Hydrothermal Exploration of the Mid-Cayman Rise

Perseverance

Chris German
Jun. 23 2013

Science progressed today.  But it didn’t come quietly.

Last night I realized that if I was sending Blog 28 ashore then I must have been gone from home for 4 weeks already.  And my personal highlight for the cruise, diving to the seafloor at the Piccard site, still lay ahead.  So I was awake at 5 this morning for the launch ofNereus 057 full of expectation for the great dive ahead.

Finally, a whole series of sensor anomalies, close above the seafloor at the Beebe Vents mound, Piccard Hydrothermal Field. I really hope we all get a chance to see these vents with Nereus tomorrow.
Finally, a whole series of sensor anomalies, close above the seafloor at the Beebe Vents mound, Piccard Hydrothermal Field. I really hope we all get a chance to see these vents with Nereus tomorrow.Chris German

The launch, just after 6am couldn’t have been sweeter: the best we have had all cruise, it was so smooth.  The next moment of concern was when we separated the float pack from the depressor: I have never seen that fail over the two Nereus cruises I have been involved with but that only totals 6 dives so I’m not really qualified to comment – I only know that the tension levels in 2009 onNereus dives 024-026 were matched only by the tension I recall as a small child watching Apollo missions return from the moon: after all that journey back to Earth there would be the period of radio silence as the command module re-entered Earth’s atmosphere.  I still get that each morning and, touch wood, each morning so far the release of the float pack has gone perfectly.  So there we were, around 8:30 this morning, 2.5 hours into the dive and Nereus halfway through its 3000m parachute drop to the seafloor, connected by a gossamer thread, when all communications were lost.

The same set of anomalies, together with the series of dashed lines showing where Max got all his samples from. Phew. What a long day!!! Now time for bed so I am ready to go again at 3am. Tomorrow is another day ☺
The same set of anomalies, together with the series of dashed lines showing where Max got all his samples from. Phew. What a long day!!! Now time for bed so I am ready to go again at 3am. Tomorrow is another day ☺Chris German

Everything was working perfectly…  until it wasn’t.

We had no choice but to recover the vehicle and that took most of the rest of the morning: 2 hours for Nereus to come all the way back and then another 45 minute or so to get it back on deck and the small rescue boat stowed back in-board as well.  Because of the long descent and ascent times, coupled with the need to have our gear back on deck by nightfall, there was no option but to postpone any further dive until the next day: but Captain Heiko has agreed that we can start at 4am tomorrow, not 6am, so we get the maximum time possible on the seafloor.

In the meantime, I figured, we can at least collect the plume-waters that Max wants for lipid analyses: so the CTD went in right after lunch, right at the position where Meg got some awesome samples above the Beebe Vents mound on Leg 1.  Nothing.  Seriously.  We went down 5000m and couldn’t see any evidence of our sensors worth sampling.

With Paul on the Bridge doing some excellent work we went North.  Nothing.  Then a little East.  Still nothing.  The south again.  Still nothing.  Then back to where we started.  Nope.  Finally, we tried going West and North again.  Nada.  Time to haul back to the surface and go again.  By 5:15pm we had the CTD back on deck and by 5:30, Capt Heiko had repositioned the ship to the North West and we were back in the water.

Shallow thoughts from a deep ocean. I found myself leaning over the side of the ship today for a while when the first CTD was coming up and while I was working out what to do for our second attempt. I’m not sure anything terribly clever came to mind but the pretty patterns of sun and shade were good for the soul. Today is done. Tomorrow is another day. Like I said – not profound at all!
Shallow thoughts from a deep ocean. I found myself leaning over the side of the ship today for a while when the first CTD was coming up and while I was working out what to do for our second attempt. I’m not sure anything terribly clever came to mind but the pretty patterns of sun and shade were good for the soul. Today is done. Tomorrow is another day. Like I said – not profound at all!Chris German

In setting up for our second cast, Chief Mate Phillip had a great idea: pick two positions that you want the ship to pass through: one at the depth for the top of the plume and the other at the depth for the seafloor so we could transition between the two.  Since we had tried NE, SE & SW away from our target site the obvious answer was to approach from the NW.  So we did.  Still nothing.  Well, not completely nothing, but mostly nothing.

Then, as we lowered to the seafloor, Phillip moved the ship the final 120m or so to position us right over the vent-site.  We saw some weedy plume signals but nothing to get excited about and then there we were: right over where the chmineys are supposed to be, 20m above the seabed, and nothing still.  What to do?  Should we come up?  One last roll of the dice…

Smiling sweetly at Nathan, and asking pretty pretty please, we lowered away slowly and cautiously to 8m above the seabed.  And were rewarded.

A dirty great Eh anomaly, particle anomalies and even the temperature sensor records went up showing we were in warm water seeping from the seafloor right over the vent-site.  Tweaking our depth back up ever so gently by a meter or two we got our rosette right in the sweet spot and fired all 24 bottles.  Finally, 16 hours into the day, we had moved science forward by collecting these novel sample types from the Piccard hydrothermal field.

It has been a long and brutal day, mentally, but we still have a week to go and I am off to bed now thinking the same as I thought last night: the best parts of this cruise, for me, are still to come.  With stubborn-ness like this, I might yet win (honorary) Yorkshire citizenship.  So long as I don’t wear scent.


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