Sputnik reported on 1 July that the United States had secretly launched a satellite from its segment of the ISS, cataloged by the space-track.org service as BD-28 with an American country code. The fact puzzled many while some offered their explanations for this, including the American astronomer Jonathan McDowell who suggested on Twitter that the satellite could belong to a private US company that didn’t want to attract attention to its activities.
“It turns out there was an error in what was posted on space-track.org, and it has since been updated," Dick said. "BD-28, also referred to as G-Satellite 2, is a Japanese CubeSat. The country code for BD-28 will be updated to JPN."
CubeSats are miniature satellites used for space research that weigh up to 3 pounds and have a cubical shape.