|Sunrise on the R/V Revelle at Axial Seamount.|
One of the areas where there is the biggest need for communication and coordination is navigation of the ship and the ROV Jason as they move together during dives around Axial Volcano. When Jason is transiting between benchmark sites for pressure measurements on our cruise the Jason navigator uses software to let the ship’s dynamic positioning system know where it needs to move to next. They need to move at a speed that keeps the Jason ROV and its cable in the correct orientation to keep the vehicle and its cable safe.
|Jason's view of the ship navigation.|
View this movie of the navigation (ship is blue, Jason is green and the acoustic buoy on the wire is pink):
Deployments and Recoveries
The Revelle’s marine technicians (referred to as ResTechs) Josh and Jim serve as the liaison between the scientists and the ship and oversee and run any deployment or recovery of instruments or vehicles over the side. They are responsible for the safety of everyone working on the deck and ensuring that no equipment is damaged during deployments or recoveries. For safety everyone involved has to wear hard hats and work-vest life jackets. For the ROV and AUV deployments the ResTechs and the rest of the ship’s crew must work in tandem with the Jason and Sentry teams that operate the vehicles.
|ResTechs Jim (left) and Josh (right).|
For example, to recover the Sentry AUV the following steps occurred. First the dives of both Jason and Sentry had to be pre-planned and designed by Chief Scientist Bill Chadwick to bring Sentry back from its long (24 hr) multibeam survey to meet the ship at a specific time and place as it moved with Jason to different sites within Axial Caldera. (This is sort of like the plan to have the Lunar Lander meet up with the orbiting Apollo space craft). In this case we have three moving objects (Sentry, Jason and the Revelle) in a 3D ocean world moving at different rates and hopefully not running into each other! The Sentry team kept checking on Sentry’s path and provided updates to Bill, the ship’s bridge, and the Jason team as the rendezvous neared.
|AUV Sentry driving toward the ship.|
There are crew from the Revelle, Jason and Sentry team members and the scientists involved in the collection and organization of all the science data during the cruise. The goal of this process is for all the navigation and science data to be cataloged and organized and made available to not just the scientists involved in the cruise but also for the general public to access. In the Jason Control Van there is always a combination of Jason team members and scientists discussing where to take samples or conduct experiments with people from the science party recording events. Photos, videos, navigation and other details are recorded continuously. This information will become part of a cruise report and will be available on-line after the cruise in what is called the Jason “Virtual Van” at this web site, click on our cruise "RR1712":
Virtual Van Website (http://www.whoi.edu/page.do?pid=12876)
|R/V Revelle's computer tech, Brent.|
Dance Missteps are Dangerous
There is risk in not managing the dance correctly - if Sentry gets to the end of its dive and the battery power gets lower than 5%, then it automatically aborts its dive wherever it is and comes to the surface. If the ship is not there to recover Sentry, it would start to drift away quickly in the surface currents. If that occurred away from where we were with Jason, we would have to abort the Jason dive, recover Jason and rush off with the ship to recover Sentry. So that's another reason "the dance" is so important and critical to get right. It could waste a lot of time and up-end our cruise plan for it to go wrong. Plus we don't want to lose Sentry!