Beautiful skys, and a heavy instrument

Wednesday, January 27th, 2010

Welcome back to another update from Antarctica with Travis and Lambchop.

The weather has been great over the last few days.  It is warmer here at 3 or 4 C (37 – 39F) then it has been back home in Michigan.  The sun has even been out some!  The winds were light.  The waves were so smooth that they were called ‘glassy’.  Lambchop just had to sneak outside and get a picture or two!

This ship has been called a “science factory” before, and now I see why.  The scientists are working in 2 groups, each working 12 hour days.  I get up at 11 a night on ship (which is 7 in the morning in Michigan).  I work from midnight on ship until noon on ship.  We are producing science all day, every day!  It will take years to analyze all the data we are collecting, and it will take many more scientists then we have on board too.

The ship is drilling all day, and we have core coming up every 2 or 3 hours.  It takes that long because we have drilled so deep that we are drilling rocks now.

If you take sediment, like the dirt outside your house, and bury it under more sediment, the deeper sediment changes.  Sediment is heavy, and the more sediment you put on top, the more the deeper stuff gets squeezed.  At first the water is getting squeezed out of the pores, but when you squeeze enough water out, the sediment starts to get hard.  Very hard.  Like you have to cut it with a special kind of saw to cut rocks!

When the sediments get this hard, they are no longer sediments, they have changed into rocks.  This process is called ‘lithification’, which is just a way of saying ‘turn to rock’ using words from old Greek.
 
And it is a lot slower to drill through rocks, because they are so hard.  So things are going more slowly for now.

Which means Lambchop has time to describe the NGR to you.  NGR is a short way to say “Natural Gamma Radiation”.  It measures the natural radiation emitted by the sediments.

This is a picture of the front of the NGR.

That small hole that Lambchop is point to is where the core goes into the NGR.

This is a picture of the back of the NGR.

The outside of the NGR looks pretty boring, but that is because it is to stop radiation going into the NGR.  Radiation can take many forms, and it is all around us.  We are used to small amounts of radiation, but too much can be bad for us.  In fact, if you have ever gotten a sunburn, that is what happens if you get too much of a certain kind of radiation that the Sun sends out.

So there is radiation all around us, but it is usually very weak.  There are also parts of the sediments in the core that produce radiation, but they are very, very weak.  So for the NGR to detect them, it has to be protected from the natural radiation that is all around.

This protection is what we see when we look at the NGR.  The protection weighs over 4 metric tons (8,800 pounds!).  If you notice how big the NGR is compared to Lambchop, you can see that is really heavy for something not that large.  A car is probably 2,500 pounds, and is much larger then the NGR.

The reason is because the protection for the NGR is very dense.  Density depends on what something is made of.  What that means, is depending on what they are made of, different objects might have the same size, but they might have very different masses.  A baseball is about the same size as an apple, but the baseball is heavier.  That is because the baseball is denser.

The denser the material, the better protection it provides.  So the protection the NGR is made of something called lead.  Lead is very dense, in fact a ball of lead the size of a baseball would weight about 2400 grams (or about 87 ounces, or just over 5 pounds) while the baseball only weighs 145 grams (about a 5.1 ounces or about a third of a pound).

That is why the NGR is so heavy, the protection it needs is heavy.  But it is very important, because how much radiation, and the type of radiation that is produced by the core tells us a lot about what the core is made of.  Knowing what the core is made of tells us about how it was made. 

The next stop for the core is the splitting table.  This is where we cut a core in half, and finally get to look at the core.  So stay tuned, because we will finally be able to see the cores we have recovered!