The research cruise is operating from the R/V Sikuliaq, pronounced [see-KOO-lee-auk], a 261-foot oceanographic research ship capable of bringing scientists to the ice-choked waters of Alaska and the polar regions.
Previous magnetic surveys used a magnetometer towed along the ocean surface. However, those surveys found it difficult to resolve individual magnetic anomalies in the Jurassic-aged seafloor because of the extreme water depth (>5 km). To overcome this issue, we are making magnetic measurements using an autonomous underwater vehicle, the AUV-Sentry. The Sentry contains a sensitive magnetometer (among other instruments), and operates ~100 meters above the seafloor, ~5 km below the ocean surface. At this depth, the Sentry’s magnetometer can record a much stronger signal than we can record at the sea surface. However, the AUV-Sentry can’t remain underwater indefinitely. It can take up to 4 hours for the AUV-Sentry to be deployed and descend to the ocean bottom, and it has enough battery power to take magnetic measurements for about 24 hours. It takes another 4 hours to ascend to the surface, and 16 hours onboard the ship to recharge its batteries.
While the AUV-Sentry is operating on its own using its own navigational instruments and software, the scientists on the ship are taking concurrent measurements using a towed magnetometer, the MISO-TowCam. The TowCam data will provide a second magnetic profile, parallel to the profile measured by the AUV-Sentry.