objectives:
1) sample A1 and A4 vents at Milli-Q
2) evaluate Milli-Q as a site for camera deployment and deploy camera at
either here or at Cannaport
3) survey Milli-Q for instrumentable flanges
4) continue Mesotech survey of the Bastille complex (not completed,
replaced with survey of Grotto and Lobo)
5) survey Grotto, Lobo and Hulk for camera sites and instrumentable
flanges (only Grotto examined)
Dive was launched late (in water 0846L, problem was with ground on
reinstalled motor controller) in moderate seas.
Our landing target was to the SE of Milli-Q, however we ended up landing
on the west wall (it is not clear to me why). After orienting, we took
a course ~065 toward Milli-Q flying without the bottom in sight (depth
~2165), lowering to the bottom in the vicinity of Milli-Q. Phillip
almost immediately sighted the 1E marker. We began to inspect Milli-Q.
Blee almost immediately ruled out A1 as a possible camera site and we
focussed in on A4. Indeed the area at the base of A4 looked possible,
but an area downslope with a second smoker looked much better and I
decided that it was a suitable location for deployment of the camera.
Before deploying the camera it seemed sensible to complete the fluid
sampling at A4 (~1115L). After positioning the sub, we prepared to sample with
the manifold, using the port side samplers. Again (like in Dive 2930)
we had trouble with the flushing pump which is drawing considerable
current and causing breakers to trip. At some time just
prior/during the triggering of the first one (port outboard major),
the manifold computer locked up (appearance of a communication port
problem, no obvious problem with cable, was a breaker tripped in
conjunction with the flush pump?), the sampling set was lost and the
sample was compromised. The other two samples appeared fine (port
inboard major, port gas tight). Temperatures reached 364 C.
We then moved downslope to deploy the camera, which was completed with
little difficulty. There is very good imagery of setup from the overhead
SIT camera, both before and after the camera has been aimed. We then
repositioned to deploy the temperature probe instrument at the same
smoker (classic comedy available while Blee is thinking we are to
do a temperature measurement with the Alvin probe). This went well
though was much more difficult because of black smoke blowing toward the
sub, away from the camera. During deployment of the temperature probe
we observed the camera lights on at 11:50:15L.
The smoker at marker A1 was then sampled (~1215L). There is a cluster
of three--two small ones at the edge of the structure and a third
larger one closest to the marker and behind the other two. The
starboard bottles on the manifold were used (starboard outboard major,
starboard inboard major, starboard gas tight). Temperatures reached
363 C.
We then circled Milli-Q, looking for flanges that would be suitable for
instrumentation. This was done counterclockwise with the structure out
the portside viewport. I saw only one flange large enough to be
consider and this was too low on the structure to be workable and had
the additional problem of a large block of oxidized sulfide blocking
access from the basalt.
We moved north somewhat and worked on the trim of the sub. (Blee had
pumped 135 pounds of ballast, 95 for the instruments and an additional
40 to be heavy for sampling). We then transited north, passing the
chain of breadcrumbs north of Bastille, toward the SE corner of Grotto,
arriving ~1245L. We then began a reconnaisance of Grotto looking for
both potential smoker and flange sites for instrument deployments. We
moved up the east side of Grotto (between Grotto and Dante). There
were many large (1-3 meters) blocks of oxidizing sulfide at the base of
the structure (which is different from my recollection of the situation
in 1991). There were many large flanges along this wall with seemingly
healthy fauna on the upper surface. However there was no indication of
overflow from any of these and the ones we examined more closely were
"dry" or extremely shallow (millimeters of fluid, with many small ridge
of sulfide minerals filling the pool. Some portions appeared
oxidized. At the northern end we moved up the structure and then moved
slowly to the west, observing a series of smokers along this edge.
Several of these looked suitable for a camera deployment include ones
at (4942,6138,2188) heading 274; (4923,6141,2186) heading 080 and
(4952,6144,2188) heading 321 (these were fixes off the 10-10.5 kHz
pair). During this work within the Grotto we located the
thermoelectric generator in the vicinity of marker K (about 1318L, we
did not see marker K in the vicinity until later) and
placed marker BA there. I then tried to get us to the west of the
structure and had thought I had succeeded but we then found marker BA
again. (I need to rexamine the navigation in this part of things, for I
felt that we had gotten to the area south of marker 98, but the fixes were
not consistent with this location.) After leaving this marker we were
enveloped in smoke and I asked for a course 180 to get over to the
south side of the structure. We ended up far to the east of where I
wanted to be and so we turned onto 270 to take us to the west wall from
where I wanted to approach marker 8B. We followed the base of the
basalt talus and reached the vicinity of 8B about 1330L, but in
following to the right of the sulfide structure there we ended up yet
again at marker BA whereas such an approach in the past would have
taken along the southern edge of the structure to the vicinity of
marker 9. My general impression is that there are more smokers on
Grotto than in past years and that there has been substantial erosion
and degradation of the central inactive portion of the structure.
A combination of the lack of active flanges and the difficulty of
guiding Blee in this area, let to my decision about 1345 to complete
the dive with a Mesotech survey of the Grotto-Lobo pair, running
several N-S tracks from 6100 to 6200. These were nominally completed
at x=4910-4900 northbound, x=4930-4940 southbound, x=4925-4910
northbound, x=4940-4950 southbound, x=4910-4050 northbound (purposely
on heading 030), and a cross line starting from (4950,6920) on heading
300 which passed somewhere further sound of the structure than I had
intended.