Slitherine

quote:

The SM-3 Interceptor
The interceptor used in the test was a Standard Missile 3 (SM-3) interceptor, which has a
lightweight exo-atmospheric projectile (LEAP) kill vehicle (also referred to as the kinetic
warhead (KW)) as its fourth stage.
The SM-3 interceptor is a modification of the Aegis Standard Missile and is being developed for
the NTW Block 1 system. The SM-3 interceptor differs from the SM-2 Block IV booster and
sustainer motor by the addition of a third-stage solid-fuel rocket motor (TSRM) and fourth stage
kinetic kill vehicle (see Figure 1).

The SM-3 interceptor reaches a speed of 3 km/s.3
The original goal for NTW Block 1 interceptor
was 4.5 km/s, but that was reportedly scaled back because modifying the Standard Missile to
reach that speed was too expensive. The lower speed means that the Block 1 system falls within
the low-speed agreement of the September 1997 Demarcation accords to the Anti-Ballistic
Missile Treaty.

The LEAP kill vehicle is designed to operate only at high altitudes where there is minimal
atmospheric density, and cannot attempt to intercept below about 100 kilometers altitude. It can
therefore only be used as part of a midcourse defense, and not for either boost or terminal
engagements.

http://carnegieendowment.org/pdf/npp/unionofconcernedscienctistpaper3-3-02.pdf