Nitrogen Tetroxide (NTO) (N₂O₄) is a storable oxidizer propellant used as a oxidizer. Storable but requires temperature control above 21°C vapor pressure. Typical ISP: 280–310 s (with hydrazines) seconds.
Nitrogen tetroxide is the most widely used storable oxidizer in rocket propulsion, igniting hypergolically on contact with hydrazine-family fuels. It exists in equilibrium with NO₂ and is a dense, reddish-brown liquid at room temperature. NTO has been used in virtually every crewed spacecraft from Gemini through the Space Shuttle orbital systems.
Used since the 1950s in missiles and spacecraft. Standard oxidizer for storable propulsion systems worldwide.
Storable, hypergolic with hydrazines, high density, well-characterized
Extremely toxic, corrosive, narrow liquid range, high vapor pressure
