Laser Transmitter/Receiver Systems for NASA Optical Communications Applications in Planetary Missions
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Demonstrator) terminal↗
Engineering topics
Lesh, J. R.
Publications and source records attributed to Lesh, J. R..
Optical Communications for NASA's Small Spacecraft Missions of the Future
NASA's space missions of the future will be dominated by more moderate sized mini- and micro- spacecraft. Such missions will place stringent requirements on the mass and power consumption required for the various spacecraft subsystems.
optical communications technology small spacecraft↗
An overview of the Galileo Optical Experiment (GOPEX)
Uplink optical communication to a deep-space vehicle was demonstrated. In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (9 Dec. through 16 Dec. 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1-6 million km. At 6 million km (15 times the Earth-Moon distance), the laser beam transmitted from TMF eight days after Earth flyby covered the longest known range for transmission and detection.
Wilson, K. E.↗
Progress Toward Development and Demonstration of Optical Communications for NASA's Future Missions
Optical communicatons is ready for serious development and implementation. NASA's missions need the capabilities and benefits enabled by optical communications.
light science↗
Results from the Galileo Laser Uplink: A JPL Demonstration of Deep-Space Optical Communications
The successful completion of the Galileo Optical Experiment (GOPEX), represented the accomplishment of a significant milestone in JPL's optical communication plan. The experiment demonstrated the first transmission of a narrow laser beam to a deep-space vehicle. Laser pulses were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The experiment took place over an eight-day period (December 9 through December 16, 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1 to 6 million kilometers (15 times the Earth-Moon distance), the laser uplink from TMF covered the longest known range for laser beam transmission and detection. This demonstration is the latest in a series of accomplishments by JPL in the development of deep-space optical communications technology.
Lasers experiment optical communications Galileo d↗
GOPEX: A Laser Uplink to the Galileo Spacecraft on its Way to Jupiter
In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galilieo spacecraft by Earth-based transmitters at Table Mountain Observatory (TMO), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (December 9 through December 16) as Galileo receded from Earth on its way to Jupiter. At 6 million kilometers (15 times the Earth-Moon distance), the laser beam sent from Table Mountain Observatory eight days after Earth flyby covered the longest known range for laser transmission and detection.
lasers↗
A Deep Space Optical Communications Demonstration with the Galileo Spacecraft on its Way to Jupiter (abstract)
The GOPEX (Galileo Optical communications from an Earth-based transmitter) demonstration was performed from transmitter sites at Table Mountain Observatory, CA and Starfire Optical Range, NM. The experiment was done over an eight day period, December 9 through December 16 as Galileo receded from Earth on its way to Jupiter. At a range of 6 million kilometers (15 times the Earth-Moon distance), the transmission from Table Mountain Observatory eight days after Earth-flyby represents the longest range for laser transmission and detection.
laser space communications experiment optical comm↗
Recent Progress in Deep Space Optical Communications
Progress in the NASA-funded optical communications program at the Jet Propulsion Laboratory (JPL) is decribed. This decription includes a system-level breadboard for an optical communications flight package, the planning for the Earth-reception facilities, and the results of a recent optical communications experiment to deep space with the Galileo spacecraft.
Voyager↗
Optical link demonstration with a lightweight transceiver breadboard
A compact optical communications transceiver breadboard was constructed. In order to keep the mass of the breadboard as low as possible the design was made very simple. The entire package weighs less than 5 kg. The optical module uses a 40 mW diode laser and a two-axis voice coil actuator for beam steering. The breadboard is capable of locking onto a laser beacon within its field of view and transmitting the diode laser beam back toward the beacon. Design of the breaboard, details of each component in the breadboard, and current experiments with the package are described.
Hemmati, H.↗
A Plan for the Development and Demonstration of Optical Communications for Deep Space
In this article, an overall plan for the development and demonstration of optical communications for deep-space applications is presented. The current state of the technology for optical communications is presented. Then, the development and demonstration plan is presented in two parts: the overall major systems activities, followed by the generic technology developments that will enable them. The plan covers the path from laboratory subsystems demonstrations out to a full-scale flight experiment system for the proposed Mars Communications Relay Orbiter mission.
Lesh, J. R.↗
Design And Analysis Of Optical Communication Links
To convey to prospective designers intuitive understanding based on unique characteristics of optical communication systems, report presents method of design and analysis of outer-space optical communication link using pulse-position modulation (PPM) and in which received signal sufficiently weak to require detection by photomultiplier operating in photon-counting mode. Step 1 requires some knowledge or assumptions about parameters of transmitter and receiver. Step 2 determination of average number of background-noise photons detected during PPM timeslot. Step 3 average number, Ps of signal photons detected per signal pulse compared with average number, Pn of noise pulses detected per PPM timeslot.
Lesh, J. R.↗
Environmental testing of a diode-laser-pumped Nd:YAG laser and a set of diode-laser-arrays
Results of the environmental test of a compact, rigid and lightweight diode-laser-pumped Nd:YAG laser module are discussed. All optical elements are bonded onto the module using space applicable epoxy, and two 200 mW diode laser arrays for pump sources are used to achieve 126 mW of CW output with about 7 percent electrical-to-optical conversion efficiency. This laser assembly and a set of 20 semiconductor diode laser arrays were environmentally tested by being subjected to vibrational and thermal conditions similar to those experienced during launch of the Space Shuttle, and both performed well. Nevertheless, some damage to the laser front facet in diode lasers was observed. Significant degradation was observed only on lasers which performed poorly in the life test. Improvements in the reliability of the Nd:YAG laser are suggested.
Hemmati, H.↗
A cost-performance model for ground-based optical communications receiving telescopes
An analytical cost-performance model for a ground-based optical communications receiving telescope is presented. The model considers costs of existing telescopes as a function of diameter and field of view. This, coupled with communication performance as a function of receiver diameter and field of view, yields the appropriate telescope cost versus communication performance curve.
Lesh, J. R.↗
A simple method for designing or analyzing an optical communication link
A simple method is described for determining the performance of a free space optical communication link. The method can be used either in the system design (synthesis) mode or in the performance evaluation (analysis) mode. Although restricted to photo counting based detection of pulse position modulated signals, the method is still sufficiently general to accommodate space-based, as well as ground-based, reception.
Lesh, J. R.↗
Integrated Laser and Light Detector
Proposed infrared optical transmitter tracks distant beacon and automatically point transmitted beam toward beacon. Essential transmitter is integrated gallium arsenide device containing electronically-steerable semiconductor injection laser and position detector that senses direction to beacon. With satisfactory optics and sufficient power, system used for long-distance transmission.
Katz, J.↗
Direct-Photon-Detection Communications
Optical communications system based on direct detection of photons rather than heterodyning of carrier with local oscillator. Direct-detection system uses single laser source, pulse-position modulation, and Reed-Solomon coding to protect against burst errors. Conventional photomultiplier tube is receiver. Technology applicable to terrestrial communications.
Lesh, J. R.↗
Lasers in space
Hinkley and Herring (1984) have considered the differences between active (laser) and passive remote sensing from space. The conclusion was reached that spaceborne lasers will eventually complement passive sensors in providing information on the distributions of key atmospheric species and meteorological parameters. Precise information can also be obtained of ice sheet and crustal dynamics for geological and mapping applications. NASA initiated recently an airborne measurement program directed toward some of these objectives. The program employs optical radar (laser radar) systems onboard the NASA advanced ER-2 high-flying aircraft. The results of the experiments are to provide important information with respect to the potential utility of spaceborne laser remote sensing. A study indicated that a spaceborne pulsed carbon dioxide laser could measure tropospheric winds. Attention is also given to measurements of atmospheric gases by spaceborne lasers, solid-state lasers for spaceborne remote sensing, and laser communication in space.
Hinkley, E. D.↗
Generation, modulation and reception of orthogonally polarized signals
The radiating electromagnetic field of a dipole antenna is considered. By allowing the dipole to rotate about its midpoint, one can construct an entire set of signal polarizations wherein distinct members of the set are mutually orthogonal. It is shown how these signals can be modulated and demodulated to convey information. These ideas are then generalized, and both balanced, as well as unbalanced quadrapole modulations are defined. Methods of receiver synchronization to such signals are described, as well as their potential application to multiple access and anti-jam communications.
Lesh, J. R.↗