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The Advanced Gun System, left, is intended to take on the role of the battleship's 16-inch guns, right. Aside from its GPS-guided shell, the digital technology of the AGS's fire control system does exactly what the USS Iowa's Rangekeeper Mark 8 did—just with fewer people and less weight. (credit: US Navy)

We are resurfacing this feature from 2014 for your reading pleasure on this holiday weekend.

The USS Zumwalt, the latest destroyer now undergoing acceptance trials, comes with a new type of naval artillery: the Advanced Gun System (AGS). The automated AGS can fire 10 rocket-assisted, precision-guided projectiles per minute at targets over 100 miles away.

Those projectiles use GPS and inertial guidance to improve the gun’s accuracy to a 50 meter (164 feet) circle of probable error—meaning that half of its GPS-guided shells will fall within that distance from the target. But take away the fancy GPS shells, and the AGS and its digital fire control system are no more accurate than mechanical analog technology that is nearly a century old.

Enlarge / Future moon bases could be built with 3D printers that mix materials such as Moon regolith, water, and astronauts’ urine. (credit: ESA/Foster and Partners)

Ever since President Donald Trump directed NASA to get boots on the Moon by 2024, the agency and its partners have been hard at work trying to make it happen. Late last month, NASA awarded contracts to three companies to develop a crewed lunar lander, but getting to the Moon is just the start. The agency also plans to build a permanent Moon basebefore the end of the decade and use it as a stepping stone to Mars.

If astronauts are going to spend weeks at a time on the Moon, they’re going to have to figure out how to live off the land—er, regolith. It’s too expensive to ship everything from Earth, which means they’ll have to get creative with the limited resources on the lunar surface. Moon dirt is a great building material and there’s water in the form of ice at the south pole that can be turned into rocket fuel. But the hottest commodity of them all may very well turn out to be an astronaut’s own pee.

Earlier this year, a team of European researchers demonstrated that urea, the second-most common compound in human urine after water, can be mixed with Moon dirt and used for construction. The resulting material is a geopolymer, which has similar properties to concrete and could potentially be used to build landing pads, habitats, and other structures on the Moon.