Atlantis Diary IX: Rescue
The bizarre hydrothermal vent field discovered a little more than two years ago surprised scientists not only with vents that are the tallest ever seen –the one that’s 18 stories dwarfs most vents at other sites by at least 100 feet — but also because the fluids forming these vents are heated by seawater reacting with million-year-old mantle rocks, not by young volcanism. The field is unlike any seen before, according to chief scientist Deborah Kelley, a University of Washington associate professor of oceanography, and co-chief scientist Jeff Karson, a Duke University professor of earth and ocean sciences. Both have visited fields of black-smoker hydrothermal vents that scientists have been studying since the 1970s.
Now the two scientists who were the first to travel in a submersible to the field after its serendipitous discovery Dec. 4, 2000, are leading a National Science Foundation-funded expedition to map and further investigate the field. The ‘Atlantis Diaries’ chronicles the expedition returning with 24 scientists onboard an exploration vessel, the Atlantis, during their 32-day expedition that spans April 21 to May 22.
Friday, May 16, 2003
Dive 3,881 today was special, not only because this was our farewell dive in the Lost City Hydrothermal Field, but, more importantly, because it marked the 500th dive that Expedition Leader Pat Hickey has made to the seafloor in Alvin. Today’s journal is a tribute to Pat and his 500th dive Thank you, Pat, from all of us!
|Lunar eclipse from the North Atlantic. Although the Earth completely masks the moon, scattered light from the Earth’s atmosphere gives the grey-ish moon a blood-red look.|
Final dives are commonly some of the most difficult because the main goals include many diverse "chores" that have somehow accumulated at the end of the program. This last dive was no different. There was a long wish list of things that people wanted: explorations of new venting sites, rocks from specific areas, suites of fluids, biology and carbonate samples from multiple places, mosaics of entire structures to obtain full-view images, and traverses around the outer edges of the huge structure Poseidon.
By 7:40 am, Pat in his quiet, efficient manner had worked through the dive checklist. He made a few jokes with bleary-eyed well wishers who had stayed up until 3 am to watch the lunar eclipse. Typical of Pat, he never let on that this was to be his 500th dive, even though it is a remarkable achievement.
Perhaps one way to put his accomplishment into perspective is to note that only one other Alvin pilot has made 500 dives in the nearly 40 years that Alvin has been in operation. As Expedition Leader, Pat has trained numerous pilots and he has been instrumental in keeping the sub updated as new technologies and equipment become available.
Pat is a generous teacher and he goes out of his way to help new divers become acquainted with the do’s and don’ts in Alvin. On this particular dive, he showed Mausmi Mehta how to operate the cameras and the controls that are used to "drive" the submarine.
Pat is a consummate pilot with an uncanny sense of where the submarine is at all times. He knows how to get to places, even when he has no navigation and has only been there once before. Because of his skills and experience, he routinely leads scientists to the best sampling sites.
By the end of today’s dive, we had a basket-load of samples from the Lost City and spectacular video and still images of the hydrothermal chimneys. Alvin released weights and rose to the surface. On deck, the entire science party and crew turned out to greet Pat as he exited the sub. In the fine tradition of Alvin pilots, he was given a multiple bucket shower of ice water.
Pat, many, many people have benefited from your help, generosity and fine piloting we all thank you and look forward to your next 500 dives.
Saturday, May 17, 2003
Alvin performed a rescue mission today. After yesterday’s dive, Atlantis traveled about 140 nautical miles, arriving at the location of a sediment trap mooring with a faulty acoustic release. The dive objective was to descend to the bottom of the mooring and cut the cable that attached it to a 2,000-pound weight, which anchored it to the sea floor. The sediment trap would then float to the surface and be retrieved by Atlantis.
|During a science dive, the basket carries milk crates for rock samples, water samplers, slurps, and bio boxes. |
The mooring consists of an anchor, sediment trap, glass floatation spheres to float the trap off the seafloor at a depth of 2,800 meters, an acoustic release, and one-fourth-inch wire rope that attaches all the pieces together.
The sediment trap is a big funnel that catches whatever might fall down into it from above. There is a rotary carousel at the bottom of the funnel that holds plastic collection bottles. Before the instrument is deployed, the user programs the time required for each bottle to be indexed at the bottom of the funnel. According to Tim Shank, the goal of such "time-series sediment traps" is to improve our understanding of how biological material is transported from the surface waters of the ocean down to the seafloor. Carbon produced by ocean surface biology such as plankton can rain down to the deep sea, providing food for many animals. This patchy supply of descending food may then influence where animals live on different regions of the seafloor.
The trap was deployed in January 2001, and was supposed to be recovered last year. The mooring was supposed to disconnect from the cable anchoring it to the seafloor when an acoustic signal was sent to the release. Unfortunately the release failed, so another method of recovery was needed. Since we were going to be in the area, it was convenient for us to attempt the recovery.
To prepare for this dive, we changed the outer basket. The normal science basket consists of bins to hold rocks, water sampling bottles, a temperature probe, and covered boxes to hold more delicate items such as biology. These were all removed, and then we mounted a hydraulically operated cutter and a backup manual cutter. We added a few push cores in order to sample the sediment at the base of the mooring.
Blee was the pilot of the day, and Noel was the pilot-in-training. Since this dive did not have the same science objectives as the rest of the cruise, Debbie Kelley kindly allowed one of the ship’s crew to experience a trip to the bottom of the ocean, and First Engineer Gary McGrath was chosen. This morning before the dive, I could easily see the giddy excitement in both Noel and Gary.
The mooring’s glass balls were good sonar targets, so they were easily located. The sub crew went to the bottom of the mooring and took the push core sediment samples. Then they cut the cable using the hydraulic cutter. As the mooring started to float up to the surface, the pilot drove the sub away to avoid any possibility of getting tangled.
Following Alvin’s recovery, the deck crew brought the mooring aboard. Tim removed the samples from the instrument and placed them in a refrigerator for storage. With our last task completed, we are now on our way towards Bermuda.
Sunday, May 18, 2003
Sub operations finished yesterday, so I got to sleep until 0730 this morning — an extra two hours. As the ET Section Leader, it’s my job to make sure the sub is electrically ready before every dive, so that means my team of electronic techs and Pilots are awake at 0530 every dive day. We start at 0600 and finish when the sub is put to sleep, which is usually late into the evening. That makes for some long days, so it feels good to now be able to sleep a little late.
There’s another treat in store for tomorrow. The ship is heading east across another time zone, so we’ll be turning the clocks back and I’ll be getting another extra hour of sleep. Joy! It’s been a long cruise and everyone could use the opportunity to catch up on their Z’s.
|Gavin helps to wash the sub while working on his tan.|
Since we’re done diving, almost everyone’s daily routine has begun to change. Attitudes are a bit more relaxed, and you start noticing faces of the night shift crew during the day, when you normally only saw them lurking around in the middle of the night. Senior scientists aren’t fussing with samples fresh off Alvin’s basket, so they use all their extra time siting in countless meetings recounting all the fine details that make the difference between just good science and great science. Even the foozball table is getting a little more attention and the competition at the Ping-Pong table is heating up. Just a few games left till the Finals. I’d have to say the Captain is the big favorite this time.
As for the Alvin Group, we’re busy as usual, getting our baby ready for our next job. We’ll be doing 15 dives with Jess Adkins and his crew during a three week long cruise. Alvin Group keeps a busy schedule, so to keep the sub in tip-top shape we’re constantly doing maintenance.
We started our day like any typical Sunday by washing our vehicle. After lots of scrubbing and lots of suds, we had one very clean Alvin. Then we started our "Post Cruise" and "25 Dive" checks. This is just a small portion of the endless testing and documentation we’re required to do to maintain our Navy certification. When we finish with that, we’ll be completely stripping all the Lost City-related science equipment and installing the next set of gear. The work never ends.
There’s only three days left before we reach Bermuda and a much-deserved break, so we’re all pushing hard to finish the work. I’m sure the thought of pulling into Bermuda is keeping everyone going. The crew and Alvin group might only get a day off in port before we sail again, but we’ll all make the most of it. Some will SCUBA dive, some might rent a scooter and cruise the island, but me, I think I’ll spend the day at Tobacco Bay thinking about things other than Atlantis for a change.
The project includes scientists, engineers and students from the University of Washington, Duke University, Woods Hole Oceanographic Institution, U.S. National Oceanic and Atmospheric Administration, Switzerland’s Institute for Mineralogy and Petrology and Japan’s National Institute of Advanced Industrial Science and Technology. Collaborators include: Jeff Karson, Duke University, Co-PI and diver during the discovery; Matt Schrenk (an astrobiology graduate student at the UW School of Oceanography); P.J. Cimino (a NASA Space grant undergraduate); and John Baross, also a faculty member in astrobiology and oceanography.