Elisavet Troupaki

Space laser transmitter development for ICESat-2 mission

The first NASA Ice, Cloud and land Elevation Satellite (ICESat) was launched in January 2003 and placed into a nearpolar orbit whose primary mission was the global monitoring of the Earths ice sheet mass balance. ICESat has accumulated over 1.8 B shots in space and provided a valuable dataset in the study of ice sheet dynamics over the past few years. NASA is planning a follow-on mission ICESat-2 to be launched tentatively in 2015. In this paper we will discuss the development effort of the laser transmitters for the ICESat-2 mission.

Space qualification and environmental testing of quasicontinuous wave laser diode arrays

NASA’s mission requirements for spaceborne laser diode arrays lead to a set of tests peculiar to space flight. The goal of these tests is to determine if vibration, radiation, or vacuum will impair the operation or lifetime of nominally 100W quasicontinuous wave 808nm laser diode arrays. To simulate the stresses expected during a mission, terrestrial tests involve mechanical vibration, simulating the acceleration of launch, exposure to the equivalent doses of ionizing radiation, and operation in a vacuum. Three sets of devices were tested: one set with random vibration up to 20 g root-mean-square (grms) applied along three axes, a second set of devices was irradiated with γ radiation (1.17 and 1.33MeV) at 744rad(Si)∕min up to 200krad(Si), and the third set was exposed to a flux of 5×1011 or 1012p∕cm2 of 200MeV protons up to 60krad total dose. Only the proton irradiated devices showed any effect attributable to the test: a slight rise in lasing threshold, which recovered over time with self-annealing. A se...

Overview of space qualified solid state lasers development at NASA Goddard Space Flight Center

NASA Goddard Space Flight Center (GSFC) has been engaging in Earth and planetary science instruments development for many years. With stunning topographic details of the Mars surface to Earths surface maps and ice sheets dynamics of recent years, NASA GSFC has provided vast amount of scientific data products that gave detailed insights into Earths and planetary sciences. In this paper we will review the past and present of space-qualified laser programs at GSFC and offer insights into future laser based science instrumentations.

Characterization of high-power quasi-cw laser diode arrays

NASAs requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

Space qualification of the optical filter assemblies for the ICESat-2/ATLAS instrument

The Advanced Topographic Laser Altimeter System (ATLAS) will be the only instrument on the Ice, Cloud, and Land Elevation Satellite -2 (ICESat-2). ICESat-2 is the 2nd-generation of the orbiting laser altimeter ICESat, which will continue polar ice topography measurements with improved precision laser-ranging techniques. In contrast to the original ICESat design, ICESat-2 will use a micro-pulse, multi-beam approach that provides dense cross-track sampling to help scientists determine a surfaces slope with each pass of the satellite. The ATLAS laser will emit visible, green laser pulses at a wavelength of 532 nm and a rate of 10 kHz and will be split into 6 beams. A set of six identical, thermally tuned optical filter assemblies (OFA) will be used to remove background solar radiation from the collected signal while transmitting the laser light to the detectors. A seventh assembly will be used to monitor the laser center wavelength during the mission. In this paper, we present the design and optical performance measurements of the ATLAS OFA in air and in vacuum prior to their integration on the ATLAS instrument.

Laser Diode Pump Technology for Space Applications

In this chapter we will discuss the use of diode pump technology in space LIDAR (Light Detection and Ranging) missions. Space applications have a unique set of engineering requirements. In general, devices need to be reliable, compact, lightweight, efficient and rugged. Satellites need to survive launch and then operate in a vacuum, high-radiation, micro-gravity environment. Because of the high costs associated with launching payloads into space, lift capacity needs to be minimized and instruments need to be lightweight and compact. Because solar arrays and batteries that are necessary to operate powered equipment need to be launched as well, efficiency should be optimized to minimize the on-orbit power draw. Finally once an instrument has been launched into space, it is critical that it operates reliably – usually for several years. For the missions we will discuss in this paper, long-term reliable operation is very important to make comprehensive global measurements needed by the science community. In addition, these missions require customized science measurements, necessitating the design of one-of-akind instruments.

Quasi-CW laser diode arrays for space applications

NASAs space-borne laser missions have been dominated by low repetition rate (<100Hz) Q-switched laser systems, which use Nd:YAG laser crystals, and are pumped by quasi-continuous wave (QCW) 808 nm laser diode arrays (LDAs). The diode group at NASA Goddard Space Flight Center (GSFC) has been responsible for the screening and qualification of LDAs for several missions. The main goal has been to identify LDAs that can withstand the harsh space environment, and minimize risks associated with LDA degradation or failure. This paper presents a summary of recent research activities, and describes the results from extended testing of multiple LDAs in air and vacuum environments.

Longevity validation of the LOLA laser design by extended vacuum testing of the LOLA engineering model laser

The Lunar Orbiter Laser Altimeter (LOLA) is one of seven instruments aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft with the objectives to determine the global topography of the lunar surface at high resolution, measure landing site slopes and search for polar ices in shadowed regions. The LOLA laser transmitter is a passively Q-switched crossed-Porro resonator. All components used in the laser have space flight heritage. The flight laser bench houses two oscillators (a primary and a cold spare) that are designed to operate sequentially during the mission. If the primary laser can no longer provide adequate scientific data products, the secondary laser will be turned on. The baseline mission calls for LOLA (and LRO) to spend about one year studying the Moon. Since LOLA operates at 28 Hz, the laser system needs to produce approximately one billion pulses during the primary one year mission. To validate that the LOLA laser design is capable of meeting this requirement, the LOLA Engineering Model (EM) laser has been subjected to extended operation testing in vacuum. In this paper we will summarize the longevity validation test effort of the LOLA EM laser.

Qualification of laser diode arrays for space applications

In the recent past, NASAs space-borne laser missions have been dominated by low repetition rate (<100Hz), Q-switched Nd:YAG lasers pumped by quasi-continuous wave (QCW) 808 nm laser diode arrays (LDA). QCW LDA reliability data is limited and their mechanisms of failure is poorly understood. Our group has been working in gathering statistically significant data on these devices and have developed testing strategies to achieve mission success in a cost-effective manner. In this paper, we present our approach for qualifying the LDAs for the Lunar Orbiter Laser Altimeter (LOLA) instrument scheduled to launch aboard the Lunar Reconnaissance Orbiter (LRO) mission. We describe our strategy to mitigate risk due to LDA failure given cost and schedule constraints. The results from extended testing of multiple LDAs in air and in vacuum are also presented.

Development and Vacuum Life Test of a Diode-Pumped Cr:Nd:YAG Laser (Heritage Laser) for Space Applications

The development and vacuum life-testing of a diode pumped Cr:Nd:YAG laser for space applications is presented. Furthermore results from long life-testing of 808-nm laser diode arrays in air and vacuum are discussed.