It's true that ancient Indians had some interesting insights into astronomy and natural sciences (recognizing the heliocentricity as early as the aitareya BrAhmaNa, and some ideas about electricity) and have some evidence about Indo-Aryan warfare being evolved with variety of weapons.

But it would sound like boomer uncles to claim that there is mention of space travel or nuclear weapons in our epics. The astra-s are simply figments of imagination.