The response of science to things out of reach is to move towards them, not to concede the territory to space aliens.
Of course all proper persuit of knowledge strives to include evermore within its grasp. However, I think you're making the same error of a previous age, the "god of the gaps' become the "science of the gaps.'
Some things that can be known are beyond the sphere of science to know. That's a GOOD thing. Science is designed to address the area of knowledge which can be most firmly known - by the senses and their extenstions, that which can be named, quantified, located, etc.
This is a great and wonderful tool, but it is an error to proclaim that all that can be known, can be known by science and that if a certain knowledge is not known by science it is not true, or does not exist - or that science will eventually know it.