Deploying a seismometer at the MARS observatory to test elements of the OOI CI

My first job at Scripps was as a shipboard computer technician taking care of computer needs, sonar operations, communications systems, and often times deck work on the large SIO research vessels. I quickly learned that a slightly different breed of scientist and tech are found on ships. The job of these sea-going personnel usually involves deploying very expensive, usually custom one-off equipment, often near the vicinity of to the sea floor. As equipment descends hundreds or thousands of meters, the pressure on the instrument package ratchets up, the salt water begins to wear on the materials, and the creatures of the sea start to take notice of the potential habitat. Throughout this process, there are plenty of opportunities for something to go wrong. Cables may part, housings may implode, electronics may short, acoustic releases may not work, gear may be installed wrong, O-rings may leak, you name it. And when something does go wrong, you cant just open it up to fix it right then and there.

The successful scientists and techs are the ones who go through a deployment with a deep calmness. The relaxation is is all about knowing that they have built a robust, deployable package and tested it thoroughly. When something doesnt make sense during development, it is investigated until understood. High quality parts are used. Backup plans are made. The what-if scenarios are thoughtfully considered and plans made for each situation. That's the idea anyways.

It was with this intent that our team of people from various SIO projects assembled a seismometer to attach to the MARS cabled observatory at the Monterey Bay Aquarium Research Institute (MBARI). The parts were robust and well tested on other projects in the past. The gear was assembled, the software was checked and rechecked, configurations were fine tuned, and the requirements were reviewed. The package consisted of a sensor ball to measure movement, an electronics cylinder to house the data logger and networking equipment, and a connector to plug into the MARS switch. The whole package was put on a frame and designed for easy deployment with an ROV.

When the package was ready to go, we did a wet test in the MBARI test tank. With our seismometer's need for precise and accurate timing, we spent the first day verifying that the timing signals we were expecting during the sea deployment were going to work with our gear. The test tank connection offered a simulation of those signals so that we could be sure the seismometer could lock up with the correct high precision time. When we were finally convinced that what we had worked with the simulated signals, we went home and planned to deploy to the sea floor in a couple of weeks. We could only hope that the simulator timing signals had the same characteristics as the real MARS signals...

Deployment day rolled around and our team headed out to sea. With the help of the Point Lobos crew, our package (complete with carefully calculated amounts of float packs attached) was deployed to the sea floor. Chasing it was the ROV Ventana. When everything was safely at the bottom, operations commenced to connect our package to the MARS node. Gear was shuffled about by the ROV, cables were plugged in carefully....and it didnt work due to an electrical short. Despite the testing and attention to details during the development of the gear, we had some bad luck. After much theorizing and testing what we could from the end of the cable, the seas started picking up and we had to leave the site before we could recover the gear for further work. With our package in the ocean, we would have to come back in a few days to recover it and investigate. Thankfully we were able to retrieve the instrument and pressure housing a couple of days later. With the equipment back on shore, we found the problem, corrected it, and scheduled another deployment. 

During the next deployment, everything went safely and smoothly to get the equipment on the sea floor. The gear was successfully plugged into the MARS node and powered up. The sensor and electronics all checked out okay and started sending data home. However, the timing was off. Is the issue in the electronics inside our package? Maybe the software running down on the sea floor? The timing pulse through the MARS node? Does it even exist? Is it the same as the simulator? Theories abound, tests have been done, and changes have been tried. There is still more work to be done to get synchronized seismic data from the sea floor. The next opportunity to investigate the connection will hopefully be soon.

-Steve Foley

The MARS seismometer project is funded by the NSF as a testbed for the OOI CI. "ITR: Collaborative Research: Looking Ahead: Designing the Next Generation Cyber-infrastructure to Operate Interactive Ocean Observatories," or "LOOKING." NSF award 0427974.