What specific contamination concern requires NASA labs to employ ultra-trace analysis techniques often measured in parts-per-trillion?

Answer

Background contamination from Earth obscuring faint signals from extraterrestrial samples

NASA labs must verify the absence of specific molecules in their own equipment using ultra-trace analysis because background contamination from laboratory solvents can overwhelm the faint signals coming from distant targets.

What specific contamination concern requires NASA labs to employ ultra-trace analysis techniques often measured in parts-per-trillion?
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