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Mark Drewery secures sampling equipment to the Alvin's science platform in preparation for tomorrow's dive. |
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| Destination reached! |
Monday, November 15th, 1999
Destination reached! After 5 ½ days underway, we finally reached the spot where we'll spend the next 15 days diving to hydrothermal vent communities about a mile and a half beneath the ocean surface.
We left port in San Diego on Wednesday afternoon, November 10th. We faced about a 1,000-mile trip before we reached our 9º North destination - 500 miles southwest of Acapulco, Mexico. Earlier that morning, Alvin took a "dip" off the San Diego Harbor dock to test out its camera systems outside, and the IMAX camera mounted inside.
IMAX team member Bill Reeve was anxious to get a few test shots looking out of Alvin's front porthole (one of three on the sub) where the IMAX camera will be mounted during his dives.
Alvin Group mechanical technician and pilot-in-training (PIT) Mark Drewery was the "swimmer" on this short mission. In general, the swimmer's job on Alvin launches is to ensure that the sub and its scientific and camera equipment are ready to dive - lines are unhooked from the A-frame, safety lines are removed from the science equipment mounted on the sub's front platform, and camera systems are airtight and functioning. Mark's task that morning was to make sure that the outside camera housings were airtight and to watch for and disperse (using "Joy" dishwashing liquid) any small oil slicks resulting from loose connections.
After about 20 minutes, satisfied with the camera operations, Mark, Bill, and the Alvin were lifted out of the water and "rolled" back into the Alvin "hangar" on deck. After the Alvin was secured and the R/V Atlantis crew had freed the dock lines, we were ready to depart. The gangplank was pulled up and we left dry land behind, beginning our 3-week expedition to explore one of the harshest, least well understood ecosystems in the world.
While the Atlantis was making her way through San Diego Harbor, I had the opportunity to talk with Stephen Low about the IMAX camera system. Stephen's company, Stephen Low Productions, produced the 1991 IMAX film Titanica, a documentary about the famous RMS Titanic shipwreck, and was now about to make the first-ever IMAX film about hydrothermal vent communities.
According to Stephen, the fact that the IMAX camera needs to be mounted inside - and not outside - the sub has nothing to do with a lack of adequate housing to protect it from the crushing pressures at such great depths. The camera is mounted inside the sub because it has to be reloaded so frequently; the standard 1000-foot roll of IMAX film captures only 3 minutes of filming. On each Alvin dive with the IMAX camera, Stephen will use between 7 and 10 rolls of film. With so many rolls of film, an 80-lb camera, and the specially built mounting system, only the pilot and cameraman will be able to dive during IMAX filming. Usually the Alvin dives with a pilot and two observers.
Diana's 1st day with the Alvin Group
Diana began her first day working with the Alvin team with a briefing from pilot BLee Williams. An advocate of hands-on education, it was BLee who suggested Diana work with the Alvin Group during this expedition. Diana will assist with the general maintenance of the sub and its hangar, pre-launch preparation of the sub, and observe launch and recovery operations. Diana is thrilled with the opportunity to gain hands-on experience and insight into this famous "workhorse" of the deep submergence community under the supervision of the Alvin team. In preparation for tomorrow's dive, Diana assisted Mark Drewery in securing the "skins" on the Alvin. The "skins" are the white fiberglass plates that cover the hydraulic and electrical components found along the outside of the sub's titanium structural frame and passenger sphere; without its skins, Alvin looks a bit like the back of a TV without its housing. Diana also observed Mark making aluminum "stop plates" for the "wrists" of Alvin's mechanical arms. The stop plates will ensure that the biological sampling equipment on the sub's science platform doesn't rotate when the arms pick it up. Diana watched as Mark demonstrated how to properly grease Alvin's hatch to prevent leakage - one of the most critical steps in ensuring the safety of the passengers inside the titanium sphere. After a briefing on the afternoon's transponder launch, Diana had completed her first day as part of the Alvin team.
Transponder Deployment
We arrived on station about 4:00pm Central Standard Time (CST) and deployed 3 transponders to the ocean floor. The transponders are instruments that send acoustic signals ("pings") back to the ship. These pings are received by an acoustic signal processor (ASP) and used to locate and track the position of the Alvin during dives. The transponders are tethered to weights that rest on the seafloor; the instrument itself sits off the bottom, high enough to be above all terrain features, usually between 185 and 300m (610 and 990 ft, respectively).
According to Expedition Leader and Alvin pilot Pat Hickey, the transponders are "streamed off the back end of the ship" and positioned a distance between 1 and 2 kilometers (0.6 and 1.3 miles) apart. When the 15 dive days of this expedition are complete, an acoustic signal from the ship will "trip" the acoustic release system of each transponder; they'll be released from their tethers and make their way to the surface where they'll be recovered by Alvin's crew. With the transponders set, the scientific equipment to be used on tomorrow's dive was positioned and secured on Alvin's science platform. Dr. Cindy Van Dover of the College of William and Mary in Williamsburg, Virginia and her graduate student Lawrence Carpenter will make the first dive of this expedition. Dr. Van Dover and Lawrence will be taking samples of mussel beds found in the vent fields. They will also deploy a number of mussel larvae settlement experiments to learn more about the larval dispersal of these organisms. More on Dr. Van Dover and her research on these unique biological communities - as well as a report on the first day of Alvin dives - in tomorrow's expedition log!
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