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The rapid growth of China's national resources in the space domain may change the gap in power between China and the United States in relevant international rulemaking. This article proposes an analytical framework for identifying, comparing, and analyzing states' power resources critical to international rulemaking and uses the framework to compare the relevant resources between China and the United States in the space domain. First, this paper develops a method for identifying resources crucial to international rulemaking in outer space. The relevant resources of the two countries are then compared in this article. Finally, the article explores comparative advantages, consensus, differences, and cooperation possibilities of the two countries in specific international space rules. The framework could be adapted to compare diverse nations' resources critical to international rulemaking in other fields; it contributes to research on space law, international legislation, and national power. [ABSTRACT FROM AUTHOR]

• An ensemble of spectro-temporal and spectro-spatial predictions for Landsat SR was proposed. • The proposed method has higher accuracy than traditional Landsat SR prediction algorithms. • The proposed method could accurately restore SR for areas with abrupt land cover changes. The cloud-induced contaminations limit the availability of Earth observation data acquired by Landsat satellites. In the field of cloud-contaminated image prediction and restoration, abrupt land cover change is an important but usually unconsidered issue. Based on the existing Time Series Models and Continuous Change Detection algorithm (TSM-CCD), an enhanced TSM-CCD algorithm (eTSM-CCD) is proposed in this paper to improve Landsat surface reflectance (SR) predictions based on all available Landsat data. The proposed eTSM-CCD method integrates time-series model estimation in the temporal domain and similar pixel replacement in the spatial domain to both address the issue of abrupt land cover changes and improve the prediction accuracy of SR. The proposed method was applied to Landsat time-series data in two study areas in the United States. The results indicated that the proposed method achieved higher overall and band-wise (especially NIR band) prediction accuracies than the original TSM-CCD algorithm. Specifically, the accuracies were improved more significantly for land cover types with distinct phenological characteristics at the peak of the growing season. In addition, compared to classical spatiotemporal prediction algorithms, such as modified neighborhood similar pixel interpolator (MNSPI) and enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM), the proposed method also yielded higher prediction accuracies and performed much better in predicting abrupt changes in land cover. The eTSM-CCD algorithm proposed in this paper is promising for the prediction and restoration of surface reflectance, especially in the vegetated areas during the peak of the growing season or in areas undergoing abrupt land cover changes. [ABSTRACT FROM AUTHOR]

In recent years, with the continuous development of Global Navigation Satellite System (GNSS), it has been applied not only to navigation and positioning, but also to Earth surface environment monitoring. At present, when performing GNSS-IR (GNSS Interferometric Reflectometry) snow depth inversion, Lomb-Scargle Periodogram (LSP) spectrum analysis is mainly used to calculate the vertical height from the antenna phase center to the reflection surface. However, it has the problem of low identification of power spectrum analysis, which may lead to frequency leakage. Therefore, Fast Fourier Transform (FFT) spectrum analysis and Nonlinear Least Square Fitting (NLSF) are introduced to calculate the vertical height in this paper. The GNSS-IR snow depth inversion experiment is carried out by using the observation data of P351 station in PBO (Plate Boundary Observatory) network of the United States from 2013 to 2016. Three algorithms are used to invert the snow depth and compared with the actual snow depth provided by the station 490 in the SNOTEL network. The observations data of L1 and L2 bands are respectively used to find the optimal combination between different algorithms further to improve the accuracy of GNSS-IR snow depth inversion. For L1 band, different snow depths correspond to different optimal algorithms. When the snow depth is less than 0.8 m, the inversion accuracy of NLSF algorithm is the highest. When the snow depth is greater than 0.8 m, the inversion accuracy of FFT algorithm is higher. Therefore, according to the different snow depth, a combined algorithm of NLSF + FFT is proposed for GNSS-IR snow depth inversion. Compared with the traditional LSP algorithm, the inversion accuracy of the combined algorithm is improved by 10%. For L2 band data, the results show that the accuracy of snow depth inversion of various algorithms do not change with the variations of snow depth. Among the three single algorithms, the inversion accuracy of FFT algorithm is better than that of LSP and NLSF algorithms. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this paper is to introduce a new deployable mast design that may provide a means to scale up solar sails to very large dimensions. The paper describes the basic analytical approach for truss beams, compares this new design with the state-of-art truss used in NASA’s solar sail development work, and provides analyses of novel applications enabled by the mast design. [Copyright &y& Elsevier]

Abstract: This paper compares two different approaches to calculate the average cross-sectional area of breakup fragments. The first one is described in the NASA standard breakup model 1998 revision. This approach visually classifies fragments into several shapes, and then applies formulae developed for each shape to calculate the average cross-sectional area. The second approach was developed jointly by the Kyushu University and the NASA Orbital Debris Program Office. This new approach automatically classifies fragments into plate- or irregular-shapes based on their aspect ratio and thickness, and then applies formulae developed for each shape to calculate the average cross-sectional area. The comparison between the two approaches is demonstrated in the area-to-mass ratio (A/m) distribution of fragments from two microsatellite impact experiments completed in early 2008. A major difference between the two approaches comes from the calculation of the average cross-sectional area of plates. In order to determine which of the two approaches provides a better description of the actual A/m distribution of breakup fragments, a theoretical analysis in the calculation of the average cross-sectional area of an ideal plate is conducted. This paper also investigates the average cross-sectional area of multi-layer insulation fragments. The average cross-sectional area of 214 multi-layer insulation fragments was measured by a planimeter, and then the data were used to benchmark the average cross-sectional areas estimated by the two approaches. The uncertainty in the calculation of the average cross-sectional area with the two approaches is also discussed in terms of size and thickness. [Copyright &y& Elsevier]

Abstract: This paper summarizes three micro-satellite impact tests completed in early 2007 through collaboration between Kyushu University and the NASA Orbital Debris Program Office. The previous experiments completed in late 2005 aimed to compare low- and hypervelocity impacts on identical target micro-satellites, whereas the new tests used larger micro-satellites as targets and aimed to investigate the effects of impact directions. Three identical micro-satellites equipped with fully functional electronic devices were prepared as targets. Their dimensions were 20cm by 20cm by 20cm, and the mass of each was approximately 1.3kg. Aluminum alloy solid spheres, with a diameter of 3cm and a mass of 39g, were prepared as projectiles. The impact velocity was approximately 1.7km/s. The impact tests were carried out using the two-stage light gas gun at the Kyushu Institute of Technology. All target micro-satellites were completely fragmented, but there were noticeable differences among the three sets of fragments due to the different impact directions. More than 1000 fragments from each test were collected, measured, photographed, and documented with material descriptions. Preliminary results of the new data and comparisons with the previous data will be presented in the paper. [Copyright &y& Elsevier]

Abstract: The NASA Orbital Debris Engineering Model, ORDEM2000, is in the process of being updated to a new version: ORDEM2008. The data-driven ORDEM covers a spectrum of object size from 10μm to greater than 1m, and ranging from LEO (low Earth orbit) to GEO (geosynchronous orbit) altitude regimes. ORDEM2008 centimeter-sized populations are statistically derived from Haystack and HAX (the Haystack Auxiliary) radar data, while micron-sized populations are estimated from shuttle impact records. Each of the model populations consists of a large number of orbits with specified orbital elements, the number of objects on each orbit (with corresponding uncertainty), and the size, type, and material assignment for each object. This paper describes the general methodology and procedure commonly used in the statistical inference of the ORDEM2008 LEO debris populations. Major steps in the population derivations include data analysis, reference-population construction, definition of model parameters in terms of reference populations, linking model parameters with data, seeking best estimates for the model parameters, uncertainty analysis, and assessment of the outcomes. To demonstrate the population-derivation process and to validate the Bayesian statistical model applied in the population derivations throughout, this paper uses illustrative examples for the special cases of large-size (>1m, >32cm, and >10cm) populations that are tracked by SSN (the Space Surveillance Network) and also monitored by Haystack and HAX radars operating in a staring mode. [Copyright &y& Elsevier]

Abstract: This paper summarizes two new satellite impact experiments. The objective of the experiments was to investigate the outcome of low- and hyper-velocity impacts on two identical target satellites. The first experiment was performed at a low-velocity of 1.5km/s using a 40-g aluminum alloy sphere. The second experiment was performed at a hyper-velocity of 4.4km/s using a 4-g aluminum alloy sphere. The target satellites were 15cm×15cm×15cm in size and 800g in mass. The ratios of impact energy to target mass for the two experiments were approximately the same. The target satellites were completely fragmented in both experiments, although there were some differences in the characteristics of the fragments. The projectile of the low-velocity impact experiment was partially fragmented while the projectile of the hyper-velocity impact experiment was completely fragmented beyond recognition. To date, approximately 1500 fragments from each impact experiment have been collected for detailed analysis. Each piece has been weighed, measured, and analyzed based on the analytic method used in the NASA Standard Breakup Model (2000 revision). These fragments account for about 95% of the target mass for both impact experiments. Preliminary analysis results will be presented in this paper. [Copyright &y& Elsevier]

This paper discusses many aspects of “casualty expectation”, defined as the expected number of people suffering death or injury due to a spacecraft entry event, normally used when planning the end-of-life disposal of satellites. United States guidelines state a disposal via atmospheric entry should be controlled rather than uncontrolled whenever casualty expectation estimates exceed a specified limit. Since this guideline can have serious impacts on the cost, lifetime, and even the mission and functionality of a satellite, it is critical that casualty expectation (Ec) be estimated well, and decision-makers understand all assumptions and limitations inherent in the result. This paper begins with an overview of relevant United States guidelines. The equation the space industry typically uses to estimate Ec is presented, along with its sensitivity to typical assumptions, models, and initial condition uncertainties. An alternate quantity is introduced, called “probability of casualty”, or Pc. Two examples are given of both Ec and Pc estimations. Because Ec and Pc are dependent on variables with significant uncertainty, confidence in the estimates themselves can be challenged. Fortunately, a precise value is rarely needed. Results typically are well above or well below guideline limits to the extent that even if all variable values were certain, the resulting recommended course of action would not change. Ec and Pc are then ideal to use in relative analyses using a standard tool to assess compliance with guidelines. [Copyright &y& Elsevier]

Abstract: Starting from 2008 experimental facilities of the Aragats Space Environmental Center (ASEC) routinely measure time series of secondary cosmic ray fluxes. At these years of the minimum of solar activity we analyze the new high-energy phenomena in the terrestrial atmosphere. Namely, Thunderstorm Ground Enhancements (TGEs) and Extensive Cloud Showers (ECSs). Several new particle detectors were designed and fabricated having lower energy threshold to detect particle fluxes from the thunderclouds; some of them have possibility to distinguish charged and neutral fluxes. During 2008–2012years ASEC detectors located at Aragats, Nor Amberd and Yerevan were detected ∼300 TGE enhancements. Amplitude of majority of them is less than 5%; however, 13 TGEs have amplitude exceeding 20%. The maximal value of observed enhancement was 271% (September 19, 2009). The paper summarizes five-years study of the TGEs on Aragats. The statistical analysis revealing the month and day-of-time distributions of TGE events, as well as the amplitude and event duration diagrams are presented. [Copyright &y& Elsevier]

Abstract: Breakup model is the key area of space debris environment modeling. NASA standard breakup model is currently the most widely used for general-purpose. It is a statistical model found based on space surveillance data and a few ground-based test data. NASA model takes the mass, impact velocity magnitude for input and provides the fragment size, area-to-mass ratio, velocity magnitude distributions for output. A more precise approach for spacecraft disintegration fragment analysis is presented in this paper. This approach is based on hypervelocity impact dynamics and takes the shape, material, internal structure and impact location etc. of spacecraft and impactor, which might greatly affect the fragment distribution, into consideration. The approach is a combination of finite element and particle methods, entitled finite element reconstruction (FER). By reconstructing elements from the particle debris cloud, reliable individual fragments are identified. Fragment distribution is generated with undirected graph conversion and connected component analysis. Ground-based test from literature is introduced for verification. In the simulation satellite targets and impactors are modeled in detail including the shape, material, internal structure and so on. FER output includes the total number of fragments and the mass, size and velocity vector of each fragment. The reported fragment distribution of FER shows good agreement with the test, and has good accuracy for small fragments. [Copyright &y& Elsevier]

Abstract: In the early 2000s, NASA made substantial progress in the development of solar sail propulsion systems for use in robotic science and exploration of the solar system. Two different 20-m solar sail systems were produced. NASA has successfully completed functional vacuum testing in their Glenn Research Center’s Space Power Facility at Plum Brook Station, Ohio. The sails were designed and developed by Alliant Techsystems Space Systems and L’Garde, respectively. The sail systems consist of a central structure with four deployable booms that support each sail. These sail designs are robust enough for deployment in a one-atmosphere, one-gravity environment and are scalable to much larger solar sails – perhaps as large as 150m on a side. Computation modeling and analytical simulations were performed in order to assess the scalability of the technology to the larger sizes that are required to implement the first generation of missions using solar sails. Furthermore, life and space environmental effects testing of sail and component materials was also conducted. NASA terminated funding for solar sails and other advanced space propulsion technologies shortly after these ground demonstrations were completed. In order to capitalize on the $30M investment made in solar sail technology to that point, NASA Marshall Space Flight Center funded the NanoSail-D, a subscale solar sail system designed for possible small spacecraft applications. The NanoSail-D mission flew on board a Falcon-1 rocket, launched August 2, 2008. As a result of the failure of that rocket, the NanoSail-D was never successfully given the opportunity to achieve orbit. The NanoSail-D flight spare was flown in the Fall of 2010. This review paper summarizes NASA’s investment in solar sail technology to date and discusses future opportunities. [Copyright &y& Elsevier]

Abstract: The European Space Agency’s Huygens probe separated from the NASA Cassini spacecraft on 25 December 2004, after having been attached for a 7-year interplanetary journey and three orbits around Saturn. The probe reached the predefined NASA/ESA interface point on 14 January 2005 at 09:05:52.523 (UTC). It performed a successful entry and descent sequence and softly landed on Titan’s surface on the same day at 11:38:10.77 (UTC) with a speed of about 4.54m/s. Since the publication of the official project entry and descent trajectory reconstruction effort by the Descent Trajectory Working Group in 2007 (referred to as DTWG#4) various other efforts have been performed and published. This paper presents an overview of the most relevant reconstructions and compares their methodologies and results. Furthermore, the results of a new reconstruction effort (DTWG#5) are presented, which is based on the same methodology as DTWG#4 but takes into account new estimates of Titan’s pole coordinates which were derived from radar images of different Cassini Titan flybys. It can be shown that the primary effect can be observed in the meridional direction which is represented by a stark southward shift of the trajectory by about 0.3deg. A much smaller effect is seen in the zonal direction (i.e., less than 0.01deg in the west to east direction). The revised probe landing coordinates are 192.335degW and 10.573degS. A comparison of these coordinates with results of recent landing site investigations using visual and radar images of the Cassini VIMS instrument shows excellent agreement of the two independently derived landing coordinates, i.e., longitude and latitude residuals of respectively 0.035deg and 0.007deg. [Copyright &y& Elsevier]

Abstract: The Advanced Life Support/NASA Specialized Center of Research and Training (ALS/NSCORT) focuses on research and development of technologies to support human habitation during space missions. This research was done as part of an effort to maintain crewmembers’ water supply in a closed life-support system. The water subsystem was the primary focus of this study because water is one of the most expensive and important resources for human survival. This paper focuses on the application of previously-developed methodologies for controlling a water-treatment system. The water-treatment and usage model was set up based on the Baseline Value and Assumptions Document (BVAD) published by NASA. The conditions, or “states”, of the system are captured hourly in the model. Control policies are defined in terms of treatment efficiencies. One control policy is to be used for the system at the beginning of each hour. A simulation is developed to study the impact of different control policies to this model. The Markov Decision Process (MDP) is used to aid the decision of choosing a policy to be used. In order for the MDP to pick the best policy, a state-space exploration technique, the Controlled Random Walk, is used for state-space exploration. This technique, together with re-initialization of initial system conditions, allow the system to visit a larger portion of the state space compared to some other techniques. In order to describe the state transitions, transition-probability matrices need to be computed. A probability-convergence technique is developed to minimize bias while computing these matrices. This technique is based on the Kullback–Leibler divergence measure, but modified for this application. A test case is constructed to assess the performance of best policies. Three scenarios with different levels of fluctuation, or disturbances, of water-consumption and treatment efficiencies are introduced in the test case. Results show that the best policies outperformed cases where fixed policies, as well as random policies, are used in all three scenarios. [Copyright &y& Elsevier]

Abstract: Since 1982, the Crustal Dynamics Data Information System (CDDIS) has supported the archive and distribution of geodetic data products acquired by the National Aeronautics and Space Administration (NASA) as well as national and international programs. The CDDIS provides easy, timely, and reliable access to a variety of data sets, products, and information about these data. These measurements, obtained from a global network of nearly 650 instruments at more than 400 distinct sites, include DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), GNSS (Global Navigation Satellite System), SLR and LLR (Satellite and Lunar Laser Ranging), and VLBI (Very Long Baseline Interferometry). The CDDIS data system and its archive have become increasingly important to many national and international science communities, particularly several of the operational services within the International Association of Geodesy (IAG) and its observing system the Global Geodetic Observing System (GGOS), including the International DORIS Service (IDS), the International GNSS Service (IGS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), and the International Earth rotation and Reference frame Service (IERS). Investigations resulting from the data and products available through the CDDIS support research in many aspects of Earth system science and global change. Each month, the CDDIS archives more than one million data and derived product files totaling over 90 Gbytes in volume. In turn, the global user community downloads nearly 1.2 Tbytes (over 10.5 million files) of data and products from the CDDIS each month. The requirements of analysts have evolved since the start of the CDDIS; the specialized nature of the system accommodates the enhancements required to support diverse data sets and user needs. This paper discusses the CDDIS, including background information about the system and its user communities, archive contents, available metadata, and future plans. [Copyright &y& Elsevier]

Abstract: With the advent of the NASA STEREO mission, we are in a position to perform unique investigations of the evolution of coronal mass ejections (CMEs) as they propagate through the heliosphere, and thus can investigate the relationship between CMEs and their interplanetary counterparts, so-called interplanetary CMEs (ICMEs). ICME studies have been principally limited to single-point, in-situ observations; interpretation of the in-situ characteristics of ICMEs has been used to derive a range of ICME properties which we can now confirm or refute using the STEREO imaging data. This paper is a review of early STEREO CME observations and how they relate to our currently understanding of ICMEs based on in-situ observations. In that sense, it is a first glance at the applications of the new data-sets to this topic and provides pointers to more detailed analyses. We find good agreement with in-situ-based interpretations, but this in turn leads to an anomaly regarding the final stages of a CME event that we investigate briefly to identify directions for future study. [Copyright &y& Elsevier]

Abstract: The National Aeronautics and Space Administration’s Balloon Program Office has invested significant time and effort in extensive ground testing of model super pressure balloons. The testing path has been developed as an outgrowth of the results of the super pressure balloon test flight in 2006. Summary results of the June 2006 super pressure test flight from Kiruna, Sweden are presented including the balloon performance and “lessons learned”. This balloons flight performance exceeded expectations, but did not fully deploy. The flight was safely terminated by command. The results of this test flight refocused the project’s efforts toward additional ground testing and analysis; a path to flight. A series of small 4m diameter models were made and tested to further explore the deployment and structural capabilities of the balloons and materials. A series of ∼27m model balloons were successfully tested indoors. These balloons successfully replicated the cleft seen in the Sweden flight, explored the deployment trade space to help characterize better design approaches, and demonstrated an acceptable fix to the deployment issue. Photogrammetry was employed during these ∼27m model tests to help characterize both the balloon and gore shape evolution under pressurization. A ∼8.5m ground model was used to explore the design and materials performance. Results of these tests will be presented. A general overview of some of the other project advancements made related to demonstrating the strain arresting nature of the proposed design, materials and analysis work will also be presented. All of this work has prepared a clear path toward a renewed round of test flights. This paper will give an overview of the development approach pursued for this super pressure balloon development. A description of the balloon design, including the modifications made as a result of the lessons learned, is presented. A short deployment test flight of the National Aeronautics and Space Administration’s super pressure balloon took place in June 2008. This flight was from Ft. Sumner, New Mexico. Preliminary results of this flight are presented. Future plans for both ground testing and additional test flights are also presented. Goals of the future test flights, which are staged in increments of increasing suspended load and altitude, are presented. This includes the projected balloon volumes, payload capabilities, test flight locations, and proposed flight schedule. [Copyright &y& Elsevier]

Abstract: Material density is an important, yet often overlooked, property of orbital debris particles. Many models simply use a typical density to represent all breakup fragments. While adequate for modeling average characteristics in some applications, a single value material density may not be sufficient for reliable impact damage assessments. In an attempt to improve the next-generation NASA Orbital Debris Engineering Model, a study on the material density distribution of the breakup fragments has been conducted and summarized in this paper. The material density distribution of the on-orbit breakup debris population may be estimated by combining three sources of data: available pre-launch information on satellite materials, ground-based satellite breakup experiments, and chemical compositions of residuals collected from returned surfaces. Analysis of these data provides a basis to compile a simple mass density distribution. For example, about 75% of on-orbit breakup debris fragments come from upper stages, which are simpler and more standardized than payloads in construction and composition. Available material information from manufacturers can be used to develop a reasonable distribution function for this component. For spacecraft breakup debris, it has been found that the range of material densities may be simplified into three representative values: high (e.g. steel), medium (e.g. aluminum), and low (e.g. plastic). The current study develops preliminary distributions for breakup debris: rocket body debris is 90% medium-density and 10% high-density (by number); payload debris is 70% low-density, 27% medium, and 3% high-density. Although the three data sources mentioned above are not comprehensive, and some interpretation and extrapolation are needed, the resulting density distributions still represent a step forward in providing more reliable damage assessments for future debris models. Future work will refine the data and provide distributions as functions of particle size and orbital altitude. [Copyright &y& Elsevier]

Abstract: MODIS is a major instrument for NASA’s Earth Observing System (EOS) missions. It is currently operating on-board the EOS Terra and Aqua spacecraft, launched in December 1999 and May 2002, respectively. The MODIS instrument was developed with improvements over heritage sensors in terms of its spectral, spatial, and temporal resolutions, and with more stringent calibration requirements. It makes observations in 36 spectral bands covering wavelengths from 0.41 to 14.4μm and at three nadir spatial resolutions: 250m, 500m, and 1km. Together Terra and Aqua MODIS have produced more than 10 years of global data sets that have significantly helped scientists worldwide to better understand the Earth as an interacting system and the impacts on this system due to human related activities. In order to maintain on-orbit calibration and data product quality, MODIS was built with a complete set of on-board calibrators (OBCs), including a solar diffuser (SD), a solar diffuser stability monitor (SDSM), a blackbody (BB), a deep space view (SV) port, and a spectro-radiometric calibration assembly (SRCA). In this paper, we provide a brief description of both Terra and Aqua MODIS on-orbit operation and calibration activities and present results of on-orbit radiometric, spatial, and spectral characterization. Examples of short-term stability and long-term response changes are illustrated using observations made with the on-board calibrators. On-orbit performance parameters, including detectors noise characterization, are also compared to pre-launch design specifications. [Copyright &y& Elsevier]

Abstract: On October 25th, 2006, NASA’s two STEREO spacecraft were launched which are designed to increase our knowledge of the physics of the solar system. On board they carry a sophisticated radio experiment, called S/WAVES. The key technology, used by S/WAVES is the direction finding capability in addition to the use of two spacecraft which makes it possible to triangulate radio sources. Direction finding requires the reception properties of the antennas to be known very accurately. We applied several different methods to calibrate the S/WAVES antennas. In this paper the methods are described and compared and the results are presented and discussed with respect to advantages and disadvantages of the different methods. [Copyright &y& Elsevier]

Abstract: In this paper, we have investigated the intermediate-term periodicities of the relativistic (E >10MeV) solar electron flares measured by IMP-8 satellite of NASA for the time period of 1986–2001. This period of investigation includes the entire solar cycle 22; ascending, maximum and a part of descending phase of the current solar cycle 23. To determine accurately the occurrence rate of electron flux, we have employed three different spectral decomposition techniques, viz. fast Fourier transformation (FFT); maximum entropy method (MEM) and Lomb–Scargle periodogram analysis method. For solar cycle 22, in the low frequency range, power spectrum analysis exhibits statistically significant periodicities at ∼706, ∼504 and ∼392 days. In the intermediate frequency range, we have found a series of significant periodicities ∼294, ∼221, ∼153, ∼86, ∼73 and ∼66 days. For short term, periodicities of ∼21–23, ∼31 and ∼37 days were found in power spectrum. When solar cycle 23 is considered the significant periodicities are ∼20, ∼23, ∼29, ∼39, ∼54, ∼63, ∼118, ∼133 and ∼154 days. These results provide evidence that the best known Rieger period (∼153 days), appeared in the high energetic electron flux data for cycle 22 and also likely during maxima of cycle 23. The existence of these periodicities has been discussed in the light of earlier results. [Copyright &y& Elsevier]

Abstract: The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment is one of four instruments on NASA’s Thermosphere–Ionosphere–Energetics and Dynamics (TIMED) satellite. SABER measures broadband infrared limb emission and derives vertical profiles of kinetic temperature (Tk) from the lower stratosphere to approximately 120km, and vertical profiles of carbon dioxide (CO2) volume mixing ratio (vmr) from approximately 70km to 120km. In this paper we report on SABER Tk/CO2 data in the mesosphere and lower thermosphere (MLT) region from the version 1.06 dataset. The continuous SABER measurements provide an excellent dataset to understand the evolution and mechanisms responsible for the global two-level structure of the mesopause altitude. SABER MLT Tk comparisons with ground-based sodium lidar and rocket falling sphere Tk measurements are generally in good agreement. However, SABER CO2 data differs significantly from TIME-GCM model simulations. Indirect CO2 validation through SABER-lidar MLT Tk comparisons and SABER-radiation transfer comparisons of nighttime 4.3μm limb emission suggest the SABER-derived CO2 data is a better representation of the true atmospheric MLT CO2 abundance compared to model simulations of CO2 vmr. [Copyright &y& Elsevier]

Abstract: The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums. [Copyright &y& Elsevier]

Abstract: Many United States, school children perceive science, technology, engineering, and mathematics (STEM) as difficult, boring and often irrelevant subjects. The possible reasons for this problem are endlessly debated. However, the economic, social, and overall national importance of producing graduates who are technically literate and enthusiastic in their support of a rational scientific world is essential to our nation. This apparent STEM crisis should motivate the many scientific and engineering societies to develop STEM outreach programs aimed at students, parents, teachers and schools (grades K-12). The American Institute of Aeronautics and Astronautics (AIAA) is among those organizations that have identified the need to educate students and teachers about STEM current events and their direct effects on the United States population in a way that motivates both. The AIAA has established a pre-college outreach program that has several major elements that will be described in this paper. Elements focused on the teachers include a pre-college Educator Associate Membership program, classroom grants to support hands-on learning activities, Educator of the Year awards and recognition program and two national workshop events. The first workshop event, Passport to the Future, is held annually in conjunction with the Joint Propulsion Conference. It is intended to provide summertime training in Aerospace science education to classroom teachers, in conjunction with a national professional conference. The second workshop, Education Alley, is held in the fall in conjunction with the “Space” series of conferences. This program is aimed at direct outreach to local students in the conference host city, providing fun, interesting, and educational events that promote STEM. The AIAA also encourages and supports pre-college outreach activities sponsored by the local AIAA sections through leadership training, activity and material support. [Copyright &y& Elsevier]

Abstract: An elementary science education professional development partnership between Culver City Unified School District teachers and UCLA has been formed. The project was designed to assist teachers to comfortably present introductory space science concepts, to support them in their efforts, and to aid them in encouraging their students to develop inquiry skills related to space sciences. The project encourages teacher use of observational science techniques in their classrooms, the use of NASA solar mission images and enhanced use of astronomical observation to facilitate discovery learning. The integrated approach of the project has fostered collegial learning activities among the participating teachers and offered them opportunities for continued renewal and professional development of teacher competencies in astronomy and space science. The activities used in the classroom were developed by others, classroom tested, and specifically address National Science Education and California Science Content Standards. These activities have been sustained through on-going collaboration between the scientist and the teachers, a summer Research Experience for Teachers program, and on-going, grade-specific, district-sponsored workshops. Assessment of the value of the program is done by the school district and is used to continuously improve each workshop and program component. Culver City (California) Unified School District is a small urban school district located on the Westside of Los Angeles. This paper describes the program and the plans for incorporating IHY-themed science into the classroom. [Copyright &y& Elsevier]

Abstract: Lunar laser ranging (LLR) measurements are crucial for advanced exploration of the laws of fundamental gravitational physics and geophysics as well as for future human and robotic missions to the Moon. The corner-cube reflectors (CCR) currently on the Moon require no power and still work perfectly since their installation during the project Apollo era. Current LLR technology allows us to measure distances to the Moon with a precision approaching 1mm. As NASA pursues the vision of taking humans back to the Moon, new, more precise laser ranging applications will be demanded, including continuous tracking from more sites on Earth, placing new CCR arrays on the Moon, and possibly installing other devices such as transponders, etc. for multiple scientific and technical purposes. Since this effort involves humans in space, then in all situations the accuracy, fidelity, and robustness of the measurements, their adequate interpretation, and any products based on them, are of utmost importance. Successful achievement of this goal strongly demands further significant improvement of the theoretical model of the orbital and rotational dynamics of the Earth–Moon system. This model should inevitably be based on the theory of general relativity, fully incorporate the relevant geophysical processes, lunar librations, tides, and should rely upon the most recent standards and recommendations of the IAU for data analysis. This paper discusses methods and problems in developing such a mathematical model. The model will take into account all the classical and relativistic effects in the orbital and rotational motion of the Moon and Earth at the sub-centimeter level. The model is supposed to be implemented as a part of the computer code underlying NASA Goddard’s orbital analysis and geophysical parameter estimation package GEODYN and the ephemeris package PMOE 2003 of the Purple Mountain Observatory. The new model will allow us to navigate a spacecraft precisely to a location on the Moon. It will also greatly improve our understanding of the structure of the lunar interior and the nature of the physical interaction at the core–mantle interface layer. The new theory and upcoming millimeter LLR will give us the means to perform one of the most precise fundamental tests of general relativity in the solar system. [Copyright &y& Elsevier]

Abstract: Planetary protection requirements for future human missions to Mars will strongly influence mission and spacecraft designs, particularly those related to the operation of advanced life support systems (ALS), extravehicular activity (EVA), laboratory and in situ sampling operations, and associated environmental monitoring and control systems. In order to initiate communication, understanding and working relations among the ALS, EVA, and planetary protection communities in NASA and ESA, a workshop was held (May 2005; ESA/ESTEC; Nordwijk, The Netherlands) to focus on mission-specific planetary protection issues associated with future human missions to Mars. The “Mars Planetary Protection and Human Systems Research and Technology Joint NASA/ESA Workshop” considered the range of knowledge and information necessary to establish planetary protection requirements with respect to ALS and EVA systems, including the identification of potential contaminants, contamination pathways, and potential off-nominal events typical of such systems and of space exploration. The top-level workshop goal was to determine how compliance with planetary protection requirements should be implemented before, during, and after human Mars missions, and what standards of contamination control should apply to human explorers. Workshop discussions considered operations and technology concerns, science operations, backward contamination prevention requirements, and the protection of both the human habitat on Mars and the Earth upon crew return. A list of future research and development needs were also identified for ALS, EVA and Mars robotic missions, including specific precursor mission information necessary to understand and prepare for human support systems and science operations on long duration Mars missions. This paper summarizes the findings and recommendations of the workshop including an overall approach to contamination control, waste and consumable management, and off-nominal events, as well as the research and development necessary to cope with planetary protection requirements during future human missions to Mars. [Copyright &y& Elsevier]

Abstract: In this paper we revisit the 1995 Kaman database of the SOCIT4 fragment characteristics with added analysis of a subset of the cataloged fragments from the test. This database was compiled from the last of a series of four hypervelocity impact tests conducted under a U.S. Department of Defense program in 1991–1992. This test targeted a flight-ready, U.S. Transit navigation satellite, yielding collision fragments in the size regime of sub-millimeter through tens of centimeters. Results in this database were used in the 1998 NASA Standard Breakup Model to represent characteristic length (size) and area-to-mass distributions of fragments smaller than 10cm. In this analysis we explore, in detail, the tabulated fragment material and shape. What emerges is a clear distinction in fragment area-to-mass ratio between primarily metal and primarily non-metal fragments. Metal fragments, which are dominated by aluminum, follow the characteristic curve of increasing area-to-mass ratio with decreasing characteristic length: objects move from the character of large irregular bent shards to that of small solid spheroids. Non-metal fragments, dominated by phenolic/plastic, do not appear to move towards solid spheroids as easily as metals. Also unlike the metals, their area-to-mass ratio curve plateaus in the midsize region (smaller than 1cm), coinciding with a peak in plate-like, non-metal fragments. The internal structure of the Transit payload, with its phenolic surface skin and packed arrays of plastic circuit boards, certainly governs this plateau behavior. In the small fragment regime (smaller than 4mm) phenolic/plastic ellipsoidal ‘Nuggets’ dominate the population. They outnumber aluminum ‘Nuggets’ by over four to one. Through this study we gain a more detailed understanding of the collisional-breakup process of this particular payload, but also have begun to determine how these data may apply to other breakups. Our long-term goal is to apply this new understanding to future upgrades of the NASA Standard Breakup Model. [Copyright &y& Elsevier]

Abstract: Recently, several improvements were made in the DORIS data processing at the IGN/JPL (Institut Geographique National, France; Jet Propulsion Laboratory, California Institute of Technology, USA) analysis center: use of GRACE-derived gravity fields, data preprocessing and station discontinuity detection, etc. This allowed enhanced performances for ground station geodetic positioning (typically 10mm using a week of data), as well as for polar motion (0.5–1.0 mass for daily determination). However, since the loss in 2004 of the DORIS receiver on the TOPEX/Poseidon mission, only four satellites (SPOT-2, SPOT-4, SPOT-5, and ENVISAT) are currently equipped with DORIS receivers. Furthermore, most of them are aging and some have already far exceeded their expected lifetime. The goal of this paper is to analyze how the geodetic performances could be degraded in the future if one or more of these satellites would unfortunately be lost, and to envisage which satellites are currently the most critical in the DORIS geodetic performances. We have reanalyzed 1 year of recent DORIS data (2005), processing all possible combinations of satellite constellation sub-sets. We then compared these results (station coordinates and polar motion) with those obtained in regular data processing when using DORIS data from all four available satellites in 2005. We demonstrate the importance of the SPOT-5 data, equipped with a new type of on-board DORIS receiver. The study also shows some possible weaknesses in our current ENVISAT orbit computations. Fortunately, new DORIS satellites are also expected in the near future (Jason-2, CRYOSAT-2 and AltiKa), which could improve current DORIS-derived geodetic results due to their specific type of orbit (different from the SPOT sun-synchronous orbits) and also to enhanced on-board receivers. [Copyright &y& Elsevier]

Abstract: The Primary Atomic Reference Clock in Space (PARCS) mission is designed to perform certain tests of relativity theory, to study the performance of individual GPS space-vehicle clocks, to study the dynamics of atom motion in microgravity, to advance the state-of-the art for space clocks, and to serve as a pathfinder for precision instruments based on laser cooling of atoms. After a brief overview of the project, this paper discusses the specific objectives of PARCS, describes the key subsystems, and discusses the systematic frequency shifts that limit the accuracy of the clock. [Copyright &y& Elsevier]

Abstract: NASA has been making statistical measurements of the orbital debris environment for more than a decade using the MIT Lincoln Laboratory Haystack radar. The goal has been to characterize the environment for debris sizes as small as possible. Like all sensors which operate in the presence of noise, the Haystack radar has limited sensitivity. As the returned energy from small targets begins to approach the sensitivity limit of the radar, the probability-of-detection decreases, eventually approaching zero. The slope of the cumulative size distribution of debris begins to flatten out. This paper explores the possibility of extending the cumulative size distribution to smaller sizes by adjusting the distribution for probability-of-detection. [Copyright &y& Elsevier]

Abstract: Over the past six years, NASA’s Office of Space Science has implemented what may well be the largest single program in astronomy and space science education ever undertaken. The program goals include the public sharing of the excitement of space science discoveries, enhancement of the quality of science, mathematics and technology education, particularly at the precollege level, and supporting the creation of our 21st century scientific and technical workforce. This paper provides an overview of the program origins, policies and philosophies, and describes the development and growth of the program. Program accomplishments and the challenges that remain are discussed along with potential opportunities for international collaboration. [Copyright &y& Elsevier]

The National Aeronautics and Space Administration (NASA) Ultra-Long Duration Balloon development project is attempting to extend the potential flight durations for large scientific balloon payloads. The culmination of each of the development steps has been the fabrication and test flight of progressively larger balloons. This new super-pressure balloon is a pumpkin balloon design. This paper concentrates on the super-pressure balloon development test flights that have been, and are currently being planned by the NASA Balloon Program Office at Goddard Space Flight Center''s Wallops Flight Facility. Descriptions of two test flights from early 2001 are presented along with lessons learned. Results are also presented of a July 2002 test flight of a full-scale 610,500 m3 balloon with a 2800 kg suspended load that incorporated the lessons learned. [Copyright &y& Elsevier]

Safety requirements and the increase in balloon flight duration make a computerized balloon control system essential. Starting with a global thermodynamic model of a stratospheric balloon (NASA-SINBAD) and 48-h wind forecast data, a flexible system can be built to predict its trajectory. In order to increase the trajectory forecast accuracy, the thermodynamic model of SINBAD, related to infrared radiation and albedo, has been improved. The model and the methodology have been evaluated by comparing the altitude excursion of some already flown zero-pressure balloons, with the altitude excursion computed by SINBAD; meteorological and satellite data (METEOSAT) and meteorological forecast data have been used as input. This system, connected during the mission to the balloon''s managing unit, will continuously update the forecast trajectory and will enable real and simulated data to be compared. In this way it will also be possible to simulate the balloon flight trajectory in case of any failures. This paper explains the solution adopted for this system and the application that was carried out for the Italian Space Agency''s 2002 summer balloon campaign. [Copyright &y& Elsevier]

Initial studies of the thermal profiles on scientific balloons along with preliminary results are discussed in this paper. This document also emphasizes the impact thermal modeling will have on the design and future development of the scientific balloons. Progress of study and future steps to keep up with the design criteria is also included in this document. [Copyright &y& Elsevier]

The Upper Atmosphere Research Satellite (UARS) was the first satellite to be launched under the Earth Observing System (EOS) science program of multi-mission observing systems of the National Aeronautics and Space Administrations (NASA). The EOS program was conceived to advance the understanding of the Earth-Atmosphere system on the global scale. The UARS was launched in September 1991 with ten instruments dedicated entirely to increase the understanding of chemistry and dynamics of the Earth''s stratosphere and mesosphere. After 10 years of successful data collection (far exceeding the originally projected lifetime of 3 years), the official mission ended in September 2001. However, seven instruments aboard UARS are still operational and six regularly take measurements. It is expected that the UARS will overlap the Earth Observing System (EOS) Aura satellite (to be launched in early 2004) for several months before the end of the UARS mission. The UARS data and atmospheric chemistry and dynamics data from other satellites are archived at the NASA Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) and are available free to the public and science user community. The UARS data and related documents may be accessed through the GES DAAC website (http://daac.gsfc.nasa.gov). This paper gives an overview of the UARS data products. Detailed information on UARS instruments, mission highlights and related publications are available from the UARS project website (http://umpgal.gsfc.nasa.gov) [Copyright &y& Elsevier]

In the present paper we study variations of the nitrate content in Greenland ice core for the last 400 years. These data were obtained by high-precision measurements performed by the University of Kansas. It is shown that approximately 20-year periodicity dominates in the nitrate series during the Maunder minimum (1645-1715) due to similar variations of galactic cosmic ray intensity. During times of normal high solar activity level, the 4–6-year periodicity dominates in the nitrate series. This is probably due to a superposition of fluxes of galactic and solar cosmic rays, and due to the creation of favourable conditions for the nitrate precipitation. [Copyright &y& Elsevier]