Pusphak Vimana (plane) in Ramayana and Brahmastra (which has the effect of atomic bomb) used in Mahabharata and Ramayana are two of the most important incidents often used to relate ancient Hindus with UFOs and Nuclear Weapons. This is also a pet theme of UFO researchers. They believe that the knowledge about Nuclear weapons and planes were passed on to ancient Hindus by Extraterrestrials (ET).
Such articles are published regularly on the internet without any new finds, sticking to the old revelations which are not yet backed by any solid proof. Most of the articles are repetitions of the articles published the past several decades.
Recently, Sri Lanka Tourism had mentioned about the Ramayana Sites in the country and in it they talk about Werangatota, which is believed to be the place the Pushpaka Vimanam (flying machine of Ravana) could have landed. Werangatota is about 10 km from Mahiyangana, east of Nuwara Eliya.
So Did Ancient Hindus Know about Nuclear Weapons and UFOs? Nobody can say a firm No or a firm Yes. But what has been talked about in Mahabharata and Ramayana, which were dismissed as fantasy and fiction 100 years ago, are a reality today.
This article in Cite Libre is the latest one that talks about Ancient Hindus and Nuclear Weapons.
It is in ancient Indian epic poems such as such The Mahabarata and The Ramayana that we can read what appear to be references to an otherwise relatively primitive people having the capacity to wield highly destructive nuclear weapons. Not surprisingly it is as a direct consequence of such compelling passages that many UFOlogists like Erich Von Daniken and W. R. Drake (According to The Evidence - Souvenir, 1977 and Gods & Spacemen In The Ancient East - Sphere, 1976), have argued that the highly advanced capacity to use (and misuse) nuclear weaponry must have being handed down to these ancient people by the "gods" or, in other words, highly-advanced extra-terrestrial spacemen.
Reading through the various passages of The Ramayana and The Mahabarata with an eye to references of destructive nuclear type weapons certainly does lend itself to believing such claims, too. The evidence does appear to be highly compelling. For instance on p.383 of the Drona Parva we come across the following lines which certainly could be construed as evidence of the loathsome effects of detonating a nuclear weapon of some sorts:
"Encompassed by them (bowmen)... Bhisma smiting the while and uttering a leonine roar, took up and hurled at them with great force a fierce mace of destruction of hostile ranks. The mace of adamantine strength, hurled like Indra's thunder by Indra himself, crushed, O King, thy soldiers in battle. And it seemed to fill. the whole earth with a loud noise. And blazing forth in splendour, that fierce mace inspired thy sons with fear. Beholding that mace of impetuous course and endowed with lightening flashes coursing towards them, thy warriors fled away uttering frightful cries. And at the unbelievable sound .of that fiery mace, many men fell down where they stood and many car (vimana or flying vehicle) warriors also fell down from their cars."