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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Laser network survey and orbit recovery

Simulations were performed for the anticipated GEOS-C laser network stations at Goddard, Bermuda, and Florida to predict how well survey and orbit will be recovered. Lasers were added one at a time at Grand Turk, Antigua, and Panama to estimate the contribution from these additional sites. Time tag biases of 50 microseconds, survey uncertainties of 10 meters in each coordinate, laser range biases and noise estimates of 20 cm each, and conventional gravity uncertainties were included in the simulations. The results indicate that survey can be recovered to about 1 meter and Grand Turk can be recovered better than Antigua or Panama. Reducing the probably pessimistic assumed time tag biases and gravity field uncertainties improves the results. Using these survey recovery estimates, the short arc GEOS-C satellite heights for altimeter intercomparison orbits can be recovered within the calibration area to better than the required two meters.

Berbert, J. H.↗
NASA NTRS1973

Task five report: Laser communications for data acquisition networks

Laser communication technology and laser communication performance are reviewed. The subjects discussed are: (1) characteristics of laser communication systems, (2) laser technology problems, (3) means of overcoming laser technology problems, and (4) potential schedule for including laser communications into data acquisition networks. Various types of laser communication systems are described and their capabilities are defined.

Source record↗
NASA NTRS1993

Laser ranging network performance and routine orbit determination at D-PAF

ERS-1 is now about 8 months in orbit and has been tracked by the global laser network from the very beginning of the mission. The German processing and archiving facility for ERS-1 (D-PAF) is coordinating and supporting the network and performing the different routine orbit determination tasks. This paper presents details about the global network status, the communication to D-PAF and the tracking data and orbit processing system at D-PAF. The quality of the preliminary and precise orbits are shown and some problem areas are identified.

Massmann, Franz-Heinrich↗
NASA NTRS2004

NASA Satellite Laser Ranging Network

I will be participating in the International Workshop on Laser Ranging. I will be presenting to the International Laser Ranging Service (ILRS) general body meeting on the recent accomplishments and status of the NASA Satellite Laser Ranging (SLR) Network. The recent accomplishments and NASA's future plans will be outlined and the benefits to the scientific community will be addressed. I am member of the ILRS governing board, the Missions working group, and the Networks & Engineering working group. I am the chairman of the Missions Working and will be hosting a meeting during the week of the workshop. I will also represent the NASA SLR program at the ILRS governing board and other working group meetings.

Carter, David L.↗
NASA NTRS1986

The coordinate frame of the lunar laser ranging network

The geocentric coordinates for four instruments, which were derived using lunar laser ranging, are compared with the 84L02 coordinates determined from the Lageos satellite. The determination of the geocentric coordinates for the 2.7 m and McDonald Observatory laser ranging system telescopes at McDonald Observatory, the Haleakala site, and the CERGA site near Grasse, France is described. Consideration is given to the McDonald Observatory colocation and station motion due to continential drift. A rms difference of 18 cm is determined for the two sets of geocentric coordinates; however, removing a data anomaly reduces the rms difference to 13 cm.

Williams, J. G.↗
NASA NTRS2019

Potential Improvements in Global Carbon Flux Estimates from a Network of Laser Heterodyne Radiometer Measurements of Column Carbon Dioxide

We present observing system simulation experiments (OSSEs) to evaluate the impact of a proposed network of ground-based miniaturized laser heterodyne radiometer (mini-LHR) instruments that measure atmospheric column-averaged carbon dioxide (XCO2) with a 1 ppm precision. A particular strength of this passive measurement approach is its insensitivity to clouds and aerosols due to its direct sun pointing and narrow field of view (0.2°). Developed at the NASA Goddard Space Flight Center (GSFC), these portable, low-cost mini-LHR instruments were designed to operate in tandem with the sun photometers used by the AErosol RObotic NETwork (AERONET). This partnership allows us to leverage the existing framework of AERONET's global ground network of more than 500 sites as well as providing simultaneous measurements of aerosols that are known to be a major source of error in retrievals of XCO2 from passive nadir-viewing satellite observations. We show, using the global 3-D GEOS-Chem chemistry transport model, that a deployment of 50 mini-LHRs at strategic (but not optimized) AERONET sites significantly improves our knowledge of global and regional land-based CO2 fluxes. This improvement varies seasonally and ranges 58%–81% over southern lands, 47%–76% over tropical lands, 71%–92% over northern lands, and 64%–91% globally. We also show significant added value from combining mini-LHR instruments with the existing ground-based NOAA flask network. Collectively, these data result in improved a posteriori CO2 flux estimates on spatial scales of ∼10 km2, especially over North America and Europe, where the ground-based networks are densest. Our studies suggest that the mini-LHR network could also play a substantive role in reducing carbon flux uncertainty in Arctic and tropical systems by filling in geographical gaps in measurements left by ground-based networks and space-based observations. A realized network would also provide necessary data for the quinquennial global stock takes that form part of the Paris Agreement.

Palmer, Paul I.↗
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 NTRS1978

Gravity field, geoid and ocean surface by space techniques

Knowledge of the earth's gravity field continued to increase during the last four years. Altimetry data from the GEOS-3 satellite has provided the geoid over most of the ocean to an accuracy of about one meter. Increasing amounts of laser data has permitted the solution for 566 terms in the gravity field with which orbits of the GEOS-3 satellite have been computed to an accuracy of about one to two meters. The combination of satellite tracking data, altimetry and gravimetry has yielded a solution for 1360 terms in the earth's gravity field. A number of problems remain to be solved to increase the accuracy of the gravity field determination. New satellite systems would provide gravity data in unsurveyed areas and correction for topographic features of the ocean and improved computational procedures together with a more extensive laser network will considerably improve the accuracy of the results.

Anderle, R. J.↗
NASA NTRS1987

The rotation of the earth

In the four years between 1983 and 1986, two developments have led to significant improvement in the measurements and theoretical studies of the earth's rotation: the upgrading of the laser network of the NASA, and the expansion of VLBI observations. In this report, observations conducted with the purpose of regular monitoring of the earth's orientation are described, and the use of the data to compute variations in the length of the day and to determine corrections to the earth's nutation are discussed. The improved accuracy and resolution of recent observations made it also possible to measure and account for polar motion on time scales of a month or less.

King, Robert W.↗
NASA NTRS1991

Laser geodynamic satellite (LAGEOS II)

The Laser Geodynamic Satellite 2 (LAGEOS 2) is nearly identical to the LAGEOS 1 satellite, which was launched by NASA in 1976. However, LAGEOS 2 is completely passive, and is equipped with fused silian corner reflectors for ranging with ground-based lasers. The addition of LAGEOS 2 will provide the GSFC laser network with significantly increased satellite tracking opportunities, because LAGEOS 1 is at a 110-degree inclination and LAGEOS 2 will be at a 52-degree inclination. The flight profile is given, and information is presented in tabular form on the following topics: Deep Space Network support, frequency assignments, telemetry, tracking, and tracking support responsibility.

Portelli, C.↗
NASA NTRS2024

Envisioning an Optimal Network of Space-Based Lasers for Orbital Debris Remediation

The rapid increase in resident space objects, including satellites and orbital debris, poses a significant threat to the safety and sustainability of space missions. This paper explores orbital debris remediation using a network of collaborative space-based lasers, leveraging laser ablation for momentum transfer on debris. A novel delta-v vector analysis framework quantifies the e↵ects of multiple simultaneous laser-to-debris (L2D) engagements by using vector composition of the imparted delta-v vectors. The paper introduces the Concurrent LocationScheduling Problem (CLSP), which optimizes the placement of laser platforms and the scheduling of L2D engagements to maximize debris remediation capacity. Due to the computational complexity of the CLSP, it is decomposed into two sequential subproblems: (1) optimal laser platform locations are determined using the Maximal Covering Location Problem, and (2) a novel integer linear programming-based approach schedules L2D engagements within the network configuration to maximize remediation capacity. Computational experiments are conducted to evaluate the proposed framework’s e↵ectiveness under various mission scenarios, demonstrating key network functions such as collaborative nudging, deorbiting, and just-in-time collision avoidance. A sensitivity analysis further examines how varying the number and distribution of laser platforms a↵ects debris remediation capacity, providing insights into optimizing the performance of space-based laser networks.

David O Williams Rogers↗
NASA NTRS1985

Precision laser tracking for global and polar motion

This paper provides an overview of the Goddard Laser Tracking Network (GLTN). GLTN station locations, equipment, possible improvements, and data flow are discussed. Locations of the other major laser tracking networks and their present or expected performance are also provided. The material includes a listing of the Lunar Laser Ranging Stations (LLRSs) and their actual or expected performance.

Shawe, M. E.↗
NASA NTRS2018

Applicability of Neural Networks to Etalon Fringe Filtering in Laser Spectrometers

We present a neural network algorithm for spectroscopic retrievals of concentrations of trace gases. Using synthetic data we demonstrate that a neural network is well suited for filtering etalon fringes and provides superior performance to conventional least squares minimization techniques. This novel method can improve the accuracy of atmospheric retrievals and minimize biases.

diode laser spectroscopy↗
NASA NTRS1977

Polar motion and earth tides from laser tracking

The paper discusses techniques available for measuring polar motion, earth rotation and earth tides with laser tracking of satellites. In a discussion of future prospects, it is noted that when the Laser Geodynamics Satellite is launched, a network of laser stations is projected to be able to achieve better than 10 cm from each coordinate from less than one day of tracking.

Kolenkiewicz, R.↗
NASA NTRS1971

Laser net - A concept for monitoring wingtip vortices on runways

Network of laser beams passes over runway to photodetectors on opposite side, magnitude of beam deflection indicates magnitude of density gradient encountered. Visual display of beam deflections affects go, no-go decision for takeoff and landing.

Funk, B. H.↗
NASA NTRS1977

Lageos orbital acquisition and initial assessment

Orbital elements for the satellite Lageos, launched on 4 May, 1976, were generated through use of Baker-Nunn camera data. Camera observations of the apogee kick motor provided the node and perigee, the inclination and the eccentricity, while the mean anomaly and the mean motion were determined from observations of the satellite. During the month following the launch, the Smithsonian Astrophysical Observatory and NASA laser tracking networks acquired about 110 satellite passes. The laser tracking system has been applied to a variety of orbital configurations, including elevation angles below 20 deg. Single-pass range residuals versus time were plotted for 741 laser observations of the satellite; the standard deviation of the total system noise was found to be 7 cm.

Pearlman, M. R.↗
NASA NTRS1994

Tracking strategies for laser ranging to multiple satellite targets

By the middle of the decade, several new Laser Geodynamic Satellites will be launched to join the current constellation comprised of the laser geodynamic satellite (LAGEOS) (US), Starlette (France), Ajisai (Japan), and Etalon I and II (USSR). The satellites to be launched, LAGEOS II and III (US & Italy), and Stella (France), will be injected into orbits that differ from the existing constellation so that geodetic and gravimetric quantities are sampled to enhance their resolution and accuracy. An examination of various possible tracking strategies adopted by the network of laser tracking stations has revealed that the recovery of precise geodetic parameters can be obtained over shorter intervals than is currently obtainable with the present constellation of satellites. This is particularly important in the planning of mobile laser tracking operations, given a network of permanently operating tracking sites. Through simulations, it is shown that laser tracking of certain satellite passes, pre-selected to provide optimal sky-coverage, provides the means to acquire a sufficient amount of data to allow the recovery of 1 cm station positions.

Robbins, J. W.↗