E-8 Joint STARS

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An experimental design pressed into successful service in the 1991 Gulf War, the E-8C Joint Surveillance Target Attack Radar System, or Joint STARS, is a large airborne intelligence, surveillance and reconnaissance system built around a specialized imaging radar, the AN/APY-7.

E-8C Joint STARS. Note antenna "canoe" under the fuselage.

While the E-3 Sentry AWACS is also a C3I aircraft built around a specialized radar, the AN/APY-2, the missions of the two aircraft is very different. The E-8's radar gives a comprehensive picture of the land battle, both tracking moving targets and creating images of some. It gives land commanders a literal overview of the disposition of their forces and those of the enemy; the information is downlinked to ground command posts rather than having the battle manager in the aircraft.

The JSTARS radar has several operating modes, so it can map an area, and then track moving objects in it.

As opposed to the E-3 Sentry, the present E-8 do not carry a battle staff. A variation, however, will take the command staff from current EC-130 ABCCC aircraft, which will be retired. Still, there is a trend to put the staff for C3I-ISR aircraft on the ground.

Another development, with the cancellation of the Air Force E-10A multipurpose C3I-ISR aircraft in the FY 2008 budget, may involve replacing the aging E-8 with P-8 Poseidon aircraft equipped with the Littoral Surveillance Radar System (LSRS).

Sensors

Where the E-3 radar is a "flying saucer" on top of the fuselage of the modified Boeing 707 airframe, the E-8 AN/APY-3 radar is in a canoe-shaped enclosure underneath the fuselage, pointing downwards; the radar antenna proper can be swiveled off the centerline, inside its pod.[1]

Moving targets

The principal radar operating mode, using a Moving Target Indicator (MTI) function, is the Wide Area Surveillance / MTI (WAS / MTI). It can detect and track vehicles in an area in excess of 150 nmi radius. It can distinguish between wheeled and tracked vehicles, can track slow moving helicopters, and has an option to be used for maritime rather than land search.

Sector Search Mode (SSM) gives a closer look at an area of 18 nmi per side, with an update every 60 seconds. For finer-grained tracking, Attack Planning Mode (APM) goes into high resolution, with 6 second updates for a 7nmi square.

Fixed target/imaging

A very different mode, which can be correlated with MTI to assess the results of an attack, is the Synthetic Aperture Radar / Fixed Target Indicator (SAR / FTI). By making multiple antenna passes over the same area, the SAR/MTI constructs near-photographic images of an area approximately 110 nmi to either side of the flight path. - in SAR/FTI mode the radar can produce a near photographic image of the target area by building up a mosaic of images from multiple radar sweeps.

Communications

Since the E-8 does not contain the land forces command post, communications are critical. The aircraft is linked into current Army networks such as the Force XXI Battle Command, Brigade and Below (FBCB2) "Blue Force" tracking of friendly ground forces. It has a wide range of multiservice voice radios: 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.

Secure communications to air and ground command systems use JTIDS (Joint Tactical Information Distribution System]] communications for the Tactical Data Information Link-J (TADIL-J) generation and processing.

Consumer access to data

JSTARS information can be displayed on Common Ground System workstations of the Military Intelligence company of a Brigade Combat Team, as well as at higher levels all the way to national intelligence agencies.

Future directions

JSTARS was put on a 707 airframe only because it was cheaply available. As with the E-3, the airframes are coming to the end of their service lives. In the case of Japan, the E-3 electronics was moved to a modern 767 airframe.

There seems to have been a desire to take the sort of radar on the E-8 and put it into a satellite, but the spaceborne platform cost estimates are, to coin a phrase, going into higher and higher orbit. Replacing the E-8 with a perhaps more capable space system has had estimated costs of well over $15 billion dollars, and the estimates are climbing.

In principle, the JSTARS function might lend itself to being placed on a large UAV, since the information is used on the ground either with the present system or with a UAV downlink. There are no public statements of direction.

Defensive systems

The infrared countermeasures was not limited to flares, but directed energy from the AN/ALQ-157 system.[2] The aircraft has an AN/ALE-47 Countermeasures Dispenser System [CMDS], is a "smart" dispenser that connects directly to infrared and radar warning receivers, release expendable and towed/retrivable decoys, as well as helping the pilot with situational awareness of the threat.

Specifications

According to the U.S. Air Force:[3]

  • Primary Function: Airborne battle management
  • Contractor: Northrop Grumman Corp. (primary)
  • Power Plant: Four Pratt and Whitney TF33-102C
  • Thrust: 19,200 pounds each engine
  • Wingspan: 145 feet, 9 inches (44.4 meters)
  • Length: 152 feet, 11 inches (46.6 meters)
  • Height: 42 feet 6 inches (13 meters)
  • Weight: 171,000 pounds (77,564 kilograms)
  • Maximum Takeoff Weight: 336,000 pounds (152,409 kilograms)
  • Fuel Capacity: 155,000 (70,306 kilograms)
  • Payload: electronic equipment and crew
  • Speed: 449 - 587 miles per hour (optimum orbit speed) or Mach 0.52 - 0.65 (390 - 510 knots)
  • Range: 9 hours
  • Ceiling: 42,000 feet (12,802 meters)
  • Crew: (flight crew), four; (mission crew) normally 15 Air Force and three Army specialists (crew size varies according to mission)
  • Unit Cost: $244.4 million (fiscal 98 constant dollars)
  • Initial operating capability: December 1997
  • Inventory: Total Force wing, 17; Reserve, 0

References