What do the file names for the images and directories on the Galileo CD-ROMs mean?
On the Galileo imaging CD-ROMs containing raw data, each of the images is placed into top level directories indicating the object name, for example Venus, Earth, Calibration, etc. Under that lies directories with names of the form Cnnnnnn and in each of those, images with names of the form xxxxR. These names are derived from the spacecraft clock time. Because the spacecraft clock time is measured in seconds (down to fractions of a second) from launch, the number is quite large and gets larger as time goes by. Because there are approximately 30 million seconds in a year and the mission is expected to last through 1997 at least, the file names could get quite big. Rather than do this, the last two digits of the spacecraft clock time and the first two places to the right of the decimal in the spacecraft clock time are used to make up the file name; the R on the end indicates it is “raw” (i.e., unprocessed) data. The directory names are then obtained by dividing the spacecraft clock time b
