Development of 5G system as a global telecommunication infrastructure is accelerating to realize the concept of a unified network infrastructure incorporating all access technologies. The potential of Low Earth Orbit (LEO) constellation systems has emerged to support wide range of services. This could help to achieve 5G key service requirements for enhanced Mobile Broadband (eMBB), Massive Machine-Type Communications (mMTC), and Ultra-Reliable Low-Latency Communication (URLLC). The integration of satellite communications with the 5G New Radio (NR) is stimulated by technology advancement to support challenging service requirements and demand for ubiquitous connectivity with the best possible quality of service. In this paper, we surveyed the opportunities of integrating terrestrial mobile and satellite networks, key technical challenges and proposed solutions. We also introduced a mobility management scheme that reduces signaling overhead and minimizes service interruption during inter satellite handover process.