The transit to North Pond took just about a week, we arrived Monday afternoon at our sampling site. We had spent the transit cleaning and prepping our gear. Monday morning was filled with a little bit of anticipation and plenty of preparation for sending our sampling equipment down to the seafloor.
Clarisse and I are here to collect fluid from borehole observatories installed previously called Circulation Obviation Retrofit Kits (CORKs). These CORKs allow us to access the fluid under the seafloor. We essentially hook a hose up to the CORK and fill specially designed bags with the crustal fluid. The bags are held on Jason in one large box on the front of the ROV (the “front porch”) and six smaller boxes on the back. To fill the smaller boxes, we divert the water to a manifold with multiple ports. In addition to the boxes, there are ports connected to filters so that we can pass water through them while Jason is sitting on the seafloor. From the Jason control van (aka the command center), we can change which port the water is flowing through, so our routine includes filling up all the bags in the boxes and passing fluid through the filters.
Monday evening the anticipation built as we strapped our equipment onto Jason and the Jason engineers then went through their pre-dive to check that everything was ready to roll. We wrapped up yet another fantastic meal (the food has been seriously amazing), then Jason was hoisted into the air, over the side of the ship, into the rolling swells. Deploying the ROV at night made for a dramatic first dive, but…life is full of challenges, even more of them when you’re working at over 4,000 meters deep, and not long into the dive one of the hydraulic arms started leaking oil in a steady stream, the dive was definitely over.
After a 3 hour ascent, time to repair the arm, and a quick look to make sure everything was still strapped on tightly, Jason was sent back down to about 4,300 meters. Another few tasks were accomplished before yet. another. leak. Major bummer, we didn’t get to start collecting fluid samples and already two dives had met untimely ends. Jason was hauled onto the deck yet again, but this time they didn’t just do a quick fix, the whole ARM was replaced. Rough night for Jason, undergoing surgery before heading back to work.
Third time’s a charm though, and on that dive numero tres we managed to collect over 100 liters of crustal fluid. Everyone was happy to grab their bags of water, and I can’t tell you how stoked Clarisse and I were that it was a success. We might be the main people orchestrating the water collection, but these samples are key to multiple experiments for different labs on the ship.
Whew, what a relief! We unloaded our first set of boxes, and turned around to load the next set up – when working to get everyone’s samples and experiments in, time is of the essence! We had two more successful dives after that first round, this week has been a packed cycle of pulling samples off the ROV and loading everything back up to do it again. The actual fluid sampling process takes about 7 or 8 hours in the control van and as I type, equipment for our last sampling run is sitting on Jason on the deck ready to head down to the bottom.
In addition to whatever experiments and gear we have to deal with on board, all of the scientists are assigned a 4 hour block of time during the day or night to go oversee logs as well as take photos and videos of any experiments performed during the dive. The watch is only required if Jason is in the water, so we get to spend time sitting in the control van.
I was a lucky duck yesterday morning since there was some time to kill before the dive was ended and I got a few minutes to sit in the driver’s seat and fly Jason around the sea floor. Probably the coolest thing I’ve ever done, and not to be forgotten soon. More water sampling is on the way, our fingers are crossed for the next round!
Contributed by Kelle Freel, a postdoc at the Hawaii Institute of Marine Biology, University of Hawaiʻi at Mānoa.