Make the parts work as one spacecraft

Once a design advances, teams turn requirements into hardware, software and operational procedures. Components arrive with specifications, configuration records and their own test evidence. Integration — open definition combines them into larger assemblies. At each step, previously abstract interfaces become real cables, messages, mechanical connections and timing relationships.

Two parts can each meet their own specification yet fail together if their interface definitions disagree. Imagine an instrument that reports temperature in kelvin while receiving software interprets the numbers as degrees Celsius. Both might pass isolated tests built around different assumptions; an integrated test must examine what crosses the boundary.

Verification asks whether the system meets specified requirements. Validation asks whether it serves the intended use. These questions overlap but differ. A file can have the required format and still omit information that scientists need to interpret a measurement. A mission must connect technical compliance with the actual investigation.

For a fictional camera, a component test confirms that the detector records light. An integrated sequence then checks pointing, exposure, time labels, storage and eventual ground decoding. That sequence examines a chain of behavior. It does not prove survival of launch vibration; environmental evidence addresses a different requirement.

Suppose an instrument’s data packet grows from 2 to 3 megabytes while the recorder allocation stays at 30 megabytes. Ignoring overhead, capacity falls from fifteen packets to ten. A “small” software change has altered the observing plan even if the detector itself works exactly as before.

Record the configuration tested, assess the affected interfaces and repeat the relevant checks. Repeating every historical test may be wasteful, but assuming that old results automatically cover the changed system is unsafe reasoning. Reviews should identify what evidence still applies and what new evidence is needed before the next mission phase.