The U.S. Air Force has decided to spend half a billion dollars to begin a refurbishment and upgrade program for its 17 E-8C Joint STARS (JSTARS) ground surveillance aircraft. This will keep the E-8Cs operational for another 40 or 50 years. The E-8C aircraft are already old and for over a decade have undergone as many upgrades as the air force could afford. That plan was only going to keep the E-8Cs flying until 2030. In the last few years, it was realized that there would not be a new model JSTARS aircraft based on a smaller two-engine jet like the Boeing 737. Until recently it was believed that the next version of JSTARS might be a large UAV, like the Global Hawk, with all the human operators working from the ground. That option will not be possible in time, thus the decision for a major refurbishment to give the air force several decades to develop a replacement.
The E-8 is a militarized Boeing 707 commercial airliner. The 707 is a 1950s design that is used for the KC-135 aerial tanker and other U.S. Air Force electronics warfare aircraft. The JSTARS is unique in that it uses a ground search radar that has two modes. One is wide-area (showing a 25 by 20 kilometer area) search and the other shows a lot more detail but only in an area 4,000 by 5,000 meters. The radar can see out to several hundred kilometers and each screen full of information can be saved and brought back to later 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.
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. Subsequently, the E-8Cs have been regularly used to support counterterror and intelligence operations throughout the Middle East.
Since 2010 the plan has been to upgrade and refurbish the existing JSTARS as much as possible so they would last until a replacement design was in service. To that end, in 2010, the air force ordered replacement engines for two of its E-8Cs, at a cost of $112 million per aircraft. The first E-8C with the new engines was flying in 2011 and proved to be a success. The new JT8D engines are modern designs similar to those used on commercial aircraft. The JT8D is also very similar in size and weight to the older JT3D engines long used on the E-8. This makes it easier and cheaper to replace the older engines with the similar JT8D. The new engines enable the E-8C to maintain the most effective altitude and burn 17 percent less fuel doing it. The new engines also require less maintenance and produce more electrical power. The success of JT8Ds on those two E-8Cs led the air force to go ahead with putting the new engines on the other 15 aircraft gradually, as money became available. Most of the new half-billion dollar program will go to scrutinizing each aircraft and replacing or rebuilding components suffering the most from age.
In 2013 there was a major upgrade of the primary E-8C radar. The improved JSTARS radar could now spot and track UAVs and ultralight aircraft over water. This LSS (Low, Slow, Small) airborne targets upgrade also included a new receiver for the JSTARS, enabling the radar to get a good image of these small aircraft and make identification possible. This is one of several recent radar upgrades. Back in 2007, JSTARS software was upgraded so the radar could spot ships and small boats at sea and, in general, be useful to naval forces operating in crowded coastal waters (like the Persian Gulf). This upgrade took into account the wave movements, which had previously created a lot of false hits until new signal processing software was developed which, in effect, prevented moving water from messing up the JSTARS view of what was on the surface.
The air force spent about $100 million on upgrading each of the 16 E-8Cs operated by reservists (the Air National Guard). The Internet type comms proved too expensive, so the JSTARS will have to get along with satellite data links it already has. Since 2010 the air force has tested or installed several upgrades for its 16 JSTARS aircraft. This included successfully testing an MS-177 very-high-resolution digital camera. The MS-177 enables the JSTARS to identify details of a vehicle its radar has spotted on the ground. The MS-177 is similar to a camera carried in U-2 reconnaissance aircraft since the 1990s. The MS-177 can distinguish a car from a van up to 80 kilometers away, while the JSTARS is at an altitude of 11,200 meters (35,000 feet). The MS-177 was linked to the JSTARS navigation system, thus providing precise location of whatever it saw and enabling targets to be confirmed in a minute or so, rather than waiting for an aircraft with a targeting pod to get close enough to clearly identify the target. Without the MS-177 the JSTARS radar merely indicates something down there is moving and what size it is. Despite the successful test, the air force was unable to equip more than one of the E-8Cs with the 591 kg (1,300 pound) camera. That's because the camera costs $15 million, and installing it in the aircraft costs another $4 million. It is possible to modify several E-8Cs to handle the MS-177 so that one or two of the cameras can be used on whatever aircraft are available.