Homeworld Effects Manual: setLifespanDist()
setLifespanDist(float value)
Adds an uncertainty of value seconds to an object's lifetime.
Default value: 0
Legal values: all real numbers
value can be an integer constant, a floating-point constant, or a floating-point variable. Using an integer variable will not cause a crash, but has the same effect as setLifespan(0), which is not very useful.
Yet another exapmle of Homeworld's robust randomization, this command lets you make things that last different lengths of time. When creating several objects at once, each object will get a different Lifespan attribute.