December 2, 2011 Slideshow

The Jason team readies the remotely operated vehicle (ROV) for a dive to Urania Basin. (l-r) Dara Scott, Lisa Borden, Hugh Popenoe, Tito Collasius, Scott Hansen. The blue and yellow portion of Jason is low-density foam, which makes the ROV buoyant.

Scott Hansen checks the height of the ocean swells as he waits to operate the winch that will lift Jason off the deck of R/V Atlantis and set it gently into the water.

Photographs from Jason’s Science Camera reveal the weird world of Urania Basin. In this shot, Jason is near the halocline. The water is murky because it is very dense and contains many fine particles of detritus. Jason throws out two red laser beams that are 10 cm apart, to help estimate the size of things seen through the camera. The scientists think the swirly white material is the top of the halocline.

At an area of normal seawater, Jason finds its own footprint from earlier in the dive. Notice how clear the water is and how far in front of the basket you can see. Compare this with the next photo, which was taken when the bottom of Jason was in the halocline.

Where did the light go? You can tell Jason’s lights are still on, because the equipment on the basket is still lit up. But the dense DHAB brine seems to swallow the light. Even the laser beams nearly disappear in the murk.

Determined to get samples of sediment from the Urania Basin, the scientists called on WHOI technician Ellen Roosen and the multicorer. Although this instrument brings back beautiful cores of sediment, it does not preserve the samples at the seafloor, and it cannot be directed to a specific spot.

The MC800 multicorer goes over the side. It consists of a teepee-like frame of eight legs with a ring of eight large core tubes mounted on a weighted carriage. When the feet touch down, the carriage continues moving, driving the core tubes into the sediment.

When the multicorer came back from Urania Basin, its tubes were empty but some of its feet held dark, gooey mud from the floor of the DHAB. The mud stank of sulfide.

Chunks of rocky material found on a foot of the multicorer after its deployment to Urania Basin. The science team thinks it is composed of calcium carbonate. The chunk in the light is about 1.5 inches (3.8 cm) long.

[ Back to today's journal ]