Mass Properties Testing Transcript

Today we did the mass property measurements for the Wide Field camera 3 enclosure
and radiator. We basically placed the test item on top of an adapter fitting on 
top of the moment of inertia mass property table, It's called the Miller Table
here at Goddard. We placed the item on top of and then we conducted the first test 
determine the moment of inertia. The moment of inertia is just a measurement of 
the resistance an item has to motion in this particular case, just spinning around 
the vertical axis and that's done by just simply measuring the time it takes to 
complete one oscillation. It turns out to be about 2.96 sec for the oscillation to 
occur, that's directly proportional to the moment of inertia, which is the 
resistance. The other item that we found out by putting it up on the table was to 
calculate its center of gravity. We knew approximately the center of gravity of 
the test item was 8inch away from the latch lines B and C. Once we calculated 
where it was expected we could place it on the table near the center of the table 
by taking the measurements of the moment using the table we calculated that the 
center of gravity was approximately a half inch off one axis on the table and 
approximately 2 inches off the other axis of the table. The center of gravity is 
needed for anything that gets launched so that you can calculate the forces where 
ever you need attach that item into the spacecraft or into the shuttle or into 
another enclosure and that center of gravity is very important because it 
determines the magnitude of those forces at those attachment points. So we'll take 
another reading of Wide Field camera 3 sometime in about 4 months once it's fully 
loaded and maybe another one in about 6 months so everything will be calculated 
before it analyzed to be sent off to be installed inside the shuttle.