Science party participant Eivind Straume, a PhD student at the Centre for Earth Evolution and Dynamics, University of Oslo, put together an excellent outreach video that graphically illuminates the science and technology associated with our voyage. View it here.
Just after daybreak on June 8, the Kilo Moana slid into her home berth at the University of Hawaii Marine Center in Honolulu, drawing to a close an adventuresome 31 days at sea for the YoungORCA recovery team. We’d sailed over 10,000 km, collecting seafloor and water-column data along the way; sampled seafloor rocks from three volcanic locations; read and analyzed seven research papers; presented and discussed seven student thesis projects; processed thousands of km of high-resolution multibeam bathymetry data (see figure); deployed over a dozen independent oceanographic floats; and most importantly, successfully recovered the 30 OBS that we had deployed on the seafloor over a year prior. Along the way, students and staff alike gained appreciation for the unique opportunities offered by seagoing science – the importance of discipline, cooperation, and teamwork, the risks associated with exploring unknown realms, and the rewards provided by unique new observations.
As previously detailed, YoungORCA is the first of two OBS arrays designed to image convection in Earth’s mantle that drives the motion of tectonic plates and associated surface deformation such as earthquakes and volcanism. Successfully pursuing those goals will require careful, detailed analyses back on shore of the data still being extracted from the OBS. Preliminary data viewed on the ship provide tantalizing evidence of abundant recordings of earthquakes necessary for successful imaging (see figure). In the meantime, our partners at the OBS Instrumentation Center and Scripps will refurbish the OBS and prepare them for redeployment from the KM in fall of 2019, at our second (OldORCA) location in the far southwestern Pacific, midway between Tahiti and New Zealand.
As we sign off, the YoungORCA recovery team would like to acknowledge a number of critical partners and contributors. First, the captain, crew, and science technicians (OTGs) of the KM provided a professional, supportive, and friendly platform for us to pursue our science. (They also made excellent partners and trainers in the transition from polliwogs to shellbacks, which most of us underwent. Photos remain classified.) The SIO OBS team of Ernie and Mark were exceptional in deploying and recovering the OBS, and providing training and insight into OBS operations. Finally, the National Science Foundation’s Marine Geology and Geophysics program provided the financial support for the project, including travel support for the apply-to-sail early-career participants in the science party.
Hope to see you all in November for the OldORCA deployment!
-Jim Gaherty, for the YoungORCA recovery team
A deeply buried memory clawed into my consciousness earlier this week – a recollection of confusion and frustration, a younger me struggling to grasp meaning from Beckett’s absurd play Waiting for Godot, thrust upon me by a (sadistic?) high-school English teacher. The prompt for the burst of memory was laughably simple. The image of a recovery team waiting for the surfacing of an OBS in the surrounding expanse of the night-time ocean and banter in the main lab on witty names for the science-party watch teams (e.g. “Team No-BS”) led to my own comic tagline for our primary activity: Waiting for Godot-BS (hint: “Godot” is French). Pretty good, huh? I even saw a thematic connection: Beckett’s play (as I recall) centers on uncertainty and yearning by two characters (and the audience) as they await the ever-impending arrival of Godot. Waiting for the emergence of an OBS from a full year on the seafloor beneath nearly 3 miles of ocean recalled, for me, the characters’ angst-filled wait. Unlike Godot, however, our OBS do arrive – all 30 of them, very good indeed. Furthermore, my wittiness was lost on the rest of the science party, as apparently Godot was not part of a millennial’s high-school curriculum. With the arrival of the OBS, my Godot analogy fizzled, and we moved on to the next site, my tagline forgotten.
After we wrapped up our science activities and turned onto our long (7.5 day) transit back to port, however, the analogy continued to nag at me. True, we have all of our OBS, but now I have new questions and new uncertainties. What data do the OBS hold? Will our analyses support the ideas on small-scale convection that motivated the experiment? Would they lead us down new paths of discovery and highlight the need for new observations? The OBS are not Godot, but maybe the answers to those questions are? I can’t wait to get the data back to shore and start finding out!
— Jim Gaherty, in this case NOT representing the Young Orca recovery team
An unofficial poll amongst the scientific party on expedition KM1908 has indicated that many are not ready to go home. I have good news: if this month at sea has changed you, you will not be going home. A place, e.g., “home”, is defined to us by our experiences there; experiences that are filtered and interpreted by who we are at the time. The lat/lon’s of our various residencies remain, but some of us have changed. For those people, “home” will be a different place.
We walked from the shore,
Our lights prismed by the sea,
Same homes, different streets.
And here, again, repeated from my first post, is the ~1,300 year-old, anonymously-penned Japanese poem: Poem #461 from the Man’yoshu, translated by Arthur Waley:
Because Fate cannot be stayed
Going forth from my splendid house
I have hidden among the clouds.
Inochi ni shi areba,
Iye yu wa idete
Get home safe,
— Theresa Sawi
By May 27th, the OBS recovery mission ended successfully. In the past 20 days, I have learned a lot about western culture and vocabulary. For instance, I’ve learned terms to describe ways to cook eggs, names of different types of bread, names of different sauces and how to match them with dishes… um, and the terms describing the ship movement: roll, pitch, heave. While many suffered from seasickness, I was woken up several times at night by the winch noise (since there are only 9 of us in the science team, we each have our own cabin on the ship). However, I was not upset, because that indicated we were sampling the ocean floor!
In the previous OBS deployment cruise, scientists found three special areas to look into based on the backscatter and bathymetry data: the first was a suspected young lava flow, the second a seamount, and the third a strangely shaped volcanic feature. This time we decided to look into them by dredging (please refer to William’s blog for further information).
On the first dredging site, we found a mass of manganese nodules mixed up in mud. It took Theresa and Veselina nearly two hours to sort them out—and they became mud girls in the process. Still, it turned out to be quite frustrating since we are looking forward to finding basalt. (It felt a little silly, since manganese nodules are valuable natural resources and basalt forms the ocean floor.) Merely because I was the first to identify the manganese nodules, the other team members asked me lots of detailed questions about the nodules—I wish I remembered more! When cleaning out the nodules, we found a small hard piece of higher density. Ashley tried to break the piece in half but failed. Thus, that might be something we were looking for. The whole team cheered up. We searched more carefully, finding the second, the third pieces… For the third dredging, we found volcanic rocks from a relatively shallow area (but still 4100m deep!). There was little mud but big rocks, which was very different from the first one. We even used “Thor’s hammer” to break them into pieces in order to lift and move them. Ultimately, all the samples will be taken to the petrologists and chemists for further analysis.
The ocean is vast and deep, and we have to put in a lot of effort to figure out a drop in the bucket. I am glad that I have these friends in the same camp, and we like to rock and roll!
第一次采样，我们在淤泥里找到了很多锰结核，Theresa 、 Veselina等人花了近两个小时，近乎变成泥人，才将它们从淤泥里分离开。但这令我们沮丧，因为我们期待的是玄武岩（这大概就是所谓的买椟还珠吧。。毕竟锰结核是各国都非常重视的资源矿产呢！而玄武岩，整个海底都是。。）大概因为我是第一个识别锰结核的人，其他学生都问我相关问题，但是很惭愧我相关的知识全部还给老师了！
大海广袤幽深，我们穷尽浑身解数，期待能够窥一其斑。前路漫漫，但幸好有这么志同道合的人携手，且有rock and roll相伴!
At heart, science is a cooperative community endeavor – invariably, great discoveries build upon unheralded contributions of scientists who collecting new data, and propose and test hypotheses that ultimately lead to a slow build-up of understanding. This is particularly true for those of us in Earth and Ocean sciences, who depend on community operation of crucial facilities to collect data on a truly global scale – satellites, ships, networks of instruments such as seismometers, for example. Our experiment critically depends on at least three such efforts: the operation of the ship that we are sailing on (www.unols.org), the support for OBS instrumentation (obsic.whoi.edu), and the archival and distribution of the data that we collect (iris.edu and marine-geo.org).
Our expedition to a remote locale in the south Pacific provides an opportunity to contribute back to the greater oceanography community. Along our journey, we are deploying 17 free-floating sensors that will provide new observational data for the coming months to years. These sensors are of two types. Twelve of them are ARGO floats (www.argo.net), deployed on behalf of the Pacific Marine Environmental Laboratory at NOAA, and a research group at the School of Oceanography at the University of Washington. ARGO are ~4 ft-long torpedo-shaped tubes, each containing sensors to measure temperature, pressure, and electrical conductivity (which can be used to estimate salinity), a buoyancy system that allows it to control its depth, and satellite communications. After deploying, the floats dive to 1000-m depth, where they sit undisturbed, carried by the currents. Every 10 days, the dive to 2000-m, and then rise to the surface, measuring temperature and salinity profiles along the way. They transmit their data home, and then return to 1000-m to wait for their next cycle. Modern ones last for ~6 years, producing hundreds of observations of in their lifetime. The data are available nearly instantly after deployment and the first satellite transition, and are helping oceanographers world-wide better understand critical research questions on ocean dynamics and the climate system. The second type of floats are Spotter Buoys (sofarocean.com), which are a bit bigger than a basketball and contain inertial sensors to measure wave height and periodicity, solar panels for power, and satellite communications. They float freely in the ocean, providing high-precision measurements of wave behavior for oceanographers studying weather and climate systems.
The floater deployments offer a fun diversion during our long transits to and from the study site, and between stations. With varying degree of finesse, we carry the units to the aft rail, and lower or drop them into the ocean as we transit along at full speed. They are now bobbing along, delivering data to the oceanography community.
– Jim Gaherty, for the Pacific ORCA recovery cruise.
The first part of our cruise is now over. All thirty instruments were successfully recovered from the ocean floor, and sit securely on the deck. Their compact rectangular design and the bright yellow float are attractive, even playful—we’ve been comparing them to SpongeBob SquarePants. It’s a little hard to believe when I look at them that these cute little characters have spent the last year in complete darkness, under the immense pressure of almost three miles of water, in temperatures that are only marginally above freezing, silently and precisely recording nearly imperceptible movement of the seafloor. These instruments are able to record the shaking caused by a magnitude 6 earthquake anywhere in the world. Their benign demeanor belies the intensity of the science they have performed for us since May 2018.
We have now moved on to the second part of our mission: dredging. Dredging is the way in which we bring rocks up from the seafloor to the surface. We cannot simply go down and pick them up. Instead, we use something called a “dredge basket.” Imagine a butterfly net made entirely of steel, about eight feet long and two feet across with three-inch long steel teeth around the rim, and clocking in at about 400 pounds. We lower this into the water at the stern of the ship using a thick steel cable, and lower it all the way to the seafloor, 4.5 kilometers (almost three miles) down. We can track where it is from a screen in the computer lab that shows how much cable we’ve let out, and what the tension is on the cable. When we let out the same amount of cable as the water depth, there is a lot of tension on the wire: not only is there the weight of the dredge basket, but the cable we use also weighs 1.4 pounds per meter—all told, we’re registering more than 5800 pounds of tension when it reaches the seafloor. Once we know it’s been set down, we then drive the ship over the seafloor a couple of miles while still dropping cable, so that hopefully the dredge basket doesn’t move yet. When the ship gets far enough away, we stop the ship and begin to winch in the cable slowly, dragging the basket across the seafloor. It gets stuck occasionally, and the tension will rise above 10,000 pounds, but will suddenly drop—we call this a “bite,” and we hope it’s a good sign! We hope that whatever rock was causing it to hang up is now inside our basket.
The whole process takes about 8 hours. Once the basket comes to the surface, we carefully take it out of the water, a process that requires four winches and seven people. We dump out all the rocks on the deck, and once the basket is safely secured, the scientists all rush in to see what rocks we got! We’re looking for basalt. Basalt is the frozen lava that comes out of volcanos, and the entire seafloor is made of it. If the basalt that we pull up is just regular seafloor, it will be about 40 million years old. If, however, we find basalt that’s much younger than that, it would be a puzzle—why would a volcano erupt on the old ocean floor? We cannot tell just by looking at these rocks how old they are. Instead we let them dry, wrap them up, and put them in boxes. When we get back to land, we will run precise chemical tests that will give us a good idea of how old they are. Until then, we’ve more rocks to collect: off to the next dredge site!
— William Hawley