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At least 109 records · Page 6

Adaptive Deployable Entry Placement Technology (ADEPT) Development for Small Sat Class Venus Missions

The Adaptable, Deployable Entry and Placement Technology (ADEPT) is a novel approach for entry vehicle design. Similar to an umbrella, it is stowed during launch and deployed prior to entry. ADEPT employs a high performance, 3-D woven, carbon fabric to serve as the primary surface of the mechanically deployed system. The successful ADEPT sounding rocket flight test matured the 1-meter Class ADEPT in the areas of deployment and structural integrity, and provided aerodynamic flight characteristics of the ADEPT open-back configuration from Mach 3 to Mach 0.3. Aerocapture uses the aerodynamic drag from a single hyperbolic atmospheric pass to provide the delta-V needed for orbit insertion. Studies suggest that, compared to propulsive orbit insertion, aerocapture could increase delivered payload by 70 percent at Venus. Drag modulation aerocapture, which shows promise of being simpler and more cost-effective than the more-often studied lift modulation methods, uses in-flight transformations of an entry vehicle's drag area to control the amount of deceleration produced during an atmospheric pass. In single-event drag modulation, a drag device is jettisoned after the appropriate deceleration. ADEPT, due to its unique ability to fold and unfold, is being considered for this SmallSat class payload mission applications.

Cassell, Alan M.↗

Large-scale fine-resolution products of forest disturbance using new approaches from spaceborne SAT interferometry

Spaceborne SAR interferometry (InSAR) has the potential ofdetecting forest change on a global scale with fine (meter-level)spatial resolution as well as on a monthly/weekly basis under allweather conditions. This is significant to characterize the land usechange and its impact on climate change. In this paper, bothsingle-pass and repeat-pass SAR interferometry from spacebornesensors are combined in order to detect and quantify (withNormalized RMSE 30%) forest disturbance at a large scale(dozens of kilometers) however with a fine spatial resolution (<1 hectare) based on two newly developed approaches. The singlepassInSAR approach is not only able to detect forest disturbancebut also capable of characterizing meter (or even sub-meter)level change of forest phase-center (mean) height due to forestgrowth and/or degradation. The methodology described in thispaper can be considered as complimentary tools and thus can becombined with the existing PolInSAR technique (that has beenwidely used for retrieving forest height from single-pass SARinterferometry). These methods are extensively validated with thepast and current spaceborne single-pass and repeat-pass InSARmissions (i.e. JAXA’s ALOS-1, ALOS-2 and DLR’s TanDEM-X)over subtropical forests in Australia as well as tropical forestsin Brazil. Such techniques also serve as observing prototypes forthe fusion of the future spaceborne InSAR missions (such asNASA-ISRO’s NISAR and DLR’s TanDEM-L).

Schmidt, Michael↗

A GNSS Receiver for Small-Sats Enabling Precision POD, Radio Occultations and Reflections

A low cost, low power, and low mass GNSS receiver (called Cion) has been developed and is currently flying on the CICERO cubesats. The receiver was designed in less than a year by JPL for Tyvak and GeoOptics for use in the GeoOptics CICERO constellation and leverages 25 years of JPL GNSS reciever design experience. Cion uses a commercial off-the-shelf (COTS) computer along with existing space qualified RF down-converters, software, and firmware to produce atmospheric Radio Occultation (RO) data. By combining a FPGA with dual core ARM processor and an embedded system controller, the Xilinx Zynq processor is an enabling technology that provides a customizable digital signal processing platform integrated into the computer (System on a chip) and enables off-the-shelf hardware to become the main engine behind this software defined radio. Using Linux for the on-board computer allows for fast development times and liberal use of existing open source software libraries. The parts of the receiver that require realtime implementation are performed in the Field Programmable Gate Array (FPGA), which can also be reprogrammed in flight. While the Zynq is not rad hard, the silicon on insulator (SOI) technology is rad tolerant ‘by accident’, allowing for its use in many space-based applications. Early results show that the Cion is working as designed, has demonstrated the first known GLONASS occultations, and obtains high quality atmospheric profiles with excellent lower troposphere penetration (near Earth’s surface).

Young, Larry↗

Online Small-Sat Knowledge Repositories and Modeling Tools for Risk Reduction and Enhanced Mission Success

Developers of small satellites face the challenges of a short development schedule, incomplete information about parts from vendors, and limited budgets. The situation is complicated by the need to use commercial electronic parts rather than radiation hardened parts to meet performance and budget constraints. Fortunately, a number of organizations are standing up new modeling and data resources that are available for free online. Motivation for sharing models, part data, and lessons learned include shorter development times, increased mission success likelihood, and training the next generation of space professionals. The purpose of this paper is to make these resources and their complementary capabilities known to the small satellite community.

Small Satellites↗

Small Sat Simulated Space Environment MagLev Testbed

Development of a ground-based planar testbed with a near frictionless, vacuum environment for small spacecraft allows for higher fidelity, 3 degree of freedom (3DoF) testing of fully integrated propulsion systems and control algorithms prior to launch. This provides empirical data at a relatively low cost that can be used to reduce risk of on-orbit failures thereby mitigating contributions of small spacecraft to the growing orbital debris issue.

Jeremy Bruggemann↗

TechEd Sat-11 Cognitive Engine-1 Experiments

This presentation discusses the experiment concept of operations, flight and ground software, and current status of Technology Educational Satellite 11 (TechEdSat-11).

Rachel Dudukovich↗

Access to Space for NASA Small Sats: Current and Future Needs

Small spacecraft technology advancements have fundamentally shifted how NASA’s Science Mission Directorate (SMD) executes science investigations. To support this approach, the SMD Rideshare Office (SRO) was established in 2020 to lead the definition and implementation of a directorate-wide rideshare strategy. Serving as the central point of contact for coordinating compatible NASA payloads with launch opportunities, the SRO maximizes science, exploration, and technology return on investment by enabling rideshare or other access to space opportunities for small spacecraft on SMD primary mission launches, VADR commercial launch procurements, and other government agency launch opportunities. As NASA seeks to reduce costs and increase the rate of discovery, small satellites and multi manifest access to space have become integral to achieving the agency’s strategic vision. While NASA has created the above-mentioned mechanisms to expand access to space and achieve lower launch costs for its small satellites, many factors have limited full exploit of the opportunity these mechanisms can bring. NASA continues to evolve its mission cultures and technical requirements to adapt and take advantage of burgeoning commercial launch and rideshare advancements. To do so NASA requires collaboration with small satellite manufacturers, principal investigators, and commercial industry partners. Current needs include technical development and design of structurally robust spacecraft buses capable of withstanding varied launch loads, which will increase rideshare interchangeability and versatility. Further, instrument and spacecraft designs must also evolve to handle diverse launch environments and loads factors, while reducing reliance on complex purge and cleanliness constraints, sensitivities to silicones and hydrocarbons, and magnetic requirements. Continued maturation of small and medium launch providers in the near-term is also essential to drive down costs through competition. The current mission selection cadence often complicates the ability to synchronize multiple missions on a single launch. Future needs can include affordable space maneuverability options such as enhanced spacecraft propulsion systems and unique orbital maneuvering capabilities for our individual smallsats or constellations. These emerging capabilities offer a path to unique science orbits for NASA small satellites, but only under the condition that their cost remains affordable and competitive to accommodate inherently smaller mission budgets. Additionally, the projected surge of multiple SMD small satellites launching simultaneously and to unique deep space science orbits necessitates evaluation of expanding deep space communications capabilities. This presentation provides a comprehensive overview of NASA SMD’s access to space landscape and offers further unique insights and discussion, backed by NASA rideshare experiences and lessons learned, on the current and future developments required to unleash the full potential of rideshare opportunities.

Rideshare↗

Northern Hemisphere Winter Air Temperature Patterns and Their Associated Atmospheric and Ocean Conditions

The Northern Hemisphere (NH) has experienced winter Arctic warming and continental cooling in recent decades, but the dominant patterns in winter surface air temperature (SAT) are not well understood. Here, a self-organizing map (SOM) analysis is performed to identify the leading patterns in winter daily SAT fields from 1979 to 2018, and their associated atmospheric and ocean conditions are also examined. Three distinct winter SAT patterns with two phases of nearly opposite signs and a time scale of 7–12 days are found: one pattern exhibits concurrent SAT anomalies of the same sign over North America (NA) and northern Eurasia, while the other two patterns show SAT anomalies of opposite signs between, respectively, NA and the Bering Sea, and the Kara Sea and East Asia (EA). Winter SAT variations may arise from changes in the SOM frequencies. Specifically, the observed increasing trends of winter cold extremes over NA, central Eurasia, and EA during 1998–2013 can be understood as a result of the increasing occurrences of some specific SAT patterns. These SOMs are closely related to poleward advection of midlatitude warm air and equatorward movements of polar cold airmass. These meridional displacements of cold and warm airmasses cause concurrent anomalies over different regions not only in SAT but also in water vapor and surface downward longwave radiation. Anomalous sea surface temperatures in the tropical Pacific, midlatitude North Pacific, and North Atlantic and anomalous Arctic sea ice concentrations also concur to support and maintain the anomalous atmospheric circulation that causes the SAT anomalies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A structural equation modeling approach to leveraging the power of extant sentiment analysis tools

Machine-derived sentiment analysis has become a pervasive and useful tool to address a wide array of issues in natural language processing. Leading technology companies such as Google now provide sentiment analysis tools (SATs) as readily accessible online products. Academic researchers develop and make available SATs to support the research enterprise. One of the major challenges with SATs is the inconsistencies in results among the various SATs. Consequently, the selection of a SAT for a specific purpose may significantly impact the application. This study addresses the foregoing problem by utilizing structural equation modeling to merge the outputs of SATs to develop a combined sentiment metric without the need for a labeled training dataset. This method is applicable to a wide range of text-based problems, is data-driven, and replicable. It was tested using three publicly available datasets and compared against seven different SATs. The results indicate that as a continous measure, the proposed method outperformed other SATs in the movie reviews and SemEval datasets, and achieved a tie for first place with IBM Watson on the Sentiment 140 dataset. Also, compared to the published major alternatives, the arithmetic mean solution, this approach performed better across these three datasets.

97 MATHEMATICS AND COMPUTING↗