Analysis of the degradation of a spaceflight tape recorder

Beginning shortly after launch, and continuing from orbital insertion around Venus through the prime science mission, one of the two magnetic tape recorders aboard the Magellan spacecraft experienced an increasing bit-error rate. As depicted in Figure 1, the bit errors from the recorder eventually caused the percentage of Venusian radar data frames experiencing errors to exceed 5%, and caused the recorder to be deemed unusable. The bit errors were manifested not as single-bit errors nor as burst errors, which are common errors that may be expected from tape recorders. Instead, as shown in Table 1, the errors were usually characterized by occurrences of slipped bits associated with flipped bits. For example, "1001" radar data patterns were recovered from the recorder as "111" patterns.