21 January, 1998
Hi from the Ross Sea! This has been a long day on the Nathaniel B. Palmer. Have you every had one of those days when nothing seems to go right? That's been our equipment today! It could be because of ice, but many of our instruments broke today and the ASA crew is working very hard to get everything fixed. It's a good thing that they are so handy! (It's not like we can run out and buy more instruments . . . we have to be able to fix things right here on ship) Everyone is very confident that things will be fixed, but fixing things takes time away from collecting data. The only things that worked successfully today were the corers.
In looking at the last few journals, I think there is only one more major piece of equipment that I haven't described yet. It's called a "deep tow," and it is another way of using sound waves to make a picture of the bottom and to determine what the top layers of sediments look like. This instrument, however, is not attached directly to the boat. We pull it behind the boat by a long cable. The "fish" hangs in the water and sends out "chirps" of sound which bounce down to the bottom. The sound waves that go from the sides of the "fish" go down at an angle (like the sides of a triangle) and make a map of the bottom. The sound waves that go straight down actually penetrate the sediments. They are used to make the profile (or side view) of the sediments. The readings are recorded digitally on a computer as well as visually on a printer. Like the Bathy-2000, this instrument is used to look at the top 10 meters of sediments and to make a "map view" of the bottom. This biggest difference is that the deep tow gives us a much clearer picture. Also, the Bathy-2000 is attached to the ship, so it runs all the time. The deep tow has to be placed in the water, so the scientists are very selective about where and when we are using it.
We have finishedcollecting data in one area of the Ross Sea. We are now headed toward a different area to begin another study. We are heading to Cape Adare to collect data for Julia Smith and Tony Rodriguez. For the last few days, we have not moved very far in the Ross Sea. Now, the ship is moving much faster (about 10 knots) as we have a 24 hour transit to our next location. Our latitude is now 74 degrees, 00 minutes South, and our longitude is 174 degrees, 08 minutes East. We are heading towards 71 degrees, 12 minutes South and 170 degrees, 20 minutes East. How do you suppose that we know our exact latitude and longitude?
You might be wondering how we know how long it will take us to get to our next area of study. Do you know what "knots" stands for? It means nautical miles per hour. One nautical mile is equal to one minute of latitude or about 1.1 miles (about 1.8 kilometers). There are 60 minutes of latitude in each degree of latitude. So, let's look at a little problem. Suppose that we had to travel one degree of latitude (60 minutes of latitude). At 10 knots, how long would that take? Answer: 6 hours! Of course, that's assuming that we don't have to slow down for icy seas or drive around any icebergs (which always slow us down, but look absolutely gorgeous)! Every day, we figure out the approximate time it will take us to get to each location in addition to how long we will be collecting data in that spot or area. We call this the "plan of the day." We use math problems like this over and over!
Let's take a look at yesterday's question: Why do you suppose that we would want to see a bucketful of sediments (from the grab sampler) rather than sending down a nice core every time? If we are unsure what the sediments are made of, a grab sampler can give us some sort of indication. If there are too many rocks and gravel, they can break a piston core and/or the cores will come up empty. So, we use a grab sampler to get an indication of what's below us. Sometimes we already know, based on previous data and all of our other equipment. If we don't know, a grab sampler is one of those things to make sure we are "better safe than sorry!"
Since we will be in transit for my entire watch tomorrow, we will be able to split the watch among the four of us (3 hours each). Since I will have some more time off, I have a goal . . . to see penguins! Keep in touch to see if I find any! Keep those questions coming -- I love hearing from all of you!
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