Goddesses of Mud
Now into the second week of the cruise, the boat has settled into more of a routine. During the day the ROV is down in the canyon. At night, either the CTD or the Box Core is over the side. There are two shifts of scientists, just like the crew. We cross paths at breakfast and dinner. Sharing the same cabin, it is dark in the sleeping quarters almost all the time.
The Box Core is a most interesting contraption. While the ROV is all high tech with digital cameras, robotic arms, and laser sights, the Box Core is all brute force. Its purpose is to ram a metal tube about the size of a 5 gallon bucket into the substrate and haul it back to the surface. It does not matter to what depth beneath the surface of the sea it goes, the Box Core is all metal and spring operated, and there is no power to lose or electronics to worry about.
The Box Core is set up by pulling down on the swing arm and then engaging a horizontal locking pin which holds the cable in place. This locking pin is attached to a spring which will soon pull it free; another vertical bar prevents this from happening. On the vertical bar is a small lever, which is the key to the whole contraption.
As the Box Core reaches the bottom, the frame contacts the canyon floor and pushes up the releasing lever, moving the bar down, freeing the pin, which is pulled back by the force of the spring, and frees the cable attached to the swing arm. Meanwhile the metal tube is plunging into the bottom. As the cable is tightened, the swing arm, released when the pin was withdrawn, swings down through the substrate and seals the bottom of the metal tube, forming a bucket. Then as the cable is drawn up, the bucket is sealed on the top too which allows for an undisturbed surface layer. In effect, a punch biopsy of the ocean floor is headed back towards the surface, including all the fine surface sediments and the 3-4 inches of water that was adjacent to the bottom.
The substrate is composed of silt, sand, and gravel, often generically referred to as mud. Several scientists on board are interested in it and the animals that live in it. They all really love the mud and are not afraid to show it! You can read more about their work at http://oceanexplorer.noaa.gov/explorations/12midatlantic/logs/logs.html.