Eco-friendly alternatives to fossil fuels are venturing beyond Earth—and into space.

The rocket is part filled with water, and air is pumped in with a foot pump. When the rocket is released from the launcher, the high pressure inside the bottle equalizes with the air outside ...

Water gets pushed down, bottle flies up. Done? Oh no! The first step into more sophistication is the aerodynamics. But honestly, if you make something vaguely rocket-shaped with fins, it’ll ...

The basic idea is to use several chambers on the water rocket, one which provides an initial short “boost” phase of high acceleration, followed by a longer “sustain” level of acceleration ...