooled solid state detectors on the low-altitude (220 km) three-axis stabilized S81-1/ stimulated emissions of energetic particles (SEEP) satellite and on the spinning 400 km x 5.5 <i>Re</i> (where <i>Re</i> is Earth radii) Combined Release and Radiation Effects Satellite (CRRES). During magnetic storms ENA and ion precipitation (<i>E</i>>10 keV) are evident over the low-altitude equatorial region based on data from the SEEP (ONR 804) spectrometers and CRRES ion mass spectrometer (IMS-HI) (ONR 307-8-3) ion composition and ENA instrument. The MS-HI neutral atom spectrometer covers the energy range from 20 to 1500 keV with a geometrical factor of 10^-3 cm² sr and uses a 7-kG magnetic field to screen out protons less than about 50 MeV. During the strong magnetic storm of 24 March 1991 the first ENA and ion mass composition measurements were obtained of ring current partides below the inner belt and these fluxes are compared to the MS-HI flux measurements in the ring current. Recently, an advanced spectrometer, the Source/Loss-cone Energetic Particle Spectrometer (SEPS), has been developed to image electrons, ions, and neutrals on the despun platform of the POLAR satellite (~1.8 x 9 <i>Re</i>) for launch in the mid 1990s as part of NASA's International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program. To improve particle imaging by increasing sensor spatial resolution and sensitive area, a 256-element solid state pixel array having 6.25 cm² area has been developed for SEPS along with three new low-power application-specific integrated circuit (ASIC) microcircuits.