A decade ago, an experiment on the International Space Station successfully conducted 3D printing in space, using plastic. But plastic isn't very useful for making say, durable replacement parts. So now the European Space Agency has successfully 3D printed with metal on the ISS.

Obviously you can't use SLA or SLS in space; there's no gravity, and metal powder on a space station is a safety no-no. Instead the 3D printer, developed by Airbus and the UK's Cranfield University, works like an FDM 3D printer. A stainless steel wire is fed through a nozzle and melted into goo by a laser:

A time lapse:

The resultant parts ain't pretty, but they're real:

As ESA explains:

"As exploration missions expand to the Moon and Mars, mission duration will increase, as will the importance of autonomy for the mission and its crew as resupply missions become more challenging. Additive manufacturing in space is a solution to this, providing an opportunity to manufacture needed parts, to repair equipment or construct dedicated tools, on demand during the mission, rather than relying on resupplies and redundancies."

The feat is bound to have lasting implications. This month Elon Musk announced that SpaceX will send an uncrewed ship to Mars in 2026, as a test run before sending a manned ship in 2028. Humans on Mars in four years. Holy crap (if he's right).