To tell about this context an easiest way is to take the Ancient Script ' Vaimanika Sastram'.....It explains about the Aeronautical Engineering and making of Space ships. Most people know that Ravana- A demon used to have a beautiful ,luxury Flight.....which can accommodate any number of people and leaves space for one more person.
At the time of Bhoja Raja ....he used to have few planes of different types that which can run for few hundred kilo meters to Few thousand kilometers.The technology is not this polluting technology here. In the Vaimanika Sastra...they explained different space ships ...as one inside the Earth..another to next planets..and another one is very large distance traveling...like Maharloka which is above these all Planets....it is explained here the main qualifications of a Pilot...and how to face a war on ship if somebody is attacking from ground and from another ship....how to take care of them selves when they reached to space...and when they face sun.
Lets explore one more important topic....Pandora...the Planet as explained in Avatar...In the Ancient Text...'Yoga Vasistam' Vasista explained how similar earths are there in he world and how similar they would be with the Earth......He said there are different earths in the Universe..few are very similar and almost happens same like our earth......and few are different with different laws and nature.
In all these Space crafts Mercury Engines are used....which are very sophisticated from Existing Technology.... mercury engines can be found in the ancient Vedic text called Samaranga Sutradhara.
There was a Secret of the Anti Gravity which is kept in secret library in India./tibet...to keep away from Evil Hands.
Ashoka....has started a secret Association of 9 scientists to explain the Ancient Texts, Alexander and his historians Chronicled that In INDIA at one point they were attacked by flying Machines...and flying saucers been explained in Ramayana and Drona parva......Mahabharata....which has been proved by Historians it self as 5000 years ago story...these flying Saucers are Explained.
Explore India.......Nothing is new in India, Just need to explore the Ancient methods in New way. 1000 years old Temples....great architecture...with lot of hidden secrets.