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Polar Radar for Ice Sheet Measurements

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Home>PRISM Update>Radar Team- The Sandbox

Testing the Radar in the Sandbox

Clicking on the thumbnails below will allow you to see a larger image.

  The Sandbox



An artifact  

Here is a view of the "Sandbox" where we will test the radar. Sand has similar reflective properties to snow. The depth of the sand in this box is about two meters.

  The silver piece is one of the metal targets that will be placed in the sand. The metal target is made of half of a styrofoam ball covered in aluminum foil. There is a small dowel through the center to help with exact positioning of the target. There are also air-filled targets of the same shape made of paper mache. The metal targets should be more reflective and easier to see on the radar. We will see if the radar detects all the targets.  
  Radar Antenna   Antenna track  
  These are the radar antenna that are attached to rails on the sandbox. They can be positioned anywhere by using the computer.   The radar antenna move along tracks on two sides of the "sandbox". Here is a close up of one of the tracks and the wiring.  
  Placement of targets   Marking the artifacts  
  The placement of the targets is carefully planned. This grid shows the placement of the targets in the sandbox.   The red arrows show the dowels of the targets sticking up out of the sand. John will initially line up the radar antenna with one of the targets.  
  Raking the sand   Tamping the sand  
  John has planted the targets and is now raking the sand around them to make it smooth.   Next he jumps on this sheet of metal to make the sand more compact and level. This will make it more like the snow and ice.  
  Smoothing the sand by hand   Checking for level  
  John is squatting on the piece of metal to be sure the surface stays flat while he smooths the surface by hand.   Now he is using the level to check the area he just smoothed to make sure it is absolutely flat. Though the snow and ice won't be level, during this test it is important to know the distance from the top of the sand to the target.  
  Cleaning the track   Cleaning the track  
  When the targets are planted and the surface is raked and smoothed, sand and dust go everywhere. It is very important that all of the tracks are cleaned thoroughly before moving the antenna along the track. First it has to be vacuumed.   Next the track has to be wiped down with a damp cloth.  
  Cleaning the track   Starting position of antenna  
  Then it is wiped again to dry it. And you thought housework was bad!   The antenna in the starting position.  
  Aligning the antenna   Computer screen of output  
  John carefully aligns the antenna.   Here he is checking the settings for the radar.  
  Antenna moving   Radar image  
  Here the radar antenna are moving. It takes about eight hours to complete the test.   This is the radar image. You can see two targets at the bottom (red arrows) that are 0.4 meters apart.  
  Radar image  
Radar image
  This is another radar image. The targets at the bottom of this image are 0.2 meters apart. You can clearly see the difference as they are closer together.   This shows all ten targets. See if you can find them (it works better if you use the larger image). If you aren't sure, use the grid that we showed you before to help you find them.  

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