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NASA NTRS2018

Space User Visibility Benefits of the Multi-GNSS Space Service Volume: An Internationally-Coordinated, Global and Mission-Specific Analysis

The number and scope of Global Navigation Satellite System (GNSS)-based space applications has grown significantly since the first GNSS space receiver was flown in the early 1980's. The vast majority of GNSS space users operate in Low-Earth Orbit (LEO), where the use of GNSS receivers has become routine. However, the use of GNSS has expanded to other orbit regimes like Geostationary Orbits (GEO) and High Eccentric Orbits (HEO) but has been very limited due to the challenges involved. The major challenges for such types of orbits including much weaker signals, reduced geometric diversity, and limited signal availability. In any case, considering the recent development of multiple GNSS constellations and ongoing upgrades to existing constellations, GNSS signal availability will improve significantly. As a result, this expanded multi-GNSS signal capability will enable improved on-orbit navigation performance and will also allow the development of new mission concepts. High altitude space users will especially benefit from this evolution, which will provide GNSS signals to challenging regimes well beyond Low Earth Orbit. These benefits will only be realised, however, if additional signals are designed to be interoperable, are clearly documented and supported. In order to enhance the overall GNSS performance for spacecraft's in regimes from LEO, GEO to HEO and beyond, all Satellite Navigation constellation providers and regional augmentation system providers are working together through the United Nations International Committee on GNSS (ICG) forum to establish an interoperable GNSS Space Service Volume (SSV) for the benefit of all GNSS space users. This paper provides an overview of the technical work and in particular the simulations, performance analysis and discussions of the outcomes and results obtained by the UN ICG Working Group-B in the context of the GNSS Space Service Volume activities, which were supported by all GNSS service providers.

systems↗

NASA NTRS2018

The Multi-GNSS Space Service Volume

Global Navigation Satellite Systems (GNSS), now routinely used for navigation by spacecraft in low Earth orbit, are being used increasingly by high-altitude users in geostationary orbit and high eccentric orbits as well, near to and above the GNSS constellations themselves. Available signals in these regimes are very limited for any single GNSS constellation due to the weak signal strength, the blockage of signals by the Earth, and the limited number of satellites. But with the recent development of multiple GNSS constellations and ongoing upgrades to existing constellations, multi-GNSS signal availability is set to improve significantly. This will only be achieved if these signals are designed to be interoperable and are clearly documented and supported.All satellite navigation constellation providers are working together through the United Nations International Committee on GNSS (ICG) to establish an interoperable multi-GNSS Space Service Volume (SSV) for the benefit of all GNSS space users. The multi-GNSS SSV represents a common set of baseline definitions and assumptions for high-altitude service in space, documents the service provided by each constellation, and provides a framework for continued support for space users. This paper provides an overview of the GNSS SSV concept, development, status, and achievements within the ICG. It describes the final adopted definition and performance characteristics of the GNSS SSV, as well as the numerous benefits and use cases enabled by this development, and summarizes extensive technical analysis that was performed to illustrate these benefits in terms of signal availability, both on a global scale, and for multiple distinct mission types.

navigation↗

NASA NTRS2019

Hydrological Land Surface Data and Services at NASA GES DISC

NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is one of twelveNASA Earth Observing System (EOS) data centers that process, archive, document, and distributedata from Earth science missions and related projects. The GES DISC hosts a wide range ofremotely-sensed and model data and provides reliable and robust data access and services to usersworldwide. This presentation, focusing on hydrological land surface data, provides a summary tablefor the hydrological data holdings, along with discussions of recent updates to data and data services.

Rui, Hualan↗

NASA NTRS2016

Managing and Servicing Physical Oceanographic Data at a NASA Distributed Active Archive Center

The NASA Earth Science Data Information Systems Project funds and operates 12 Distributed Active Archive Center(s) (DAAC) throughout the United States. Of these 12 centers, the Physical Oceanography DAAC (PO.DAAC) is committed to providing long term archival, distribution and stewardship for NASA physical oceanographic data, primarily derived from space-born satellite systems, but also including a growing set of recent and future in situ observations from the SPURS-1 and SPURS-2 campaigns. Notable NASA missions supported include: Seasat, TOPEX/Poseidon, NSCAT, QuikSCAT, ISS-RapidScat, Jason-1, Jason-2/OSTM, GRACE, Aquarius, GHRSST, and MODIS. The following interagency and international missions are also supported by PO.DAAC: AVHRR, Coriolis, DMSP, MetOp-A, MetOp-B, Oceansat-2. The PO.DAAC currently holds 525 datasets in public distribution, spanning the following observational parameters: sea surface temperature, sea surface salinity, ocean color, ocean surface currents, ocean surface wind speed, ocean surface wind direction, sea surface height, significant wave height, ocean water mass/thickness, and sea ice age. A hundred of these datasets are available in near-real-time. Datasets are distributed through a variety of open-source access protocols including FTP, OPeNDAP, and THREDDS. FTP will soon be phased out in favor of a recently introduced HTTPS PO.DAAC Drive interface that supports WebDAV and interoperable machine-to-machine communication. OPeNDAP supports remote data/metadata query, subset, and download. THREDDS provides the features of OPeNDAP with the additional feature of temporal aggregation. PO.DAAC also offers proprietary tools and services to further enhance the data discovery, visualization and analysis experience, including but not limited to: State of the Ocean, Web Services (data/metadata discovery and extraction), HiTIDE Level-2 subsetter, Live Access Server (LAS), Webification (w10nsci), and Rich Site Summary (RSS) Datacasting. To assist with provenance of datasets, PO.DAAC has implemented DOIs for the data it distributes so that they can be properly cited. There is a user forum and helpdesk that contains data recipes and via which users can get guidance. In summary, this presentation aims to provide a general overview of PO.DAAC’s web portal and data holdings along with a set of illustrative examples leading prospective data users into the practical utility of its tools and services.

Moroni, David F.↗

NASA NTRS2019

Demonstration Testing for Ground Servicing of the Commercial Crew Vehicle Emergency Breathing Air Assembly

The new Commercial crew vehicle (CCV) Breathing Air Assembly (CEBAA) is a Composite Overwrapped Pressure Vessel (COPV) filled with high-pressure air, which is designed to provide portable emergency breathing air for up to five crew in the event of an ammonia leak aboard the International Space Station (ISS). Industrially, several common methods of delivering breathing air exist; however, ground processing constraints and flight requirements necessitate the more unusual approach of servicing a COPV with high purity gaseous nitrogen and oxygen serially to achieve a specific mixture of breathing air at approximately 4000 PSIA. A dwell period allows the gases to mix before sampling for composition verification. The novelty of this approach led to concerns about acceptable gas mixing and the ability to deliver accurate gas compositions. Tests examining mixing rate over a series of post-servicing dwell periods were conducted to determine the optimal time for achieving a homogeneous mixture. Further testing was conducted to examine process accuracy using temperature-pressure load criteria to target a specific concentration of oxygen and nitrogen. Test results show that while some stratification of nitrogen and oxygen was observed, a seven-day dwell is adequate time to achieve an acceptable level of mixing, and that existing ground support equipment can accurately service CEBAA COPVs to the required temperature, pressure and composition for flight.

Active Thermal↗

NASA NTRS2019

Demonstration Testing for Ground Servicing of the Commercial Crew Vehicle Emergency Breathing Air Assembly

The new Commercial crew vehicle (CCV) Emergency Breathing Air Assembly (CEBAA) is a Composite Overwrapped Pressure Vessel (COPV) filled with high-pressure air, which is designed to provide portable emergency breathing air for up to five crew in the event of an ammonia leak aboard the International Space Station (ISS). Industrially, several common methods of delivering breathing air exist; however, ground processing constraints and flight requirements necessitate the more unusual approach of servicing a COPV with high purity gaseous nitrogen and oxygen serially to achieve a specific mixture of breathing air at approximately 4000 PSIA. A dwell period allows the gases to mix before sampling for composition verification. The novelty of this approach led to concerns about acceptable gas mixing and the ability to deliver accurate gas compositions. Tests examining mixing rate over a series of post-servicing dwell periods were conducted to determine the optimal time for achieving a homogeneous mixture. Further testing was conducted to examine process accuracy using temperature-pressure load criteria to target a specific concentration of oxygen and nitrogen. Test results show that while some stratification of nitrogen and oxygen was observed, a seven-day dwell is adequate time to achieve an acceptable level of mixing, and that existing ground support equipment can accurately service CEBAA COPVs to the required temperature, pressure and composition for flight.

Active Thermal↗

NASA NTRS2019

Flexible Modem Interface (FMI) in Space - Extending Standardized Commercial Satellite Communications Services to Space Users

Recent innovations are producing a multitude of advanced commercial satellite communications (COMSATCOM) systems that could deliver massive amounts of SATCOM capacity at a fraction of current cost while also offering reliability and availability that is critical to achieving mission success for orbiting assets. Recognizing the alignment of commercial capabilities with the National Aeronautics and Space Administration's (NASA) diverse mission requirements, the agency is proactively engaging industry to formulate strategies leading towards a NASA communications architecture that includes advanced commercial capabilities. To fully leverage the expanded space resources, NASA must also address the integration of commercial waveforms into its space terminals. In pursuit of similar goals, the United States Department of Defense (DoD) is leading the standardization of the flexible modem interface (FMI) to address service integration for their tactical terminals in pursuit of a DoD Wideband SATCOM Enterprise.This paper describes how NASA is adapting this FMI standard to work with the Space Telecommunications Radio System (STRS) software-defined radio (SDR) framework to address the challenging size, weight, and power resource requirements for terminals in space. A full adaptation would include waveform compatibility with modular baseband processing, frequency compatibility with a wideband front end, and radiated beam control with an electronically steerable antenna to enable multi-provider commercial service capability in a feasible package for space terminals. Security is also a key aspect to be addressed for this integration since data will flow through commercial networks, commercial service providers have their own security mechanisms, and space terminals must be able to securely load proprietary software and firmware needed to access the commercial networks on demand. Success of this effort means commercial partners will be able to allow network-compliant implementations to be hosted on STRS-compliant SDRs in space for reliable and capable network access.

COMSATCOM↗

NASA NTRS2018

Independent Configurable Architecture for Reliable Operation of Unmanned Systems with Distributed Onboard Services

This paper presents the development of ICAROUS-2 (Independent Configurable Architecture for Reliable Operation of Unmanned Systems with Distributed Onboard Services), the second generation of a software architecture that integrates several algorithms as distributed onboard services to enable robust autonomous UAS applications. In particular, the ICAROUS architecture defines a framework to perform detect and avoid, geofencing, path monitoring, path planning, and autonomous decision making to ensure safety and mission progress. Most of the core algorithms implemented in ICAROUS are formally verified using an interactive theorem prover. These algorithms are composed together using a plan execution engine, whose operational semantics is formally specified. A description of the integrated architecture, services currently available, and flight test results highlighting the capability of ICAROUS are presented.

Balachandran, Swee↗

NASA NTRS2018

Independent Configurable Architecture for Reliable Operation of Unmanned Systems with Distributed Onboard Services

Balachandran, Swee↗

NASA NTRS2019

NASA Global Satellite and Model Data Products and Services for Tropical Cyclone Research

The lack of observations over vast tropical oceans is a major challenge for tropical cyclone research. Satellite observations and model reanalysis data play an important role in filling these- gaps. Established in the mid-1980's, the Goddard Earth Sciences Data and Information Services Center (GES DISC), as one of the 12 NASA data centers, archives and distributes data from several Earth science disciplines such as precipitation, atmospheric dynamics, atmospheric composition, hydrology, including well-known NASA satellite missions (e.g. TRMM, GPM) and model assimilation projects (MERRA-2). Acquiring datasets suitable for tropical cyclone research in a large data archive is a challenge for many, especially for those who are not familiar with satellite or model data. Over the years, the GES DISC has developed user-friendly data services. For example, Giovanni is an online visualization and analysis tool, allowing users to visualize and analyze over 2000 satellite- and model-based variables with a Web browser, without downloading data and software. In this chapter, we will describe data and services at the GES DISC with emphasis on tropical cyclone research. We will also present two case studies and discuss future plans.

Liu, Zhong↗

NASA NTRS1994

The International GPS Service for Geodynamics - Benefits to Users

The International GPS Service for Geodynamics is an international scientific service which began formal operation at the beginning of 1994, following several years of planning and 1-1/2 year pilot service.

satellite↗

NASA NTRS2018

Next Generation Relay Services at Mars via an International Relay Network

Nearly all data acquired by vehicles on the surface of Mars are returned to Earth via Mars orbiters – more than 1.7 terabits so far. Successful communication between the various spacecraft is achieved via the careful implementation of internationally recognized CCSDS telecommunications protocols and the use of planning and coordination services provided by NASA’s Mars Program Office and the Multimission Ground Systems and Services (MGSS) Program at the Jet Propulsion Laboratory in Pasadena, CA. This modern Mars relay network has evolved since its inception in 2004 with the addition and loss of several missions, but it has fundamentally remained unchanged. Ground interfaces between the various spacecrafts’ mission operations centers on Earth remain largely unique for each participant, each mission maintains its own interfaces with deep space communications networks (e.g. DSN, ESTRACK), which are similar but still unique; and relay sessions at Mars require careful ground planning, coordination, and implementation. This paper will discuss the existing architecture and consider how several technologies may be applied to the next generation of relay services at Mars. Ultimately, these are expected to lead to the implementation of a delay and disruption tolerant network at Mars, a precursor to becoming a major element in an emerging Solar System Internet.

Edwards, Charles D. Jr↗

NASA NTRSDate not supplied

An Approach to Reasoning Service Migration in Data and Reasoning Fabric (DRF) Implementation

In this paper we consider service placement problem for Data and Reasoning Fabric (DRF) enabled airspace operations assuming a fixed cloud/edge infrastructure with allocated computing, storage and power resources, where cloud/edge servers, and communication stations are in a wired connected network, while vehicles use a wireless network for communication. The objective is to automatically select the best location for the requested service execution, which achieves minimum cost while satisfying the user quality of service (QoS) and available resources constraints. To this end, we estimate for each potential location the response time, consumed energy and total cost; formulate an optimization problem for cost minimization given the users QoS constraints and network infrastructure limitations; and solve it using nonlinear programming tools. The approach is applied to trajectory re-planning use case to handle a no-fly zone contingency in real time.

Vahram Stepanyan↗

NASA NTRSDate not supplied

Defining Services, Functions, and Capabilities for an Advanced Air Mobility (AAM) In-time Aviation Safety Management System (IASMS)

NASA’s vision for Advanced Air Mobility (AAM) Mission is to help emerging aviation markets to safely develop an air transportation system that moves people and cargo between places previously not served or underserved by aviation. The integration of new operational paradigms and vehicle classes in this system requires a transformation of the National Airspace System (NAS) that includes substantive changes critical for assuring safety. These changes are compelled by unique challenges posed by AAM to the safety management system (SMS). These challenges were assessed by committees of the National Academies in their reports on a vision for an In-time Aviation Safety Management System (IASMS) and a blueprint for AAM [1,2]. In their description of an IASMS, the top recommendation was development of a concept of operations (ConOps) for IASMS. This paper describes the high-priority recommendations from the National Academies for its IASMS vision and how they are addressed through a distributed system-of-systems architecture. The IASMS architecture is structured on the services, functions, and capabilities (SFCs) necessary for In-time System-wide Safety Assurance (ISSA)initially developed for urban air mobility (UAM). The paper then posits where these SFCs would reside across vehicles, airspace, or service suppliers such as Supplemental Data Service Providers (SDSPs), and how SFCs scale with increasing complexity in design and operations of AAM. SFCs are foundational building blocks for a system that targets an individual or family of risks using a Monitor-Assess-Mitigate risk paradigm for anomalies, precursors and trends. An IASMS could be conceived that uses a portfolio of SFCs for AAM in general or prioritizes SFCs for a specific domain or operation.

K Ellis↗

NASA NTRSDate not supplied

DIP Architecture and Data Integration Services

This workshop will cover DIP architecture and data integration services. Participants will get a look at how the DIP architecture is set-up as well as how data integration services are planned to be hosted on the platform. The DIP architecture review is intended to cover how DIP was envisioned and how DIP is being developed to address data needs across the industry. Participants will have a chance to provide feedback on the DIP architecture and gain insight into how one might interface with the DIP to send or receive data. The data integration services portion is intended to cover DIP’s technical approach to data integration. As an example implementation, there will be a first look at possible data fusion on the platform, including utilizing NASA’s Fuser, and tailoring for industry data consumers. Descriptions, at a high-level, of input to and output of the Fuser will also be discussed.

ATM-X↗

NASA NTRSDate not supplied

Recap of DIP Workshop Series: #1 DIP Architecture and Data Integrations Services

This workshop will cover DIP architecture and data integration services to obtain feedback from America for Airlines (A4A) Air Traffic Management Council (ATMC). Participants will get a look at how the DIP architecture is set-up as well as how data integration services are planned to be hosted on the platform. The DIP architecture review is intended to cover how DIP was envisioned and how DIP is being developed to address data needs across the industry. Participants will have a chance to provide feedback on the DIP architecture and gain insight into how one might interface with the DIP to send or receive data. The data integration services portion is intended to cover DIP’s technical approach to data integration. As an example implementation, there will be a first look at possible data fusion on the platform, including utilizing NASA’s Fuser, and tailoring for industry data consumers. Descriptions, at a high-level, of input to and output of the Fuser will also be discussed.

ATM-X↗

NASA NTRSDate not supplied

Reasoning Service Exemplars for NASA’s Data and Reasoning Fabric

Future operations for Urban and Advanced Air Mobility are enabled by a distributed network of reliable and secured data and reasoning services referred to here as a fabric. In the aggregate, such a system must be all encompassing and mission agnostic, but specific use-cases are still needed to improve understanding and drive design paradigms. For this purpose, three reasoning service exemplars for Target Selection and Routing, Trajectory Generation, and Battery Health Management were developed and integrated into a specific NASA proposed data and reasoning fabric. These services were then used to build a mission reasoning application for lightning strike reconnaissance developed in collaboration with the Civil Air Patrol. Autonomous mission execution was then demonstrated using a multivehicle simulation platform with a full envelope 6 Degree-of-Freedom dynamics model for a concept electric Vertical Takeoff and Landing aircraft.

Autonomy↗

NASA NTRSDate not supplied

Implementation of Field-Oriented Control in Joint Actuator Electronics for Satellite-Servicing Robotics

NASA’s OSAM-1 (On-orbit Servicing, Assembly, and Manufacturing 1) is a robotic spacecraft designed to extend the life of a satellite. Launching in 2026, the OSAM-1 servicer will use a robotic arm to grasp, refuel, and relocate Landsat 7. In order to accomplish the various servicing operations, including the critical auto-grapple capturing operation, the robot arm uses active compliance and visual servo control loops. These sophisticated control algorithms are enabled by the high performance Joint Control Boards (JCBs). At the core of the robot arm control architecture, the JCBs employ field-oriented control (FOC) to accurately commutate and efficiently control joint actuator torque. FOC offers numerous benefits over other current control methods, allowing the JCBs to achieve the high bandwidth and performance required by the outer control loops. As an added benefit, a torque feed-forward term allows the FOC loop to simulate microgravity actuator performance during ground testing. In this paper, a FOC implementation for space robotics applications and an end-to-end actuator calibration process are discussed.

Sam Zhao↗