Are you referring to the Black Knight? Here is NASA's handy-dandy-ohsotruthful explanation: There are several pictures circulating the internet of what is thought to be the Black Knight. These pictures, according to NASA, are images of a thermal cover dropped during a spacewalk or during some type of extra-vehicular activity on the ISS. During this expedition, one astronaut purportedly finished his mission early and was asked to cover the space station’s trunnion pins with thermal covers. The astronaut was asked to complete this as a free-floating task, despite not having the cover properly attached, inevitably losing track of it as it floated off. When asked later which pin he lost the cover to, he said he could not remember and that he was too upset with himself to think about it. NASA maintains that the photographs most people point to as evidence of the black knight are images of this thermal cover. There is also a video of the astronauts inside the space station filming and photographing the cover as it floats off. https://www.gaia.com/article/the-black-knight-satellite