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

This allowed [Zach] to test the geometry of the parts, operation of the mechanism ... Perhaps it could even launch a two-stage water rocket?

Water rockets are plenty of fun, but they can be even more fun if you go wild with the engineering. [The Q] is one such experimenter, who built a dual-thrust water rocket that even has a parachute ...

The launch would also be impossible for missiles whose fuel was replaced with water. While Bloomberg ... a safer and more efficient option for daily rocket operations. Solid fuel has the added ...