Sunday, March 27, 2016
Saturday, March 26, 2016
Thursday, March 24, 2016
Yesterday we spent most of the day collecting cores from the seabed. So, what is a core…well, if you can imagine sticking a tube into the ground and pulling it out with a plug of the bottom. Think about it this way…know when you have a drink at a restaurant, waitress gives you a straw…the you put the straw in your drink and put your finger over the top and pull some drink out of the glass in your straw. You have essentially created a suction in the straw allowing the drink to remain in the straw when you remove it from the glass. We are doing essentially the same thing, but on the sea floor. This allows us to collect "sediment" from the ocean.
To be clear, sediment is the dirt, the soil of the ocean. Particles that wash of the continent or are created in the water column sink through the depths of the ocean and accumulate on the sea floor. This has been happening for thousands, hundreds of thousands of years. So, these sediments hold a record of earth's history…information on ocean properties, changes in climate, alteration of the coast. All of these processes influence the physical and chemical character of the sediments being deposited on the sea floor. So, we collect these sediments to gain information on processes that are occurring in the overlying water column, the atmosphere, and the adjacent continents. These sediments act as a window into the geologic and recent past. The longer core we collect (longer straw), the further back in time we can see…
Given that background, we are interested in using these cores to gain a better understanding of how the continental margin, particularly the shelf-slope break, off NC, has changed and processes that lead to the accumulation or down-slope transport of sediments. We use geochemical tools (natural radionuclides, organic matter, among others) and physical character (grain size, porosity, bulk density, etc.) of the sediments to interpret the source, mechanisms of delivery, age, and how the sediments have been altered with time. The data collected form the sediments, together with the information gained from the multibeam, EK80, and Knudsen (se earlier blog post) will provide the initial data for several working hypotheses we hope to test in greater detail in the near future.
As you walk down the stairs to the main deck, you're faced with a near-life-sized photograph of Neil Armstrong, the ship's namesake. It's a striking photo. Despite the space suit and lunar background, he looks so human, so normal.
Neil Armstrong was an amazing individual: a naval aviator, experimental test pilot, aerospace engineer, university professor, and, of course, world-renown astronaut. It's reported that he flew over 200 different models of aircraft, including the X-15 hypersonic rocket plane (https://www.nasa.gov/centers/glenn/about/bios/neilabio.html). His first step on the moon was a monumental occasion, and indeed, it symbolized much more than a space walk.
Neil Armstrong led the Gemini 8 mission which launched on March 16, 1966 - exactly 50 years prior to the start of our oceanographic research cruise. It's an honor to have one of the first research cruises aboard the R/V Neil Armstrong. I must admit when I boarded the ship, I questioned why it was named after him. I didn't doubt his accomplishments or abilities, but I wondered why not honor a marine scientist. But now I realize there couldn't be a more fitting name for a research vessel - to celebrate one of the United States' greatest explorers. Armstrong has inspired generations of young scientists. To this day, his moonwalk still seems unfathomable. Let's hope a new wave of ocean scientists will use this ship to better understand our water planet.
It is always exciting to go to sea, but this voyage is particularly energizing as we are approaching it with a spirit of exploration. Unfortunately, this is not always possible as most research today (even oceanography) is conducted in a very calculated and controlled fashion, requiring proposals, hypotheses, clear plans and detailed budgets. Certainly, this is important as effective research must follow the scientific method and funding must be invested wisely. But, because this expedition is for scientific verification of the new ship, it is allowing us to have a more flexible and free approach. This is wonderfully refreshing, and the vibe on the vessel seems different as a result (i.e., less stressed and more excited). I'm hopeful that many other scientists that come aboard this vessel will be inspired by Armstrong. Like space, the oceans are vast and largely unexplored. We need more scientific adventurers to help us explore and understand the depths of the sea.
By: David Sybert
The Kasten Core has been unleashed! In an effort to get a more complete and deeper core scientists aboard the R/V Armstrong have turned to the Kasten Core. The Kasten Core is a large square stainless steel tube that is pushed into the sediment by a series of weights that are positioned above the steel tube. The core is dropped down to the seafloor, the weights push the tube into the sediment, and as the core is brought out of the sediment two small doors close inside the tube, which keeps the sediment in the tube as it is brought back to the surface. When it arrives back on deck a side of the tube is removed allowing access to the core inside. Samples are then collected for the numerous studies using the sediment.
Yesterday there was much success in coring with enough mud for everyone! Samples were taken from over 400 meters underwater. As the evening drew late there was also sampling of potential methane seeps on the sea floor using a CTD and deep-water camera. Stay tuned for some imagery of what the sea floor looks like around one of the potential seeps.
Wednesday, March 23, 2016
A few days on an ocean research vessel, you kind of get into a groove... whatever watch you're on. Today was a beautiful, cool day. After another long shift, I visited the bridge at sunrise to give a few more waypoints. After breakfast (my dinner of blueberry pancakes) I was very happy to go to bed at ~10 AM. I woke up at 5 PM to grab some yummy grilled mahi mahi for breakfast. Then I checked out what's happening with the day shift. As the sun set, the day watch worked quickly to process a core on deck and get ready for the next sampling effort. I grabed a cup of coffee and did a little work before watch at 9 PM. The moon was rising to light up my night.
Monday, March 21, 2016
A significant part of our cruise has been to "survey" the sea floor. Well, what in the world does that mean, you ask? We are using several instruments to map the sea floor and sub-bottom to learn more about the geologic history and the modern processes shaping the continental margin and influencing the overlying water chemistry.
We are using three primary instruments…an EK80 echo sounder, a multibeam system (EM710), and a Knudsen chirp system. Each of these instruments use sound at different wavelengths to provide data of the water column, seafloor, and shallow sediments below the sea floor.
JP has been leading this effort. Although it was always in our cruise plan, we have been doing a lot more surveying using these instruments than originally planned…at sea, plans change as needed (see previous blog post). Our over the side operations have been stopped for the last two days due to weather (7-12 foot seas) and problems with the vessels bow thrusters (help hold the vessel in one place while instruments are lowered over the side). So, until the weather clears, we are learning a lot about the sea bottom!
The EK80 echo sounder is a VERY impressive and high tech fish finder…that's about as simple as I can state it. It has very high resolution returns from fish, bubbles, essentially most things that have a significant density difference compared to seawater. We, and the USGS and WHOI group on the ship, are using it to provide information on methane seeps along the shelf edge. You can pick up these "flares" of bubbles coming out of the sea floor (see picture). It also provides information on potential turbidity events near the sea floor, or large schools of fish (interesting, but not part of scientific interest).
The multibeam system is essentially a very high tech depth sounder. Anyone that own a boat has a depth sounder so they don't run the boat aground. Well, your depth sounder sends out one ping of sound every 10th of a second or so. The sound leaves the vessel, bounces off the bottom and returns to the boat. Knowing something about the speed of sound in seawater, the instrument can calculate the depth of the water. The EM710 is sending out 500 pings of sound, so rather than hitting one point beneath she ship, you can think of it like a lawn mower, measuring a "swath" of depth as the ship moves over the bottom. That width of that swath is dependent on depth…this one measures a width approximately 4 times the water depth. I should mention that the accuracy of the depth is within a couple centimeters!! So, we can measure the bathymetry very accurately!
Finally, the Knudsen uses a lower frequency sound to penetrate INTO the seafloor. This provides information on sediment deposition with time. In regions of active sediment deposition, you will often see "striping" beneath the seafloor. Sort of like a layered cake…packages of sediment laid on the seafloor over time. This data can help guide our coring operations (assuming we will be able to get back to those later in the cruise).
So, we are doing some really sound science out here…literally and figuratively!
Weather and Wildlife
By : Dave Sybert
Weather the last few days aboard the R/V Armstrong has been what I would refer to as "sporty." Rough seas and strong winds have limited deck operations but there is still plenty of data being collected. The last few days we have been conducting transects back and forth across the western edge of the Gulf Stream and have experienced some pretty fast swings in the weather. The water temperatures change nearly 20 degrees from the Gulf Stream to the shelf water. We have seen very thick sea smoke, warm sunny skies and cold rainy weather depending on what water body we were steaming over. In these areas of great change we have experienced high seas at times, and also had the opportunity to see some amazing wildlife. Turtles, whales, many many sharks and manta rays were all spotted from the bridge.
"Where's the next point?" That's a question the Chief Scientist hears a lot throughout a cruise. As Chief Scientist, it is your responsibility to make sure all tasks are being completed and that the captain and crew remain informed with the science plan…which changes almost daily!
Don't get me wrong…the Chief Scientist isn't doing this alone! It takes a good team to make sure a cruise goes smoothly. So, I am trying to always talk with the other lead scientist about the plans for the next several hours. As new data comes in, we assess what we have learned and plan the next several hours. That's not to say we didn't put together a fairly detailed science schedule prior to the cruise...we did!! I worked out a plan for each day, literally down to the hour we would move to the next science task, next sampling area, and back to port (see the first map). I knew it would change, but it is important to make sure everyone has an idea what is planned on the cruise prior to arriving at the ship.
It was Einstein that said, "It is always good to have a plan, for no other reason than to document what you had planned to do and what you actually accomplished. The two are often very different things."
Wise man, that Einstein! So, yes, plans continue to be very fluid while at sea (pun intended…sorry, I couldn't resist). I interact quite frequently with the Captain and Mates on the bridge regarding our cruise track for surveying or the next several stations we want to do over the side operations. We are working with a great Captain and crew aboard the R/V Armstrong. They have been very accommodating with my frequent changes to visits to the bridge to change cruise tracks (see photo of me talking with Chief Mate on the bridge and a view from the bridge), moving waypoints, altering plans as needed to accommodate the science.