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Wright, Malcolm W.

Publications and source records attributed to Wright, Malcolm W..

13 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Power Beaming for Deep Space and Permanently Shadowed Regions

Power beaming involves the wireless transfer of power, and could provide a revolutionary new way to power spacecraft and vehicles operating in difficult to access regions. Power beaming has the potential to represent an alternative solution to power spacecraft and landers where sunlight is unavailable. It could provide a source of power to robotic systems in permanently shadowed regions (PSR) or power landers and rovers from orbiting spacecraft (e.g., Moon, Mars, Europa, Enceladeus, Miranda).

Elliott, John↗
NASA NTRS2016

Deep Space Optical Communications

Introduction: Successful space-to-ground technology demonstrations have been completed -Past two decades; A number are planned toward the latter part of this decade; The farthest range has been lunar with the Lunar Laser Communication Demonstration (LLCD); NASA is planning a deep-space technology demonstration of laser communication -In radio frequency communications deep-space is considered to be 0.013 AU (Astronomical Units) -The Deep-space network services missions beyond geostationary orbit (GEO) -Link difficulty (megabytes per second per AU squared) increases with increasing distance -Pursuing technologies to address link-difficulty out to approximately 3 AU -Progress report on subset of these technologies -- Other papers will cover some other technology development -Extension to farther ranges beyond 3 AU will be pursued in the future -Inclusion of laser ranging and light science (optical equivalent of radio science) is also anticipated

Biswas, Abhijit↗
NASA NTRS2016

Deep Space Optical Communications

A number of laser communication link demonstrations from near Earth distances extending out to lunar ranges have been remarkably successful, demonstrating the augmented channel capacity that is accessible with the use of lasers for communications. The next hurdle on the path to extending laser communication and its benefits throughout the solar system and beyond is to demonstrate deep-space laser communication links. In this paper, concepts and technology development being advanced at JPL in order to enable deep-space link demonstrations to ranges of approximately 3 AU in the next decade, will be discussed. Considerations for ranges extending farther will also be discussed briefly. The potential for light science (the optical equivalent of radio science) with the advancement of deep-space laser communications will also be touched upon.

Biswas, Abhijit↗
NASA NTRS2015

Lessons Learned from Optical Payload for Lasercomm Science (OPALS) Mission Operations

This paper provides an overview of Optical Payload for Lasercomm Science (OPALS) activities and lessons learned during mission operations. Activities described cover the periods of commissioning, prime, and extended mission operations, during which primary and secondary mission objectives were achieved for demonstrating space-to-ground optical communications. Lessons learned cover Mission Operations System topics in areas of: architecture verification and validation, staffing, mission support area, workstations, workstation tools, interfaces with support services, supporting ground stations, team training, procedures, flight software upgrades, post-processing tools, and public outreach.

Sindiy, Oleg V.↗
NASA NTRS2015

Upwelling Radiance at 976 nm Measured from Space Using a CCD Camera

The Optical Payload for Lasercomm Science (OPALS) Flight System on-board the International Space Station uses a charge coupled device (CCD) camera for receiving a beacon laser from Earth. Relative measurements of the background contributed by upwelling radiance under diverse illumination conditions and varying terrain is presented. In some cases clouds in the field-of-view allowed a comparison of terrestrial and cloud-top upwelling radiance. In this paper we will report these measurements and examine the extent of agreement with atmospheric model predictions.

Biswas, Abhijit↗
NASA NTRS2015

Optical PAyload for Lasercomm Science (OPALS) link validation

Recently several day and nighttime links under diverse atmospheric conditions were completed using the Optical Payload for Lasercomm Science (OPALS) flight system on-board the International Space Station (ISS). In this paper we compare measured optical power and its variance at either end of the link with predictions that include atmospheric propagation models. For the 976 nm laser beacon mean power transmitted from the ground to the ISS the predicted mean irradiance of 10's of microwatts per square meter close to zenith and its decrease with range and increased air mass shows good agreement with predictions. The irradiance fluctuations sampled at 100 Hz also follow the expected increase in scintillation with air mass representative of atmospheric coherence lengths at zenith at 500 nm in the 3-8 cm range. The downlink predicted power of 100's of nanowatts was also reconciled within the uncertainty of the atmospheric losses. Expected link performance with uncoded bit-error rates less than 1E-4 required for the Reed-Solomon code to correct errors for video, text and file transmission was verified. The results of predicted and measured powers and fluctuations suggest the need for further study and refinement.

ISS↗
NASA NTRS2014

Optical Communications Telescope Laboratory (OCTL) Support of Space to Ground Link Demonstrations

The NASA/JPL Optical Communication Telescope Laboratory (OCTL) was built for dedicated research and development toward supporting free-space laser communications from space. Recently, the OCTL telescope was used to support the Lunar Laser Communication Demonstration (LLCD) from the Lunar Atmospheric Dust Environment Explorer (LADEE) spacecraft and is planned for use with the upcoming Optical Payload for Lasercomm Science (OPALS) demonstration from the International Space Station (ISS). The use of OCTL to support these demonstrations is discussed in this report. The discussion will feed forward to ongoing and future space-to-ground laser communications as it advances toward becoming an operational capability.

ground operations↗
NASA NTRS2013

The Lunar Laser OCTL Terminal (LLOT) Optical Systems

The Lunar Laser OCTL Terminal is an auxiliary ground station terminal for the Lunar Laser Communication Demonstration (LLCD). The LLOT optical systems exercise modulation and beam divergence control over six 10-watt fiber-based laser transmitters at 1568 nanometers, which act as beacons for pointing of the space-based terminal. The LLOT design transmits these beams from distinct sub-apertures of the F/76 OCTL telescope at divergences ranging from 110 microrad to 40 microrad. LLOT also uses the same telescope aperture to receive the downlink signal at 1550 nanometers from the spacecraft terminal. Characteristics and control of the beacon lasers, methods of establishing and maintaining beam alignment, beam zoom system design, co-registration of the transmitted beams and the receive field of view, transmit/receive isolation, and downlink signal manipulation and control are discussed.

laser communications↗
NASA NTRS2009

Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

fiber amplifier↗
NASA NTRS2008

Varying the Divergence of Multiple Parallel Laser Beams

A provision for controlled variation of the divergence of a laser beam or of multiple parallel laser beams has been incorporated into the design of a conceptual free-space optical-communication station from which the transmitted laser beam(s) would be launched via a telescope. The original purpose to be served by this provision was to enable optimization, under various atmospheric optical conditions, of the divergence of a laser beam or beams transmitted from a ground station to a spacecraft.

Kovalik, Joseph M.↗
NASA NTRS2005

Method and apparatus for a multibeam beacon laser assembly for optical communications

An optical beacon is comprised of a telescope having a primary focal plane or Coud? focal plane, a plurality of fiber coupled laser sources for generating a plurality of beams, a collimator for collimating the plurality of beams, and optics for combining and focusing the plurality of collimated beams onto the primary or Coud? focal plane of the telescope. The telescope propagates the optical beacon, which is arranged into a ring of incoherent plurality of collimated beams. The apparatus further comprises fiber splitters coupled to each laser source to provide at least eight beams from at least four laser sources. The optics comprises a prism assembly, a combiner lens, a focusing lens and a field lens for focusing the plurality of collimated beams onto the primary focal plane or Coud? focal plane of the telescope.

Biswas, Abhijit↗
NASA NTRS2001

45 Km horizontal path optical link demonstrations

Observations made during a mountain-top-to-mountain-top horizontal optical link demonstration are described. The optical link spans a range of 45 Km at an average altitude of 2 Km above sea level. A multi-beam beacon comprised of eight laser beams emerging from multi-mode fiber coupled lasers (780 nm) are launched through a 0.6 m diameter telescope located at the JPL Table Mountain Facility (TMF) in Wrightwood, California. The multibeam beacon is received at Strawberry Peak located in the San Bernadino Mountains of California. The NASA, JPL developed optical communications demonstrator (OCD) receives the beacon, senses the atmosphere induced motion and using an upgraded fine steering loop compensates the re-transmission of a communications laser beam (852 nm, 400 Mbps) to TMF. The eight-beam beacon allowed a four reduction in normalized irradiance or scintillation index. This in turn was sufficient to eliminate beacon fades sensed b the OCD and allowed the fine steering loop performance evaluation. The uncompensated tracking error was determined to be 2.2 - 3 prad compared to a model prediction of 3.4 prad. The paper also discusses various auxiliary observations made during the campaign

Page, Norman A.↗