John Horne, David Barbee, and Dick Kreisberg
Deployment
Transporting, placing, and connecting an instrument package in nearly 900 m of water is not a trivial task. The science team and ROV pilots worked together to plan the details of deploying DEIMOS from the RV Point Lobos using the ROV Ventana. This included modifying the bottom of the DEIMOS sled to fit snugly on the front porch of the ROV. It also meant fabricating a three-point harness to be able to move DEIMOS off of the sled and, one day, to recover the package.
The cable that connects DEIMOS to the MARS node was problematic. The ROV crew noticed that the cable would not unwind without creating kinks. Kinks could lead to fractures if the cable was stretched tight. After working with us, the crew rewound the cable to minimize kinks.
When the Point Lobos returned Wednesday afternoon from deploying another MARS project, we moved DEIMOS to the ship. The crew re-examined the instrument package and finalized a plan for deploying DEIMOS from the front porch of the Ventana. Once they were satisfied, we left DEIMOS secured to the Ventana for the next day's mission.
Right: ROV pilot Knute Brekke secures DEIMOS to the front porch of the Ventana.
The Point Lobos steamed for 2 hours before reaching the MARS science node on Smooth Plane. Medium winds made for an interesting ride on a boat with a well deserved reputation. After one last inspection, the Ventana was lifted overboard and released from the crane. With all systems go, the ROV began diving to the sea floor while the crew piloted it from the ship.
Right: After a bouyancy check, the Ventana began diving for the bottom.
After a long trip down to the MARS node, the Ventana was piloted 40 meters to the East. DEIMOS was gently set on the flat bottom in an upright position. The ROV manipulated DEIMOS using two robotics arms. One arm is very strong. The second arm has very fine control for manipulating delicate objects.
Right: DEIMOS resting on the sea floor. Note that the front of the sled is sitting in very soft material. © 2009 MBARI
Once DEIMOS was oriented so that the transducer faced north, the drawer on the Ventana sled was opened and the cable was slowly played out until the ROV was back at the MARS node. The ODI underwater cable connector was then plugged into a science port. This is a very delicate process, since the connector must be positioned carefully in 3D space using only the cameras mounted on the ROV.
After successfully connecting DEIMOS to the MARS node, the power was turned on. A few tense moments pass, and voila! DEIMOS began immediately to transmit and receive acoustic echoes. As the ROV Ventana passes over the package, we saw a large echo from the vehicle. DEIMOS is definitely working. Time for the Ventana to return to the surface.
