Impacts of anthropogenic noise on marine mammals are becoming increasingly important for regulatory and research study, yet assessing and mitigating these impacts is hindered by current technology: archival underwater acoustic recorders have their data analyzed months after the activity of interest, and towed hydrophone arrays suffer from nearby ship and seismic air gun noise. This work addresses these drawbacks by developing an acoustic data acquisition and transmission system for use with a Wave Glider, to provide near real-time data for marine mammal monitoring and mitigation. The goal of the system is to be capable of months of autonomous monitoring in areas that would otherwise not be surveyed, and to transmit acoustic data within minutes of acquisition to enable rapid mitigation. Sea tests have demonstrated the proof-of-concept with the system recording four channels of acoustic data and transmitting portions of those data via satellite. Ongoing work is integrating a detection-classification algorithm on-board the Wave Glider and a beam-forming algorithm in the shore-side user interface, to provide the user with a topographic view of the Wave Glider; a sound source direction estimate; and aural and visual review of the detected sounds.
To facilitate the accurate placement and alignment of the corrective optics space telescope axial replacement (COSTAR) structure, mechanisms, and optics, the COSTAR Alignment System (CAS) has been designed and assembled. It consists of a 20-foot optical bench, support structures for holding and aligning the COSTAR instrument at various stages of assembly, a focal plane target fixture (FPTF) providing an accurate reference to the as-built Hubble Space Telescope (HST) focal plane, two alignment translation stages with interchangeable alignment telescopes and alignment lasers, and a Zygo Mark IV interferometer with a reference sphere custom designed to allow accurate double-pass operation of the COSTAR correction optics. The initial setup is configured to mimic the as-built optical axis and latch geometry of the Bay 4 position (high speed photometer) in the HST. The system is used to align the fixed optical bench (FOB), the track, the deployable optical bench (DOB), the mechanisms, and the optics to ensure that the correction mirrors are all located in the required positions and orientations on-orbit after deployment. In this paper, the layout of the CAS is presented and the various alignment operations are listed along with the relevant alignment requirements. In addition, calibration of the necessary support structure elements and alignment aids is described, including the two-axis translation stages, the latch positions, the FPTF, and the COSTAR-mounted alignment cubes. CAS SATISFIES DEMANDING REQUIREMENTSO-8194-1245-7/931$6.UO
Assessing and mitigating the effects of anthropogenic noise on marine mammals is limited by the typically employed technologies of archival underwater acoustic recorders and towed hydrophone arrays. Data from archival recorders are analyzed months after the activity of interest, so assessment occurs long after the events and mitigation of those activities is impossible. Towed hydrophone arrays suffer from nearby ship and seismic air gun noise, and they require substantial on-board human and computing resources. This work has developed an acoustic data acquisition, processing, and transmission system for use on a Wave Glider, to overcome these limitations by providing near real-time marine mammal acoustic data from a portable and persistent autonomous platform. Sea tests have demonstrated the proof-of-concept with the system recording four channels of acoustic data and transmitting portions of those data via satellite. The system integrates a detection-classification algorithm on-board, and a beam-forming algorithm in the shore-side user interface, to provide a user with aural and visual review tools for the detected sounds. Results from a two-week deployment in Cape Cod Bay will be presented and future development directions will be discussed.
The corrective optics space telescope axial replacement (COSTAR) configuration contains mechanisms in each science instrument channel that allow for on-orbit correction for image plane focus and for lateral and axial mapping of the Hubble Space Telescope (HST) primary mirror onto the aspheric corrector mirrors. The optical alignment of the COSTAR optics is accomplished in two phases. In Phase I, the mirror bezel tilts and lateral positions are determined through the use of surrogate flat mirrors with the mechanism's positions held at the mid-range of their travel. The Phase I alignment is followed by Phase II interferometric optimization of all five optical channels. At the conclusion of the Phase I alignment, the optics are positioned accurately enough to allow simultaneous correction of most channels on orbit through the use of the mechanism compensation and telescope fme-pointing control. Individual mirror positions and orientations are determined through the use of alignment telescopes, theodolites, alignment lasers, and reference fiducials incorporated into the COSTAR Alignment System (CAS). The proper angles and positions are transferred from the surrogate mirrors to the flight optics, bezels, and shims through use of the alignment transfer fixture (AlT). The flight optics are then installed on the mechanism arms and aligned in decenter and roll. The tolerances on the mirror positions at the conclusion of Phase I alignment are mm in lateral position, 1 mm in axial position, arc sec in azimuthal and elevation angle, and degrees in roll angle.
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