Dive and Discover : Daily Updates

After travelling full speed for nearly 2 days, RV Atlantis finally reached its destination this morning at 0710 hours. Under clear skies and fairly calm seas, the Alvin crew started work early to deploy the transponders we will be using during the dives at the East Pacific Rise. Above water, the ship uses its military grade Global Positioning System (P-Code GPS) to keep track of its position. It is accurate to less than 10 meters! So we know where we are on Earth with very great precision. This is very important for accurately mapping the seafloor and collecting many different types of oceanographic data.

Underwater, though, signals from the GPS satellites can’t penetrate into the ocean depths so Alvin has to use other means to locate itself and navigate. We always need to know where Alvin is when it is diving. The transponders that were deployed this morning are a key component of every Alvin diving program and the scientists rely on this information to know where they went during a dive and where their samples are from.

The transponders were all pushed over the side and sent to do their job at the bottom of the ocean by about 1000 hours. After they got to the seafloor, (it took them about an hour to descend) Pat Hickey spent most of the morning and early afternoon surveying them in. He did this using the P-Code GPS system and driving a circle around each one to collect acoustic travel-time information that tells us how far the transponder is from the ship at many points. This is called the acoustic slant range to the transponder. By driving a circle around each transponder, and knowing the ship’s position very accurately with the P-Code GPS, we can determine with great precision the location of each transponder. Each transponder is tethered 185 meters above an anchor weight. It is up this high so that the signals it sends and receives from Alvin are not obstructed by any hills.

The briefings continued today as the Alvin pilots talked with the scientists about how to maneuver inside the sub, operate the video cameras, and what to do in case of emergencies, like having to pee! Everyone wants to know about what happens when you have to go to the bathroom in Alvin. Well, most people are careful of what they eat before hand and don't eat a heavy meal the day before their dive. They also make sure to go to the bathroom in the morning before they get in the sub. But some people still need to pee after a few hours in the sub and the Alvin group has special red bottles that men and women can use if they have to go. It’s pretty simple, and when you have to go... you HAVE to go, even if you are on the ocean floor!

Up in the library, Dr. Margo Edwards talked about her research and experiences when she led an expedition using a US Navy nuclear submarine to map part of the Arctic Ocean basin last year. The room was packed with interested members of the science party, ship's crew and the Alvin group. We plan to have several lectures on different oceanographic and research topics during the cruise.

Meanwhile, the Towed Camera Sled continued to take shape and various pieces of equipment started to get mounted on it. Greg, Jenny and Del worked all day to make sure that the Sled is ready for its first run tonight. It’s amazing to see a simple, large steel cage transformed over two days into such a complex piece of surveying equipment! The Sled will be lowered to 7-10 meters above the sea floor, while it is being towed behind RV Atlantis at about 1/2 knots of speed as it makes traverses over the East Pacific Rise axis. The sled was put over the side at 2040 hours after a successful deck test where it flashed 5 times, indicating it was ready to get dunked and go to work taking pictures of the lava flows on the seafloor.

This also marks an interesting division in the voyage. For the first few nights, the science team has all been on pretty much the same sleep schedule- up during the day and sleeping at night. During the night operations of the Towed Camera Sled, though, there needs to be several people on watch monitoring the Sled. They need to check that all the equipment is working properly, that it is travelling over the areas they want to survey, and that it doesn’t drag along the seafloor. To do this, 4 of the scientists will be taking turns, or "standing watch" as oceanographers say, staying up to keep an eye on the Camera Sled. Greg and Jenny grabbed their mugs of coffee and turned on some music since they have first watch tonight!

The cruise Ping-Pong tournament started today as Captain Silva and Marcel Vieira had a couple of practice games in the main lab. All of the brackets are filled, and we'll keep you updated on how the matches progress. Martial Taillefert won the tournament in Cruise 1, but since he's not onboard for this leg of the trip, we'll see who can rise to capture the crown!