This application provides an example satellite, an example terminal device, an example satellite communication system, and an example satellite communication method. One example satellite communication method includes obtaining, by a first satellite, at a media access control (MAC) layer, data and/or signaling, where the first satellite is a low orbit satellite. When MAC-layer first processing needs to be performed on the data and/or the signaling, performing, by the first satellite, the MAC-layer first processing on the data and/or the signaling. The MAC-layer first processing includes at least one of hybrid automatic repeat request (HARQ) function processing or random access (RA) function processing.