The U.S. says Russia is building a nuclear weapon for space. But how would you prove there’s a warhead inside a satellite 1,200 miles up?

Nuclear explosions in space, conducted by the United States in the 1960s, produced brilliant auroras and knocked out power on Earth.

If a similar experiment were carried out in orbit today, we would lose navigation, communications, and weather forecasting for a long time.

Space is now densely populated with satellites that would not survive the electromagnetic pulse and particle streams from a nuclear explosion.

But U.S. officials are concerned that the Russian military is considering such a strike against orbital constellations — which give the Ukrainian army an advantage — and is even launching spacecraft to test components of a future “nuclear mine.” How real is this threat?

And has anyone actually put weapons in orbit?

Areg Danagoulian, an American physicist, has set out to answer these questions. ...