Construction of an ocean digital gateway through small satellites
Abstract
Traditionally, oceanographic research has relied upon the use of ships at sea for sampling as well as instrument deployment and recovery. The numbers of oceanographic ships have grown and the sophistication of hardware has increased with time. Over the past twenty years, the availability of geosynchronous satellites has provided a means for communications to the US academic fleet. The larger ships in the research fleet have been planned, funded and built by the US Navy. As with combat ships, the costs of construction and operation (largely funded by the NSF) have increased steadily and to the point where reductions in numbers and size are inevitable. Our proposal builds upon work we have done in introducing autonomous vehicles that draw upon wave energy for propulsion, solar power for instrumentation and acoustic modems for transferring data to and from deep seafloor sensor packages. This surface ~gateway~ connects to the Low Earth Orbit (LEO) Iridium satellites for transferring data to our laboratory ashore and thence to an open repositories for scientific community access. The costs for construction and operating autonomous vehicles is substantially less expensive than using research vessels. There remain many scientific problems that will continue to draw on the use of ships, but to constrain costs, we must turn more-and-more to autonomous systems.During the past two years, we acquired two first-generation ~wave gliders~ for developing an ocean gateway to the global Internet. We successfully conducted a three-month deployment in deep water beyond San Clemente with continuous streaming of data from the seafloor to a glider holding station in a pattern above the seafloor instrumentation. In this case, we deployed a broadband seismometer and pressure gauge (broadband hydrophone) at the seafloor and transmitted data to the surface with an acoustic modem developed at Woods Hole and funded by ONR. The average latency for transferring this data from the seafloor to the lab was approximately 4.3 minutes. Much of the latency was due to accessing the spacecraft. While on station using GPS, we were able to track the glider effectively and the glider, in turn held station near the seafloor seismic package. At one point a storm offshore drove the waveglider south and out of touch of the seafloor package. As the storm abated, the glider (with a top speed of 1.5 ~ 2 knots) worked its way north, acquired a signal from the bottom package, and continued to transfer data.In addition to this work, we also built a hydrodynamic ~tow-body~ capable of being transported by the wave glider. The idea is to use this mechanism to tow a seafloor package to a drop point rather than using an expensive ship for deployment. In this proposal we seek funds to purchase two new wave gliders that provide more powerfrom solar cells and feature a collapsible propeller for maneuvering when waves disappear or when currents are high enough to drive the glider off station. In addition, we are requesting funding to construct a seafloor package suitable for operation for at least two years including sufficient power to download full bandwidth data (50Hz) for at least 20 days. We will purchase two flat panel arrays for communication with small sats in LEO or Mid Earth Orbit (MEO) for downloading data at much higher rates and lower cost. These will be tested aboard a small oceanographic ship with downloads to one of the panels on the San Diego Supercomputer Center~s rooftop where our current Atlantic and Pacific antennae are mounted. The two wave gliders will be modified for operation with smaller antenna arrays to allow telemetry with the glider and the acoustic connection to the seafloor package.This new data gateway oceanographic system will revolutionize long-term measurements at sea by reducing ship use and enhancing the rates at which information is delivered to scientists and any interested user.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 15, 2019
- Source ID
- N000141912337
Entities
People
- John A. Orcutt
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego