What gas is used inside a Stinger missile?

• A. Helium
• B. Neon
• C. Argon
• D. Oxygen

Answer: (C)

Argon is used because the internal environment of the Stinger’s seeker needs to stay inert and free from moisture and reactive gases that could damage the sensitive infrared sensors. Filling and purging the sealed seeker cavity with an inert gas protects optics and electronics from oxidation, corrosion, and humidity, and it helps maintain stable operating conditions for the cooled detector.

Helium would escape too readily and isn’t ideal for long-term containment in a compact seeker. Neon is expensive and not typically required for this purpose. Oxygen would react with components and promote corrosion, which is undesirable in a precision sensor package. Argon, being inert, inexpensive, and denser than air, provides a stable purge environment and is well-suited for protecting the seeker’s delicate hardware.