Light Test for Laser-Guided Bullet

"A laser-seeking, self-steering bullet flies through the air, rendered visible by a glowing LED ensconced in its tip. No, it's not that the US military suddenly wants its enemies to see its bullets coming. Instead, its developers needed to test the weapon's in-flight steering electronics, to prove they can cope with the shock of being fired. The fact the LED stayed brightly lit means that the in-bullet circuits did indeed remain unbroken."