CybExer Cyber Ranges for Space is a cyber range platform designed for the space industry to test, validate, and train on satellite and ground system cybersecurity. The platform serves as the key technology partner for the European Space Agency's Space Cyber Range under the ESA ARTES 4.0 programme. The platform provides a safe, scalable, and collaborative environment where satellite operators, integrators, and cybersecurity experts can conduct realistic training exercises, validate space systems, and test resilience against threats. Organizations can run cyber defense exercises in environments that mirror real space and ground systems without risking live missions. The cyber range supports validation and certification readiness by testing systems and processes against ESA-grade security requirements. It enables end-to-end testing of space architectures to identify vulnerabilities in communication links and system integration before launch. The platform includes reusable training content and mission-specific simulations for modeling complex challenges such as collision avoidance and multi-actor operations. It offers both on-premises and subscription-based deployment options. The solution has been used in collaboration with the University of Tartu to create a digital twin of the ESTCube-2 satellite control system for developing and testing cybersecurity measures.