By Lora Koenig
The last week of September was a busy one for the SEAT radar team. Ludo, Clem and I spent the week at the Center for Remote Sensing of Ice Sheets (CReSIS), an NSF Science and Technology Center, at the University of Kansas preparing the radars and the radar sled for shipment to Antarctica. (Yes we are shipping our gear a full two months before we will actually arrive. It takes a long time to ship things to Antarctica.) CReSIS is a unique center that specializes in building radars for the snow and ice (cryosphere) community to use. For the educators out there CReSIS has some great resources that can be found here. (Throughout the blog we will try to insert good education links.)
It was a very fun week for us. We got out from behind our computers and spent most of our time in the metal shop or working with the radars. Our goals for the week were to test the radars, put together the sled exactly how it would be in Antarctica and pack up everything for shipping.
One of our first tasks was to mount the radar antennas on the metal cross bar of the sled. We have to make sure everything is very sturdy because the sled and radars are going to be bounced along behind a snowmobile for 600 kilometers (about 370 miles)!
The radars we will use on the traverse were designed and built by CReSIS. Aqsa Patel, who is working on her PhD in Electrical Engineering and Computer Science, along with a team of students, built the radars. Aqsa taught Ludo about all of the electronics inside the Digital Acquisition System (DAQ) for the radars.
The DAQ converts the signal received from the radars into a digital signal that is recorded by the computer. Our team will be all alone once we get into the field so the preparation time with the radars is very important. We can always call Aqsa from Antarctica—she has promised to have her cell phone with her 24 hours a day while we are on the traverse—but if anything breaks we will have to fix it. Hopefully we will never have to have the DAQ open like this again.
We are taking two radars with us, the Ku-band radar and the snow radar. (For those technical readers: Both radars are FMCW radars with the Ku-band radar operating between 12.5 and 15.5 GHz and the Snow radar operating between two and eight GHz. You can read more about the radars here.) These radars peer into the top 20 to 30 meters of the ice sheet, imaging the firn layers under the surface. Firn is snow that has persisted through one melt season. Another way of saying this is: When snow is one year old we call it firn. Firn layers are just like tree rings, counting them will tell you the age of the layer. The image below shows data gathered from the Ku-band radar last season. This type of image is called a radar echogram and is used to trace and count the layers of firn beneath the surface. How many layers can you count? There are over 20 years of accumulation history in the echogram.
By Thursday we had everything up and running. In the photo below you can see the sled put together. The red line on the laptop screen at left shows the data the radars are gathering of the metal plate placed below the antenna horns. As you can see, Clem’s work in the metal shop was successful and the antennas, horn-shaped objects at the top right of the picture, are solidly attached. The big red box, to the right in the photo, will house the radars for the traverse.
And now for a sneak peak into the future, using some pictures from last year.
When the sled and gear finally arrive in Antarctica the package will look like this:
Do you see the big red radar box?
The sled loaded with the radar in the field will look like this:
For now the boxes are packed and shipped by truck to Port Hueneme, Cal. From there a boat will take them to New Zealand and a military cargo plane will make the final leg into McMurdo, Antarctica, where we will pick them up again. We pack everything very carefully so it will not break during the shipment. We have two of almost everything from wires to computers to GPS devices. There are no stores in Antarctica and what we ship is what we get for the science instruments. Rule number one for a successful season will be to not break anything! And that starts from time the instruments are put in the box until they arrive back at CReSIS in late Mar., 2012. Though we are prepared to fix things, we are scientists and what we do best is collect and analyze data. We rely on the engineers, like Aqsa, to build and provide us great instruments.
In all we shipped over 1,400 pounds of gear just for the radars. Some of the more interesting things that we packed are density cutters to measure the snow density, an infrared camera to look at snow-grain size, strips of rubber to insulate metal that could cause frost bite, heating pads to warm up the electronics in the morning, kidney belts for protection riding the snowmobiles such long distances, field notebooks, pencils, toolkits and a small stuffed penguin that wanted to make its way to Antarctica for a photo.
In the next post we will tell you about the ice core drill we are sending and how it was tested on glaciers in Canada to make sure it was ready for the Antarctic field work.