The General Atomics Reaper unmanned aerial system (UAS) may eventually go from hunting terrorists to hunting hostile ballistic missiles.

The U.S. Air Force's Predator and Reaper UAS have been well-publicized workhorses providing intelligence and firepower on the front lines in Iraq, Afghanistan and the Arabian peninsula.

Now the Reaper may get a new mission as a frontline cueing system for the burgeoning U.S. missile defense architecture. Missile Defense Agency (MDA) officials say the Reaper and its Raytheon MTS-B sensor are showing promise. The system could plug a longtime gap by providing firing quality data to facilitate early intercept of ballistic missiles. MDA is exploring the technology and operational concepts for using electro-optical/infrared (EO/IR) -equipped UAS to eventually achieve “launch-on-remote” capabilities with Aegis ship- and land-based SM-3 interceptors. This means the fidelity of UAS data would need to be high enough for commanders to launch an interceptor before Aegis radars capture the target.

Ballistic missile patrol is one of many potential missions for the large and growing Predator/Reaper fleet. As the Pentagon plans to draw down combat forces in Afghanistan—combat operations ended a year ago in Iraq—officials insist that intelligence, surveillance and reconnaissance assets (ISR) will continue to support ongoing activities in these areas. But Pentagon planners are considering how these ISR resources can be reallocated or, if need be, modified to fill capability gaps for other missions.

UAS orbits could be placed to provide a “picket fence” of sensors if an area is expected to have hostile ballistic missile activity, says Tim Carey, vice president of intelligence for Raytheon.

MDA officials say data from early experiments show that “just a few orbits can provide substantial sensor coverage” for various regions.

Gen. Robert Kehler, who oversees U.S. Strategic Command, provides advice to the Pentagon on how to allocate ISR resources across the globe. Regional commanders in the Pacific, Africa, Europe and Central and Southern America feel the focus on U.S. Central Command and the wars in Iraq and Afghanistan have curbed their ability to monitor activities in their areas of operation. “Their view is that many of their ISR needs are not being met because of all the things we have placed in Centcom,” Kehler says.

A potential near-term application of UAS for missile defense is to support monitoring of North Korea. MDA plans to field the Persistent Tracking Satellite System (PTSS) as soon as fiscal 2016 to provide early launch detection and high-fidelity targeting data from space to ship- and land-based interceptors.

That plan, however, has two problems. First, even if fielded as planned, the sensor gap would not be closed until later this decade. Perhaps a larger issue is that funding for PTSS is in question.

Industry sources say MDA is struggling with a $4 billion budget gap in fiscal 2013-17, and a project as expensive as building satellites could slip or be axed altogether as Leon Panetta, the new defense secretary, searches for projects to cut in light of diminished funding and deficit reduction pressure.

The interim solution for MDA is to test and possibly field the Airborne Infrared system (ABIR), a UAS carrying the proper EO/IR sensors to support early intercept operations (a kill before a hostile missile reaches apogee), improved target discrimination and enhanced handling of the threat of missile raids (tens or more missiles fired nearly simultaneously).

Last year, MDA selected the Reaper as the platform of choice for the ABIR experimentation phase, which is ongoing. “If fielded, we envision a podded ABIR capability that could ride on a variety of unmanned or even manned platforms,” says Rick Lehner, MDA's spokesman. Ultimately, platform decisions would be made in consultation with the Air Force and Navy if the system is fielded, as these services will be the operators.

Since 2009, MDA has conducted 10 flight tests in which ABIR was used for data collection. Six of these trials were observed using MTS-B-equipped Reapers and the remainder featured risk-reduction tests using ground-based sensors (see chart, p. 43). For these trials, at least two Reapers are needed to provide “stereo tracking.” Each EO/IR sensor provides a “flat” view, but triangulating the target provides higher-fidelity data.

A main objective in the trials has been to expose the MTS-B—which includes visible, shortwave IR and mid-wave IR sensors—to various scenarios and targets, from short-range to intercontinental ballistic missiles.

“We have been able to improve the pointing accuracy of the sensor [and] we have demonstrated automatic acquisition and tracking of the sensor required to meet system needs,” Lehner says. “Modeling indicates the agility of the sensor will substantially improve the raid-handling capability we currently have.”

Today, X-band radars—the AN/TPY-2 and Sea-Based X-Band—are used for early tracking. Carey notes that the ABIR experiments are the first time EO/IR data have contributed to generating firing-quality data early in flight. (IR sensors typically provide only a cue to ground- and sea-based X-band radars.)

“They just never thought to look up” with the sensors, Carey says. “Everybody was surprised [by] the range at which we were able to detect the targets after burning and the accuracy with which we were able track them.”

The MDA has purchased four MTS-Bs for ABIR experimentation, two last year and two this year, Carey adds. MDA is contributing to a larger Pentagon effort to develop the two-color MTS-C; this will add a long-wave IR detection capability. While the short- and mid-wave bands are optimal during launch and rocket burn, a long-wave detector is better for tracking cold bodies, such as missiles after burnout, or plumes and exhaust.

Packaging short-, mid- and long-wave IR detectors on the same sensor ball, however, presents complex challenges, including design of proper cooling and meeting power requirements. One defense official suggests the MTS-C could be a year or more from being ready for work in this area. Lehner says the MTS-C will be delivered in the summer of 2012 and begin testing shortly thereafter.

This time frame will be a key deciding point for the future of the program. Also next summer, MDA plans to conduct a launch-on-remote exercise. “To demonstrate launch on remote, we will provide real-time tracking data to [ballistic missile defense (BMD) command-and-control] nodes,” Lehner says. “The BMD command-and-control nodes then send [the data] to Aegis in a simulated engagement in the summer of 2012.”

Carey notes that in trials thus far, ABIR has generated virtual targeting data that can be compared against data from other sensors used in the tests. But he says more command-and-control and system architecture work is needed to make the system operational.

Early tests were highly manpower intensive; targets were acquired by hand and tracked by people. Software has been developed to automate that process. But officials need to develop an operational concept of how many UAS must be orbiting in what locations for an optimum chance of achieving early launch data if there is an unpredicted hostile launch. “If you put the aircraft in the right place and we know the test is coming, we turn it on and it will perform,” he says.

Through fiscal 2012, MDA has requested $178.5 million for ABIR. Depending on results of the flight trials, the agency plans to make a development and fielding decision around 2014.

Airborne Infrared Test Events
Event Date Target Class
Aegis flight test March 2009 SRBM
WISE Delta II launch December 2009 ICBM
Ground-Based Interceptor (GBI) flight test January 2010 IRBM
Airborne Laser demo February 2010 SRBM
GBI flight test June 2010 ICBM (GBI booster)
Terminal High-Altitude Area Defense flight test July 2010 SRBM
Japanese BMD flight test October 2010 MRBM
Aegis flight test March 2011 SRBM
Missile Defense Agency tracking exercise March 2011 SRBM
Air-launched target risk-reduction test July 2011 SRBM
Source: U.S. Missile Defense Agency