How do reentry vehicles return ballistic missile warheads through the atmosphere?

Reentry vehicles (RVs) return ballistic missile warheads to Earth through the terminal phase of flight, which begins when gravity pulls the warheads back into the atmosphere toward their target area.1

During this descent, the RVs are unpowered and subject to unpredictable forces, such as wind, which can affect their trajectory. To manage these conditions, several approaches are used:1

• Ballistic Trajectory: In standard operations, the RV follows a purely ballistic path determined by the initial velocity and heading established during the missile's boost and midcourse phases.1
• Maneuverable Warheads (MaRVs): Some systems, such as the former U.S. Pershing II, utilized MaRVs equipped with radar area guidance (Radag) systems. These systems compare the terrain below with stored data and issue commands to control fins, allowing the warhead to adjust its glide and correct reentry errors.2
• Precision-Guided Warheads (PGRVs): These advanced designs are intended to actively seek a target and use flight controls to "fly out" errors, potentially allowing for high accuracy even with conventional explosives.2

Because RVs are heavy, they maintain their trajectory through the atmosphere more effectively than lighter objects like decoys or chaff, which are slowed down by air resistance upon reentry.3