IANAL, but I would think Infineon's data sheet and quote would constitute the "offer," and NASA's purchase order the "acceptance." IIANM, this meets the minimum requirement to establish a "contract" (usually called an "agreement" these days).
If the MOSFETs don't meet the specs on Infineon's data sheet, including rad hardness, then Infineon would be in breach of contract.
If the MOSFETs don't meet the specs on Infineon's data sheet, including rad hardness, then Infineon would be in breach of contract.
Is my reasoning correct?