The U.S. Air Force is reconsidering its earlier decision to upgrade and keep its E-8 JSTARS ground radar aircraft into the 2060s. That would see some of these aircraft retiring after 70 years of service. Since the E-8 is based on the Boeing 707 airliner (a 1950s design), this would result in that aircraft type still being in the air more than a century. Older aircraft, even when regularly rebuilt and refurbished, are more expensive to maintain as they get older. Nevertheless in 2008 the air force equipped its first E-8 with new JT8D-219 engines (21,000 pounds of thrust). These replace JT3Ds (19,000 pounds of thrust). The new engines are not only 10 percent more powerful, but more reliable and easier to maintain. There are also upgrades inside the aircraft, replacing a lot of 1980s era electronics with modern gear. But in the meantime a better solution became apparent.
It had already been proposed that new, smaller, aircraft be used rather than keep updating the elderly airframes already in use. Other countries are doing this with increasing frequency and have been successful at it. It took over a success for this approach to get the attention of American air force leaders. The air force had also planned to build a replacement for the E-8, the E-10, but that was cancelled because of the high cost. Using Global Hawk means the aircraft are not only cheaper to buy but much cheaper to operate. A business jet, for example, uses about a quarter of the fuel as the current JSTARS.
Whatever is done, it is clear that JSTARS is still needed. Initially designed at the end of the Cold War to track NATO and Soviet armed forces in the dreaded (but ultimately avoided) World War III, JSTARS first saw action during the 1991 Gulf War, and proved very useful. Since 2003 JSTARS proved remarkably effective in Iraq and Afghanistan. From 2003-6, E8s averaged about a hundred hours a week over Iraq and later did the same over Afghanistan. Now JSTARS is back in Iraq and over Syria as well. Since 2001 JSTARS have flown over 125,000 hours in support of combat operations.
JSTARS has proved to be remarkably flexible. It is known that the E-8 radar has been used to track where the terrorists go after an attack on American troops. Many of the attacks take place in sparely populated places, and at night. JSTARS can track vehicles on the ground over a wide area. For example, a single JSTARS can cover all of central Iraq, although its ground radar can only zoom in on a smaller area for useful information. The JSTARS radar 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).
Operators can track movement of ground units, or individual vehicles, over a wide area. Operators can also use the detail mode to pick out specific aspects of what's going on down there, like tracking the movement of vehicles fleeing the scene of an ambush. JSTARS is real good at picking up trucks moving along highways on flat terrain. 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.
After 2003 JSTARS was also used to monitor the Syrian and Iranian borders for smugglers. Some stuff comes across the borders in trucks, but much still arrives on the back of animals, which JSTARS cannot track. But tracking the movement of vehicles in western Iraq, in the middle of night, has proved useful. When the JSTARS crew (of 18 equipment and surveillance specialists) spots something, they can alert combat troops on the ground to take a closer look.
JSTARS can also send its data to computer terminals on the ground, in army brigade or division headquarters. JSTARS is also being fitted with a higher performance radar. The new equipment can spot smaller targets, although the air force won't say if this includes horses or camels, loaded with weapons, crossing the Syrian or Iranian border. The E-8s have been in Afghanistan since 2002.
The air force has 17 JSTARs, each costing about $366 million. The crews consist of active duty and reserve personnel. If the E-8s do stay in service another 60 years, they will get new engines, refurbished airframes, new electronics and possibly so much automation that they could eventually fly without crews, having been turned into UAVs.
Meanwhile large UAVs are being tested to supplement or replace the E-8. In 2008 the air force tested a new MP-RTIP AESA radar that does the same job as the E-8 JSTARS ground radar aircraft but is small and light enough to be mounted in the RQ-4 Global Hawk UAV. Meanwhile, an updated AESA (Active Electronically Scanned Array) radar for JSTARS enables them to spot smaller, man sized objects. It was mentioned that the 13 ton RQ-4 is about the same size as a business jet (but much lighter because no one is on board). To reinforce this point in 2008 the British used a 44 ton Canadian Bombadier Global Express twin engine business jet for its own JSTARS. This was the highly automated Sentinel which has two pilots and three people in the back running the surveillance equipment. Sentinel operates at about 15,000 meters (45-50,000 feet) and can track vehicles, or even people, on the ground up to 160 kilometers away. Large vehicles (like missile transporters/launchers) can be tracked at twice that range. Sorties in Afghanistan average about nine hours, although the aircraft is capable of staying in the air for 14 hours. Britain now has five Sentinel R1 aircraft in service and has been very satisfied with their performance.
In 2009 Israel put its first Gulfstream 550 AWACS into service. This was basically a long range business jet (the 40 ton Gulfstream G500) and Israeli made radar and electronics. This AWACS uses a Phalcon conformal (it is built into the lower fuselage) phased array radar, SIGINT equipment (to capture and analyze enemy electronic transmissions) and a communications system that can handle satellite signals as well as a wide array of other transmissions. There are six personnel on board to handle all this gear, plus the flight crew. These systems go for about $375 million each.
The Gulfstream G550, is an upgrade of the G500, and can stay in the air for over twelve hours per sortie, and fly as high as 51,000 feet. The G500/550 is a larger version of the Gulfstream G400, which the U.S. Army uses as the C-20H transport. The U.S. Coast Guard, Air Force and Navy also use militarized Gulfstreams. The 96 foot long aircraft has two engines and was built for long flights (over 11,000 kilometers). Current Gulfstream G500s cost about $40 million each.
At this point the air force has paid Raytheon and Northrop Grumman $130 million to come up with a proposal (and working prototype) for a JSTARS based on a business jet. These prototypes are to be ready by early 2018 and then the decision will be made on whether to buy 17 of these smaller, less expensive to buy and cheaper to operate JSTARS.