Unit 6: Selection Vocabulary 2

Once a leash of thin black whips, like the arms of an octopus, flashed across the sunset and was immediately withdrawn, and afterwards a thin rod rose up, joint by joint, bearing at its apex a circular disk that spun with a wobbling motion.

Then I shifted my position to a little knoll that gave me the advantage of a yard or more of elevation and when I looked for him presently he was walking towards Woking.

Suddenly there was a flash of light, and a quantity of luminous greenish smoke came out of the pit in three distinct puffs, which drove up, one after the other, straight into the still air.

As the green smoke arose, their faces flashed out pallid green, and faded again as it vanished.

Had that death swept through a full circle, it must inevitably have slain me in my surprise.

To figure out if this is plausible, we can start with an absolute baseline energy requirement: four gigajoules per person.

This is because of a fundamental problem with rockets: They have to lift their own fuel.

The formula for how much propellant we need to burn to get moving at a given speed is given by the Tsiolkovsky Rocket equation...

As crazy as it sounds, we might be better off trying to (1) literally climb into space on a rope, or (2) blow ourselves off the planet with nuclear weapons. These are actually serious—if audacious—ideas for launch systems, both of which have been bouncing around since the start of the Space Age.

The idea is that we connect a tether to a satellite orbiting far enough out that the tether is held taut by centrifugal force.