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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Attitude Control and Orbital Dynamics Challenges of Removing the First 3-Axis Stabilized Tracking and Data Relay Satellite from the Geosynchronous ARC

Launched on April 4, 1983 onboard STS 6 (Space Shuttle Challenger), the First Tracking and Data Relay Satellite (TDRS 1) was retired above the Geosynchronous Orbit (GEO) on June 27, 2010 after having provided real-time communications with a variety of low-orbiting spacecraft over a 26-year period. To meet NASA requirements limiting orbital debris 1, a team of experts was assembled to conduct an End-Of-Mission (EOM) procedure to raise the satellite 350 km above the GEO orbit. Following the orbit raising via conventional station change maneuvers, the team was confronted with having to deplete the remaining propellant and passivate all energy storage or generation sources. To accomplish these tasks within the time window, communications (telemetry and control links), electrical power, propulsion, and thermal constraints, a spacecraft originally designed as a three-axis stabilized satellite was turned into a spinner. This paper (a companion paper to Innovative Approach Enabled the Retirement of TDRS 1, paper # 1699, IEEE 2011 Aerospace Conference, March 5-12, 2011 sup 2) focuses on the challenges of maintaining an acceptable spinning dynamics, while repetitively firing thrusters. Also addressed are the effects of thruster firings on the orbit characteristics and how they were mitigated by a careful scheduling of the fuel depletion operations. Periodic thruster firings for spin rate adjustment, nutation damping, and precession of the momentum vector were also required in order to maintain effective communications with the satellite. All operations were thoroughly rehearsed and supported by simulations thus lending a high level of confidence in meeting the NASA EOM goals.

Benet, Charles A.↗
NASA NTRS2011

Implementing Strategic Planning Capabilities Within the Mars Relay Operations Service

Throughout this development and deployment process we have followed a few guiding principles: (1) Ensure ubiquitous access through ReSTful and web interfaces; (2) Design a system that is mission and even planet agnostic so that future missions may be added with little hassle, and the system itself may be redeployed for other planetary relay networks; (3) Accept constant input and feedback between mission operators and the development team to ensure that there is a useful product that may be used for years to come.

software development↗
NASA NTRS2012

Application of Multihop Relay for Performance Enhancement of AeroMACS Networks

A new transmission technology, based on IEEE 802.16-2009 (WiMAX), is currently being developed for airport surface communications. A C-band spectrum allocation at 5091 to 5150 MHz has been created by International Telecommunications Union (ITU) to carry this application. The proposed technology, known as AeroMACS, will be used to support fixed and mobile ground to ground applications and services. This article proposes and demonstrates that IEEE 802.16j-amendment-based WiMAX is most feasible for AeroMACS applications. This amendment introduces multihop relay as an optional deployment that may be used to provide additional coverage and/or enhance the capacity of the network. Particular airport surface radio coverage situations for which IEEE 802.16-2009-WiMAX provides resolutions that are inefficient, costly, or excessively power consuming are discussed. In all these cases, it is argued that 16j technology offers a much better alternative. A major concern about deployment of AeroMACS is interference to co-allocated applications such as the Mobile Satellite Service (MSS) feeder link. Our initial simulation results suggest that no additional interference to MSS feeder link is caused by deployment of IEEE 802.16j-based AeroMACS.

Kamali, Behnam↗
NASA NTRS2012

Application of Multihop Relay for Performance Enhancement of AeroMACS Networks

A new transmission technology, based on IEEE 802.16-2009 (WiMAX), is currently being developed for airport surface communications. A C-band spectrum allocation at 5091-5150 MHz has been created by ITU to carry this application. The proposed technology, known as AeroMACS, will be used to support fixed and mobile ground to ground applications and services. This article proposes and demonstrates that IEEE 802.16j-amendment-based WiMAX is most feasible for AeroMACS applications. This amendment introduces multihop relay as an optional deployment that may be used to provide additional coverage and/or enhance the capacity of the network. Particular airport surface radio coverage situations for which IEEE 802.16-2009-WiMAX provides resolutions that are inefficient, costly, or excessively power consuming are discussed. In all these cases, it is argued that 16j technology offers a much better alternative. A major concern about deployment of AeroMACS is interference to co-allocated applications such as the Mobile Satellite Service (MSS) feeder link. Our initial simulation results suggest that no additional interference to MSS feeder link is caused by deployment of IEEE 802.16j-based AeroMACS.

Kamali, Behnam↗
NASA NTRS2015

Applying a Space-Based Security Recovery Scheme for Critical Homeland Security Cyberinfrastructure Utilizing the NASA Tracking and Data Relay (TDRS) Based Space Network

Protection of the national infrastructure is a high priority for cybersecurity of the homeland. Critical infrastructure such as the national power grid, commercial financial networks, and communications networks have been successfully invaded and re-invaded from foreign and domestic attackers. The ability to re-establish authentication and confidentiality of the network participants via secure channels that have not been compromised would be an important countermeasure to compromise of our critical network infrastructure. This paper describes a concept of operations by which the NASA Tracking and Data Relay (TDRS) constellation of spacecraft in conjunction with the White Sands Complex (WSC) Ground Station host a security recovery system for re-establishing secure network communications in the event of a national or regional cyberattack. Users would perform security and network restoral functions via a Broadcast Satellite Service (BSS) from the TDRS constellation. The BSS enrollment only requires that each network location have a receive antenna and satellite receiver. This would be no more complex than setting up a DIRECTTV-like receiver at each network location with separate network connectivity. A GEO BSS would allow a mass re-enrollment of network nodes (up to nationwide) simultaneously depending upon downlink characteristics. This paper details the spectrum requirements, link budget, notional assets and communications requirements for the scheme. It describes the architecture of such a system and the manner in which it leverages off of the existing secure infrastructure which is already in place and managed by the NASAGSFC Space Network Project.

Cybersecurity↗
NASA NTRS2016

Ka-band Technologies for Small Spacecraft Communications via Relays and Direct Data Downlink

As the scientific capabilities and number of small spacecraft missions in the near Earth region increase, standard yet configurable user spacecraft terminals operating in Ka-band are needed to lower mission cost and risk and enable significantly higher data return than current UHF or S-band terminals. These compact Ka-band terminals are intended to operate with both the current and next generation of Ka-band relay satellites and via direct data communications with near Earth tracking terminals. This presentation provides an overview of emerging NASA-sponsored and commercially provided technologies in software defined radios (SDRs), transceivers, and electronically steered antennas that will enable data rates from hundreds of kbps to over 1 Gbps and operate in multiple frequency bands (such as S- and X-bands) and expand the use of NASA's common Ka-bands frequencies: 22.55-23.15 GHz for forward data or uplink; and 25.5-27.0 GHz for return data or downlink. Reductions in mass, power and volume come from integration of multiple radio functions, operations in Ka-band, high efficiency amplifiers and receivers, and compact, flat and vibration free electronically steered narrow beam antennas for up to + 60 degrees field of regard. The software defined near Earth space transceiver (SD-NEST) described in the presentation is intended to be compliant with NASA's space telecommunications radio system (STRS) standard for communications waveforms and hardware interoperability.

Extremely High Frequency↗
NASA NTRS2017

Laser Communications Relay Demonstration: Introduction for Experimenters

This document provides guidance to individuals or groups considering proposing an experiment for the Laser Communications Relay Demonstration (LCRD) Experiment Program. For the purposes of this document, the term experiment refers to both experiments and demonstrations. The documents goals are: (1) to introduce potential experimenters to the LCRD mission, its purpose, and its system architecture; (2) to help them understand the types of experiments that are possible using LCRD; and (3) to provide an overview of the experiment proposal process and explain how and where to obtain further information about making a proposal.

Israel, David J.↗
NASA NTRS2016

Measurement of Error Vector Magnitude (EVM) to Characterize the Impairment of the Tracking and Data Relay Satellite (TDRS) Channel

A digital signal is transmitted via a carrier wave, it demodulates at a receiver, and locates at an ideal constellation point. However, noise distortion, carrier leakage, and phase noise can force a signal to divert from its ideal position to a new position. Consequently, the performance of the signal is decreased. Bit Error Rate (BER) and Error Vector Magnitude (EVM) measurement techniques are used to enable the analysis and assessment of the extent to which the performance of a signal has been decreased. In this paper, we present the EVM measurement technique as a figure of merit to analyze and evaluate the performance of a User Services Subsystem Component Replacement (USSCR) modem. Also, we demonstrate the use of the EVM measurement technique in a Tracking and Data Relay Satellite (TDRS) system to measure and evaluate channel impairment between a satellite (transmitter) and the ground terminal (receiver) at the White Sands Complex.

Spacecraft RF Communications↗
NASA NTRS2016

Evolution of the Mars Relay Network End-to-End Information System in the Mars Human Era (2030-2040)

In order to help the reader understand this evolution from the current to the future MRN state in the Mars human era, we will provide a description of the current communication infrastructure supporting Mars mission users, and how we envision it to change in order to meet the needs and challenges of supporting both human and robotic communication by 2030-2040. This includes the introduction of new data types like audio and video, and new in-situ relay services for communications and navigation services.

Kazz, Greg J.↗
NASA NTRS2016

Evolution of the Mars Relay Network End-To-End Information System in the Mars Human Era (2016-2040)

In order to help the reader understand this evolution from the current to the future MRN state in the Mars human era, we will provide a description of the current communication infrastructure supporting Mars mission users, and how we envision it to change in order to meet the needs and challenges of supporting both human and robotic communication by 2030-2040. This includes the introduction of new data types like audio and video, and new in-situ relay services for communications and navigation services.

Kazz, Greg↗
NASA NTRS2019

Global search of resonant trasfers for a Europa Lander to Clipper data relay

Following its prime mission Europa Clipper becomes a potential asset to relay data from a proposed Europa Lander back to Earth. To this end, we describe an efficient method to globally search for trajectories that repeatedly fly over the same location of Europa. Different families of trajectories emerge with different flyby geometries that satisfy a convoluted set of landing constraints. Here, the landing location and local solar time must match a limited set derived from expected Clipper observations, while providing multiple opportunities to land in a given season. We include estimates for data volume and radiation dose associated with these resonant trajectories.

Campagnola, Stefano↗
NASA NTRSDate not supplied

Framework for NASA Space Relay Satellite Services over the Next Decade: “Development and Demonstration of the Commercial Successors to TDRS “

The United States National Space Policy provides guidance and directives for U.S. Government agencies to purchase commercial space services and capabilities to the maximum extent practical. In alignment with this guidance, the Agency has no plans to replenish the Tracking and Data Relay Satellite System (TDRSS) fleet operated by the Space Communication and Navigation Program (SCaN) and will instead pursue commercial services for communications with spacecraft in near-Earth orbit. The Communication Services Project (CSP) at GRC is leading this commercialization effort and in May 2022 it awarded six contracts to commercial SATCOM companies to demonstrate and validate commercial SATCOM capabilities for future NASA missions. The responses from the vendors indicated a strong interest in providing commercial services to NASA’s missions, and included a wide range of proposed architectures and demonstrations ideas. Overall, the responses indicated that a mature and healthy competitive environment exists with traditional satellite operators and constellation developers to provide NASA with commercial communication services in the next five years. This paper will present an overview of the proposed capability coverages, risk spread and US domestic market stimulation along with common themes and conclusions. The result of these demonstrations will serve as the basis for acquisition and provision of operational SATCOM services for NASA missions.

George F Haddad↗
NASA NTRSDate not supplied

Flight and Direct to Earth/Space Relay Communication System Architecture for GSFC CubeSat Missions

The CubeSat platform is finding increasing use in space science applications due to its low cost and comparative ease of launch. It is becoming a key scientific discovery tool in low Earth orbit (LEO) and beyond, including geosynchronous equatorial orbit (GEO), the Lagrange Points, Lunar missions, and more. The increasing complexity of these missions and their scientific goals must be supported by equal advancements in communications technology. Higher data rates and greater reliability are required every year. However, the reduced Size, Weight, and Power (SWaP) constraints of CubeSat platforms introduce unique challenges in the area of satellite communications. There is currently a lack of communication equipment tailored specifically to the CubeSat platform. This lack of standardized, tested equipment extends development time and reduces mission confidence. Furthermore, missions utilizing the CubeSat platform are often subject to more difficult design constraints. Antenna placement, size, and pointing are often subordinate to the requirements of the payload instruments and mission goals. Traditional link margin estimation techniques are insufficient in these cases, as they emphasize worst case scenarios. In reality the actual link parameters may vary widely even during a single pass. This presents new challenges in predicting communications performance and scheduling ground station contacts, but also new opportunities for improving efficiency. This paper presents the integration, testing, and validation process for a new software defined radio (SDR) designed for the CubeSat platform in conjunction with Vulcan Wireless, Inc. The SDR is planned for use on 5 upcoming CubeSat missions at NASAs Goddard Space Flight Center (GSFC) including a Geosynchronous Transfer Orbit (GTO) mission and it may also serve as a standard and well-tested option for future missions by enabling a standardized, rapid and low cost CubeSat communication system network integration process. Detailed simulations have been developed to estimate the communication performance of these missions, taking the unique antenna placements and attitude behavior of each satellite into account. These simulations allow a much more accurate analysis of the expected link margin, which varies considerably during each pass for the NASA Space Relay (SR) and Direct to Earth (DTE) network. The modelling procedures are outlined, and the results are used to predict communications performance of the missions.

Space Networks↗
NASA NTRSDate not supplied

Laser Communications Relay Demonstration: Experiments With Delay Tolerant Networking

The Laser Communications Relay Demonstration (LCRD) is a NASA mission that is presently providing a link between two optical ground stations on Earth and geosynchronous orbit; this capability will be extended to include a laser terminal on the International Space Station (ISS). From a practical perspective, LCRD provides a 1Gbps Ethernet link with an anticipated round-trip time of 4 seconds. Delay Tolerant Networking (DTN) is being used to transcend LCRDs capabilities from a point-to-point link to true network connectivity. Indeed, integrating the LCRD link into any network, such as one aboard the ISS, adds new hops and paths. In this paper, we detail DTN experiments conducted using LCRD to demonstrate how DTN and optical capabilities complement each other to enable the next generation of space communication modalities. We conclude with considerations on using LCRD to connect the ISS to the optical ground stations.

Alan Hylton↗
NASA NTRSDate not supplied

Laser Communications Relay Demonstration Optimetrics Experiment

Within this paper, we report on an Optimetrics experiment conducted on the National Aeronautics and Space Administration (NASA) Laser Communication Relay Demonstration (LCRD). The high precision two-way ranging is conducted on the optical communications link between the LCRD space terminal in a geosynchronous orbit and the Optical Ground Station 1 (OGS1) at Table Mountain, California, and is referred to as optimetrics ranging. The receiver to transmitter clock loopback is implemented in the LCRD space modem. A digital dual mixer time difference phase meter (DDMTD) is implemented in the OGS1 ground modem. The round-trip time is measured with the DDMTD by counting the frame and data clock ticks between transmitter and receiver frame synchronization markers for coarse range, and the relative phase of the transmit and receive clock for high precision range. This approach provides coverage for all potential ranges with no ranging ambiguity. The flight modem FPGA code was modified for frame and data clock loopback and the OGS1 FPGA code was modified for the DDMTD phase meter implementation. The experiment team conducted a 36-hour continuous ranging measurement. Preliminary two-way optimetrics ranging data show a noise floor of 3cm (rms). Based on our theoretical noise analysis and ground tests with spare flight modems, we expected one order of magnitude improvement on ranging precision. We are conducting detailed post data processing to identify the differences to further reduce the noise level and formulating an improved implementation approach for future missions. For reference and comparison, traditional Radio Frequency (RF) ranging between LCRD and OGS1 was conducted at the same time and indicates a ranging noise floor of 30cm(rms). Other telemetry and relevant environmental parameters such as weather and atmosphere temperature were also collected for offline data processing. The high precision ranging and range rate measurements from the laser communications data link clock and clock phase are performed simultaneously with continuous optical communication. No extra hardware added to existing system. This high precision optimetrics measurement implementation provides alternative ranging and range rate measurements for orbit determination (OD) and flight dynamics calculations with higher precision. We see significant improvement on OD for navigation upon implementation in future optical communication systems.

Rafael Garcia↗