missile.  Its  primary  mission  is  to  destroy  hostile surface   targets   such   as   combatants,   surfaced submarines, or other vessels. The Harpoon can be launched   from   surface   ships,   submarines,   or aircraft (without the rocket booster). It was introduced in the fleet on ships and sub- marines in 1977 and on the P-3  series  aircraft  in 1979. The Harpoon is being improved to add range and to decrease altitude in its sea-skimming mode. The  Harpoon  was  used  effectively  in  attacks  on Libyan  targets  in  the  Gulf  of  Sidra  in  1986.  The Navy  is  now  developing  a  new  infrared  Harpoon variant  called  the  Standoff  Land  Attack  missile (SLAM). Characteristics of the Harpoon: Length: 15 feet (surface/submarine- launched); 12 feet, 7 inches (air- launched) Diameter: 14 inches Wing span: 3 feet (with booster fins and wings) TOMAHAWK The  Tomahawk  (fig.  20-4)  is  an  all-weather submarine/surface-combatant-launched, long- range,   subsonic,   antiship   or   land-attack   cruise missile.   It   can   be   conventionally    armed    for antisurface    warfare    and    conventionally    and nuclear   armed   for   land-attack   versions.   After launch,  a  solid-propellant  rocket  booster  propels the  missile  until  a  small  turbofan  engine  takes over for the cruise portion of the flight. The  land-attack  version  of  the  Tomahawk  has an inertial and terrain contour-matching (TERCOM)    guidance    system.    The    TERCOM system compares a stored map reference with the actual terrain  to  determine  the  missile’s  position. If necessary, it then makes a course correction to guide the missile to the target. The  antiship  version  has  a  modified  Harpoon cruise   missile   guidance   system.   This   system permits the launching and flying of the Tomahawk in  the  general  direction  of  an  enemy  ship  at  low altitudes.  At  a  programmed  distance,  the  missile begins an active radar search to seek, acquire, and hit the target ship. Tomahawk   is   a   highly   survivable   weapon against  predicted  hostile  defense  systems.  Radar detection of the Tomahawk is difficult because the missile has a very small cross section and can fly at   extremely   low   altitudes.   Similarly,   infrared detection  is  difficult  because  the  turbofan  engine emits a low level of heat. Characteristics of the Tomahawk: Length: 20 feet, 6 inches (with booster) Diameter: 20.4 inches Wing span: 8 feet, 9 inches Weight: 3,200 pounds (with booster) Speed: About 550 miles per hour Range: Land-attack, nuclear warhead —1,350 nautical miles Land- attack, conventional war- head—    600 nautical miles Antiship configuration-250 nautical miles 134.54 Figure 20-4.-The first fully guided Tomahawk cruise missile in flight after being launched from an A-6 Intruder aircraft. 20-6