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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Software Tool for Tracking & Mapping the NASA Orion AA-2 Test Flight Ejectable Data Recorders in Real Time

On 2 July 2019, the NASA Ascent Abort 2 flight took place off the Florida coast to test the emergency systems to separate the Orion Crew Module (CM) from the future Space Launch System rocket in the event of a malfunction. During this high-altitude test, instrumentation data was recorded on twelve customized buoyant Ejectable Data Recorders (EDRs) and subsequently jettisoned from the CM in mid-air. Upon release, the EDRs activated their GPS-Iridium beacon systems and began transmitting Short Burst Data (SBD) messages via the Iridium satellite network to relay their individual location and system health information. To locate, track and retrieve each EDR from the ocean surface in real-time, multiple open-source programming tools (Python and Linux shells) were developed for parsing the incoming Iridium binary SBD messages. For this, a Linux laptop was used to receive the Iridium-generated emails containing the SBD messages and autonomously execute the parsing tools. The received SBD data contained location, timestamp and health status information that was translated, saved, and subsequently used for simultaneously generating a continuously updated color-coded tabular display summary and unique KML files used with Google Earth to track their locations. Once their locations were known, dedicated recovery vessels retrieved all EDRs from the ocean. An additional tool was also developed in order to generate 5- and 10-minute geolocation predictions for each EDR by deriving the displacement distance, elapsed time, displacement heading and velocity based on the latest known information available. The recovery vessels were also tracked with the use of a separate commercial GPS beacon system. After jettison, 67% of the EDRs transmitted valid data by the time they were retrieved from the ocean. However, the real-time information presented by the plotting tool allowed for the ready depiction of EDR dispersal patterns and reference drift trajectories, which contributed to the recovery of all twelve EDRs and the AA-2 flight data. Lastly, the available data showed that the distance between the software’s reported drift/predicted locations and the recovery locations did not exceed 38 meters, therefore demonstrating the advantages of this software tool for supporting real-time tracking and recovery efforts of beacon devices.

Moxey, Lucas↗
NASA NTRS2017

Integrating Communication and Navigation: Next Generation Broadcast Service (NGBS)

NASA Goddard has been investing in technology demonstrations of a beacon service, now called Next Generation Broadcast Services (NGBS). NGBS is a global, space-based, communications and navigation service for users of Global Navigation Satellite Systems (GNSS) and the Tracking and Data Relay Satellite System (TDRSS). NGBS will provide an S-band beacon messaging source and radio navigation available to users at orbital altitudes 1400 km and below, increasing the autonomy and resiliency of onboard communication and navigation. NGBS will deliver both one-way radiometric (Doppler and pseudorange) and fast forward data transport services to users. Portions of the overall forward data volume will be allocated for fixed message types while the remaining data volume will be left for user forward command data. The NGBS signal will reside within the 2106.43 MHz spectrum currently allocated for the Space Networks multiple access forward (MAF) service and a live service demonstration is currently being planned via the 2nd and 3rd generation TDRS satellites.

Navigation↗
NASA NTRS1991

Analysis of navigation performance for the Earth Observing System (EOS) using the TDRSS Onboard Navigation System (TONS)

Use of the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) was proposed as an alternative to the Global Positioning System (GPS) for supporting the Earth Observing System (EOS) mission. The results are presented of EOS navigation performance evaluation with respect to TONS based orbit, time, and frequency determination (OD/TD/FD). Two TONS modes are considered: one uses scheduled TDRSS forward link service to derive one way Doppler tracking data for OD/FD support (TONS-I); the other uses an unscheduled navigation beacon service (proposed for Advanced TDRSS) to obtain pseudorange and Doppler data for OD/TD/FD support (TONS-II). Key objectives of the analysis were to evaluate nominal performance and potential sensitivities, such as suboptimal tracking geometry, tracking contact scheduling, and modeling parameter selection. OD/TD/FD performance predictions are presented based on covariance and simulation analyses. EOS navigation scenarios and the contributions of principal error sources impacting performance are also described. The results indicate that a TONS mode can be configured to meet current and proposed EOS position accuracy requirements of 100 and 50 m, respectively.

Elrod, B.↗
NASA NTRS1996

A mission operations architecture for the 21st century

An operations architecture is proposed for low cost missions beyond the year 2000. The architecture consists of three elements: a service based architecture; a demand access automata; and distributed science hubs. The service based architecture is based on a set of standard multimission services that are defined, packaged and formalized by the deep space network and the advanced multi-mission operations system. The demand access automata is a suite of technologies which reduces the need to be in contact with the spacecraft, and thus reduces operating costs. The beacon signaling, the virtual emergency room, and the high efficiency tracking automata technologies are described. The distributed science hubs provide information system capabilities to the small science oriented flight teams: individual access to all traditional mission functions and services; multimedia intra-team communications, and automated direct transparent communications between the scientists and the instrument.

Tai, W.↗
NASA NTRS1973

The minitrack tracking function description, volume 1

The treatment of tracking data by the Minitrack system is described from the transmission of the nominal 136-MHz radio beacon energy from a satellite and the reception of this signal by the interferometer network through the ultimate derivation of the direction cosines (the angular coordinates of the vector from the tracking station to the spacecraft) as a function of time. Descriptions of some of the lesser-known functions operating on the system, such as the computer preprocessing program, are included. A large part of the report is devoted to the preprocessor, which provides for the data compression, smoothing, calibration correction, and ambiguity resolution of the raw interferometer phase tracking measurements teletyped from each of the worldwide Minitrack tracking stations to the central computer facility at Goddard Space Flight Center. An extensive bibliography of Minitrack hardware and theory is presented.

Englar, T. S., Jr.↗
NASA NTRS2016

Navigation Architecture for a Space Mobile Network

The Tracking and Data Relay Satellite System (TDRSS) Augmentation Service for Satellites (TASS) is a proposed beacon service to provide a global, space based GPS augmentation service based on the NASA Global Differential GPS (GDGPS) System. The TASS signal will be tied to the GPS time system and usable as an additional ranging and Doppler radiometric source. Additionally, it will provide data vital to autonomous navigation in the near Earth regime, including space weather information, TDRS ephemerides, Earth Orientation Parameters (EOP), and forward commanding capability. TASS benefits include enhancing situational awareness, enabling increased autonomy, and providing near real-time command access for user platforms. As NASA Headquarters' Space Communication and Navigation Office (SCaN) begins to move away from a centralized network architecture and towards a Space Mobile Network (SMN) that allows for user initiated services, autonomous navigation will be a key part of such a system. This paper explores how a TASS beacon service enables the Space Mobile Networking paradigm, what a typical user platform would require, and provides an in-depth analysis of several navigation scenarios and operations concepts. This paper provides an overview of the TASS beacon and its role within the SMN and user community. Supporting navigation analysis is presented for two user mission scenarios: an Earth observing spacecraft in low earth orbit (LEO), and a highly elliptical spacecraft in a lunar resonance orbit. These diverse flight scenarios indicate the breadth of applicability of the TASS beacon for upcoming users within the current network architecture and in the SMN.

Data Relay↗
NASA NTRS1963

Concerning satellite S66

Laser tracking device problem, directional adjustment, electronics, and reflector data for S-66 ionosphere beacon satellite

BEACON SATELLITE↗
NASA NTRS1983

NASA News

The launch of NOAA E, an advanced TIROS N (ATN) environmental monitoring satellite, carrying special search and rescue instrumentation is announced. NOAA E carries instrumentation for a demonstration to search and rescue (SAR) mission agencies for evaluation of a satellite aided SAR system that may lead to the establishment of an operational capability. The ability of a spaceborne system to acquire, track and locate existing Emergency Locator Transmitters (ELTs) and Emergency Position Indicating Radio Beacons (EPIRBs) that are being used aboard general aviation and other aircraft, and ships, and are operating on 121.5 and 243 Megahertz frequencies is demonstrated.

Source record↗
NASA NTRS2011

Initial Considerations for Navigation and Flight Dynamics of a Crewed Near-Earth Object Mission

A crewed mission to a Near-Earth Object (NEO) was recently identified as a NASA Space Policy goal and priority. In support of this goal, a study was conducted to identify the initial considerations for performing the navigation and flight dynamics tasks of this mission class. Although missions to a NEO are not new, the unique factors involved in human spaceflight present challenges that warrant special examination. During the cruise phase of the mission, one of the most challenging factors is the noisy acceleration environment associated with a crewed vehicle. Additionally, the presence of a human crew necessitates a timely return trip, which may need to be expedited in an emergency situation where the mission is aborted. Tracking, navigation, and targeting results are shown for sample human-class trajectories to NEOs. Additionally, the benefit of in-situ navigation beacons on robotic precursor missions is presented. This mission class will require a longer duration flight than Apollo and, unlike previous human missions, there will likely be limited communication and tracking availability. This will necessitate the use of more onboard navigation and targeting capabilities. Finally, the rendezvous and proximity operations near an asteroid will be unlike anything previously attempted in a crewed spaceflight. The unknown gravitational environment and physical surface properties of the NEO may cause the rendezvous to behave differently than expected. Symbiosis of the human pilot and onboard navigation/targeting are presented which give additional robustness to unforeseen perturbations.

Holt, Greg N.↗
NASA NTRS1998

Lessons Learned During Implementation and Early Operations of the DS1 Beacon Monitor Experiment

A new approach to mission operations will be flight validated on NASA's New Millennium Program Deep Space One (DS1) mission which launched in October 1998. The Beacon Monitor Operations Technology is aimed at decreasing the total volume of downlinked engineering telemetry by reducing the frequency of downlink and the volume of data received per pass. Cost savings are achieved by reducing the amount of routine telemetry processing and analysis performed by ground staff. The technology is required for upcoming NASA missions to Pluto, Europa, and possibly some other missions. With beacon monitoring, the spacecraft will assess its own health and will transmit one of four beacon messages each representing a unique frequency tone to inform the ground how urgent it is to track the spacecraft for telemetry. If all conditions are nominal, the tone provides periodic assurance to ground personnel that the mission is proceeding as planned without having to receive and analyze downlinked telemetry. If there is a problem, the tone will indicate that tracking is required and the resulting telemetry will contain a concise summary of what has occurred since the last telemetry pass. The primary components of the technology are a tone monitoring technology, AI-based software for onboard engineering data summarization, and a ground response system. In addition, there is a ground visualization system for telemetry summaries. This paper includes a description of the Beacon monitor concept, the trade-offs with adapting that concept as a technology experiment, the current state of the resulting implementation on DS1, and our lessons learned during the initial checkout phase of the mission. Applicability to future missions is also included.

Sherwood, Rob↗
NASA NTRS1979

GEOS 3 STDN S band Doppler tracking investigation

GEOS 3S Doppler band and laser ranging data, acquired from August 1975 to March 1976 in the spacecraft altimeter calibration area, are examined. An evaluation of two-way and three-way Doppler data, for the positioning of Spaceflight Tracking and Data Network S band stations is presented, as well as the Goddard Space Flight Center laser system that is used to reference the exact position of the Doppler stations. The two-way and three-way Doppler tracking devices, situated at Rosman and Bermuda, have yielded data for the recovery of GEOS 3 arc height with an uncertainty of only 1 m. Attention is given to the effects of beacon signal frequency instability, controlled by a temperature sensitive auxiliary crystal oscillator on board the spacecraft, and to the one-way range rate tracking noise that was found to be within a range of 2 to 10 cm/s. 1- and 2-way passes and their different arc meters are graphed, showing the Doppler tracking interval. It was concluded that other accurate computations and recovery of station coordinates could be performed employing tracking data from S band stations.

Rosenbaum, B.↗
NASA NTRS1994

Precision orbit determination of altimetric satellites

The ability to determine accurate global sea level variations is important to both detection and understanding of changes in climate patterns. Sea level variability occurs over a wide spectrum of temporal and spatial scales, and precise global measurements are only recently possible with the advent of spaceborne satellite radar altimetry missions. One of the inherent requirements for accurate determination of absolute sea surface topography is that the altimetric satellite orbits be computed with sub-decimeter accuracy within a well defined terrestrial reference frame. SLR tracking in support of precision orbit determination of altimetric satellites is significant. Recent examples are the use of SLR as the primary tracking systems for TOPEX/Poseidon and for ERS-1 precision orbit determination. The current radial orbit accuracy for TOPEX/Poseidon is estimated to be around 3-4 cm, with geographically correlated orbit errors around 2 cm. The significance of the SLR tracking system is its ability to allow altimetric satellites to obtain absolute sea level measurements and thereby provide a link to other altimetry measurement systems for long-term sea level studies. SLR tracking allows the production of precise orbits which are well centered in an accurate terrestrial reference frame. With proper calibration of the radar altimeter, these precise orbits, along with the altimeter measurements, provide long term absolute sea level measurements. The U.S. Navy's Geosat mission is equipped with only Doppler beacons and lacks laser retroreflectors. However, its orbits, and even the Geosat orbits computed using the available full 40-station Tranet tracking network, yield orbits with significant north-south shifts with respect to the IERS terrestrial reference frame. The resulting Geosat sea surface topography will be tilted accordingly, making interpretation of long-term sea level variability studies difficult.

Shum, C. K.↗
NASA NTRS2016

Navigation Architecture For A Space Mobile Network

The Tracking and Data Relay Satellite System (TDRSS) Augmentation Service for Satellites (TASS) is a proposed beacon service to provide a global, space-based GPS augmentation service based on the NASA Global Differential GPS (GDGPS) System. The TASS signal will be tied to the GPS time system and usable as an additional ranging and Doppler radiometric source. Additionally, it will provide data vital to autonomous navigation in the near Earth regime, including space weather information, TDRS ephemerides, Earth Orientation Parameters (EOP), and forward commanding capability. TASS benefits include enhancing situational awareness, enabling increased autonomy, and providing near real-time command access for user platforms. As NASA Headquarters Space Communication and Navigation Office (SCaN) begins to move away from a centralized network architecture and towards a Space Mobile Network (SMN) that allows for user initiated services, autonomous navigation will be a key part of such a system. This paper explores how a TASS beacon service enables the Space Mobile Networking paradigm, what a typical user platform would require, and provides an in-depth analysis of several navigation scenarios and operations concepts.

Satellite↗
NASA NTRS1972

Geodetic studies by laser ranging to satellites.

For three months in 1970, two Goddard Space Flight Center (GSFC) laser tracking systems were used to try to detect the motion of the pole of rotation of the earth. More than two hundred passes of the Beacon Explorer C spacecraft were observed as it passed between the two stations, and these data were used to determine the orbital inclination of the spacecraft. The analysis required the accurate determination of the relative positions of the two tracking stations and the identification of the perturbations to the spacecraft orbit, in particular, those due to the gravitational fields of the earth, sun, and moon and those caused by the solid-earth tides. The results to date indicate that the GSFC laser systems can determine interstation distances with a repeatability of about 25 cm and that a new value of the Love number k that represents the distortion of the earth's gravity field caused by the tidal deformation of the earth is 0.35 plus or minus 0.05.

Smith, D. E.↗
NASA NTRS1990

Design of a hybrid receiver for the OLYMPUS spacecraft beacons

The theory and design of a hybrid analogue/digital receiver which acquires and monitors the OLYMPUS satellite beacons is presented. The analogue portion of this receiver uses a frequency locked loop for signal tracking. A digital sampling detector operating at IF is used to obtain the I and Q outputs.

Sweeney, D. G.↗
NASA NTRS2001

45 Km horizontal path optical link demonstrations

Observations made during a mountain-top-to-mountain-top horizontal optical link demonstration are described. The optical link spans a range of 45 Km at an average altitude of 2 Km above sea level. A multi-beam beacon comprised of eight laser beams emerging from multi-mode fiber coupled lasers (780 nm) are launched through a 0.6 m diameter telescope located at the JPL Table Mountain Facility (TMF) in Wrightwood, California. The multibeam beacon is received at Strawberry Peak located in the San Bernadino Mountains of California. The NASA, JPL developed optical communications demonstrator (OCD) receives the beacon, senses the atmosphere induced motion and using an upgraded fine steering loop compensates the re-transmission of a communications laser beam (852 nm, 400 Mbps) to TMF. The eight-beam beacon allowed a four reduction in normalized irradiance or scintillation index. This in turn was sufficient to eliminate beacon fades sensed b the OCD and allowed the fine steering loop performance evaluation. The uncompensated tracking error was determined to be 2.2 - 3 prad compared to a model prediction of 3.4 prad. The paper also discusses various auxiliary observations made during the campaign

Page, Norman A.↗
NASA NTRS2011

Safe Laser Beam Propagation for Interplanetary Links

Ground-to-space laser uplinks to Earth–orbiting satellites and deep space probes serve both as a beacon and an uplink command channel for deep space probes and Earth-orbiting satellites. An acquisition and tracking point design to support a high bandwidth downlink from a 20-cm optical terminal on an orbiting Mars spacecraft typically calls for 2.5 kW of 1030-nm uplink optical power in 40 micro-radians divergent beams.2 The NOHD (nominal ocular hazard distance) of the 1030nm uplink is in excess of 2E5 km, approximately half the distance to the moon. Recognizing the possible threat of high power laser uplinks to the flying public and to sensitive Earth-orbiting satellites, JPL developed a three-tiered system at its Optical Communications Telescope Laboratory (OCTL) to ensure safe laser beam propagation through navigational and near-Earth space.

Optical communications↗