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This paper describes the technology development of the master oscillator (MO) as part of the NASA laser transmitter for the LISA mission. The MO is based on the non-planar ring oscillator (NPRO) resonator design.
A discussion of recent technology developments for far-infrared bolometric detector focal plane assemblies is provided. Some of the developments include strategies for fabricating high filling fraction background limited-transition edge sensor bolometric detectors, impedance-matched absorber coatings, a micromachined blackbody source, and the capability to fabricate indium bumps on non-planar substrates.
Fogging of polycarbonate spacesuit helmets is detrimental to astronaut safety and to mission success. Currently used anti-fogging methods are temporary and require the reapplication of a coating before each use. These temporary solutions have been shown to delaminate during use and have led to eye irritation and temporary blindness during spacewalks. Potential permanent solutions NASA has previously tested lack in durability and are prone to coating damage and delamination during cleaning. Lynntech is leveraging its experience with coating development to fabricate an anti-fog coating with the durability necessary for permanent use, to be applied to polycarbonate. In this SBIR Phase I project, Lynntech has demonstrated the proof of concept by applying our coating to flat polycarbonate and characterized the durability of its anti-fogging properties. Toward this end, Lynntech has developed a breath simulating testbed, exposing coatings to conditions they would experience on the interior of a spacesuit helmet during use. Additionally, Lynntech is developing an application method to uniformly deposit their coating on non-planar objects, such as a prototype spacesuit helmet.
NASA Goddard Space Flight Center (GSFC) is developing the Laser System (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency (ESA) with a launch date of 2035. The LS under development at NASA GSFC consists of the Laser Head (LH), the Frequency Reference System (FRS), and the Power Monitor (PMON) Detector Assemblies. Since late 2017, we have been developing various models to advance the technology readiness level (TRL) for the LH from prototype (TRL4) to a system model demonstration in a relevant environment (TRL6). For the LH and FRS, the models further breakdown into the optical and electronics modules where the LH is made up of the Laser Optical Module (LOM) and the Laser Electronics Module (LEM) and the FRS consists of the FRS Optical Reference Cavity (FRS-O) and the FRS Electronics (FRS-E). The LS development follows the established NASA process in demonstrating the performance requirements [1] through the TRL4 effort and then advancing the form factor and package design to meet relevant environment requirements and qualifying the TRL6 design through rigorous testing and performance verification for space applications. The LOM for the LH is a main oscillator power amplifier (MOPA) with wavelength of 1064 nm and nominal output power of 2 Watt throughout the mission. The low-power, low-noise main oscillator (MO) is a custom micro non-planar ring oscillator (µNPRO) [2] that is phase modulated then amplified by the forward pumped ytterbium-dope fiber power amplifier (PA) stage to meet the output power requirement. The FRS is baselined on the GRACE Follow-On (GFO) [3] approach with updated FRS-E design to work with the LH-LEM. The PMON is located on the Optical Bench Assembly (OBA) [4] that samples a small portion of the LH output signal and provides the feedback signal to the LH-LEM for relative intensity noise (RIN) control. In this paper, we will report on the latest status of the LH testing and system level tests, explain the other subsystems involved in the test campaigns, and discuss the path to bring each LS subsystem to TRL6. We will also present the NASA GSFC roadmap in advancing the LISA LS to TRL6+ and plans for future system level testing as well as the preparation for space flight development to meet the LISA launch date of 2035.