The U.S. Air Force has ordered replacement engines for two of its E-8C Joint STARS (JSTARS) radar aircraft, at a cost of $112 million per aircraft. Delivery will take about a year. The air forces is spending nearly $100 million on upgrading each of the 18 E-8Cs operated by reservists (the Air National Guard). This includes new engines, an Internet-like communications capability, long range optical sensors (like that on combat aircraft targeting pods) and the ability to search water surfaces.
The new JT8D engines are modern designs similar to those used on commercial aircraft. The new engines will enable the E-8C to maintain the most effective altitude, and burn less fuel doing it. The new engines also require less maintenance.
The E-8 is a militarized Boeing 707 (a 1950s design, also used for the KC-135 aerial tanker and other U.S. Air Force electronics warfare aircraft). The main capability is the JSTARS ground search radar. This system has two modes; wide area (showing a 25 by 20 kilometer area) and detailed (4,000 by 5,000 meters). The radar can see out to several hundred kilometers and each screen full of information could be saved and brought back later to compare to another view (to see what has moved). In this manner, operators can track the movement of ground vehicles, or ships. Operators can also use the detail mode to pick out specific details of what's going on down there, like tracking the movement of many small missile boats trying to rush an American warship. JSTARS can stay up there for over 12 hours at a time, and two or more JSTARS can operate in shifts to provide 24/7 coverage.
The Air National Guard aircraft can be kept in service another 40 years, although they may be replaced by cheaper, unmanned, aircraft before then. JSTARS first proved its worth during the 1991 Gulf War, where it accurately, and in real time, tracked the movement of Coalition and Iraqi ground forces.