Eight months after the U.S. Missile Defense Agency announced a renewed interest in technologies for "early intercept" of ballistic missiles, plans are beginning to take shape with a focus on the use of unmanned aerial systems (UAS) for ballistic missile target tracking.

Requirements are not yet firm for this capability, but several architecture studies will provide data on how the agency will proceed and where it plans to put its funding in the forthcoming budgets.

Early intercept (once called boost-phase or ascent-phase intercept) has been desirable for at least two reasons:

*Intercept during the threat missile's boost allows for it to be destroyed in the enemy's territory and eliminates its ability to enter the cold backdrop of space, where the U.S. struggles with tracking.

*If an early intercept attempt fails, there is generally time to assess and fire another weapon.

The latter strategy is particularly attractive for the Pentagon now, as threat assessments predict potential "raids" of ballistic missiles, which are tens of missiles fired nearly simultaneously in an effort to overwhelm defenses with sheer numbers of threats.

"We'd like to get him as early in the trajectory as possible. . . . Our main goal is to have enough time to hit him first, take a look and see what damage we've done, and then get another opportunity to shoot one more time," says Rich Matlock, MDA director for advanced programs.

"The real impact in terms of approving our warfighting capability is to be able to shoot him, look and see what damage we've done, and then shoot him again. It saves inventory."

Currently, officials may be required to shoot two interceptors at an offending missile early in its flight to assure a kill even if the first one scores a hit. What is lacking is sufficient time to assess the success of the first interceptor before deciding to dispatch a second, and this is largely because current capabilities limit engagements until later in a threat missile's flight.

MDA Executive Director David Altwegg announced in May during the annual budget briefing that some early intercept efforts were showing promise, and some were being declassified.

Now, the agency is examining how to integrate UAS into the sensor architecture to provide early tracking of ballistic missiles. In August, U.S. Army Lt. Gen. Patrick O'Reilly, MDA director, acknowledged the use of a U.S. Air Force Reaper UAS to observe the target of a missile defense test. Now, however, more information is emerging about the demonstration -- a Navy effort called Stellar Daggers that took place Mar. 26.

The trial included two targets -- a cruise missile and a short-range ballistic missile -- and they were separately intercepted by an SM-2 Block IIIA and an SM-2 Block IV, respectively.

During the test, two Reapers (one each flown by the Air Force and Navy) used onboard MTS-B medium-wave infrared sensors to track the boosting ballistic missile; two were needed to conduct "stereo" tracking. "We have the sensitivity to pick up boosting objects from hundreds of kilometers," says Matlock. "That was important to figure out. We know now that these sensors in the medium wave have the capability to pick up ballistic missiles from very long distance. Now the question is, Can we get the data from the Reaper that would allow us to do precision tracking based on that?"

The Reapers were 355-432 km. (220‑268 mi.) from the target during the Stellar Daggers test, say MDA officials. Data indicated that more automation is required in the sensor's tracking function to avoid the need for the sensor operator to follow the ballistic missile manually. "The test setup was a joystick setup, so the fellows that were tracking these ballistic missiles were actually using a joystick to track the missile based on the spot on the sensor," says Matlock. "It pointed [out] to us some modifications that we'd have to make to the sensor ball and to the data we get from the Reaper."

While refining this concept, the agency also issued a request for information (RFI) from industry to look at platform options to provide tracking "at or near threat burnout" for early intercept. The RFI considers various risk scenarios centered on fielding four systems in 2012, or 15 by 2015. It also considers various sensor mounts to maximize the system's field of view for a boosting ballistic missile.

Matlock says the MDA is not sold on the Reaper vehicle or its class and is open to ideas from industry.

The operational concept, once fielded, would be for the UAS to accept a cue from overhead non-imaging infrared satellites (such as the Defense Support Program or Space-Based Infrared System High) or ground-based radars that would be the first to detect a boosting missile. These UAS are being widely fielded to the Air Force and Army, and these services are conducting daily operations in support of forces around the globe, including anti-improvised-explosive-device work and tracking of insurgents.

"Under normal operations, [UAS] fly in a racetrack [pattern], so we are going to use other sensors to cue us on to where the ballistic missile might be coming from, and then use the sensors on the platform to get that narrowed down to a precise track," says Matlock. Theoretically, this would not call for the Pentagon to buy UAS specifically for the missile defense mission.

MDA officials hope to build off existing procurement plans as much as possible to save money, says Matlock. However, these systems are used heavily, and details must still be sorted out to add ballistic missile tracking to the mission set. One operational item that would have to be determined is whether the day-to-day tasks for Reaper call for it to fly in patterns that are suitable for handling a satellite cue for a missile attack; the aircraft and its sensor would have to be positioned in such a way as to capture the infrared plume of the weapon quickly in order to start an engagement.

The agency also is conducting an analysis of alternatives, and an interim report is expected soon. The MDA plans to fly the UAS to evaluate more elements of the tracking task early this year during a Ground-Based Midcourse Defense flight test and an attempt by the Airborne Laser to shoot down two boosting ballistic missiles.

Credit: USAF