An electrical short occurred in a power cell used to control the attitude control heating system, allowing the hydrazine fuel to freeze.

Service propulsion system: Located in the SM, this propulsion system included four tanks of hydrazine fuel and nitrogen tetroxide oxidizer.

A small leak in the suspect unit could be harmless nitrogen gas or flammable hydrazine fuel, he said.

The cruise stage has its own miniature propulsion system, consisting of eight thrusters using hydrazine fuel in two titanium tanks.

In particular, the panel warned that the hydrazine fuel for the lander's retrorockets might freeze in space, producing ignition delays, irregular pulses and possibly leading to a topsy-turvy landing.

The spacecraft eventually ran out of hydrazine fuel for its attitude control thrusters.

However, the satellite carried hydrazine fuel which is very toxic.

If the test shows a bigger potential problem, he said in a televised news conference, the crew would burn off the flammable hydrazine fuel, shut down the unit and return operating the other two.

The Space Shuttle had three redundant APUs, powered by hydrazine fuel.

The hydrazine fuel was depleted on February 22, 1991.