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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

A Day in the Life of the Laser Communications Relay Demonstration (LCRD) Project.

This presentation provides an overview of the planned concept of operations for the Laser Communications Relay Demonstration Project (LCRD), a joint project among NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MITLL). LCRD will provide at least two years of bi-directional optical communications at user data rates of up to 1.244 Gbps in an operational environment. The project lays the ground work for establishing communications architecture and protocols, and developing the communications hardware and support infrastructure, concluding in a demonstration of optical communications potential to meet NASAs growing need for higher data rates for future science and exploration missions. A pair of flight optical communications terminals will reside on a single commercial communications satellite in geostationary orbit; the two ground optical communications terminals will be located in Southern California and Hawaii. This paper summarizes the current LCRD architecture and key systems for the demonstration, focusing on what it will take to operate an optical communications relay that can support space-to-space, space-to-air, and space-to-ground optical links.

Optical↗
NASA NTRS2000

Free Space Laser Communications

This presentation concerns the use of Laser communication for deep space applications. The presentation reviews the problems with electromagnetic beams and then the advantages and disadvantages of the use of optical communication. The presentation then reviews some of the spacecraft technology with pictures of some of the devices. The ground reception systems and the simplified link calculation are also reviewed. Recent and planned demonstration projects are also reviewed.

Lesh, James↗
NASA NTRSDate not supplied

NASA’s Laser Communications Relay Demonstration (LCRD) Experiment Program: Characterization And Initial Operations

The National Aeronautics and Space Administration’s (NASA) Laser Communications Relay Demonstration (LCRD) completed the first 18 months of its Experiment Program in December 2023. The LCRD geosynchronous payload includes two laser communications terminals interconnected via an onboard electronic switch. The payload can relay information between any two of a set of three ground stations. Two optical ground stations are located in California and Hawaii, and an RF ground station is located in New Mexico. Experiments to date have included demonstration of optimetrics, demonstrations of Delay/Disruption Tolerant Networking (DTN), and measurements of the effects of the atmosphere (turbulence, weather) on the performance and availability of lasercom (pointing, tracking, communications, and adaptive optics). Furthermore, future operational scenarios including robotic and exploration missions with various network service configurations have been emulated. This paper provides an overview and highlights of the first 18 months of LCRD experiments, and a preview of the upcoming experiments, including relaying data to and from the Integrated LCRD Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) on the International Space Station. LCRD is a joint project involving NASA Goddard Space Flight Center (GSFC), the California Institute of Technology Jet Propulsion Laboratory (JPL), and Massachusetts Institute of Technology Lincoln Laboratory (MIT LL).

David J. Israel↗
NASA NTRS1995

Wavelength Selection Criteria for Laser Communications

A rationale is provided for selecting wavelengths particularly suited for free space laser communications systems. Comparisons of wavelengths are based on propagation (especially through the atmosphere), optical background noise, and the needed technologies.

lasers↗
NASA NTRS1991

Free-space laser communication technologies III; Proceedings of the Meeting, Los Angeles, CA, Jan. 21, 22, 1991

The present volume on free-space laser communication technologies discusses system analysis, performance, and applications, pointing, acquisition, and tracking in beam control, laboratory demonstration systems, and transmitter and critical component technologies. Attention is given to a space station laser communication transceiver, meeting intersatellite links mission requirements by an adequate optical terminal design, an optical approach to proximity-operations communications for Space Station Freedom, and optical space-to-ground link availability assessment and diversity requirements. Topics addressed include nonmechanical steering of laser beams by multiple aperture antennas, a free-space simulator for laser transmission, heterodyne acquisition and tracking in a free-space diode laser link, and laser terminal attitude determination via autonomous star tracking. Also discussed are stability considerations in relay lens design for optical communications, liquid crystals for lasercom applications, and narrowband optical interference filters.

Begley, David L.↗
NASA NTRS1972

Wide-band laser communications in space.

Candidate wideband (1 Gbit/sec) satellite laser communications systems are compared with respect to projected component technology and launch cost. It appears that the carbon dioxide (10.6-micron) system offers a SNR advantage over the Nd:YAG (1.06-micron) or doubled Nd:YAG (0.53-micron) systems for comparable satellite burden. The launch costs for the carbon dioxide and doubled Nd:YAG systems can be similar, but the latter is very sensitive to the projected weight of a large lightweight photon-bucket receiving aperture. The most critical technology problem for the carbon dioxide system is that of Doppler compensation.

Forster, D. C.↗
NASA NTRS1992

Electronic Subsystems For Laser Communication System

Electronic subsystems of free-space laser communication system carry digital signals at 650 Mb/s over long distances. Applicable to general optical communications involving transfer of great quantities of data, and transmission and reception of video images of high definition.

Long, Catherine↗
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↗
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 NTRS2015

Early Operations Flight Correlation of the Lunar Laser Communications Demonstration (LLCD) on the Lunar Atmosphere and Dust Environment Explorer (LADEE)

The Lunar Atmosphere and Dust Environment Explorer (LADEE) mission launched on September 7, 2013 with a one month cruise before lunar insertion. The LADEE spacecraft is a power limited, octagonal, composite bus structure with solar panels on all eight sides with four vertical segments per side and 2 panels dedicated to instruments. One of these panels has the Lunar Laser Communications Demonstration (LLCD), which represents a furthering of the laser communications technology demonstration proved out by the Lunar Reconnaissance Orbiter (LRO). LLCD increases the bandwidth of communication to and from the moon with less mass and power than LROs technology demonstrator. The LLCD Modem and Controller boxes are mounted to an internal cruciform composite panel and have no dedicated radiator. The thermal design relies on power cycling of the boxes and radiation of waste heat to the inside of the panels, which then reject the heat when facing cold space. The LADEE mission includes a slow roll and numerous attitudes to accommodate the challenging thermal requirements for all the instruments on board. During the cruise phase, the internal Modem and Controller avionics for LLCD were warmer than predicted by more than modeling uncertainty would suggest. This caused concern that if the boxes were considerably warmer than expected while off, they would also be warmer when operating and could limit the operational time when in lunar orbit. The thermal group at Goddard Space Flight Center evaluated the models and design for these critical avionics for LLCD. Upon receipt of the spacecraft models and audit was performed and data was collected from the flight telemetry to perform a sanity check of the models and to correlate to flight where possible. This paper describes the efforts to correlate the model to flight data and to predict the thermal performance when in lunar orbit and presents some lessons learned.

LADEE↗
NASA NTRS2017

Laser Communications Relay Demonstration (LCRD) Update and the Path Towards Optical Relay Operations

This paper provides a concept for an evolution of NASA's optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory - California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.

Space Communications↗
NASA NTRS2017

Laser Communications Relay Demonstration (LCRD) Update and the Path Towards Optical Relay Operations

This Presentation provides a concept for an evolution of NASAs optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), a joint project between NASAs Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory - California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.

Space Communications↗
NASA NTRS1984

Spacecraft system study: A study to define the impact of laser communication systems on their host spacecraft

The mutual influence of a laser communication system and its host spacecraft and the degree to which the mutual influence limited acquisition, tracking and pointing processes were investigated. A laser klink between a low earth orbiting (LEO) satellite and a geosynchronous earth orbiting (GEO) satellite was used as a baseline. The laser link between satellites was a generic channel transferring 500 Mbps data from the LEO to GEO using the GaAlAs laser as the laser light source. Major aspects of pointing and tracking with a satelliteborne optical system were evaluated including: (1) orbital aspects such as spacecraft relative motions, point ahead, and Sun snd Moon optical noise; (2) burst errors introduced by the electronic and optical noise levels; (3) servo system design and configurations, and the noise sources such as, sensor noise, base motion disturbances, gimbal friction torque noise; (4) an evaluation of the tracking and beacon link and the type of sensors used; (5) the function of the acquisition procedure and an evaluation of the sensors employed; and (6) an estimate of the size, weight and power needed for the satellite system.

Source record↗
NASA NTRS2012

Evaluation of Deep-Space Laser Communication under Different Mission Scenarios

A number of space agencies, including NASA, are considering free-space laser communications as a means for returning higher data-rates from future space missions. In this paper, potential deep-space missions are evaluated to show that with optical communication a 10x increase relative to state-of-the art telecommunication systems could be achieved. The maximum deep-space distance where ground transmitted laser beacons could assist acquisition and tracking; and operating points where optical communication performance degrades faster than the inverse square distance are also discussed.

mission scenarios↗