His idea is a thin dome covering a city with that is a very transparent film 2 (Fig.1). The film has thickness 0.05 – 0.3 mm. One is located at high altitude (5 - 20 km). The film is supported at this altitude by a small additional air pressure produced by ground ventilators. That is connected to Earth's ground by managed cables 3. The film may have a controlled transparency option. The system can have the second lower film 6 with controlled reflectivity, a further option.

The offered protection defends in the following way. The smallest space warhead has a minimum cross-section area 1 m2 and a huge speed 3 – 5 km/s. The warhead gets a blow and overload from film (mass about 0.5 kg). This overload is 500 – 1500g and destroys the warhead (see computation below). Warhead also gets an overpowering blow from 2 -5 (every mass is 0.5 - 1 kg) of the strong stones. Relative (about warhead) kinetic energy of every stone is about 8 millions of Joules! (It is in 2-3 more than energy of 1 kg explosive!). The film destroys the high speed warhead (aircraft, bomber, wing missile) especially if the film will be armored by stone...

(Cheap Method for Shielding a City from Rocket
and Nuclear Warhead Impacts)

Regular Technovelgy readers might be thinking of the long history of science-fictional domes, like the glass dome described in A Modern Utopia (1905) by H.G. Wells or the moon dome described in Brigands of the Moon by Ray Cummings, published by Astounding Stories of Super Science magazine in 1930.

However, I was thinking of the roofed valley from Misfit, written by Robert Heinlein in 1939. In the story, a valley on an asteroid is selected for habitation. It is fitted with a "roof":

The Captain selected a little bowl-shaped depression in the hills, some thousand feet long and half as broad, in which to establish a permanent camp. This was to be roofed over, sealed, and an atmosphere provided...

"Is this roof going to be just fifty feet high?"

"No, it will average maybe a hundred. It bellies up in the middle from the air pressure..."

Libby concentrated for an instant, then looked puzzled. "But look -- This valley is a thousand feet long and better than five hundred wide. At half of fifteen pounds per square inch, and allowing for the arch of the roof, that's a load of one and an eighth billion pounds. What fabric can take that kind of a load?"

"Cobwebs."

"Cobwebs?"

"Yeah, cobwebs. Strongest stuff in the world, stronger than the best steel. Synthetic spider silk. This gauge we're using for the roof has a tensile strength of four thousand pounds a running inch."

Don't miss these dome-related stories; Glass Dome Cities On Mars, Dreamed By Elon Musk and Space Domes Over-rated? Science Fiction Authors Have Answers.