Say I have a file containing the following data lines:
Timestamp: 00:47:14 SATID 13 VAL1 28 VAL2 227 SIGNAL 37                                     SATID 15 VAL1 22 VAL2 265 SIGNAL 30 SATID 16 VAL1 22 VAL2 265 SIGNAL 30
Timestamp: 00:48:14 SATID 13 VAL1 28 VAL2 227 SIGNAL 37                                     SATID 15 VAL1 22 VAL2 265 SIGNAL NA SATID 16 VAL1 22 VAL2 265 SIGNAL 30
Timestamp: 00:49:14                                     SATID 14 VAL1 22 VAL2 265 SIGNAL 30

##</code><code>##

For instance, the desired output would be:
Timestamp: 00:47:14 SATID 13 VAL1 28 VAL2 227 SIGNAL 37 SATID 14 VAL1 nan VAL2 nan SIGNAL nan SATID 15 VAL1 22 VAL2 265 SIGNAL 30 SATID 16 VAL1 22 VAL2 265 SIGNAL 30
Timestamp: 00:48:14 SATID 13 VAL1 28 VAL2 227 SIGNAL 37 SATID 14 VAL1 nan VAL2 nan SIGNAL nan SATID 15 VAL1 22 VAL2 265 SIGNAL nan SATID 16 VAL1 22 VAL2 265 SIGNAL 30
Timestamp: 00:49:14 SATID 13 VAL1 nan VAL2 nan SIGNAL nan SATID 14 VAL1 22 VAL2 265 SIGNAL 30 SATID 15 VAL1 nan VAL2 nan SIGNAL nan SATID 16 VAL1 nan VAL2 nan SIGNAL nan