Sorry for the radio silence – things have been understandably busy, both above deck and below. Up top, the science team has been working like crazy to deploy the rest of the moorings. SUMO2 was the first and largest to go off the back deck, but there were three more – all undersea – that had to go out before we could start retrieving old ones. And the weather’s moving in.
The undersea moorings are smaller, but in some ways trickier than the big surface mooring. Like SUMO, they’re a big long pearl necklace of electronics, but with a couple of big orange instrument-y jewels near the end. We’re deploying them in 4600 meters of water, and their tops need to be very close to 30 meters beneath the surface, so you can imagine that there’s a fair bit of measurement, calculation and a touch of nailbiting when the anchor goes over to make sure everything’s the right length. Fortunately, the multibeam profiler confirms that we’re working over the ocean floor equivalent of Kansas, so John and the deployment team do have a little leeway.
Anyhow. So, they knocked it out in four days: SUMO2, the two subsurface flanking moorings and the final center mooring. All appear to be operating as intended, but the work is only half done. Less than half done, in fact. In some ways, this was the easy part.
You see, this whole deployment is intended to replace the existing constellation of moorings, which is showing its age and the effects of being thwacked around the southern ocean for a year. And now that we’ve pushed the new stuff over the side, it’s time to pull the old stuff back in.
The first challenge in retrieving the old undersea moorings is getting them to stop being “undersea”. To help with that, they’ve got acoustic releases built into their cables near the anchor. There’s a box down there – a couple of boxes, actually, for redundancy – each with a battery-powered, hydro-microphone-equipped little computer, just sitting there, constantly listening for its programmed acoustic “launch code” that will tell it to release the anchor so the whole shebang float to the surface. And yes, we’ve got a folder of launch codes for each of the moorings (Barry tells me that, on a previous ship he worked, a now-defunct manufacturer of acoustic release devices wasn’t so good on unique keys, and for a while, research ships around Woods Hole kept accidentally popping other peoples’ undersea moorings.
The seas are still unreasonably flat, and the sky as drizzly as ever this morning as we’re perched somewhere just abeam FLMA1, the first of the old flanking moorings the team is going to retrieve. It’s 5:45 a.m., but already there’s a hitch: leaning in to the wall of electronics with headphones pressed to his ears like Red October’s “Jonesy,” John tells me that he’s getting too much audio interference. We’ve shut the Knudsen and multibeam mappers off, but something is still filling the water with chatter, and he can’t establish a connection with the acoustic release.
Maybe it’s the ADCP – do I know how to turn off the ADCP? I try, and flail about a little. Okay, it looks like the ADCP is off. Still too much noise. Better call Tina. She swings in, takes a quick survey of the blinking lights, and turns off the ADCP for real. Still too much noise. She tries an ear to the headphones. Maybe it’s the bow thrusters? No, doesn’t sound right. There’s something about that sound…
She ducks into the space between the RVDAS and Science racks: there’s a cable stretching across the walkway. Face palm. Where’s Mark?
The glider ops guys (I prefer to think of them as undersea robot-wielding overlords) were doing some tests last night, chatting with the non-rogue gliders around the array (no doubt warning them against making a run for it like #486 tried), and left the transducer cable attached to their rig. The reason all we could hear over on the RVDAS side was noise was because we weren’t actually hooked up to anything. Mark reattaches the cable to the EdgeTech unit, and John fires it up. Within a minute, the top module of FLMA1 is bobbing off the back deck.
But that’s the easy part. (Something I’m learning about marine ops is that, whatever the operation, the part you’ve just managed to get done is always “the easy part”). As Eric, our Mission Coordinator, pointed out, it’s a lot easier to drop something off the back deck (a mooring, for example) than it is to pick it up out of the water and get it back on.
Short story: they got it. Now only five more to go. They’ll try retrieving the lower half of FLMA after breakfast, and if time and conditions allow, will launch the new gliders this afternoon. I’m really hoping I can get Mark to say “Deploy the undersea robot army!”
Top and bottom modules of FLMA1 made it on deck uneventfully, but the difference in their conditions was…remarkable. The lower module, stationed about 500 meters down, came up clean and shiny. But the top ball looked much the worse for the wear. Even better, it was occupied by freakish little bivalve space aliens. They may be gooseneck barnacles but shockingly, we don’t appear to have any marine biologists on board to confirm.
Regardless of what they are, they’ll freaky and nightmarish, flopping around and probing with their little feeders like something out of Mare Internum (someone inform Der Shing that we’ve found her floppy friends?). They are also, of course doomed, since they’re stuck to the module like, um, barnacles, and the module’s not going back in the water until basically never. But don’t be surprised if tomorrow I sound like I didn’t get much sleep last night.
Lower Module of FLMA1
Upper Module of FLMA1
They’ve cleaned out the algae they can reach from their perches
No, that’s not nightmarish at all. Actually it is.