Improving operations efficiency and sharing ground resources among a large number of spacecraft, such as for satellite constellations or multi-mission facilities, has become a major goal of satellite operators and Space Agencies. Ways to operations efficiency and autonomy are through automation, standardization and sharing of ground resource between several spacecraft or missions. However, spacecraft commanding still requires high levels of safety, reliability and flexibility. These needs are often felt to be exclusive since they require on-line scheduling. We have developed an approach that makes on-line scheduling an operational reality, by integrating resource allocation and task planning (i.e. Scheduling) with schedule execution and supervision within a consistent framework, in short-loop interaction. This integration allows the operations schedule to be quickly and safely updated when new requests are introduced or when unexpected events happen, so as to always make maintain a consistent and safe use of available resources (antennas, equipment, network, ...). Short-loop re-scheduling also represents significant reduction of workload as compared to manual planning. This approach has been implemented by EADS Astrium on several missions, some being already in operations, such as the INTELSAT Control Center that runs highly automated operations for up to 30 satellites, and the HELIOS II observation satellites user segment. The resulting operational software, named TIMELINE, has now significant operational and functional maturity. Potential applications include Galileo, the future European constellation navigation system, and multi-mission ground stations and operations schedule management systems for Space Agencies.