The Space Shuttle returns to earth, but some of the equipment brought back on it begins to behave strangely. Scientists are unsure what is happening, and decide to take all necessary precautions.
I did see this once on video many years ago. I thought it dumb that the aliens who otherwise had superior technology were somehow (I can't recall exactly) dependent on a circa 1970 NASA Lunar Module to execute their plans for conquest.
Of the two choices you provide, the second one is more in line with my opinion.