E-vents from the RV Atlantis (Week 2)Sunday, 16 September, 2007RV AtlantisSo What is a CORK, Anyway?By V. Soutar, Science teacher Popping the cork from a bottle of champagne usually indicates a celebration is taking place and CORKS are certainly something worth celebrating. When a CORK is downloaded, vast amounts of information can be analyzed revealing exciting things worth celebrating. A borehole drilled into the Earth’s crust by the JOIDES Resolution drill ship allows scientists to insert a CORK (Circulation Obviation Retrofit Kit) into the hole to monitor fluid temperatures, pressures and flow in the basaltic ocean crust. The fluid, driven by heat from the Earth’s interior, influences changes in the physical, chemical and biological components of the ocean and lithosphere. The chief scientist on board the RV Atlantis is Keir Becker from the University of Miami’s Rosenstiel School of Marine Science. Working with Earl Davis of the Geologic Survey of Canada, they have been able to obtain some very interesting data. Making sure the data loggers can store the information for extended periods is the responsibility of Robert Medlum from the Geologic Survey of Canada. Data is retrieved or downloaded using the Alvin submersible. Also working with the CORKS is Alison LaBonte, a post doctorial student representing the Neptune Observatory Research Group and the University of Victoria. These scientists are not only downloading data on this trip, but are installing new generation data loggers with special plug-ins that will allow them to become part of the Neptune Observatory. Working on her PhD and assisting in this vital research is Katherine Inderbitzen, from the University of Miami, RSMAS. Another job being done is resealing CORKS that failed to remain sealed after an earlier installation. A CORK contains instrumentation to document the flow of fluids that circulate through and between the Earth’s igneous crust and the sediments deposited on top. This fluid transfers heat and chemicals between the Earth’s interior and exterior. Temperature, pressure and composition of the fluids are analyzed to determine the role it plays on our Earth as it circulates. One of the scientists referred to the basaltic ocean crust as the “world’s largest aquifer”. An aquifer is earth material that is both porous and permeable so that it can store and transport water. Basalt can range from low porosity or less vesicular basalt (having less fractures and fewer holes caused by gas escaping as the molten material cools on or at the Earth’s surface) to higher porosity basalts. Geoff Wheat, from the University of Alaska, is working to collect fluid from osmosamplers that sample water from rocks deep below the CORK seals. His analysis of the fluid’s chemistry and analysis of a variety of tracers can help determine such things as transport and mixing within the aquifer between boreholes. He is also responsible on this cruise for making sure that previous boreholes get resealed with his new cement mixture to prevent contamination from sea water entering from above (see Saturday Problem Solving, above). Here's a back-of-the-napkin drawing of a CORK.
The situation here at the Juan de Fuca Ridge is unique, according to the scientists, the new crust is being insulated rather quickly by the deposition of overlying impermeable sediments, which prevents water entering from above. Another great reason for doing their studies here is the fact that it is an area where new ocean crust is formed at the ridge system, ages, and moves to where it is destroyed at the subduction zone landward, within a small distance compared to other ridge system much further from the subduction zone. Transform or strike slip faults also can be found in the ridge area so the Juan de Fuca plate offers a variety of tectonic settings in a small space. Scientists are finding some interesting relationships between the fluid pressure and aseismic and seismic events. Tidal loading, plate deformation, earthquakes and tsunamis all seem to cause pressure changes in this subsurface fluid. Graphs produced by the researchers from CORK data (see Geohydrology and CORKs) show crustal fluid pressure increases as an earthquake P wave (primary wave) or compressional wave passes through the Earth from the source of the earthquake known as its focus. If a tsunami follows, it too can be detected. Could the discovery of this relationship lead them to find less obvious signals to detect the onset of seismic activity leading to earlier detection and warning? Monday, 17 September, 2007RV AtlantisBy Ron Prescott, Physcial science teacher All I remember is hearing the words, “ The sub is returning to ship,” just 30 minutes after it was successfully deployed from the ship. The word spread like wildfire. Everyone got kind of silent for a few moments in wonder and worry. Next we heard that a warning indicator had signaled a “battery leak” (later we learned this could mean several different possibilities). We had just completed cleaning off the deck from mixing the cement that had been sent to the bottom (which is still there). In those tense moments I realized the seriousness of what we are doing and the dangers that are involved. It made me appreciate the Alvin crew and the Atlantis crew so much more because of their commitment to safety first. It made me appreciate the fact that so much training and effort has been made to insure the safety of everyone on board and especially those that are cleared to go in the Alvin. In fact to be cleared you must go through several training workshops. One is an orientation of what diving in the Alvin is like. One involves trying on the oxygen scrubber mask. And a last training is held as they actually take you into the Alvin to orient you on how to use the cameras, the sitting arrangement, some of the procedures while on board, and other details of what to expect. Today was kind of solemn as the Alvin had to abort its mission and return to ship. It seems a sensor indicating a battery leak had caused a buzzer to sound. The leak detector is a meter, which monitors several different systems and is continually checked by the pilot. The crew that only had one scientist (Katie Ingerbitzen) and the pilot plus a pilot in training had to return to ship after getting down about 430 meters. Later we learned it was not too serious but that for obvious reasons they must make the best decision for safety; again, something we learn about while working in the lab at school. Everyone was on deck as the Alvin was brought back aboard and as soon as it was placed in the cradle that holds it, the crew went to work on disassembling the side panels to discover the problem. Later, the official word came that it would not be going back down today, Monday, somewhat due to the high seas and the late start. This disappointed the scientists as they lost their opportunity to pour a mixing of cement that was already sent to the bottom. The rest of the day was spent in different ways for all. Some worked on project work, some watched movies in the movie room that has surround sound, some caught up on sleep, and one (me) graded physical science papers all day. I did have time Monday night to catch a Stephen Segal movie. Tuesday, 18 September, 2007RV AtlantisBy Alison LaBonte This is my third Atlantis cruise, but each cruise always presents new excitement and anxiety. What did I forget to bring with me? Will the instruments I helped put together work after they are deployed? Will we successfully recover data from the instruments currently at the seafloor? Will some old cruising buddies be on board so I can seek help and a listening ear when needed? Will I get to dive in Alvin? I finished my Ph.D. at Scripps Institution of Oceanography only a few months ago. I was excited to learn about the available position as a “Borehole Research Associate” funded by NEPTUNE Canada well before graduating. I pinned the job description above my office desk as an inspiration. My job is “to join a team of university faculty and government research scientists to plan, design, build, and deploy a suite of seafloor and sub-seafloor instruments for long-term monitoring using the Neptune deep seafloor fibre-optic cable system." I couldn’t ask for a better fit for my interests, and I have a chance to work with the best people in my field, subseafloor hydrogeology. I have now only been on the job for three months, and already I’m at sea deploying instruments. The best part of this cruise so far was my Alvin dive on Day 2 of the cruise. I was pleasantly surprised that the chief scientist, Kier Becker, and my new boss, Earl Davis, elected me to dive to a borehole site and take on the responsibility of downloading the data from the logger at the site. This site is one that has been logging seafloor and subseafloor, or “formation” pressures for the better part of the last 11 years. On the morning of September 13, I descended to 2600 meters depth (my deepest dive yet!) in Alvin with the pilot, Sean, and first time diver Michael. When we got to the borehole, Sean had the hardest task: connecting the Underwater Mateable Connector (UMC) at the end of a cable from the Alvin submersible to our logger on the borehole. I then hooked up a laptop to the other end of the cable inside Alvin. This order of plugging in the instrument at one end, and the laptop at the other is very important because seawater is an electrical conductor. When the UMC is exposed to seawater, we definitely don’t want to send it any electricity from the laptop. The electrical current would likely cause the contacts on the connector to corrode. After hooking up, I ran the program to talk to the logger, and to my relief it talked back! I was successful in downloading the last two years of data that were saved on the logger’s compact flash card. This was the best part of the dive for me.
With my tasks for the dive accomplished, I could relax and really enjoy the scenery. I saw some of my favorite sea creatures, but in very weird forms: giant pycnogonids (sea spiders), an anemone that looked like a Venus fly trap, and translucent sea cucumbers. I had trouble figuring out even what phylum a lot of the critters at the bottom were, like the beautiful animal filter feeding from the top of its stalk that looked like a bunch of lilies.
Here is some of the pressure data Alison downloaded at Site 1027 C. Can you interpret this graph? Find out by printing the data and answering the following questions. These may seem like quite a challenge if you're new to earth and ocean science, but with a little thought about the oceans, you'll figure it out. The ANSWERS -- check the bottom of the page... Click here to download Alie's complete exercise.
Thursday, 20 September 2007RV AtlantisBy Ron Prescott, Physcial science teacher “ The best laid plans of mice and men…” Yes, as scientists, one of the things you quickly learn is that not everything works out the way you planned or according to what your hypothesis said. The plan today was to go to boreholes 1024 and 1025 and install some new pressure sensing equipment. However, the swells were too high and the boat was bouncing. When you are loading and unloading a twenty-five million dollar piece of equipment you don’t take chances, and today we didn’t. So the plan for today has been extended to tomorrow. We will go down to 1024, install the equipment, travel in the sub for eight kilometers to 1025 and install the equipment there. So today we worked on interviews of other scientists and crew.
1. What buoyancy is needed to balance a container of cement mix that has 6 bags of cement at 42.6 kg each and displaces 70 gallons of water? The weight of the steel barrel is 490 N. a. Determine the total weight being lowered to the bottom of the ocean in newtons. b. Determine the total weight of the water displaced. c. Find the difference.
4. Watch what happens when an empty cement container was released from the CORK. Yo Yo and Tow YoBy V. Soutar, Science teacher Our hopes and emotions were up and down like a yo yo today. Due to high winds and choppy seas, it was unwise to risk the safety of the Alvin submersible and its passengers as well as the launch and recovery divers. The cancellation was a real downer for our yo yo emotions. In an effort to make the most of the day and in hopes of better weather, we moved to a new location. We moved to the Endeavor Vent field and the hydrothermal vent Dante where Dr. Di Iorio’s research is being conducted on the flow or plume. Using the ROV Jason, Dr. Di Iorio’s acoustic scintillation device was moored to the seafloor at this site back in early August where it has been collecting data. As a sound pulse is transmitted through the hydrothermal vent’s plume, the transducer picks up the signal and the data is stored in the acoustic scintillation device’s microchip. Once on site, the moorings were released using an acoustical signal sent from a transmitter lowered over the side of the ship to communicate with the acoustic release attached to the moorings on the seafloor. It is amazing to watch them “talk” to each other over 2,200 meters down! Once the release was “awakened” and received the signal, the bright yellow floats with their radio beckons, zenon flashers and precious load of instruments headed to the surface. We watched for them to pop up and listened for their signal with a receiver. Soon we saw them pop up and the crew expertly recovered them so that the science team could disassemble the casings to retrieve the data. It was a tense moment when the casings were opened, hoping as Dr. Di Iorio had said earlier, that we would be “getting the instruments out of the water not the water out of the instruments”. After a successful recovery our emotions yo yoed back up again. Next came a real yo yo of an operation called a Tow Yo. The “tow” part of the operation comes from the fact that the CTD (Conductivity, Temperature and Depth Instrument) is towed by the ship on a predetermined course; in this case through an area of the Endeavor segment around Dante. The “Yo” part refers to the fact that after the CTD is initially lowered from the ship it is repeatedly brought up and down for 300 meters, all the while collecting data. We were measuring the variables over the area within 20 meters of the seafloor (or slightly closer at times -- oops) and picking up buoyant plumes that registered mainly as changes in temperature. We watched this information come into the ship’s computers and watched as a graph of the data was created. Ron Prescott and myself, along with the help of Dave Sims and other crewmembers, were responsible for deploying the CTD, recovering it, and recording the data. After completing this operation over a three hour period ending around 11:00 pm, we were happy, but tired and the next day would start early with Dr. Di Iorio’s first Alvin dive. Friday, 21 September, 2007RV Atlantis“Dr. D” Meets DanteDr. Daniela Di Iorio or “Dr. D,” as my National Ocean Sciences Bowl Team likes to call her, has been listening to her hot topic of research, Dante, for a while. She used the ROV Jason and the research ship the RV Atlantis to deploy her instruments back in August. A moored transmitter sends signals through the plume of Dante. On the other side acoustic receivers pick up the signals and log the amplitude and time of arrival. Her hot choice for research, Dante, has been recorded at 3300C. While imaging Dante with acoustical devices allows her to “see” Dante using sound waves, it was quite a different story today. She laid eyes on Dante in person for the first time. V. Soutar By Dr. Daniela Di Iorio, Principle Investigator
Sunday, 23 September, 2007RV AtlantisBy Ron Prescott, Physcial science teacher “TWO hundred years ago, a great deal of the world as we now know it was still undiscovered; there were yet very many islands, small and great, on which the eyes of white men had never looked, seas in which nothing bigger than an Indian canoe had ever sailed. A voyage in those days was not often a pleasant thing, for ships then were very buff-bowed and slow-sailing, and, for a long voyage, very ill-provided with food. So, when a man said good-by to his friends and sailed away into the unknown, generally very many years passed before he came back - if ever he came back at all. For the dangers of the seas were then far greater than they now are, and if a ship was not wrecked some dark night on an unknown island or uncharted reef, there was always the probability of meeting a pirate vessel and of having to fight for life and liberty.” from Gulliver’s Travels – Voyage to Lilliput by Jonathan Swift. This was just our case as we prepared to complete dive tasks at boreholes 1024 and 1025; a deployment of a new pressure sensor at 1025 and the retrieval of data from over two years of data collection at 1024. But the weather had different plans, and the seas bounced our ship, and for several days in a row we had to cancel dives with Alvin. Disappointed hopes, changes of plans, and missed opportunities caused a little despair and a lot of disappointment -- for me personally because I was scheduled and rescheduled for each of those dives. And as they were being canceled, I knew my hopes of the adventure of journeying to the bottom of the sea in Alvin were rapidly diminishing. But thanks to Dr. Keir Becker, chief scientist, and his patience and desire for me to dive, the third attempt today, September 23rd was a special day. The winds subsided during Saturday night, the seas calmed and Sunday morning was a go for Alvin dive 4349.
We were scheduled to complete the tasks at boreholes 1024 and 1025 thwarted by weather previously, which involved an attempt to make a submersible transit of over 8 km between the boreholes, thereby saving a lost dive. This attempt has been made on several occasions but because of the distance and drain on battery power, the sub has only accomplished this task twice before. Today, however, with the help of lead pilot Bruce Strickrott, and the able assistance of scientist Bob Meldrum, we were once again successful with power to spare. We named Bob the official “power police” as he cautioned us to turn off any extra power or lights continuously. The temperature at the bottom was 1.7 degrees Celsius, and the temperature inside the sub was 10 degrees Celsius, so you have to dress in natural fabrics ( fire hazard regulations) and in layers to stay warm. This was the longest transit Bruce had ever made with the sub and it was my first ride in any sub. We were excited as we accomplished the goals that had been set and during the three hour transit we saw a number of sea creatures from the deep including sea cucumbers, giant star fish, sea-anemones, sea spiders, some type of blue fish, miniature pink and white shrimp, and numerous bioluminaries. We encountered an octopus that would not let go of a part on the instrumentation at site 1025. We finally had to take the robotic arm and shake it off to finish our task. What an exciting adventure and what amazing science is going on 2600 meters deep in the Pacific Ocean. Of course, as all new divers experience upon their return the bucket brigade, I too would not be relieved of this “chilling experience”. Knowing this, I decided to prepare for the dousing by bringing my bathing suit and changing in the sub before exiting. This just made everyone laugh including myself. We did not get caught by pirates, or wreck on a reef, but we did say goodbye to our friends and sail slowly (30 meters per minute) into the unknown and returned eight hours later savoring the memories of the journey of a lifetime. The Answer to Alison's Questions? #3. Tides, of course! #4. It causes in increase in pressure in the crust.Week 3 (more or less) -- Updates from RV Atlantis, DSV Alvin, and the Seafloor Return to E-vents Week 1 | |
