I suppose we need a one-way valve, such that information about the sample can flow to us while nothing can affect the sample. Conceptually like a Heimlich valve

I suppose we need a one-way valve, such that information about the sample can flow to us while nothing can affect the sample. Conceptually like a Heimlich valve. Or, as a wild alternative, we could amplify the signal in some way, perhaps using sterile equipment in space, such that any Earth life would drown out in alien life and contamination would no longer pose as big an issue.