We encountered a problem with our experiment before we were able to test the density of the ice.  The water never froze to ice while inside the centrifuge.  Therefore we were not able to test our hypothesis.  We did five trials of running the centrifuge in the freezer with the water.  The freezer was at 7.9°F for the trials.  After the first two, we realized that it was going to take longer than we thought for the water to freeze.  Our first trial was for 20 minutes, as a preliminary test to see how long it would take.  We had assumed that it would not take any longer than normal for that small of an amount of water to freeze, even if it was at high gravity.  We checked the tubes at 20 minutes and the water was not frozen.  We started over the experiment, this time running the trial for 45 minutes.  The water still did not freeze.  We then tried a trial for 70 minutes and another for 210 minutes, both ending in the same result.  We did not anticipate that the water would not freeze and so we did not take the temperature of the water after each of these four trials.  We obtained a thermometer before our final trial and also decided to try testing with the lid of the centrifuge open to let more cold air into the centrifuge.  The temperature of the water after the final trial of 100 minutes with the lid open was 33.8°F in one tube and 32.4°F in a second tube.  In the middle of the centrifuge, the temperature was 30.4°F.