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At least 739 records · Page 41

Government/Industry Workshop on Payload Loads Technology

A fully operational space shuttle is discussed which will offer science the opportunity to explore near earth orbit and finally interplanetary space on nearly a limitless basis. This multiplicity of payload/experiment combinations and frequency of launches places many burdens on dynamicists to predict launch and landing environments accurately and efficiently. Two major problems are apparent in the attempt to design for the diverse environments: (1) balancing the design criteria (loads, etc.) between launch and orbit operations, and (2) developing analytical techniques that are reliable, accurate, efficient, and low cost to meet the challenge of multiple launches and payloads. This paper deals with the key issues inherent in these problems, the key trades required, the basic approaches needed, and a summary of the state-of-the-art techniques.

Source record↗

Thermal systems analysis for the Space Infrared Telescope Facility dewar

Thermal systems analysis models were used to design SFHe cooled dewar for the Space Infrared Telescope Facility (SIRTF), a 1 m class cryogenically cooled observatory for IR astronomy. The models are capable of computing both the heat leaks into the dewar and the operating temperature of a SFHe tank. The models are aimed at predicting the ability of the SIRTF cryogenic system to satisfy a five-year mission lifetime requirement and maintain the SFHe tank operating temperature of 1.25 K to provide sufficient cooling for science instruments and the optical system. The thermal models are very detailed and very fast with a typical steady state run of about 20 sec on a VAX minicomputer.

Bhandari, Pradeep↗

CME Prediction from Line-of-Sight Magnetogram

We have previously shown for bipolar active regions that measures of active-region nonpotentiality from vector magnetograms are correlated with active-region CME productivity. We have now obtained a measure from line-of-sight magnetograms that is well correlated both with our measures of active-region nonpotentiality from vector magnetograms and with active-region CME productivity. The measure is the length of strong-gradient main neutral line (L(sub G)). This is the length of the bipolar region's main neutral line on which the potential transverse field is greater than 150G, and the gradient in the line-of-sight field is greater than 50G/Mm. From the sample of 17 MSFC magnetograms of 12 basically bipolar active regions used in our previous paper, we find that L(sub G) is strongly correlated with one of our vector-magnetogram measures of nonpotentiality, the length of strong-gradient main neutral line L(sub SS) (99.7%). We also find that L(sub G) is as strongly correlated with CME productivity (99.7%) as is L(sub SS). Being obtainable from line-of-sight magnetograms, L(sub G) makes the much larger data set of line-of-sight magnetograms (i.e. from SOHO/MDI and Kitt Peak) available for CME prediction study. This is especially important for evolutionary studies, with SOHO/MDI having no daylight, cloudy weather, or atmospheric seeing problems. This work was supported by funding from NSF's division of Atmospheric Sciences (Space Weather and Shine Programs) and by NASA's office of Space Science (Living with a Star program Solar and Heliospheric Physics Supporting Research and Technology program).

Falconer, D. A.↗

Characteristics and Trade-Offs of Doppler Lidar Global Wind Profiling

Accurate, global profiling of wind velocity is highly desired by NASA, NOAA, the DOD/DOC/NASA Integrated Program Office (IPO)/NPOESS, DOD, and others for many applications such as validation and improvement of climate models, and improved weather prediction. The most promising technology to deliver this measurement from space is Doppler Wind Lidar (DWL). The NASA/NOAA Global Tropospheric Wind Sounder (GTWS) program is currently in the process of generating the science requirements for a space-based sensor. In order to optimize the process of defining science requirements, it is important for the scientific and user community to understand the nature of the wind measurements that DWL can make. These measurements are very different from those made by passive imaging sensors or by active radar sensors. The purpose of this paper is to convey the sampling characteristics and data product trade-offs of an orbiting DWL.

Kavaya, Michael J.↗

Assessment of the Mars Science Laboratory Entry, Descent, and Landing Simulation

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was only the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel and untested Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle.

Way, David W.↗

Preliminary Assessment of the Mars Science Laboratory Entry, Descent, and Landing Simulation

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was only the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel and untested Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multibody computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle.

Way, David W.↗

The HyMeX Special Observation Period in Central Italy: Precipitation Measurements, Retrieval Techniques and Preliminary Results

The Mediterranean area concentrates the major natural risks related to the water cycle, including heavy precipitation and flash-flooding during the fall season. The capability to predict such high-impact events remains weak because of the contribution of very fine-scale processes and their non-linear interactions with the larger scale processes. These societal and science issues motivate the HyMeX (Hydrological cycle in the Mediterranean Experiment, http://www.hymex.orgl) experimental programme. HyMeX aims at a better quantification and understanding of the water cycle in the Mediterranean with emphasis on intense events. The observation strategy of HyMEX is organized in a long-term (4 years) Enhanced Observation Periods (EOP) and short-term (2 months) Special Observation Periods (SOP). HyMEX has identified 3 main Mediterranean target areas: North-West (NW), Adriatic (A) and South-East (SE). Within each target area several hydrometeorological sites for heavy rainfall and flash flooding have been set up. The hydrometeorological sire in Central Italy (CI) is interested by both western and eastern fronts coming from the Atlantic Ocean and Siberia, respectively. Orographic precipitations play an important role due to the central Apennine range, which reaches nearly 3000 m (Gran Sasso peak). Moreover, convective systems commonly develop in CI during late summer and beginning of autumn, often causing localized hailstorms with cluster organized cells. Western fronts may heavily hit the Tiber basin crossing large urban areas (Rome), whereas eastern fronts can cause flash floods along the Adriatic coastline. Two major basins are involved within Cl region: Tiber basin (1000 km long) and its tributary Aniene and the Aterno-Pescara basin (300 km long). The first HyMeX SOP1.1 was carried out from Sept. till Nov. 2012 in the NW target area The Italian SOP1.1 was coordinated by the Centre of Excellence CETEMPS, University of L'Aquila, a city located in the CI heart. The CI area was covered by a uniquely dense meteorological instrumentation thanks to a synergy between Italian institutions and NASA-GSFC. The following RADARs were operated: a Doppler single-polarization C-band radar located at Mt Midia; the Polar 55C Doppler dual-polarization C-band radar located in Rome; a Doppler C-hand polarimetric radar located at Il Monte (Abnazo); a polarimetric X-band mini-radar in L' Aquila; a polarimetric X-hand portable mini-radar in Rome; a single-polarization X-band mini-radar in Rome. DISDROMETERs were also deployed: 4 Parsivel optical disdrometers in Rome (at Sapienza, CNR-ISAC and CNR-INSEAN); 1 2D-video disdrometer in Rome; 3 Parsivels optical disdrometer respectively in L'Aquila (Abnazo), Avezzano (Abruzzo) and Pescara (Abnazo). Other INSTRUMENTS were available: 1 K-band vertically-pointing micro rain-radar (MRR), 2 Pludix X-band disdrometers, 1 VLF lightning sensor, 1 microwave radiometer at 23-31 GHz in Rome (at Sapienza); the raingauge network with more than 200 stations in Central Italy. Three overpasses in CI were also performed by the Falcon 20 aircraft equipped with the 950Hz cloud radar RASTA Analysis of the SOP1.1 main events in CI will be described by focusing on the raindrop size distribution statistics and its geographical variability. Intercomparison of rainfall estimates from disdrometers, raingauges and radars will be illustrated with the aim to provide a quality-controlled and physically consistent rainfall dataset for meteorological modeling validation and assimilation purposes.

Gatlin, Patrick↗

Experimental Products Development Team (EPDT) Supporting New AWIPS : Capabilities - Part 2

In 2012, the Experimental Products Development Team (EPDT) was formed within NASA's Short-term Prediction Research and Transition (SPoRT) Center to create training for development of plug‐ins to extend the National Weather Service (NWS) Advanced Weather Interactive Processing System (AWIPS) version 2. The broader atmospheric science community had a need for AWIPS II development training being created at SPoRT and EPDT was expanded to include other groups who were looking for training. Since the expansion of the group occurred, EPDT has provided AWIPS II development training to over thirty participants spanning a wide variety of groups such as NWS Systems Engineering Center, NWS Meteorological Development Laboratory, and several NOAA Cooperative Institutes. Participants within EPDT solidify their learning experience through hands‐on learning and by participating in a "code-sprint" in which they troubleshoot existing and develop plug‐ins. The hands‐on learning workshop is instructor lead with participants completing exercises within the AWIPS II Development Environment. During the code sprints EPDT groups work on projects important to the community and have worked on various plug‐ins such as an RGB image recipe creation tool, and an mPing (crowd sourced precipitation type reporting system) ingest and display. EPDT has developed a well‐defined training regime which prepares participants to fully develop plug‐ins for the extendible AWIPS II architecture from ingest to the display of new data. SPoRT has hosted 2 learning workshops and 1 code sprint over the last two years, and continues to build and shape the EPDT group based on feedback from previous workshops. The presentation will provide an overview of EPDT current and future activities, and best practices developed within EPDT.

Burks, Jason E.↗

Orbit Determination and Navigation Software Testing for the Mars Reconnaissance Orbiter

During the extended science phase of the Mars Reconnaissance Orbiter's lifecycle, the operational duties pertaining to navigation primarily involve orbit determination. The orbit determination process utilizes radiometric tracking data and is used for the prediction and reconstruction of MRO's trajectories. Predictions are done twice per week for ephemeris updates on-board the spacecraft and for planning purposes. Orbit Trim Maneuvers (OTM-s) are also designed using the predicted trajectory. Reconstructions, which incorporate a batch estimator, provide precise information about the spacecraft state to be synchronized with scientific measurements. These tasks were conducted regularly to validate the results obtained by the MRO Navigation Team. Additionally, the team is in the process of converting to newer versions of the navigation software and operating system. The capability to model multiple densities in the Martian atmosphere is also being implemented. However, testing outputs among these different configurations was necessary to ensure compliance to a satisfactory degree.

Deep Space Network↗

Detecting Hail from Space: Using a Multi-Frequency Passive-Microwave Retrieval to Analyze the Global Climatology and Diurnal Cycle of Severe Hail

Severe hail poses myriad threats to society, causing extensive damage to infrastructure and agriculture. As hail is severe, relatively infrequent, and highly localized, it is difficult to measure in-situ and if left unresolved in models and precipitation retrievals, hail can cause large errors and uncertainties. The difficulty in measuring hail in situ and the inconsistency of surface-based hail reporting drive the motivation to use spaceborne remote-sensing platforms to retrieve hail and construct climatologies in a globally uniform way. We leverage the scattering signatures of severe hail in spaceborne passive-microwave datasets paired with surface hail reports to construct a multi-frequency hail retrieval using Tropical Rainfall Measuring Mission (TRMM) microwave imager (TMI) data. Using coincident Global Precipitation Measurement (GPM) Ku-band precipitation radar, we assessed this retrieval and several others in the literature for their effectiveness and regional variability. We use this retrieval to construct global passive-microwave climatologies of severe hail using the TRMM, GPM, Advanced Microwave Scanning Radiometer for EOS (AMSR-E), and Advanced Microwave Scanning Radiometer 2 (AMSR2) sensors and extend into the pre-TRMM era to the Special Sensor Microwave Imager/Sounder (SSMI/(S)) data. We also leverage the sensors in inclined orbits to assess the diurnal variability of severe hail globally and the effect the diurnal cycle has on the detection of hail by sensors in sun-synchronous orbit. The goal is to construct a robust, multi-decade multi-satellite climatology of hail. As part of the NASA Disasters Applied Sciences program, we assess these climatologies against other satellite severe weather datasets and use these climatologies in collaboration with stakeholders and end-users to help them assess risk, and improve the prediction, preparation, and response to severe storms around the world.

Sarah D Bang↗

Technical Note: AQMEII4 Activity 1: Evaluation of Wet and Dry Deposition Schemes as an Integral Part of Regional-scale Air Quality Models

We present in this technical note the research protocol for phase 4 of the Air Quality Model Evaluation International Initiative (AQMEII4). This research initiative is divided into two activities, collectively having three goals: (i) to define the current state of the science with respect to representations of wet and especially dry deposition in regional models, (ii) to quantify the extent to which different dry deposition parameterizations influence retrospective air pollutant concentration and flux predictions, and (iii) to identify, through the use of a common set of detailed diagnostics, sensitivity simulations, model evaluation, and reduction of input uncertainty, the specific causes for the current range of these predictions. Activity 1 is dedicated to the diagnostic evaluation of wet and dry deposition processes in regional air quality models (described in this paper), and Activity 2 to the evaluation of dry deposition point models against ozone flux measurements at multiple towers with multiyear observations (to be described in future submissions as part of the special issue on AQMEII4). The scope of this paper is to present the scientific protocols for Activity 1, as well as to summarize the technical information associated with the different dry deposition approaches used by the participating research groups of AQMEII4. In addition to describing all common aspects and data used for this multi-model evaluation activity, most importantly, we present the strategy devised to allow a common process-level comparison of dry deposition obtained from models using sometimes very different dry deposition schemes. The strategy is based on adding detailed diagnostics to the algorithms used in the dry deposition modules of existing regional air quality models, in particular archiving diagnostics specific to land use–land cover (LULC) and creating standardized LULC categories to facilitate cross-comparison of LULC-specific dry deposition parameters and processes, as well as archiving effective conductance and effective flux as means for comparing the relative influence of different pathways towards the net or total dry deposition. This new approach, along with an analysis of precipitation and wet deposition fields, will provide an unprecedented process-oriented comparison of deposition in regional air quality models. Examples of how specific dry deposition schemes used in participating models have been reduced to the common set of comparable diagnostics defined for AQMEII4 are also presented.

Air Quality Model Evaluation International Initiat↗

The Gravity Probe B Experiment

This presentation briefly describes the Gravity Probe B (GP-B) Experiment which is designed to measure parts of Einstein's general theory of relativity by monitoring gyroscope orientation relative to a distant guide star. To measure the miniscule angles predicted by Einstein's theory, it was necessary to build near-perfect gyroscopes that were approximately 50 million times more precise than the best navigational gyroscopes. A telescope mounted along the central axis of the dewar and spacecraft provided the experiment's pointing reference to a guide star. The telescope's image divide precisely split the star's beam into x-axis and y-axis components whose brightness could be compared. GP-B's 650-gallon dewar, kept the science instrument inside the probe at a cryogenic temperature for 17.3 months and also provided the thruster propellant for precision attitude and translation control. Built around the dewar, the GP-B spacecraft was a total-integrated system, comprising both the space vehicle and payload, dedicated as a single entity to experimentally testing predictions of Einstein's theory.

Kolodziejczak, Jeffrey↗

NASA/MSFC FY92 Earth Science and Applications Program Research Review

A large amount of attention has recently been given to global issues such as the ozone hole, tropospheric temperature variability, etc. A scientific challenge is to better understand atmospheric processes on a variety of spatial and temporal scales in order to predict environmental changes. Measurement of geophysical parameters such as wind, temperature, and moisture are needed to validate theories, provide analyzed data sets, and initialize or constrain numerical models. One of NASA's initiatives is the Mission to Planet Earth Program comprised of an Earth Observation System (EOS) and the scientific strategy to analyze these data. This work describes these efforts in the context of satellite data analysis and fundamental studies of atmospheric dynamics which examine selected processes important to the global circulation.

Arnold, James E.↗

EOS Aqua Mission Status at Earth Science Constellation MOWG Meeting @ LASP April 13, 2016

This presentation reflects the EOS Aqua mission status, spacecraft subsystem summary, recent and planned activities, inclination adjust maneuvers, propellant usage and lifetime estimate, orbital maintenance maneuvers, conjunction assessment high interest events, ground track error, spacecraft orbital parameters trends and predictions.

Aqua mission status↗

ROSAT guest investigator program (AO-1). On a search for coronal x ray emissions from white dwarfs

We have suggested that cool magnetic white dwarfs may be sources of X-ray coronal emission and proposed several prominent candidates for this emission. One of these candidates (EG 250) was approved for the C-category observation by the National and International Committee and was observed by ROSAT on April 17, 1991. Unfortunately, the granted exposure time (1071 s) was much shorter than that which was required by theoretical predictions to observe coronal X-ray emission from this object. The tape containing the data was send to us in November 1991. Since then we have analyzed the data visiting the ROSAT Science Center at NASA Goddard Space Flight Center. The analysis of the data taken during this short observation show, as expected, no X-rays. It is our hope that EG 250 will be observed again during the AO-2 phase of pointed observations, as 10,000 s of observing time was granted to V. Trimble for the C-category observation of this star. We have a close contact with Dr. Trimble regarding this matter. Because our all targets (GD 90, KUV 2316-123 and GD 356) proposed for the observation during the AO-2 phase of pointed observations have been approved by the National and International Committee, we have installed the required software at NASA/MSFC to be able to carry out the data analysis in Huntsville. Two of our targets have already been observed (KUV 2316-123 was observed on Dec. 3, 1991 with 10,000 s of the exposure time, and GD 356 was observed on Jan 4, 1992 with 5,000 s of the exposure time). We just received the data and will begin the analysis soon. The results of our analysis will be reported to the scientific community by publishing papers in the Astrophysical Journal Letters. Our intention is to submit a paper when the analysis of the data taken during AO2 is completed. The data taken during the observation of EG 250 will be a part of this paper.

Musielak, Z. E.↗

Conceptual Study of Intelligent Data Archives of the Future

A conceptual architecture study is under way to address the problem of getting the most scientific value from the large volumes of Earth and space science data that NASA expects to accumulate in the future. This involves efficient storage and access, but goes beyond that to facilitate intelligent data understanding and utilization through modeling realistic virtual entities with predictive capabilities. The objective of the study is to formulate ideas and concepts and to provide recommendations that lead to prototyping and implementation in the period from 2010 to 2020. The approach consists of the definition of future scenarios and needs for data usage in applications (in consultation with scientific and applications users), projection of advances in technologies, and an abstraction of an intelligent archive architecture. Strategic evolution is considered in various areas such as storage, data, information and knowledge management, data ingest and mining, user interfaces, and advances in intelligent data understanding algorithms.

Ramapriyan, H. K.↗

Earth Science Futuristic Trends and Implementing Strategies

For the last several years, there is a strong trend among the science community to increase the number of space-based observations to get a much higher temporal and spatial resolution. Such information will eventually be useful in higher resolution models that can provide predictability with higher precision. Such desirability puts a tremendous burden on any single implementing entity in terms of budget, technology readiness and compute power. The health of planet Earth is not governed by a single country, but in reality, is everyone's business living on this planet. Therefore, with this notion, it is becoming an impractical problem by any single organization/country to undertake. So far, each country per their means has proceeded along satisfactorily in implementing or benefiting directly or indirectly from the Earth observation data and scientific products. However, time has come that this is becoming a humongous problem to be undertaken by a single country. Therefore, this paper gives some serious thoughts in what options are there in undertaking this tremendous challenge. The problem is multi-dimensional in terms of budget, technology availability, environmental legislations, public awareness, and communication limitations. Some of these issues are introduced, discussed and possible implementation strategies are provided in this paper to move out of this predicament. A strong emphasis is placed on international cooperation and collaboration to see a collective benefit for this effort.

Habib, Shahid↗

Gradient Driven Fluctuations

We have worked with our collaborators at the University of Milan (Professor Marzio Giglio and his group-supported by ASI) to define the science required to measure gradient driven fluctuations in the microgravity environment. Such a study would provide an accurate test of the extent to which the theory of fluctuating hydrodynamics can be used to predict the properties of fluids maintained in a stressed, non-equilibrium state. As mentioned above, the results should also provide direct visual insight into the behavior of a variety of fluid systems containing gradients or interfaces, when placed in the microgravity environment. With support from the current grant, we have identified three key systems for detailed investigation. These three systems are: 1) A single-component fluid to be studied in the presence of a temperature gradient; 2) A mixture of two organic liquids to be studied both in the presence of a temperature gradient, which induces a steady-state concentration gradient, and with the temperature gradient removed, but while the concentration gradient is dying by means of diffusion; 3) Various pairs of liquids undergoing free diffusion, including a proteidbuffer solution and pairs of mixtures having different concentrations, to allow us to vary the differences in fluid properties in a controlled manner.

Cannell, David↗