The expedition arrived this evening at Physalia seamount. Although seamounts and canyons are usually named after the ship or vehicle that discovered them, physalia is also the scientific term for the Portuguese man-of-war, the spectacular jellyfish-like colonial organism with a large bladder-like float and long stinging tentacles. Knowing this, I can’t stop seeing a resemblance between the striated hump of that creature protruding above the water and the ridged hump of the seamount rising over the abyssal plain. We were delayed a day by software integration problems with the new color cameras installed in the Waitt Institute’s two autonomous underwater vehicles (AUVs), Ginger and Mary Anne. The color cameras will facilitate in identifying any specific deep sea coral species we may see and, besides, seeing a 15-foot high pink “bubblegum” coral in black-and-white is just not the same.
We will shortly be setting up the acoustic network of transponders that the AUVs will use to navigate. The REMUS 6000 AUVs’ navigational systems are so sophisticated that photos of the vehicles’ innards are prohibited for national security reasons – the technology is used in missiles and 4 out of the 7 of this AUV type in existence are owned by the U.S. Navy. After the transponders are deployed, a route will be pre-programmed into each AUV. They will then be launched into the water using a launch and recovery system (LARS) custom-made for these AUVs, which is capable of doing its job in more than 6 foot high seas.
Once in the water, each AUV will “fly” its track, doing either an initial mapping run using sidescan sonar or a follow-up close-up imaging run. For these REMUS 6000 AUVs, the programmed track can cover 10 miles, span 22 hours and go as deep as 3.73 miles (an extraordinary depth made possible by a titanium spine with all the machinery secured inside water-tight, pressure resistant metal containers surrounded by non-crushable syntactic foam). Once the track is down and the AUV back on board, the data is downloaded, the vehicle recharged, and – with another track programmed – launched again.
Tomorrow, when the data from the first AUV run of the expedition is downloaded, we will start to find out what biological discoveries this 21st century technology have made possible. This expedition is, in part, an exercise in “proof of concept” – to determine whether and how AUVs can be effectively used in the highly-challenging terrain of the Atlantic seamounts and submarine canyons. To date, the AUVs have been used in the deep ocean past the continental slope, over huge flat expanses of bottom where speed is at a premium. If, on this expedition, the AUVs can be flown to take images clear enough to be used for biological inquiry – without running into a canyon or seamount wall – significant possibilities in marine ecological investigation are opened up. The AUVs can cover much more area than a towed camera or a remote operated vehicle, and obviously do not have the physical impacts of a trawl net survey.
We start the first test tomorrow. I look forward to reporting how it goes.
