JSTARS is a joint development project of the US Air Force and Army which provides a picture of the ground situation equivalent to that of the air situation provided by AWACS. Operating from a stand-off position often in excess of 200 km, it can detect, locate and classify tracks and can target potentially hostile ground movement in all weather. It relays tactical pictures via secure data links to air force command posts, army mobile ground stations and centres of military analysis far from the point of conflict and also functions as battle management, command and control aircraft.
JSTARS was first deployed in Operation Desert Storm in 1991 when still in development, and has since been deployed to support peacekeeping operations in Bosnia-Herzegovina and during the Kosovo crisis. Recently, the lawmakers “were recently informed that the Air Force wishes to explore alternate intelligence and surveillance platforms instead of continued pursuit of the recapitalization of the E-8C Joint Surveillance Target Attack Radar System (JSTARS) fleet,” Isakson and Perdue said in a letter sent to Defense Secretary James Mattis. “The Air Force remains in source selection for a follow-on to JSTARS as we continue to evaluate alternative approaches for battlefield command and control that could be more effective in high-threat environments,” Grabowski said in an email to Military.com.
In 2018, the Air Force announced its plans to cancel its JSTARS replacement program and pursue a system-of-systems approach it called Advanced Battle Management System or ABMS. This was partly due to their increasing vulnerability of airborne ISR platforms to sophiticated air defense systems like S-400 and S-500. Flying below 40,000 feet, the JSTARS radar horizon is about 230 miles. That is within the reported range of the Russian S-400 SAM system—and a Boeing 707 has a large radar return. In addition amazing capabilities now available from commercial satellites, and an ambitious aim to intelligently network a variety of sensors from all domains.
The Trump administration’s national defense strategy directs the military to focus on “contested environments.” That means figuring out how to fight in places that are within the range of Chinese or Russian surface-to-air missiles. That would make JSTARS a nonstarter, Air Force Chief of Staff Gen. Goldfein argued. “They know what our asymmetric advantages are and they’ve invested in capabilities to take those away from us.” Their strategy is to “hold us off at ranges where we can either no longer perform our mission.” If JSTARS were taken down during a conflict, U.S. troops on the ground would be “blind to enemy activity.”
The service said it would keep the existing JSTARS until the mid-2020s. Meanwhile, it would investigate how to “network current and new sensors from air, space, land, and sea and fuse the information to create a more comprehensive battle management picture…coupled with an agile, resilient communications architecture.”
The U.S. Air Force has started work on a data architecture for its Advanced Battle Management System, the family of platforms that will eventually replace the E-8C JSTARS surveillance planes. The service in March 2019 named Preston Dunlap, a national security analysis executive at Johns Hopkins University Applied Physics Laboratory, as the program’s “chief architect.” Dunlap will be responsible for developing the requirements for ABMS and ensuring they are met throughout the menu of systems that will comprise it.
The Air Force is still deliberating what ABMS will look like in its final form, although officials have said it will include a mix of traditional manned aircraft, drones, space-based technologies and data links.
The E-8C can respond quickly and effectively to support worldwide military contingency operations. It is a jam-resistant system capable of operating while experiencing heavy electronic countermeasures. The E-8C can fly a mission profile for 9 hours without refueling. Its range and on-station time can be substantially increased through in-flight refueling.
It can be utilized in missions ranging from peacekeeping operations to major theater war, to provide targeting data and intelligence for attack aviation, naval surface fire, field artillery and friendly maneuver forces. The information helps air and land commanders to control the battlespace.
The two E-8A development aircraft were deployed in 1991 to participate in Operation Desert Storm where it accurately tracked mobile Iraqi forces, including tanks and Scud missiles. Eight JSTARS aircraft flew more than 50 missions in support of Operation Iraqi Freedom in March / April 2003. The Moving Target Indicator (MTI) radar installed in the E-8 enabled ground forces to receive the latest picture of the battlefield, even in the appalling sandstorms which hit a few days into the war.
E-8 Joint Surveillance Target Attack Radar System (Joint STARS)
The Joint Surveillance Target Attack Radar System, or JSTARS, is a key warfighting asset that provides airborne battle management command and control of joint and coalition forces, as well as intelligence, surveillance and reconnaissance information about ground movements to detect and track enemy forces.
Northrop Grumman E-8C is an aircraft modified from the Boeing 707-300 series commercial airliner. The propulsion system of the JSTARS aircraft consists of four Pratt & Whitney JT3D-3B turbojet engines, each providing 18,000lb of thrust. The aircraft has a flight endurance of 11 hours or 20 hours with in-flight refuelling.
Joint STARS evolved from separate United States Army and Air Force programs to develop, detect, locate and attack enemy armor at ranges beyond the forward area of troops. It is capable of determining the direction, speed and patterns of military activity of ground vehicles and helicopters. On a standard mission the aircraft has a crew of 21 with three flight crew and 19 systems operators. On a long endurance mission, the aircraft has a crew of 34, with six flight crew and 28 system operators.
The E-8 carries specialized radar, communications, operations and control subsystems. The most prominent external feature is the 40 ft (12 m) canoe-shaped radome under the forward fuselage that houses the 24 ft (7.3 m) side-looking APY-7 phased array antenna.
Sensors and Communications
Northrop Grumman has tested the installation of a very-high-resolution digital camera MS-177 camera on an E-8C to provide real time visual target confirmation The MS-177 enabled the JSTARS to identify details of a vehicle its radar has spotted on the ground. The MS-177 can distinguish a car from a van, at up to 80 kilometers, 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. However, with the camera costing $15 million, and installing it another $4 million, it may not be installed in many aircraft A 24ft antenna is mechanically swivelled and pointed to scan in elevation, and scans electronically in azimuth to determine the location and heading of moving targets.
It is located in a canoe-shaped structure on the underside of the plane, affording a 120-degree field of view across areas up to 50,000 square kilometers in size.The main operating modes of the AN/APY-7 radar are wide area surveillance, fixed target indication (FTI), synthetic aperture radar (SAR), ground moving target indicator (GMTI) and target classification modes.
The system’s SAR modes can produce images of stationary objects. Objects with many angles (for example, the interior of a pick-up bed) will give a much better radar signature, or specular return. In addition to being able to detect, locate and track large numbers of ground vehicles, the radar has a limited capability to detect helicopters, rotating antennas and low, slow-moving fixed-wing aircraft.
Fixed high value targets are detected through Synthetic Aperture Radar (SAR). In SAR, Doppler shifts from the motion of the radar relative to the ground are used to electronically synthesize a longer antenna, where the synthetic length (L) of the aperture is equal to: L = v x t, where “v” is the relative velocity of the platform and “t” is the time period of observation. Depending on the altitude of the platform, “L” can be quite long. The time-multiplexed return signals from the radar antenna are electronically recombined to produce the desired images in real-time or post-processed later.
To pick up moving targets, the radar looks at the Doppler frequency shift of the returned signal. It can look from a long range, which the military refers to as a high standoff capability. The antenna can be tilted to either side of the aircraft for a 120-degree field of view covering nearly 50,000 km² (19,305 mile²) and can simultaneously track 600 targets at more than 250 km (152 miles).
The GMTI modes cannot pick up objects that are too small, insufficiently dense, or stationary. Data processing allows the APY-7 to differentiate between armored vehicles (tracked tanks) and trucks, allowing targeting personnel to better select the appropriate ordnance for various targets.
The US Air Force has awarded Northrop Grumman a contract to develop the next generation JSTARS as part of the radar technology insertion programme (RTIP). The new much more powerful radar will be an electronically scanned 2D X-band active aperture radar which will have a helicopter detection mode and inverse synthetic aperture (ISAR) imaging capability, as well as MTI (moving target indicator) mode, allowing real-time imaging of moving objects. ISAR technology uses the relative movement of the target rather than the emitter to create the synthetic aperture.
The E-8’s ground-moving radar can tell approximate number of vehicles, location, speed, and direction of travel. It cannot identify exactly what type of vehicle a target is, tell what equipment it has, or discern whether it is friendly, hostile, or a bystander, so commanders often crosscheck the JSTARS data against other sources. Using Reduced Vertical Separation Minimum (RVSM), the E-8 can reduce the required distance between it and other aircraft sharing the same airspace allowing it to safely fly more optimal routes, gain fuel savings and increase airspace capacity. The weather radar system was upgraded in 2004-05.
JSTARS aircraft are being fitted with Force XXI Battle Command, Brigade and Below (FBCB2) ‘Blue Force’ tracking, which significantly improves the ability to locate and track the movement of friendly ground forces.
Signal processing techniques are implemented through four high-speed data processors, each capable of performing more than 600 million operations a second. Processed information is distributed via high-speed computer circuitry to tactical operators throughout the aircraft. In 1997, the US Air Force awarded Northrop Grumman two contracts for a computer replacement program to take advantage of the latest commercial off-the-shelf technology (COTS). The program integrates new Compaq AlphaServer GS-320 central computers that are significantly faster than the original system.
The programmable signal processors have been replaced and a high-capacity switch and fibre-optic cable replaces the copper-wired workstation network. The first upgraded aircraft under the computer replacement plan (CRP) was delivered in February 2002 and the programme was completed in August 2005.
JSTARS has secure voice and datalinks to the army’s ground command and communications stations and to the air force command centres. Voice communications systems include 12 encrypted UHF radios, two encrypted HF radios, three VHF encrypted radios with provision for single channel ground and airborne radio system (SINCGARS) and multiple intercom nets. The SATCOM modification allows the Joint STARS to transmit and receive UHF SATCOM voice and digital data to beyond-line-of-sight locations.
The digital datalinks include a satellite communications link (SATCOM), a surveillance and control datalink (SCDL) for transmission to mobile ground stations, and Joint Tactical Information Distribution System (JTIDS). The JTIDS provides tactical air navigation (TACAN) operation and Tactical Data Information Link-J (TADIL-J) generation and processing.
The Cubic Defense Systems SCDL is a time division multiple access datalink incorporating flexible frequency management. The system employs wideband frequency hopping, coding and data diversity to achieve robustness against hostile jamming. Uplink transmissions use a modulation technique to determine the path delay between the ground system module and the E-8 aircraft.
JSTARS command and control systems
The radar and computer subsystems on the E-8C can gather and display broad and detailed battlefield information. Data is collected as events occur. This includes position and tracking information on enemy and friendly ground forces. The information is relayed in near-real time to the US Army’s common ground stations via the secure jam-resistant surveillance and control data link (SCDL) and to other ground C4I nodes beyond line-of-sight via ultra-high frequency satellite communications.
JSTARS aircraft have 17 operations consoles and one navigation / self-defence console. Eighteen operator workstations display computer-processed data in graphic and tabular format on video screens. Operators and technicians perform battle management, surveillance, weapons, intelligence, communications and maintenance functions. A console operator can carry out sector search focusing on smaller sectors and automatically track selected targets.
USAF recently awarded Northrop Grumman a contract to help maintain the E-8C fleet’s relevance until the new JSTARS recapitalisation aircraft enter service. On 8 August, the firm announced a contract awarded by the USAF to upgrade existing E-8C radio terminals with Air Force Tactical Receive System-Ruggedized (AFTRS-R) terminals. Company spokesperson Danielle Shoot told Jane’s on 30 August that the AFTRS-R contract is valued at USD7 million.
Lima, Northrop Grumman programme director lead for manned command, control, intelligence, surveillance, and reconnaissance (C2ISR) said via a spokesperson on 30 August that the AFTRS-R terminals will assure capability for the E-8C fleet, and those interacting with the weapon system, to receive intelligence reports, including threat warnings in hostile environments. AFTRS-R, he added, provides data feeds from airborne and overhead electronics intelligence collectors and allows E-8C aircraft to detect and track mobile threats, including enemy air defence and theatre ballistic missile assets.
Lima said the AFTRS-R capability will modernise the Integrated Broadcast Service (IBS) by replacing the current Commander’s Tactical Terminal/Hybrid-Receive Only (CTT/H-R) radio. This modification, he said, also addresses cryptographic modernisation and diminishing manufacturing source (DMS) issues with the CTT/H-R radio.
Lima added that the USAF has additionally requested Northrop Grumman to add new capability for greater target detection on smaller objects, with the company accordingly continuing work to refine the ability of the aircraft’s radar to detect increasing emerging threats.
A new capability employed by the E-8 during OIF was downlinking MTI target information directly into the cockpit of the US Army’s AH-64D Longbow Apache helicopter, which obviously shortened the time between a target being detected and being attacked. On 28 November 2010, amidst escalating danger of war breaking out between North and South Korea, the South Korean government requested the U.S. to implement JSTARS in order to monitor and track North Korean military movements near the DMZ. In Afghanistan, JSTARS trials were designed to develop tactics, techniques and procedures in tracking dismounted, moving groups of Taliban.
Hitting Moving targets
DARPA Affordable Moving Surface Target Engagement, or AMSTE program, developed by Northrop Grumman, was a program to demonstrate the ability to precisely engage moving surface targets with modified precision-guided weapons. Real-time information on a moving target is developed from radar sensors. The resulting tracking data is relayed from a Joint STARS aircraft directly to a modified weapon system in flight, such as Boeing’s Joint Direct Attack Munition, or JDAM, or Raytheon’s Joint Stand-off Weapon, or JSOW
The Joint STARS aircraft must first establish a communications link with another radar system, in this case Northrop Grumman’s test radar installed in a BAC-111. Together, the two radar systems track a moving vehicle along the ground while “talking” to the weapon. Finally, the data link guides the weapon in flight onto the vehicle moving on the ground.
Joint STARS aircraft has demonstrated its ability to guide anti-ship weapons against surface combatants at a variety of standoff distances in the NEW architecture. To support the demo, members of the Joint STARS modernization branch developed prototype software called Link 16 Network Enabled Weapon for the Joint STARS testbed aircraft. With it, the aircraft served as the command-and-control node as well as a node for transmitting in-flight target updates to Navy joint standoff weapons during the three days of tests in the Point Mugu Sea Range off the coast of California.
Joint Surveillance Target Attack Radar System, or JSTARS future role
“JSTARS will only become more relevant to future air combat scenarios as we will be competing in an environment of diminished electronic warfare superiority with the potential for disrupted datalinks and communications, which will result in the need to increasingly rely on airborne battle management,” said Austin Scott.
“It grants an unparalleled wide-area tracking of ground moving targets (ground moving target indication or GMTI), allowing battle management and target identification to make our combat aircraft more efficient. By decreasing loiter time — the time aircraft need to spend searching for their target — it enhances their lethality and saves the lives of our service member,” he further said.
“If a capability gap emerges, trying to restart a BMC2/GMTI mission from scratch would cost an exorbitant amount for taxpayers, because the workforce, knowledge and experience associated with flying the E-8Cs would have been lost,” says Austin Scott a member of the House Armed Services Committee.
U.S. Air Force Chief of Staff Gen. Mark Welsh said the replacement for the service’s aging ground surveillance plane could begin testing as early as 2021 and be delivered ready for mission just two years later. Georgia Republican Tom Graves and other US lawmakers urged the government to accelerate the programme to replace the JSTARS. They said in a letter: “JSTARS has flown well over 100,000 combat hours in support of recent contingencies, reinforcing the importance of its mission for combatant commanders world-wide.” Replacing the existing fleet with next generation aircraft is essential, which is why we want to ensure that the critical mission performed by the JSTARS team is not jeopardised by a lengthy acquisition process.”
Air Force’s analysis of alternatives (AOA) study in 2012 had recommended, buying a for a mix of new business jet-based ISR aircraft, such as an Air Force version of the Navy P-8 Poseidon, the unmanned Northrop Grumman Block RQ-4B and Global Hawk Block 40. However, at a Senate Armed Services Committee meeting on 20 March 2012, the Air Force said it cannot afford a new ISR platform and the E-8 was considered viable in the near and medium terms.
The Northrop Grumman Global Hawk UAV can theoretically reach 60,000 feet, but only toward the end of a mission. However, it offers very long endurance, and in the USAF’s Block 40 version, a very capable AESA surveillance radar designated MP-RTIP, that was originally planned for retrofit to JSTARS as well. The same airframe/radar combination is entering service with NATO as the Alliance Ground Surveillance (AGS) system. But the Global Hawk is not stealthy and can therefore also not get close to defended ISR targets.
U-2, which flies up to 15,000 feet higher than the UAV and carries similar sensors can be another candidate. Lockheed Martin says that “an enhanced defensive suite…enables the U-2 to operate in and around contested airspace.” That is one reason why the Pentagon decided to retain the U-2 until at least 2024. The Dragon Lady’s Advanced Synthetic Aperture Radar System (ASARS) is being upgraded with an AESA. The maker, Raytheon, says that this doubles the radar’s range and improves moving target tracking (a JSTARS specialty) while retaining the very high mapping resolution of the current system.
JSTARS’s ground moving target indicator and battle management command functions could be done elsewhere by other platforms, she said. The future battle-management network would be a vast improvement over JSTARS because it would bring in data from sensors in space, from C-130s, drones and F-35 fighters. War commanders want this, Wilson said. “Fuse all of that data to give you a much more comprehensive picture on what’s going on on the ground.” Operators “don’t really care what platform it came off of.”
Some analysts think that stealthy, fifth-generation platforms such as the F-35 can take over the airborne ISR mission. They certainly have state-of-the-art EO, IR, and radar sensors. But as a study by two officers with over 4,000 hours experience on JSTARS and AWACS noted recently, “their air pictures continue to be local by design. Their bubbles of awareness are short-range. Networked fifth-gen surveillance solves the access problem, but can’t provide a comprehensive, persistent picture.”
Rep. Trent Kelly (R-Miss.) reminded Air Force officials that soldiers and Marines could be endangered if JSTARS was removed from service. “And I hope you guys will really rethink this because we really cannot accept a gap and our capabilities until we have a replacement,” Kelly told Air Force leaders. “We shouldn’t chase shiny objects until we have one that works,” he said. “We still have counterinsurgency fight going on and we can’t afford to just fight a peer fight, we have to fight them both.”
The JSTARS debate, meanwhile, has stirred speculation about the possibility of shifting missions to space, by developing a constellation of radar remote-sensing satellites that would provide global coverage. The project was nixed in the 2000 budget. Fred Kennedy, director of DARPA’s tactical technology office, said there is certainly a possibility of moving that mission to space and doing the control segment somewhere. You would have global coverage as opposed to limited airborne coverage today. “Now we have the communications infrastructure, the ground segment,” he told SpaceNews in a recent interview. “I simply have to plant sub-constellations into the network, the nodes that we want. [Radiofrequency] nodes, or optical sensing nodes,” he said. “I‘ll be able to use the resources of the space internet, the processing and storage. I don’t see why we couldn’t plant a node with a ground moving target indicator…I think we’re smart enough to figure out how to do it now.”
There are tradeoffs, however. “You have to give up some advantages of airborne platforms like having to look from thousands of kilometers away. It would be an interesting trade in terms of what kind of radar we build,” he said. “It might be interesting to do a demonstration of an RF mission of this class just to see if it can be done.”
John Johnson, former vice president and general manager of Northrop Grumman Electronic Systems, said some of the JSTARS functions could be moved to space. “The Air Force and the [National Reconnaissance Office] should take a look at that,” he told SpaceNews. As to what the Air Force is trying to do, “I applaud them,” Johnson said. “They are trying to eliminate singular mission platforms. What they are doing I think is the right thing: Put everything into an integrated architecture,” he said. It will not be easy, though. “It will be really a struggle,” Johnson said.