http://www.livescience.com/58603-how-tomahawk-missiles-work.htmlSyria Bombing: How Do Tomahawk Missiles Work?By Tia Ghose, Senior Writer | April 7, 2017 04:23pm ET
Sophisticated navigation
To navigate, the missiles use a combination of digital scene matching and global positioning system (GPS) to pinpoint their targets with better accuracy. Digital scene matching takes images captured by the missile while in flight toward its target and matches them to images taken prior to the flight, during mission planning, according to a 1994 paper describing digital scene matching from the Johns Hopkins University Applied Physics Laboratory, which helped design the system. Another aspect of the system's navigation is a tool called terrain contour matching. This system compares images from a previously acquired contour map and compares them with measurements that a radar altimeter makes on board the missile. Based on input for the terrain-matching algorithm, the system can update its inertial navigation system — a set of sensors, such as accelerometers and gyroscopes to measure rotation — to reorient itself.
Tomahawk missiles can also make real-time updates to their position."The missile is sending constant emails back to the controlling agency; then the controlling agency can send updated guidance via essentially a data email back to the missile," Harmer said.