Yesterday, we landed our first of three CORKs in the ocean floor! As we all anxiously watched via TV, Bubba, Captain Alex and the drill team expertly placed our CORK into our first drill hole of the expedition. This requires great skill because 1) the Captain has to keep the boat in one place despite the wind and currents, 2) the CORK has to be put together properly (which takes days), 3) our scientific team needs to load all instruments and experiments on the CORK correctly, and 4) the CORK has to be lowered and placed inside the hole via the re-entry cone without damaging anything. Whew! With all that tension on board to get it all together, we waited with bated breath as it was lowered into the hole. And WOOHOO! We made it! One down, 2 to go. Oh, and an old CORK to pull up. We're a long way from the edge of the woods but every step counts!
If you're wondering what a CORK looks like and what it does, take a look at the photo to the left. The CORK is essentially a metal contraption with a plug at the top that corks the borehole sealing it off from seawater. The top of the CORK is to the right in the photo. Instruments to measure temperature and experiments to measure water chemistry and biology are fit inside the CORK in a way that they can be retrieved in later cruises. There are valves on the part of the CORK that sticks out above the seafloor that can be tapped with an ROV during later cruises to download data and check up on the health of the borehole. See the black plastic rectangular things in the CORK photo? Those are the valves.
It has taken years to design these CORKs and they've undergone several retrofits. On this expedition, we are pulling up a CORK put down in the mid-90s during Expedition 301. This is an older style CORK and the new ones are WAY better!! Below is an illustration Dinah did showing how the CORK fits in the borehole. You can see the CORK platform (what the octopus is hanging on to) where the ROV lands to do the CORK servicing and data downloading. The part that sticks above the platform is where the valves are . The part below the seafloor is where our experiments are. Pretty nifty, eh?Beth Orcutt, the other microbiologist on the JR has made a wonderful CORK video that can be seen via YouTube. Thanks, Beth!!
http://www.youtube.com/watch?v=UEVVUob75rc
Amanda,
ReplyDeleteThis topic made us ask MANY questions, so here goes:
L-What happens if the CORKS break, you can't find them, or forget about them?
C-What happens if there is an earthquake? Can the CORKS move to a different position?
Q-Do divers ever go down to look at the CORKS?
Why do you leave them down so long?
R-Do you/can you still use the CORK you will pull up that was from the mid 90's?
Mrs. T-What do you hope to find when you pull it up? Did someone make a record of experiments and what they want to investigate?
Q-Will you take any pictures of the old one after you pull it up? We'd like to see them!
Please tell Dinah that her picture helped make this more understandable for us. We also liked the octopus! Your blogs are very fun to read and we hope you are having a great day!
Oh, I love questions! Thanks for posting some!
ReplyDeleteL - The CORK itself is really strong. What does break sometimes is the top part that we use to service the CORK and to pull it out of the seafloor. We're actually having a really hard time right now pulling out the old CORK because the tool we use for it had been shortened in a previous cruise. We're spending a good day and a half just to fix the tool. If we can't do it, it will have to stay down there. :(
We're really good at finding them. We use latitude/longitude coordinates so we know exactly where we left them. They're too expensive to lose!
C - Earthquakes do happen but fortunately, they don't ruin the CORKs or move them. The ocean crust is pretty strong but flexible at the same time. When earthquake waves move through the crust, they just rattle everything, not really tear them up like you see in the movies. Remember also that our CORKs are pretty long (~15 meters) so, for them to move, they would have to move A LOT of rock out of their way! So, we're pretty confident that they're pretty safe from earthquakes. Good thing too!!
Q - We use submersibles like Alvin or ROVs like Jason to go down to the CORKs. Its too deep for us humans to dive to. The pressure down there is enough to crush our fragile human bodies. We need a submersible or ROV to withstand all that pressure from 3000m of water above us.
We leave them down there so long because we want to make long-term observations about what life is like below the seafloor. There is water moving through the seafloor but it moves really slowly, so the longer we keep the CORK down there, they more data we can collect about what the water is like, the temperature, what microbes are in the water, etc. Plus, cruises to go out and service the CORKs and change out our experiments are REALLY expensive (over $100,000 a day)!! So, we have to pick and choose when we want to go out there to get our data.
R - Not really. This old CORK really doesn't do much except plug the borehole. The new ones we're using today are super fancy! Not only do they plug the hole, but they have space inside them for experiments to measure water chemistry and microbiology. PLUS, they have 6 or 7 spigots at the top to download data and collect water whereas the old ones only had 1. We've learned a lot since the mid 90's and this is just one hole of many that will is being updated with the newer, cooler CORKs. I'm not sure what will happen to the old ones. I can ask though.
Mrs T - With this old style CORK, there isn't any room to put our water/microbio experiments inside, so us chemists/microbiologists aren't getting anything from it when they pull it up. However, we have a thermistor string down there that the geophysicists will be thrilled about! It will give us a better idea as to how hot this hole is (and ultimately how the water is flowing down there - up through this borehole or down.) They made very detailed notes on how deep their thermistors were so when they get back the data, they'll know what the T is an very discrete depths. The really cool science for us will come when we deploy some new experiments with the new CORK in this hole.
Q - Definitely! We still don't know if we can get this one out of the hole, but if we can, everyone on board will be very curious to see it and take pictures. I'll definitely post them if we can get this dang CORK out.
Dinah says "Oh Great! I'm glad!" Did you know that almost every CORK we've gone down to service has had at least one octopus on it? Check out one of the previous blogs that shows what I painted on the CORK. I figured they needed an "Octopus Parking ONLY" sign just for them! :)
I'm glad to hear that our research is exciting for you! We can talk about it more when I come to visit. I'm bringing a few surprises with me too!