Alvin Sub and Hot Seafloor Vents

Chapter 7.  The Alvin Research Submersible and Seafloor Hydrothermal Vents

     The Alvin-Atlantis cruise on which I participated in August of 2009 was focused on visiting the subsea geothermal vent region along the 300 mile Juan de Fuca Ridge, located offshore Washington and Oregon and British Columbia, Canada.  For details of why I was there and the basic background of the research submersible, Alvin, see Chapter 6 of this blog.  Half of the expedition was to be devoted to CORK observatory servicing; the other half involved marine biologists intent on studying unique biological communities around the hydrothermal vents, in particular for this group of scientists, the sulfide worms.  Both groups used Alvin as their undersea access vehicle, allowing 3-person teams to dive to about 8500 feet water depth to conduct their specific research.

     A little about my first experience diving in Alvin.  When you board Atlantis as an Alvin dive participant designee one of the first things that happens is one of the Alvin pilots finds you and schedules you for an Alvin dive refresher course (if you have been in Alvin previously), or for a basic Alvin dive prep course (for us rookies).  The prep course takes place in the Alvin hangar on the fantail of Atlantis.  The quick course includes two parts; an outside tour intro and inspection followed by inside how-to instruction.

Alvin submersible in its hangar
onboard Atlantis

    The outside inspection tour is fascinating for an engineer, like me.  Everything outside the 8-ft diameter titanium personnel pressure sphere is allowed to feel full hydrostatic seawater pressure.  So there are no bulky pressure cases with sealed openings designed especially for drive motors/thrusters , batteries, electronics/electrical boxes, buoyancy modules, cameras, manipulator arm mechanisms, etc.  There may be a one or two small external pressure cases that I didn’t notice but essentially the only significant pressure housing is where the people go.  It is rated to 4500m (14,760 ft) depth, or about 6600 psi external pressure.  Virtually all of the external hardware and systems are flooded in advance with non-conductive (and virtually incompressible) hydraulic fluid, which is automatically pressure compensated to match the ambient seawater pressure at any depth.  (This non-intuitive and clever design approach to high ocean pressure management impressed me enough that I used the same technique in designing a novel undersea release tool a couple years later.  It included a small conventional DC motor that the manufacturer said could certainly not be used that way – simply because they had never heard of such a thing and no one had told them the marine science community was already doing it).

     But the most important part of the pre-dive course was on the inside – beginning with how to get in and out of the sub.  The only access is through the top hatch located in the sail. 

The hatch into Alvin - tighter than it looks

This is made easy by a small balcony in the hangar that takes you to the hatch.  It is tougher to negotiate with Alvin on deck ready to launch.  Once through the rather tight hatch (rotund people have to pass through a bit like toothpaste leaving the tube) you carefully feel with your toes for a lightweight aluminum ladder that helps you get down the ~7 feet to the padded “deck” very near the bottom of the sphere.  They pull the ladder out when everybody is inside because even its space is needed.  Inside the sphere you find where you will sit as an “observer”, behind and left or right of the pilot who sits middle/forward where he can work the controls and see out the center viewport.  It is fun to picture the pilot sitting in a starship command chair, but in actuality he gets a little swiveling stool that the Alvin dive group constructed themselves.  It is hollow and everybody’s sack lunch for the day goes in it.  Some artist’s conceptions of Alvin’s interior show the pilot in an easy chair and the two observer’s laying prone and facing forward like the Wright brothers on their first flight at Kitty Hawk, but actually the two observers have no option but to sit with their backs to the sphere facing each other and their legs bargaining for the small bit of space between.  You get immediately friendly with your dive partner.  I drew Dr. Jim Cowen from the University of Hawaii, an Alvin dive veteran and extremely nice and patient man.  That is him demonstrating how to crawl through the top hatch.



Alvin, being lauanched from
Atlantis with A-frame

     Inside the sub almost all the space is consumed by equipment.  Controls panels, communications gear, recording decks for the outside video images, pilots controls, computers, etc, etc.  They don’t even try to indoctrinate the new dive participants on all of it.  You do, however, get a thought-provoking primer on the survival necessities:  how to contact the surface with the underwater comm gear if the pilot were to pass out, say.  Where to find the CO2 rechargers and how to change out canisters.  Where to find the sleeping bags plus emergency water and rations that could be used for up to three days if the sub got stuck on the bottom for some reason and you had to wait for rescue from the surface.  I was told that none of that gear has ever been used in an emergency situation.  Still, though, it makes you think.  And then there is the legendary emergency release “T-handle”.  In the hypothetical case where Alvin gets stuck on the bottom and the crew has no other recourse to get back to the surface to save their lives the last alternative is to pull the T-handle located under the floor plates and release the titanium personnel sphere for a free (and no doubt thrilling) ride straight to the surface.  This feature has also never been used except in testing.  People have asked me a number of times, “wouldn’t coming up that fast give everybody the bends?”  No, the inside of the sphere is atmospheric pressure; there is no change of interior pressure as the sub dives or ascends. 

     You get a few other pointers – what to wear (somethng warm and comfortable but no polyester – too flammable), how to pee, how to operate your designated video camera, what a typical dive schedule can be, and so on.  If you haven’t had a change of heart about the whole adventure by then you are checked off as ready for a dive.



Alvin, getting ready to go down

     The night before the dive the necessary experimental equipment is tested one last time and loaded in the work basket mounted on the front of the sub and the dive plan is verbally worked out with the dive master and the selected Alvin pilot for the next day.  On dive day everybody is busy from daybreak until dusk.  The sub goes in the water about 8 am and plans to return around 5 pm in order to assure both launch and recovery are conducted in daylight.  Time is money in this expensive business and dives are scheduled for as much bottom time as possible so one long day of diving in a single dive is vastly preferable to multiple short trips.  Dive and recovery is assisted by swimmers – everybody on the Atlantis crew is eligible for this swim/assist duty and many of them love it – never mind the frigid water temperatures sometimes involved. 



The first creature I saw on the
bottom.  I have no idea what it is.

     Our dive to one of the CORKs was to a depth of about 8500 feet.  Descent took around 45 minutes.  Below 100 feet or so it was completely black outside the sub except for some phosphorescent creatures briefly sighted along the way.  The sub does not power itself to the bottom, it just overloads with ballast water and slowly sinks; less use of precious battery power that way.  We navigated by a sophisticated sonar system housed on both the sub and the mother ship.  When we reached bottom and turned on the outside lights we were right near the first target – a set of instruments on a buoyed line we had tossed carefully over the side the night before that were destined for insertion into the CORK.  We towed the instrument string over to the CORK we were going to service and spent the day working on inserting that gear into one of the feed-through ports, then conducted some water chemistry experiments using a special pump and chemistry monitoring system brought along by Jim Cowen. 



Jellyfish just drifting by --
at 8500 ft below the sea

     Voice communication is essentially constant (and perfect) with Atlantis during a dive but I think our dive experience was fairly typical in that you get an explorer’s isolation mentality very quickly once 
you are on the bottom – hence, a lot of chatter with topside seems unnecessary and even a bit intrusive.  The crew up on the mother ship understands and don’t pester the sub crew any more than necessary.  On my dive and on several others the sub crew for the day was asked to talk briefly over a complex sonar-satellite-telephone multiple comm link to some junior high school kids in California, as part of an educational outreach experiment.  The most memorable question the kids asked was, what is the biggest fish you have ever seen?



The region was home
to lots of purple optopi

     In the process of getting to the CORKs and working on the bottom we got to see some pretty weird and interesting local wildlife.  Some of our pictures are included here.  Notice the vivid colors of the jelly fish that happened to drift by and the fish, octopi and other strange looking creatures.  This seemed downright strange to me since no light had ever reached these depths in millions of years (until we brought our artificial lights along).  What possible reason could there be for these creatures to exhibit such striking coloration?  And I am sure I saw eyes on some of them.  Why would they have eyes?



     Hot vents and sulfide worms.  We did not explore over to the hydrothermal vent region on our dive because those areas were a handful of miles away from our CORK installations.  However, I did get to review all of the dive logs and photos from the other dives on the vent regions.  As I mentioned earlier the main purpose for those dives during our cruise was so the biologists could perform research on sulfide worms.  The photo in the anecdote at bottom is borrowed from another online source but shows the sulfide worm colonies as I remember seeing pictures of them – they are not known for their striking beauty, although I have since read that some versions have fancy plumage, as compared to these that look a bit like discarded cigarette butts.  There were also some of the classic “black smokers” in the area.  The bright red line in the adjacent photo is from the sub – a parallel pair of such laser rays is used to provide scale in the photos later.



A black smoker active vent

     On my dive we performed our planned tasks successfully (well, the pilot and Jim did, I mostly gawked and said, Wow), ate our lunch, tried not to get too cramped, and when our allowed time on bottom ran out we dropped some expendable ballast weights and headed for home, i.e., the surface.  On the way up we killed the time filling out our individual dive logs, taking pictures of ourselves in the sub and telling each other our abbreviated life stories.  As a successful first time dive participant I had one more obligation when we got the sub back on deck and emerged to the cheering crowds (okay, they were politely watching and waiting).  The picture at below shows the traditional greeting for a first timer – the seawater in those orange buckets had been left in the freezer all day in preparation for the ceremony.

   Oh yeah, after the freezing-water-in-the-face initiation I had one more duty – emptying the pee bottles from the sub.  I had used them more than the other two guys so figured I could handle the whole job.

    

References:

[1]   For an excellent primer on creatures associated with hot vents, see

“Hydrothermal Vent Communities”, by Carolyn Scearce

http://www.csa.com/discoveryguides/vent/review.pdf

[2]  A little more about the hydrothermal regions of the Juan de Fuca Ridge

http://www.marine-conservation.org/media/shining_sea/place_epacific_juandefuca.htm

Anecdote:  “Spiritual Metaphysics of Sulfide Worms”

     During our expedition aboard Atlantis to use Alvin to dive on the subsea hot vent regions of the Juan de Fuca Ridge I was involved directly only in the inspection and servicing of the CORK seafloor observatories.  However, I paid some attention to the other half of the science crew who were employing Alvin to dive near the actual vents themselves to conduct zoological research on the unique organisms who made that area their habitat.  In particular, this group of scientists was there to investigate the sulfide worm colonies and learn some basics about these newly-discovered critters.  For them this was the equivalent of discovering living creatures on another planet – absolutely nothing was known about the worms for the purposes of characterization in a marine biology textbook.  They were intent on using their limited dive and lab time to conduct every experiment possible on live worms to discover their temperature and chemical tolerances, biochemistry, eating habits, means of locomotion, you name it.  I don’t think they were able to study reproductive methods but maybe I missed that tidbit.

The little white things are
sulfide worms (I think)

    So how does a marine biologist actually perform such studies?  Well, if you think about it, the options are limited and many approaches are quite straightforward.  One technique I learned about was how they studied temperature tolerance.  They knew going in that these little animals lived in hot, sulfur-rich seawater, at high seawater hydrostatic pressure and temperatures up to 200-300 deg C.  But what was their range of acceptable living condition temperatures?  One of their tools taken down in the Alvin work basket became known as the “worm wok”.  The idea was to gently pick up a few worms from the seafloor, drop them in the wok while still at the full depth, then seal the wok and apply heat slowly.  They then observed the worms through a clear lid.  When the worms seemed to die that was the recorded maximum tolerance temperature.  Sounds a bit gruesome, doesn’t it. 

     I didn’t pry into their techniques for examining the worms that were captured and brought back to Atlantis for study in the labs.  But I know the biology group came prepared with some well-made pieces of experimental apparatus intended to subject the worms to a wide variety of conditions in order to determine their responses and, hence, begin the process of scientifically characterizing the creatures.  A picture of some of their custom experimental worm experimentation equipment is shown here; but no casual observer would ever guess what it was for.  Whatever the specifics were, I am pretty sure of one thing -- none of the worms were gently interviewed and then sent home intact or unharmed.

Lab apparatus for examining sulfide worms

     So, I began to look at the picture from the point of view of the worms.  It is a bit profound if you consider it from their perspective; a life or death issue for them.  Imagine Mr. and Mrs. Sulfide Worm sitting one evening on their hot, stinky sulfide-infused rock on the seafloor 8000 feet below the surface of the Pacific Ocean.  (Actually “evening” would mean nothing to them because at that depth no light has ever penetrated in the history of the sun or the oceans.)  There they were in their perfect environment; warm, comfortable, surrounded by relatives, with lots of food (whatever they eat), apparently not threatened by their benthic neighbors since the worms are found fully exposed and unmolested on the seafloor outcroppings.     At some point you can additionally imagine that one of them waxes philosophic and points out what a secure and wonderful life they lead.  They are, after all, living in the absolute safest place on the face of the planet.  In an isolated spot with rare sulfurous hot water vents nearby.  Thousands of feet below the sea, fully isolated by local conditions from the rest of the ocean bottoms, in perpetual darkness and near silence, their existence completely unknown by any other beings on the planet except for the occasional fish swimming by who can’t bother them because they can’t penetrate into the small heated water zone where the worms thrive.   How can it get any more idyllic and secure than that?

     And then one day it all changes.  A huge, ship appears overhead with LIGHTS and horrible mechanical arms making an ungodly racket.  (Picture the alien spacecraft in Close Encounters of the Third Kind except even more out of place and not as photogenic.)  This is going to turn out to be a close encounter of the worst kind for the worms.  Soon word spreads in the worm colony – they are capturing some of our relatives and taking them into the ship thing!  And then, after a few hours of this terror, the alien ship leaves as mysteriously as it arrived.

     But what has become of our missing relatives, the worms ask themselves?  Here is where the metaphysical part comes in because you just KNOW that the argument among the worms must have broken down into the two inevitable camps.

     Worm Camp 1:  Those were angels from some higher realm.  And they have taken our friends to a better, more wonderful, heavenly place.

     Worm Camp 2:  Don’t believe it.  Those were aliens from another world.  They came to capture our relatives so they could take them away for torture, horrible experiments and death!

     And, of course, the lucky surviving worms would never learn the truth.  But we humans know the answer here.  We don’t have to guess which camp had it right.