Salient_Characteristics_1.pdf

Specifications For Seafloor Geodetic Capability with an Autonomous Ocean‐Surface Vessel

In order to fulfill our mission of assessing earthquake hazards during the inter‐, co‐, and post‐ seismic phases of the seismic cycle, we require the capability of making cm‐ to sub‐cm resolution (repeatability) location measurements of benchmarks located on the seafloor in an integrated system using the GPS‐A (Global Positioning System – Acoustic method). The system must include an autonomous ocean‐surface vessel to be used as a platform for a GPS‐a module that provides satellite positioning, vehicle inertial navigation corrections, and communicates with networks of acoustic transponders on the seafloor. The GPS‐ The system must be portable enough so that it may be shipped on short notice (for example, immediately following an earthquake in U.S. territory) using cargo trucks of 12 ft length and deployed from boats with minimum requirement of a deck crane.

Specifications for Integrated System

‐ The acoustic transponder must be capable of immediately and seamlessly attaching to the autonomous surface vessel in a manner which minimizes hull noise and bubble entrainment across the transducer.

‐ The integrated system must be capable of being assembled and disassembled within 24 hours and preferably within 2 hrs for rapid response deployment

‐ The integrated system must be small enough so that it may be shipped by ground in a cargo van with length dimension as small as 12 ft. It must also be small enough so that it can shipped by standard air‐freight shipping following standard air cargo unit load device (UDL) component dimensions

Specifications for Autonomous Ocean‐Surface Vessel

‐ Length: less than 10.5 ft.

‐ Length of mission capacity: up to 1 year at sea ‐ Locomotion: (1) ability to hold on station in prevailing currents of 2kts; (2) low noise vehicle propulsion to avoid interference with acoustic ranging ‐ Power payload: minimum 15W, desired 20W ‐ Solar capacity: more than 185W ‐ Battery capacity: more than 4.5kWh ‐ Communications capability: ability to send and receive information via satellite telemetry at programmable intervals as short as 2 minutes; telemetry must be able to permit transmission of subsampled data and statistics to shore for quality assessment;

cellular phone communication capacity

‐ Location reporting capability: primary and secondary GPS tracking must be provided by independent on‐board satellite transponders. If primary power payload is absent the secondary GPS tracker must have the ability to send location information via satellite every 6 hours for a minimum of 1 month

‐ Mission piloting capability: Mission piloting protocol and interface must permit direct piloting control by USGS and/or 3rd party pilots that USGS designates.

‐ Station keeping capability: ability to hold station within 30‐40 meters.Payload capacity:

upwards of 6 payload bays with pressure rating and watertight sealing capacity

Specifications for GPS‐A Module

‐ Integrated inertial navigation unit and dual multi‐frequency GNSS antennae/receiver capable of delivering cm‐scale positioning when post‐processed using industry or academic packages

‐ Integrated mounting onto an autonomous ocean‐surface vessel ‐ Compatibility with existing Sonardyne Fetch medium frequency (19‐34kHz) acoustic transponders deployed by USGS and National Science Foundation projects implemented by Scripps Institution of Oceanography.

‐ Ability to precisely synchronize timing of outgoing acoustic interrogations to GPS pulse‐ per second timing signal

‐ Precise heading, attitude, and GNSS positioning of the acoustic transducer.

‐ Ability to time acoustic returns using GPS derived timing signal ‐ Minimum of 64GB dual redundant internal storage of 20Hz INS and 1Hz GNSS data