If you took biology in high school, you’ve probably thrown a square frame on the ground and counted whatever landed inside it. It’s called quadrat sampling, it’s about as low-tech as field science gets, and it hasn’t changed much in a century. Four sticks, some string, a notebook.<\/p>\n
NOAA Ocean Exploration<\/a> just did the same thing 3.2 miles underwater, using a 9,700-pound robot to set the frame down.<\/p>\n The frame measured 25 by 25 centimeters, or 10 inches on a side. A manipulator arm placed it on the seafloor during the fourth dive of an expedition off American Samoa, on a patch of abyssal plain carpeted in black lumps. Then the arm scooped up the lumps inside the square and left everything outside it alone. Sediment scoops and push cores came off the same site.<\/p>\n NOAA puts that piece of seafloor at roughly 5,140 meters down, which it rounds to 3.2 miles and which converts to about 16,863 feet.<\/p>\n Here’s why one small square is the whole point. You can photograph a mile of seafloor and still have no real idea how much metal’s sitting on it, because a photo gives you a texture and not a total. Put a frame of known size on the bottom, count and weigh what’s inside it, and now you’ve got lumps per square meter, which you can multiply across the area you already mapped by sonar. It’s the least glamorous thing anybody did on that dive and arguably the most useful.<\/p>\n A frame sitting on the surface won’t tell you what’s buried under the sediment, though, and NOAA’s plan for a later nodule field specifically flags buried nodules in the area. So the square gives you a floor. Whatever’s underneath doesn’t get counted.<\/p>\n I went looking for a date on that photograph and couldn’t find one. NOAA’s field update published August 31 lists Dive 04 for that day and no dives for the three days after, and the agency posted its write-up of the samples on September 1, so August 31 is my best read of it. That schedule was labeled tentative, which on this expedition turned out to matter.<\/p>\n Weather wrecked the first week. High winds and rough seas meant the team could only safely launch once in those seven days, and the dive numbers got reshuffled twice on the public schedule.<\/p>\n Polymetallic nodules, which is a mouthful for rocks that grow out of seawater. They build up on abyssal sediment over millions of years, layer by layer around something small, running on manganese and iron oxides. Against the 10-inch frame in NOAA’s photograph, most of them look about fist-sized.<\/p>\n What gets trapped in those layers is the interesting part. NOAA’s own write-up files nickel, copper, cobalt and manganese from these nodules under critical minerals, and three of the four go into the battery pack of whatever EV you passed on the way to work. Right now that nickel comes out of places like the Ontario shaft where Glencore put battery locomotives 8,530 feet underground<\/a>. The nodules also pick up thorium and radium, which are radioactive, and that turns out to matter later.<\/p>\n Abyssal plains sit between 3,000 and 6,000 meters down, and NOAA says they cover close to half of Earth’s surface. We’ve mapped a rounding error of that in any detail.<\/p>\n The robot is called Deep Discoverer<\/a>, D2 to the people who work on it, and it isn’t autonomous. It hangs off a cable that runs up to a second vehicle called Seirios and then to the ship, and pilots from the NOAA Ocean Exploration Cooperative Institute fly it from a control room on board while scientists on shore watch the same video and tell them where to point it.<\/p>\n A cable’s a real limitation and a real advantage at the same time. You can’t wander far from the ship. But somebody with a joystick can put a 10-inch frame exactly where a geologist sitting in an office wants it, in real time, at a depth where seawater adds about one atmosphere of pressure every 33 feet. That’s the frame sitting under north of 500 atmospheres, which is the same neighborhood the French composite float that goes to 19,700 feet<\/a> was built to survive.<\/p>\n D2 weighs 9,700 pounds and runs 10.4 feet long. It carries 28 LED lights and a primary camera that can zoom in on a 3-inch organism from 10 feet away, and it’s rated to 19,685 feet, so the dive-04 seafloor left it about 2,800 feet of margin. Twenty-eight lights sounds like overkill until you remember there’s no other light down there at all. It’s been working since 2013, which is a long run for a machine that gets dropped to crush depth for a living.<\/p>\n It also sinks at 98 feet per minute. Run that against the dive-04 depth and you get just under three hours of descent before anybody sees anything, which lines up with NOAA’s own plan for a later dive that allowed exactly three hours between launch and the bottom.<\/p>\n So why bottle the water as well as the rocks? Because of that thorium.<\/p>\n Thorium drifts around in seawater and sticks to nodules, then decays into radium. Radium decays into radon, and radon’s a gas that dissolves. So a field of nodules should be quietly leaking a faint radon signal into the water sitting right above it. If that holds up, you could sample deep water and get a read on what’s on the bottom without ever looking at the bottom, which would be a whole lot cheaper than sending a 9,700-pound robot down for three hours at a time. It’d also let you cover ground, which is the thing nobody can do at these depths right now, not even the rover crawling the seafloor off California on two watts<\/a>.<\/p>\n That’s the pitch. It is not a result.<\/p>\n The correlation between radon levels and nodules was worked out globally from extrapolated data and predicted abundance, which in plain terms means nobody had checked it against a patch of seafloor somebody had actually counted. That’s what the square’s for. Katlin Bowman Adamczyk<\/a>, the USGS marine geochemist co-leading the science on this expedition, wrote that the team is pairing direct nodule abundance measurements with radon measurements to test whether the idea can sharpen up where seabed minerals are predicted to be.<\/p>\n I can’t tell you how it came out, because nobody can yet. The samples go to a lab at the US Geological Survey. Nothing about this dive validated a radon detector, and nothing about it identified a deposit anyone could mine.<\/p>\nSo what’s in those lumps?<\/h2>\n
So who’s actually flying it?<\/h2>\n
The radon idea is still just an idea<\/h2>\n
Most of these dives happen where mining is already banned<\/h2>\n