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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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NASA NTRS1993

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↗
NASA NTRS2004

Liquid Crystal-Based Beam Steering Device Development for NASA Applications

The NASA Computing, Information and Communications Technology (CICT) Program is supporting the development of liquid crystal-based beam steering devices. The device would use inexpensive, light-weight, optical components, and it would have the following capabilities: electronic beam scanning to angles above 1 milliradian, and submicroradian beam pointing accuracy. In order to correct for the imperfections resulting from the space-deployable optics, the technique of wave-front correction would be implemented. Hence, the output beam quality would be maintained. The potential applications could include satellite tracking, near-Earth inter-satellite communications, deep-space communications, and optical phased array systems. The status of the beam steering device development based on the liquid crystal technology and its relationship to prospective NASA mission scenarios will be described.

Pouch, John↗
NASA NTRS2006

Implementation of a Coded Modulation for Deep Space Optical Communications

We present an efficient implementation of a coded modulation for the deep space optical channel. NASA designed this so called serially concatenated pulse position modulation (SCPPM) code to provide an optical link that can operate within one dB signal energy of the Shannon capacity during a nominal mission condition from Mars. Here, we describe some of the challenges in realizing the SCPPM decoder on a field-programmable gate array (FPGA). Through various architectural optimizations, we achieve a 6 Mbps decoder on a single FPGA. Moreover, we demonstrate that it is possible to communicate reliably on an efficient bits-per-photon count in an end-to-end SCPPM coded system.

turbo codes↗
NASA NTRS2003

Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep Space Optical Communications

The feasibility of using long wavelength Earth thermal (infrared) images for telescope tracking/pointing application. for both Deep Space Free- pace Optical Communications has been investigated and is reported her. The advantage of this technology rests on using full Earth images in this band, which yield more accurate estimates of geometric centroids than that of Earth images in the visible band. Another major advantage is that these images are nearly independent of Earth phase angle. The results of the study show that at a Mars range, with currently available sensors, a noise equivalent angle of 10 to 150 nanoradians and a bias error of better than 80 nanoradians can be obtained. This enables precise pointing of the optical communications beam for high data rate links.

free-space optical communication↗
NASA NTRS2019

NASA's Deep Space Optical Communications - an update

NASA is developing a new space and ground technologies to demonstrate deep space optical communications in the 2022-2024 time frame. This paper provides an update on the status of this development.

Biswas, Abhijit↗
NASA NTRS1991

Spatial acquisition and tracking for deep-space optical communication packages

The problem of acquiring and tracking a sun-lit earth, which poses a rather stringent demand on the design of the pointing acquisition and tracking subsystem for a deep-space optical communication package, is addressed. The acquisition subsystem must be capable of locating and tracking the receiver location based on a sun-lit earth image that is blurred by the point spread function of the imaging optics and spatially quantized by the detector pixels. Spatial tracking must be performed at bandwidths in excess of 1 kHz to effectively reject platform jitters. A simple solution of locating the earth limb shows a great potential for providing the necessary acquisition and tracking accuracy. By using separate acquisition and tracking detectors, the system can be implemented without extensive technology development. The slow bandwidth required for the acquisition process can be readily accomplished with an available CCD array, and an analog tracking loop can be implemented using a quadrant tracker and calibrated centroid tracking without the excessive computing overhead of the array detector-based spatial tracker.

Chen, Chien-Chung↗
NASA NTRS2005

Adaptive optics for daytime deep space laser communications to Mars

This paper describes JPL research in adaptive optics (AO) to reduce the daytime background noise on a Mars-to-Earth optical communications link. AO can reduce atmosphere-induced wavefront aberrations, and enable single mode receiver operation thereby buying back margin in the deep space optical communications link.

adaptive optics↗
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↗