Network Centric Airborne Defense Element (missile)
The Network Centric Airborne Defense Element (NCADE) is both a new approach to ballistic missile defense (BMD), simultaneously seen as a low-risk, moderate capability anti-ballistic missile (ABM), largely derived from commercial-off-the-shelf technology. As opposed to all other U.S. ABMs, it would be launched from an F-15 Eagle aircraft rather than from the ground. The Missile Defence Agency awarded a study contract early in 2007; based on early successes, it awarded an additional $10 million in September 2008.
While the initial focus is on ABM applications launched from a specific air superiority fighter, both other missions and other launching platforms are being considered. Since it its physical form factor will be very close to the operational AIM-120 AMRAAM missile, any AMRAAM-capable aircraft (e.g., F-16 Fighting Falcon, F-15E Strike Eagle, F-18 Hornet, F-18 Super Hornet, F-22 Raptor, Joint Strike Fighter can carry it. European aircraft, including the Eurofighter Typhoon, Saab JAS-39 Gripen, and Panavia Tornado all have operated the AMRAAM. In moving to these platforms, the major challenge, other than in with the planned upgrade of the Strike Eagle radar, have different radars.
Radically different launchers are also under consideration, including unmanned aerial vehicles (UAV), warships and even remotely controlled surface platforms, and aerostats. At least for the airborne types, it would probably be simplest to port the designated F-15 radar, the AN/APG-63 V(3). That radar might need supplementation to get sufficient range from surface, but inherent in the NCADE concept is that the launch platform would receive information from other local, theater, and national sensors.
A somewhat similar Russian system, the Novator R-172, apparently has been intended as a very-long-range air-to-air missile to be used against radar, intelligence, and other C3I-ISR aircraft that fly far behind the battle line.
Since the terminal guidance of NCADE is infrared, it may offer improved performance against stealth aircraft, which put more effort into low radar observability than low infrared observability.
Boost phase capability
It is focused on boost phase intercept, for which no operational or near-operational U.S. BMD system was designed. Still experimental, the U.S. Air Force Airborne Laser, carried by a Boeing 747 aircraft, would be able to engage in both the boost and terminal phases. The challenge for a boost phase kill mechanism is that it needs to operate near the launch site. A Boeing 747 would need considerable escort to exist in a hostile airspace; a fighter is far more survivable.
The RIM-161 Standard SM-3, while designed for terminal phase intercept, is launched from a warship: a Burke-class destroyer, a Ticonderoga-class cruiser, or a Japanese Kongo-class destroyer. Engaging a North Korean missile launched from a facility near the coast of the Sea of Japan is a plausible scenario, but there are many other launch sites that would be far inland.
Derivation and design
NCADE is a two-stage missile. Its first stage would be a derivative of the AIM-120 AMRAAM, already operational on the F-15 Eagle as its beyond-visual-range air-to-air missile. This would carry the second stage, which would put a modified version of the infrared seeker from the AIM-9X Sidewinder onto a new rocket motor intended for maneuvering against a boosting, or at least ascending, ballistic missile.
Pre-launch targeting would come from the latest version of the F-15 radar, the AN/APG63V(3), which is the second version of the AESA radar for the F-15. The fighter, however, could be cued toward the target by a variety of sensors, ranging from space-based infrared launch detection and tracking satellites, to forward-deployed AN/SPY-2 seaborne or AN/TPY-2 land-based transportable radars. RC-135 COBRA BALL aircraft use electro-optical MASINT sensors for tracking and analyzing missile launches.
An NCADE-modified seeker, on an AIM-9X fired from an F-16 Fighting Falcon, successfully intercepted a boosting test rocket in December 2007. Development now focuses on the divert and attitude control (DACS) system, a general term for the type of maneuverability needed for missile intercept.
The second stage will be quite small, so that the overall NCADE will be approximately the same size as the existing AMRAAM. It will make use of a new high-energy monopropellant, hydroxylammonium nitrate, which, while powerful, is also stable and could be approved for shipboard launch. Given that the F-18 Hornet, F-18 Super Hornet and future F-35C Lightning II carrier fighters all support the AIM-120, and, at least in the latter two, have radars comparable to the AN/APG-63, a sea-based NCADE is a reasonable projection.
Sea-based NCADE, however, need not depend on a manned aircraft.  By using UAVs, a continuous patrol against boosting missiles can be maintained, with reusable but unmanned UAVs purpose-built for carrying NCADEs, without the overhead of life support systems. The Heritage Foundation, a policy research center of generally conservative views, has recommended funding NCADE integration with the Air Force Predator or Reaper UAVs. , but emphasized this is a low-cost and flexible approach to missile defense.
Potentially relevant experience
In the 1980s, an anti-satellite missile, the ASM-135, was developed to be carried by modified F-15 aircraft. While it was successfully flight tested against a satellite, the program was cancelled for a variety of reasons. Costs were escalating dramatically and there were concerns it would violate treaties on the militarization of space.  Nevertheless, engineering data from the experience of launching a large missile from an F-15, aimed at a target at the edge of space, should contribute to reducing the risk of the NCADE program.
Stealth aircraft and missiles are primarily optimized for low radar observability. Even though the B-2 Spirit specifically addressed reduced infrared signature, it still can be detected with infrared sensors.  Eurofighter showed a vivid infrared image of the B-2 in a briefing about their infrared search and track (IRST) capability. Even the low radar observability principally intended to defeat terminal guidance radar; when tradeoffs must be made, stealth designers will, reluctantly, prefer they be visible to low-resolution search radar.
If a long-range sensor can cue an interceptor into infrared seeker range, the stealth platform has a much greater challenge to survive. At present, the U.S. space-based Defense Support Program satellites give global launch detection, but little tracking. A constellation of low-orbiting satellites, the Space Tracking and Surveillance System (STSS), is described to give at least some infrared tracking of ballistic missiles, principally during the boost phase. STSS information could cue the NCADE carrier into radar range of a mobile launcher.
AIM-120 variations for longer range are separately being developed for use against high-value aircraft behind the battle line. Russia has made "AWACS killers" a high priority for several missile generations. Whether it would be better, however, to use NCADE's infrared guidance against a relatively unmaneuverable target, which, as with the E-3 Sentry, emits an enormous radar signature, is open to question. Still, future airborne radar using AESA will have lower probability of intercept, and a variety of high-value aircraft, including intelligence collectors, tankers, and cruise missile launchers will not be radiating.
Possible Russian counterpart
Russia has been developing the Novator R-172 (missile), for its new Su-35BM fighter. This combination has been seen as an extremely long-range "AWACS killer", or general threat to C3I-ISR aircraft. 
- "NCADE - An ABM AMRAAM?", Defense Industry Daily, September 22, 2008
- Ehrhard, Thomas P. & Robert O. Work, Range, Persistence, Stealth, and Networking: The Case for a Carrier-Based Unmanned Combat Air System, Center for Strategic and Budgetary Assessments,p. 150
- Ehrhard & Work, pp. 150-152
- Spring, Baker (April 28, 2008), Congress Should Fund Development of Air-to-Air Missile Defense Technology
- Parsch, Andreas, Vought ASM-135 ASAT, Directory of U.S. Military Rockets and Missiles
- Eurofighter infrared image of B-2 
- Kopp, Carlo, "Hard Kill Counter-ISR Programs", Air Power Australia