Date: Sun, 9 Feb 1997 06:17:09 +0000 (GMT)
From: Jason Goodman <sci5@knorr.whoi.edu>
To: seadiary@MIT.EDU
Subject: Real Work today
Message-Id: <Pine.SUN.3.91.970209054039.1527C-100000@mike.knorr.whoi.edu>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

  After a full day of sailing (which I didn't bother to describe 
yesterday), we reached the first station today.  I was on watch for the 
second station.  At the risk of boring you, I'll describe how this goes.
  Half an hour before we arrive at the sample site, we prepare the CTD
package for its plunge.  This entails cocking the triggers for the sample
bottles, setting up the electronics, and getting the rigging in order. 
When we arrive, we drop an XBT (expendable bathythermograph).  This is a
little free-falling torpedo which falls 2 km through the water, measuring
temperature and sending the data back to the ship via a fine copper wire
which spools off the back.  The wire eventually breaks, and the torpedo
sits on the bottom of the sea for eternity.  The CTD package lives in a
hangar on the starboard side, amidships.  We open the hangar door, and
roll the package out on deck using a little railroad car mounted to the
deck.  The process is reminiscent of the vehicle which carries space
shuttles from the assembly building to the launch site.  We use a pair of
guide ropes to keep the package from swinging around as the winch operator
lifts the package into the air, over the side, and drops it in the water. 
The data (temperature, salinity, pressure, and oxygen) are sent back up
along the winch cable: we go back inside and send the package down,
communicating with the winch operator by intercom.  There's a pinger on
the CTD package: we have a sonar trace which scans across a long roll of
paper once a second, making a black mark every time there's a sound.  When
the black marks representing the pings gets close to the black marks
representing the reflection of the pings off the bottom, we know we're
near the bottom.  Then we head back up, firing bottles at specified
depths.  The winch goes at 70 meters/minute, and the bottom's at 3.5
kilometers... there's a lot of waiting involved here.  Anyway, it
eventually comes to the surface; the winch operator lifts it out of the
water, we grab it with hooks on the ends of poles and use ropes attached
to the hooks to guide it back onto the railroad car, then drive it back
into the hangar.  Easy to say, but the ropes are generally frozen, the
package (which weighs a ton or two) is swinging wildly, there's an inch of
snow on the deck, it's driving snow so thick you can hardly see the end of
your pole, and your fingers are frozen but your torso is roasting, 
because the gloves suck but the work-vest works too well.  Anyway, when 
the package is in the hangar, I change into lab gloves and raingear and 
start sampling.  The procedures are completely paranoid about 
contamination... even the easiest requires three rinses of the bottles 
before filling.  I started quoting bits of Sweeney Todd: "Three times 
through the grinder, slowly, slowly, slowly..."  It takes about 2 hours 
to sample all 24 bottles.
  The work-vests are kind of neat: they're insulated, waterproof, and 
buoyant, so you're safe from freezing, soaking, and drowning.  They're 
also bright orange.  To get an idea of what deployment and retrieval look 
like, imagine a group of tiny bright orange marshmallow men running around 
under a big steel swinging erector-set creation.
  And then it's off to the next station.  We're going to do this about 
eighty times in the next six weeks.  The next one's in an hour and a half.

					J