Laser Space Communications Study /LACE/ FINAL Summary Report
Program planning to determine atmospheric effects on laser space-ground cummunication system
PROGRAM MANAGEMENT↗
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Results for “space laser”
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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Combinatorial pulse position modulation for power-efficient free-space laser communications
A new modulation technique called combinatorial pulse position modulation (CPPM) is presented as a power-efficient alternative to quaternary pulse position modulation (QPPM) for direct-detection, free-space laser communications. The special case of 16C4PPM is compared to QPPM in terms of data throughput and bit error rate (BER) performance for similar laser power and pulse duty cycle requirements. The increased throughput from CPPM enables the use of forward error corrective (FEC) encoding for a net decrease in the amount of laser power required for a given data throughput compared to uncoded QPPM. A specific, practical case of coded CPPM is shown to reduce the amount of power required to transmit and receive a given data sequence by at least 4.7 dB. Hardware techniques for maximum likelihood detection and symbol timing recovery are presented.
Budinger, James M.↗
Space Lasers Have Bright Future in Communications
NASA scientists and engineers seeking faster connectivity with their data-gathering spacecraft are moving away from radio frequency-based communication and turning to laser communications.
Space lasers↗
A survey of beam-combining technologies for laser space power transmission
The combination of laser beams holds much promise for obtaining powerful beams. Methods are surveyed for beam combination (coherent and incoherent) and two of them are identified as the most effective means for achieving high power transmission in space. The two methods as applied to laser diode arrays are analyzed, and potentially productive work areas for the advancement of technology are delineated.
Kwon, J. H.↗
In-Space Laser Forming Simulated Under Thermal Vacuum (TVAC) Conditions
NASA Marshall Space Flight Center is investigating laser forming under thermal vacuum conditions representative of the space environment through a partnership with the DARPA NOM4D program. The thermal gradient mechanism (TGM) is used to bend a metal sheet towards the laser optics. Laser equipment and process parameters are being optimized for thermal vacuum conditions. Such conditions are representative of the extreme cold and hot temperatures and high vacuum that exist on orbit or on the lunar surface. in situ photogrammetry and thermography assess the bend/counterbend and elucidate the TGM in thermal vacuum. Structured light scanning and metallography after bending reveal the macroscopic and microscopic structure after TGM.
thermal vacuum↗
NASA Space Laser Technology
Over the next two decades, the number of space based laser missions for mapping, spectroscopy, remote sensing and other scientific investigations will increase several fold. The demand for high wall-plug efficiency, low noise, narrow linewidth laser systems to meet different systems requirements that can reliably operate over the life of a mission will be high. The general trends will be for spatial quality very close to the diffraction limit, improved spectral performance, increased wall-plug efficiency and multi-beam processing. Improved spectral performance will include narrower spectral width (very near the transform limit), increased wavelength stability and or tuning (depending on application) and lasers reaching a wider range of wavelengths stretching into the mid-infrared and the near ultraviolet. We are actively developing high efficiency laser transmitter and high-sensitivity laser receiver systems that are suitable for spaceborne applications.
Electro-Optics↗
Space Laser Power Transmission System Studies
Power transmission by laser technique is addressed. Space to Earth and space to space configurations are considered.
Williams, M. D.↗
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↗
Laser space rendezvous and docking tradeoff
A spaceborne laser radar (LADAR) was configured to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. The LADAR, configurated using existing pulsed CO2 laser technology and a 1980 system technology baseline, is well suited for the envisioned space tug missions. The performance of a family of candidate LADARS was analyzed. Tradeoff studies as a function of size, weight, and power consumption were carried out for maximum ranges of 50, 100, 200, and 300 nautical miles. The investigation supports the original contention that a rendezvous and docking LADAR can be constructed to offer a cost effective and reliable solution to the envisioned space missions. In fact, the CO2 ladar system offers distinct advantages over other candidate systems.
Adelman, S.↗
Integration and test of high-speed transmitter electronics for free-space laser communications
The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.
Soni, Nitin J.↗
Development of a safe ground to space laser propagation system for the optical communications telescope laboratory
Furthering pursuits in high bandwidth communications to future NASA deep space and neat-Earth probes, the Jet Propulsion Laboratory (JPL) is building the Optical communications Telescope Laboratory (OCTL) atop Table Mountain in Southern California. This R&D optical antenna will be used to develop optical communication strategies for future optical ground stations. Initial experiments to be conducted include propagating high-powered, Q-switched laser beams to retro-reflecting satellites. Yet laser beam propagation from the ground to space is under the cognizance of various government agencies, namely: the Occupational Safety and Health Administration (ISHA) that is responsible for protecting workforce personnel; the Federal Aviation Administration (FAA) responsible for protecting pilots and aircraft; and the Laser Clearinghouse of Space Command responsible for protecting space assets. To ensure that laser beam propagation from the OCTL and future autonomously operated ground stations comply with the guidelines of these organizations, JPL is developing a multi-tiered safety system that will meet the coordination, monitoring, and reporting functions required by the agencies. At Tier 0, laser operators will meet OSHA safety standards for protection and access to the high power lasers area will be restricted and interlocked. Tier 1, the area defined from the telescope dome out to a range of 3.4-km, will utilize long wave infrared camera sensors to alert operators of at risk aircraft in the FAA controlled airspace. Tier 2, defined to extend from 3.4-km out to the aircraft service ceiling in FAA airspace, will detect at risk aircraft by radar. Lastly, beam propagation into space, defined as Tier 3, will require coordination with the Laser Clearinghouse. A detailed description of the four tiers is presented along with the design of the integrated monitoring and beam transmission control system.
laser safety↗
Earth/Moon System Star Tracking Sensor for Improved Deep Space Laser Communications
The goal of this research is to improve deep space communication links by exploring a new concept in stellar navigation that uses images of the Earth/Moon system to obtain precise pointing information so that the laser signal from the satellite can be directed at the ground station with unprecedented accuracy. Currently, the concept for satellite pointing relies on a dual axis star tracker that compares images of the celestial sphere to a star catalog to obtain a 3-axis orientation solution. Most star trackers are designed with a wide field of view (required to obtain enough bright starts to achieve a navigational fix) and only provide reliable pitch and yaw estimates thus necessitating the use of a second star tracker looking at an axis perpendicular to the first one to obtain an accurate estimate of the roll of the spacecraft. In the new concept the optical design will be modified to ensure that both the Earth and the Moon will be within a narrow field of view centered on Earth relative to the field of view of most star tracking systems. Because of the proximity of the bodies, it is possible to obtain highly accurate estimates of the pitch, yaw and roll of the spacecraft relative to the Earth/Moon system. The new tracker will allow for accurate 3-axis control of the spacecraft from a single tracker thus allowing the second star tracker, which would normally be pointed in a direction perpendicular to the one pointed at earth, to obtain the spacecraft roll estimate. This wide field star tracker facilitates functions like the initial satellite pointing during the acquisition phase of establishing the laser communication link or solving the lost in space problem should the system need to be reset. This new design will be tested in simulation and compared for 3-axis pointing accuracy against a standard commercial star tracker.
Star tracker↗
Use of Commercially Available Fiber Optic Components in Emerging Space Laser Communications Applications
Explore the source record for details and available documents.
Space Communications↗
Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit
Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.
laser communication↗
Quaternary pulse position modulation electronics for free-space laser communications
The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (QPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.
Budinger, J. M.↗
Quaternary pulse position modulation electronics for free-space laser communications
The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (GPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.
Budinger, J. M.↗
Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems
Accomplishments in the following areas of research are presented: receiver performance study of spaceborne laser altimeters and cloud and aerosol lidars; receiver performance analysis for space-to-space laser ranging systems; and receiver performance study for the Mars Environmental Survey (MESUR).
Davidson, Frederic M.↗
Optical phase-locked loop (OPLL) for free-space laser communications with heterodyne detection
Several advantages of coherent free-space optical communications are outlined. Theoretical analysis is formulated for an OPLL disturbed by shot noise, modulation noise, and frequency noise consisting of a white component, a 1/f component, and a 1/f-squared component. Each of the noise components is characterized by its associated power spectral density. It is shown that the effect of modulation depends only on the ratio of loop bandwidth and data rate, and is negligible for an OPLL with loop bandwidth smaller than one fourth the data rate. Total phase error variance as a function of loop bandwidth is displayed for several values of carrier signal to noise ratio. Optimal loop bandwidth is also calculated as a function of carrier signal to noise ratio. An OPLL experiment is performed, where it is shown that the measured phase error variance closely matches the theoretical predictions.
Win, Moe Z.↗