BAIKONUR, Kazakhstan — On a sultry desert evening, as bats fluttered about this town’s riverfront park, a man emerged from a reedy marsh carrying a bundle of grass tied with twine.

Setting it down to brush himself off, he explained that he was keeping a calf in the courtyard of an apartment building across town, where he had settled in recently after the previous occupants, engineers with the Russian space program, moved out.

Baikonur, in remote western Kazakhstan, was once the pride of the Soviet Union, the home of the Baikonur Cosmodrome, the launching site of Sputnik, the dog Laika and the first man in space, Yuri Gagarin. But today, nomadic herders from the nearby steppe are moving into abandoned buildings.

That is just one of the signs of the city’s long fade into the sunset of post-Soviet social and economic problems, which are all the more remarkable given that much of the world, including the United States, still relies on Baikonur for manned space launchings. The only other site for such liftoffs is in Jiuquan, in the Gobi Desert in China.