D. Barry Coyle

Laser Ranging bBetween the Mercury Laser Altimeter and an Earth-Based Laser Satellite Tracking Station over a 24-Million-km Distance

Using the Mercury Laser Altimeter, a 10-cm laser ranging precision was demonstrated between Earth and the MESSENGER spacecraft over a 24-million-km distance in space.

Laser production for NASA's Global Ecosystem Dynamics Investigation (GEDI) lidar

The Lasers and Electro-Optics Branch at Goddard Space Flight Center has been tasked with building the Lasers for the Global Ecosystems Dynamics Investigation (GEDI) Lidar Mission, to be installed on the Japanese Experiment Module (JEM) on the International Space Station (ISS)1. GEDI will use three NASA-developed lasers, each coupled with a Beam Dithering Unit (BDU) to produce three sets of staggered footprints on the Earths surface to accurately measure global biomass. We will report on the design, assembly progress, test results, and delivery process of this laser system.

Lifetest of the High Output Maximum Efficiency Resonator (HOMER) laser for the SAFFIRE instrument on NASA's DESDynI project

We update the status of a diode-pumped, Nd:YAG oscillator that is the prototype laser for NASAs DESDynl mission. After completing TRL-6 testing, this laser has fired over 5.5 billion shots in lifetesting.

Qualification and Issues with Space Flight Laser Systems and Components

The art of flight quality solid-state laser development is still relatively young, and much is still unknown regarding the best procedures, components, and packaging required for achieving the maximum possible lifetime and reliability when deployed in the harsh space environment. One of the most important issues is the limited and unstable supply of quality, high power diode arrays with significant technological heritage and market lifetime. Since Spectra Diode Labs Inc. ended their involvement in the pulsed array business in the late 1990s, there has been a flurry of activity from other manufacturers, but little effort focused on flight quality production. This forces NASA, inevitably, to examine the use of commercial parts to enable space flight laser designs. System-level issues such as power cycling, operational derating, duty cycle, and contamination risks to other laser components are some of the more significant unknown, if unquantifiable, parameters that directly effect transmitter reliability. Designs and processes can be formulated for the system and the components (including thorough modeling) to mitigate risk based on the known failures modes as well as lessons learned that GSFC has collected over the past ten years of space flight operation of lasers. In addition, knowledge of the potential failure modes related to the system and the components themselves can allow the qualification testing to be done in an efficient yet, effective manner. Careful test plan development coupled with physics of failure knowledge will enable cost effect qualification of commercial technology. Presented here will be lessons learned from space flight experience, brief synopsis of known potential failure modes, mitigation techniques, and options for testing from the system level to the component level.

A mission-enabling UV laser for mass spectrometry (UVMS) with continuously selectable output for in-situ planetary exploration

Ultra-compact, nanosecond-class spaceflight-compatible UV lasers are finding increasing application in laser desorption, excitation, and ionization analytical applications on planetary missions, such as the detection and characterization of potential molecular biosignatures on Mars or icy moon surfaces. A short pulsed, solid state, UV laser is under development with selectable pulse energy capabilities for optimized sample ion production at a planetary surface.

Component-level selection and qualification for the Global Ecosystem Dynamics Investigation (GEDI) laser altimeter transmitter

Flight quality solid-state lasers require a unique and extensive set of testing and qualification processes, both at the system and component levels to insure the lasers promised performance. As important as the overall laser transmitter design is, the quality and performance of individual subassemblies, optics, and electro-optics dictate the final laser unit’s quality. The Global Ecosystem Dynamics Investigation (GEDI) laser transmitters employ all the usual components typical for a diode-pumped, solid-state laser, yet must each go through their own individual process of specification, modeling, performance demonstration, inspection, and destructive testing. These qualification processes as well as the test results for the laser crystals, laser diode arrays, electro-optics, and optics, will be reviewed as well as the relevant critical issues encountered, prior to their installation in the GEDI flight laser units.

Adapting a ground-based laser ranging system at NASA-GSFC for identification and tracking of orbital debris

The mitigation of orbital debris was addressed in the most recent release of the National Space Policy directing space faring agencies to pursue technologies that will “mitigate and remove on-orbit debris.” No matter what abatement technology is developed and deployed, still lacking is the remote sensing infrastructure to locate and track these objects with adequate precision. We propose using GSFCs ground-based laser ranging facility to provide meter-level or better ranging precision on optically passive 10-30 cm orbital debris targets with the goal of improving current predictions up to 85%. The improved location accuracy also has the immediate benefit of reducing costly false alarms in collision predictions for existing assets.

A hybrid fiber/solid-state regenerative amplifier with tunable pulse widths for satellite laser ranging

A fiber/solid-state hybrid seeded regenerative amplifier capable of achieving high output energy with tunable pulse widths has been developed for satellite laser ranging applications. The regenerative amplifier cavity utilizes a pair of Nd: YAG zigzag slabs oriented orthogonally to one another in order to symmetrize thermal lensing effects and simplify optical correction schemes. The seed laser used is a fiber-coupled 1064 nm narrowband (<0.02 nm) diode laser which is intensity modulated by a fiber Mach-Zender electrooptic modulator, enabling continuously tunable seed pulse widths in the 0.2 - 2.0 ns range. The seed laser pulse energy entering the regenerative amplifier cavity is ~10 pJ, and is amplified to ~1.6 mJ after 37 round trips, representing a gain of ~82 dB. When seeded with 200 ps pulses at a 2 kHz repetition rate, the regenerative amplifier produces >2 W of frequency-doubled output (>1 mJ/pulse at 532 nm).