Which current type do they use in space?

Question

Do they use AC or DC current in space, such as the ISS and shuttles? I know that AC needs a ground, but can that be artificially generated in space?

Answer 1

The ISS uses direct current at about 160 volts.

Other spacecraft tend to use DC more than AC.  DC voltages for control applications in unmanned spacecraft standardize at 14 and/or 28 volts.  There's no one single answer, except that DC voltages dominate.

There is no problem inherently with AC on a spacecraft; a chassis ground works just as well as an Earth ground. There just isn't much need for AC current on a spacecraft.  But the technology to step voltages up and down and to covert between AC and DC current are well-developed and commonplace, so it doesn't really matter much how the spacecraft's power-management system is designed.

Power management on spacecraft is usually a matter of overall mass minimization and optimizes for power sources and storage technology.  So engineers are going to be far more worried about where the electricity is coming from and how they will store it than they are about what voltages and currents to provide.