A plug-in that is an interface to the NAIF SPICE "chronos" utility.
Here's what is available:
User's guide
PChronos.java: Source code
PChronos.class: Compiled Java application
Installation instructions
1. Place the "PChronos.class" file in $JAVA_HOME/jre/lib/pdsppi
2. Add "$JAVA_HOME/jre/lib/pdsppi" to your CLASSPATH environment variable
Note: The application also uses various classes contained in pdsppi.jar
You will need to download and install this Jar file as well.
Important additional information.Read This