BERLIN—The German government said Monday it supports plans for a North Sea spaceport that would be used to launch small satellites into space from Europe. Economy Minister Peter Altmaier said the government would act as an “anchor customer” for the floating launch site off the German coast. “We want to strengthen the national space program,” he said at an event marking the signing of cooperation agreements between the German Offshore Spaceport Alliance and four European rocket manufacturers—two from Germany, one from the Netherlands, and one from Britain. Siegfried Russwurm, head of the Germany industry association BDI, said a spaceport in the North Sea would make it easier to launch satellites into polar and sun-synchronous orbits. There are more than 20 spaceports around the world already, but European space companies currently rely mostly on launches from Russia’s site in Kazakhstan, French Guiana in South America, and from the United States.