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

The trials verify that the fuel can survive the harsh environment of a nuclear rocket reactor. Up until now, the main way of propelling spacecraft has been through chemical rockets. To be fair ...

but the first step is to drain the New Glenn rocket of its fuel. Blue Origin began filling the vehicle’s fuel tanks with liquid methane, hydrogen and oxygen late Sunday evening. “From there ...

After lift-off, the rocket quickly burns through its fuel. Once the tanks are empty, they break away from the rest of the rocket and fall back to Earth. When the astronauts reach the ISS ...