The new wonder-paste is composed of aluminium powder and ordinary water ice, and is known as Al-ice or ALICE. The clever bit is that the aluminium powder is extremely fine - "nanoscale" fine - giving it much greater surface area and letting it react with the water much more vigorously. The vid above, courtesy of Purdue university, explains in more detail.

An ALICE-fuelled rocket was flight tested in Indiana earlier this month, apparently, reaching thrust of 650 pounds as it soared into the sky.

"ALICE can be improved with the addition of oxidizers and become a potential solid rocket propellant on Earth," says Dr Steven F Son of Purdue university. "Theoretically, ALICE can be manufactured in distant places like the moon or Mars, instead of being transported to distant locations at high cost."

The jury's still out on whether there are useful amounts of water ice on the Moon, but there's known to be some on Mars. Being able to make rocket fuel on either body would be good news for prospective interplanetary expedition planners, as lugging fuel out from Earth for the return journey takes up a distressing amount of the outbound spacecraft's payload.

As for environmental friendliness here on Earth, it would be hard to be a lot friendlier than the commonly-used liquid hydrogen-oxygen rockets in common use - their exhaust is made up of water vapour. But the new ALICE tech could well be nicer than some present-day solid fuels.