Picking, Slurping, and Plunging
Collecting a sea star from a shipwreck at the bottom of the sea may sound like a difficult task, but with the ROV Jason it is accomplished with the mere twist of an arm. Jason is equipped with two powerful robotic manipulator arms that assist with underwater tasks when appendages are needed. Both arms have six joints that allow them to move over a wide area and extend up to five feet. The right arm is made of aluminum while the left arm is composed of titanium with a claw that has a grip of 1,000 pounds. They are controlled by the pilot in the ROV van with two multi-jointed joysticks that allow for almost human-like arm movement. When a sample is spotted in one of the cameras, the ROV pilot can extend the arm and, despite the power contained within the arm’s grip, gently pluck it from the substrate. The sample can then be placed in one of the bio-boxes, a box with a lid that the manipulator arm can open, place a sample in, and then close, or in a quiver tube, a smaller sample container used to keep unique samples separated.
Some samples cannot be easily picked though. For example, some organisms are firmly attached to a substrate. During our dives we see many creatures attached to parts of the wreckage (bivalves, anemones, hydroids, and more). If we try to use the robotic arm’s grip on samples such as these we may risk damaging the organisms or possibly the shipwreck. Alternatively, there may be instances where we need to collect several specimens or specimens that are too small to collect with the grip. In these cases we use the suction sampler, colloquially referred to as the slurp sampler (some find it hard not to make a ‘Slllllluuuuurp’ sound when seeing it in action). This sampler looks like an industrial vacuum cleaner dusting tube. It runs from the front of Jason to a chamber inside Jason’s chassis. This chamber contains five different sampling buckets that can be switched out for each sample. When this type of sampling is required the titanium arm grasps the suction tube and holds it up to the sampling surface. The pilot then presses a button, and the slurping begins.
When a sample from the wreck or water column is not enough, we can use Jason to collect sediment samples. For this we have push core samplers and Ekman grab samplers. A push core sampler consists of a big plastic tube with one open end and a one-way valve with a handle for Jason to grab. With its manipulator arm, Jason can plunge one of these samplers into the sediment and collect a neatly preserved core consisting of the layer of water just above the sediment and down 30 cm. This type of sampling allows researchers to analyze the organisms living at different depths in the sediment, or sediment chemistry, or grain size at a very fine scale. The Ekman sampler can be used in instances where the substrate is not fine grained, such as sandy bottoms. It looks kind of like a square Pac-Man, a box with two big curved jaws that can snap shut with springs to keep the collected sediment in place.
These are just some of the many capabilities of the ROV Jason, but if you need a sample from the bottom of the sea, you know who to call.