ROV Rescue at 2000 Meters

On Thursday, August 26, 2021, the cable detached that was connecting two deep-sea exploration ROVs (remotely operated vehicles- unmanned machines that allow us to see and explore the deep sea) to their ship on the surface. All of a sudden Argus and Hercules were stranded on the sea floor at a depth of over 2000 meters off the coast of British Colombia. These amazing machines can do a lot of cool stuff, but they cannot rescue themselves when stranded, so over the week following their loss a team of rescuers came together to help the Nautilus and her crew rescue the stranded ROVs. The Woods Hole Institute’s ROV Jason came to help, along with the University of Washington’s R/V Thomas G. Thompson.Yesterday (September 1, 2021) Jason did an exploratory dive and set up the rigging for today’s recovery operation, and today Argus and Hercules were recovered successfully. The Nautilus crew will be hard at work figuring out what went wrong that allowed the ROVs’ cable to detach, and checking over everything on both ROVs before they are allowed to dive again.

I love deep sea dive videos, which are really the stuff of sci-fi. I can sit in my apartment in a landlocked state, and watch live video of the depths of the ocean thousands of miles away, literally one of a handful of people in the world seeing some of those places for the first time. I am sure classic sci-fi writers would be amazed if they could see these videos. Many of the research teams with ROVs gather footage for their own use, but a few – Falkor/SuBastion(which streamed the above image of a very alien-looking deep-sea critter), Nautilus/Hercules&Argus, and Okeanos- stream their dives live so that everyone can watch.

But the adventure this week is one out of a different subgenre of classic sci-fi, the rescue of robots, by robots, in a hostile environment. The humans in this drama remained on the surface of the ocean the entire time, while the real action was going on over 2000 meters below. That is over 6000 feet, or over a mile deep. Without ROVs like Jason available to help, one simply cannot retrieve dropped robots that are sitting that deep on the ocean floor.

The Argus is the ROV that works closest to the sea floor, either suspended or actually sitting on the bottom. When the ROVs were lost, the Argus remained sitting on the bottom, with the crabs and fishes to keep it company in the dark. Hercules works a couple dozen meters above the Argus, acting as a lookout and making maneuvering easier. Both vehicles have lots of cameras, as well, so with the two-ROV team more imagery can be sent back to the surface. The tether cable between the two ROVs was still intact, so when the ROVs were located Hercules was still floating a short distance above Argus.

The rescue team rigged the Hercules to be extra buoyant during the first rescue dive, and attached webbing to Argus. Today Jason cut the tether between Hercules and Argus using a hydraulic band saw.

Once the tether was severed Hercules bobbed to the surface (though it still took a few minutes for Hercules to reach the surface- it takes a while to travel over a mile, even for a buoyant, newly rescued robot). A small boat from the Nautilus followed a locator beacon attached to Hercules and brought the bobbing ROV back to the ship for recovery.

Once Hercules was onboard, the Nautilus crew shifted to recovering Argus, which had been rigged by Jason to be pulled up from the surface.

This was not the first time an ROV has had to be rescued, but these situations are still really rare. I am sure this has been a very stressful week for the Nautilus team, as they have been working out what went wrong and what to do next. But it is still cool to see how this sort of rescue operation works. One can easily imagine how rescue operations like this might be experience for future rescues of manned vehicles under the sea or in space.

And, of course, those of us watching enjoyed the skate that made an appearance during the recovery dive. When we are actually watching for them, we might watch hours of dive footage with no more than a few egg cases, but all we have to do is not be looking for critters to have the more charismatic megafauna photobombing the cameras. 🙂

I would not be surprised if the Nautilus folks come up with a great video all about this recovery operation, but in the meantime you can check out the https://nautiluslive.org/ website for more information about the recovery and all the great exploration and science work this team have accomplished this dive season.