Day 9 A thimble from the deep

The back deck during snow showers

Meet Mr Cup - a standard styrofoam cup
with pingu and a beer can for scale

Mr Cup tied to the CTD frame inside an old sock

The CTD goes down to 4715 metres

Mr Cup after the experiment

There is an adorable scene in first of the Lord of the Rings films, just after Sam and Frodo have left the shire. In the middle of a corn field Sam suddenly stops, as if he has hit an invisible wall. Frodo asks why and Sam replies "If I take one step further, I will be further from Hobbiton than ever before in my entire life".

On this journey I had many Sam & Frodo moments - and experienced my  first time moments. I had never seen snow at sea before - only in the mountains or generally on land during winter. The day had a very Antarctic feel about it - snow showers blew across the deck of the ship. The sea is still calm, but nothing says "Welcome to Antarctica" like a row of icebergs on the horizon.

As for venturing out in to the unknown... Where my line in the cornfield lies, I do not know. Had I been ever further away from home than now? I made it as far as Fiji once, so that might beat it in terms of sheer distance. But what I do know - I have never been further south than today! The James Clark Ross had finally reached her furthest south position on this cruise:

63° 20.81 S, 29° 34.07 W

From here we'll go north and gradually west again. This position marks the first of a CTD transect of about 30 stations, in regularly spaced distances from here to South Georgia. At each station we take a CTD cast
to measure "C"onductivity, "T"emperature, and "D"epth. For the upper ocean many such measurements already exist - the oceans are regularly monitored by a fleet of automated drifting robots. These "floats" rise
and sink through the water column and drift with the ocean currentsm all the while taking readings of the sea water. When they sink, they measure Temperature and Salinity, when they're at the surface they beam the data back via satellite.

These automated floats can dive to 2000m, but mostly monitor the upper 1000m only. This simple fact makes observations of the deep ocean quite rare. If you want to know what lurks at the bottom of the ocean (i.e. which water masses flow down there) such floats will not cut it, and you still need a ship. That's one of the reasons we're here - to measure the deep ocean waters. And down here the ocean is very deep.

Our first station at over 63° south was at a depth of 4725m - nearly five kilometres or almost 3 miles down. Even if a person volunteered to go down there - the pressure would be intolerable. That's due to the weight of a tower of 3 miles of water stacked on top of the poor volunteer. The instruments are robust enough not to implode, but people just have too many air-filled cavities in their bodies. These would inevitably crushed to a fraction of their former size. Try to dive to the bottom of the swimming pool and the ears start to hurt as the water pressure increases. 3 miles down? No thanks!

Did I say lots of air-filled spaces? Well I can think of a slightly more willing volunteer who matches that description. Meet my volunteer for a journey to the deep - a polystyrene cup. Mister Cup is full of bubbles, and these air-filled bubbles which insulate very well from the scalding heat of lovely tea. But this time the plastic foam shall demonstrate what would happen to any air cavities when they take a deep dunk down to 4715m (the CTD stops 10m off the bottom).

In the first photo, Mr Cup can be seen in his original state posing next to Pingu, the mascot for this trip, and a can of Antarctica beer, which was emptied yesterday in celebration of reaching the furthest south I have ever been. Then Mr Cup was bundled into an old sock and cable-tied it to the CTD frame. The CTD went on the winch, over the side and the sock was swollowed by the waves. Soon it would get uncomfortable for Mr Cup.

I always knew that the cup would get compressed. Obviously - the form is full of air, and that will get squashed under the pressure. But by how much, I had no idea. When the cup came back up after a few hours I was astounded - the cup had shrunk to the size of thimble. I could not believe how small it was now. I posed the cup with Pingu and beer can for scale. That's a lot of pressure at 4715m. It makes tiny cups, and it tells us about the deep ocean. From this and many more measurements to come we'll be able to work out whether the deep Antarctic Ocean is warming, and how these deep waters affect the climate for us living on the surface. It'll be a while until the data is analysed - we haven't even finished the transect yet.

But I shall have a cup of tea first. Just a very small sip. From a very small cup....