But reserving enough fuel to do that promptly can be expensive, particularly for cash-strapped foreign space programs. So Johnson and his team have worked with the French, Russian, and even the Chinese space agencies to explain to them easy, cheaper ways to avoid orbital explosions. When you leave an upper stage in orbit, there's almost always some residual propellant. If you get rid of that residual propellant, there's never a problem. You don't have to understand the specific chain of events for each spacecraft.
Problems can occur in satellites too, since many are equipped with engines and batteries.
That means all systems with residual energy must have that energy drained out. For upper stages of rockets, that usually means venting or burning off any excess fuel. For satellites, it may mean purposefully draining the batteries, or venting any gas used in power cells. Momentum wheels, the fast-spinning internal gyroscopes used to control a spacecraft's orientation, must be allowed to slow down. Johnson said that every spacecraft that has fully passivated has remained intact in orbit.