***Preliminary Version***
KIOST’s 2025 Pacific Ocean Expedition
R/V Isabu August 14 – September 9, 2025
From August 14 – September 9, 2025, 8 CSSF team members supported the Korean Institute of Ocean Science and Technology (KIOST) aboard the R/V Isabu for their MIRAE 2025 Expedition. The science team’s objectives were to implement their new drilling program for subsea crust. [Add: More context from the science team]. Our team’s main objective was to drill as many crust core samples as possible.
There were 2 components to this expedition: drilling and science. The crust drilling component lasted for 25 dives. We aimed to drill ~150 core samples, and we were able to collect ~130. For this expedition, we added a sub-bottom profiler to ROPOS, which allowed us to collect imagery of the layers of sediment lying below the surface of the seafloor and will be used by the scientists to measure the distance between the top of the sediment and the crust that sits underneath. The sub-bottom profiler is new, and we were testing it out, in conjunction with the drill. On every dive, we collected 10 cores. We would drill, then transit to the next point for 1 km; during transit, we used the sub-bottom profiler. After this was completed, we placed a rock box on the side of ROPOS to pick up manganese nodules with one of ROPOS’s scoops. For the second component of the expedition, we switched to science configuration for ~4 dives, where we fitted the front porch with bio boxes, and attached the suction sampler and a setup for push cores. Using this, we collected biology samples, including corals and sponges.
[Add: Highlights for the science team]
Highlights for our team included the integration of an acoustic instrument called a sub-bottom profiler onto ROPOS for the first time, as well as a new fiber optic gyroscope (FOG) and doppler velocity logger unit (DVL), a new navigation setup which has been one year in the making. The FOG gives our team ROPOS’s orientation relative to the seafloor (called “attitude”), while the DVL gives ROPOS’s speed over the seafloor. On this expedition, the FOG and DVL, together, made navigation more accurate and rendered our Loki system (a navigation program that uses sensor data to locate ROPOS on the seafloor; developed by Vince Auger, our former IT and Navigation Manager) obsolete. Our team is also getting more successful with drilling crust cores. Sometimes a drill core can fall off, and if a core is on the seafloor, we can’t put it back into the magazine because it’s too sensitive of an area on ROPOS for the manipulator arms to touch. Our team needed a place to put the core after the manipulator arms pick it up. So, Luke Girard, our Mechanical Technician and Science Manager, developed a holster that attaches to the side of ROPOS to hold one. A personal highlight was our Operations Manager, Keith Tamburri, winning two arm wrestling matches with the captain of the Isabu!
We faced a few challenges on this expedition. A bustle of hoses and cables, including fibre optics to our main Zeus camera, got caught in one of the thrusters. It took 12 hours to replace the bustle, but we persevered and successfully got the system up and running again! We also experienced an electrical short circuit in our power cube, which is the electric power distribution unit for ROPOS. There are a lot of electrons in there, and this caused the ship’s breakers to trip during a dive. This meant that mid-drilling, we lost power, and ROPOS was stuck to the seafloor! Luckily, we have a fail-safe relief system that includes a ball detent mechanism, which is similar to the one that allows a rachet to secure itself to a socket — this is how a core attaches to the spindle. In the end, the ball detent mechanism allowed us to detach ROPOS from the seafloor and perform a safe recovery. To fix the electrical outage, our team was able to replace the short-circuited cables in the power cube and work with the ship’s crew to successfully get ROPOS’s power back up again!
