Explore the Deep Sea
Expedition 2: Hot Vent Hunting
- Locate seafloor vents suitable for later expeditions to study
- Make detailed maps of these areas and photograph the animals living there
- Recover rocks from the seafloor for further analysis back on land
More than twenty researchers and students from over a dozen research institutions took part, studying everything from the chemical composition of seawater to the distribution of animals. Findings were passed to the third expedition. Like all the expeditions in this series, the research is designed to help us understand the relationships between different components of the system in this ocean basin: how and why tectonic plates move and stretch, and how this affects the overlying ocean: its chemical make-up and the life it contains.
New vent-hunting approach works well
This September 2004 expedition visited target sites where maps from the previous expedition suggested that vents might be present. Researchers tried a new method of finding active vents by searching near the seafloor in a staged way:
- First, an instrument (a CTD, or Conductivity Temperature Depth recorder) is dragged behind the ship to sample seawater near the seafloor. By measuring water temperature and composition, this instrument can detect the mineral-rich plumes of warm fluid that drift up from the vent.
- Second, a robot submarine (ABE) is sent out to map areas containing plumes in more detail, using sonar: first from a height of 250 m above the seafloor, then (if the 250 m results look promising) again from 50 m. If the 50 m results suggest a vent is present, ABE is then used to take detailed photographs from just a few meters above the seafloor.
- Finally, a camera towed behind the ship (TowCam) is used to take even higher-resolution images.
The approach worked well: several vents were located using this method.