Internet of Space Things (IoST), also known as CubeSats, elaborates the uses and functionalities of traditional Internet of Things (IoT) by not only providing a constantly available satellite back-haul network, but also by providing real-time satellite-captured data. IoST can be applied for various applications, like weather forecasting, navigation, satellite phone, satellite TV, satellite Internet, radio, military, and many more. It requires support of mechanisms of Intelligent Transportation System (ITS). In an IoST communication environment, the communication among various users, satellite access points, ground stations, and smart IoT devices occur through insecure channels, i.e., Internet. Due the transmission of data over an insecure channel, various potential attacks are possible. Due to the existence of various attacks, the important data of IoST may be altered or revealed. To mitigate these issues, an authentication and key management framework for secure and intelligent transportation of IoST has been proposed (in short, SAKM-IoST). Through the proposed SAKM-IoST, a legitimate user can access the data of ground station in a secure way. The security analysis reveals that SAKM-IoST is resilient against a variety of potential threats and attacks. Additionally, SAKM-IoST's performance is compared with other approaches that are similar in nature. It has been noted that SAKM-IoST offers robust security, in addition to extra functional characteristics. Therefore, SAKM-IoST seems to be more suitable for its deployment in the critical applications of the IoST as compared to other competing approaches.