The development of next-generation radar, communications, and imaging systems operating at radio frequency (RF) in space-borne applications demands requires the reliability of electronics under harsh radiation and extreme temperatures. In order to support such applications, SiGe BiCMOS technology is proposed. To this end, SiGe BiCMOS devices and circuits were subject to cryogenic temperatures, total-ionizing dose (TID), and single-event effects (SEEs) to evualuate their performance for operation in space. At the transistor-level, excellent tolerance is demonstrated to TID at both room temperature and cryogenic temperature. Meanwhile, SiGe-based circuits are still sensitive to SEEs, and a radiation-hardening-by-design technique is proposed for microwave oscillators, which serve as frequency references vital to any RF system. Overall, SiGe BiCMOS should be strongly considered as a foundational technology supporting the future of commercial and scientific space applications.