First switch on for ESA-JAXA Ramses asteroid mission

The European Space Agency and Japan Aerospace Exploration Agency's Ramses planetary defence spacecraft has been switched on for the first time by prime contractor OHB Italia, a major milestone in a time-critical development schedule. Ramses must launch by spring 2028 to rendezvous with the cruise-liner-sized asteroid Apophis as it passes Earth on Friday 13 April 2029, giving the team less than three and a half years from contract signing to lift-off.

The spacecraft's Core Module, containing its main electronics, is being assembled in OHB Italia's Milan cleanroom. Key units have been mounted inside the module's U-shaped body and connected by the intricate spacecraft harness. The integrated switch-on applied power to Ramses's On-Board Computer together with integrated subsystems inside the spacecraft body. Those subsystems include the Mass Memory Unit for data storage, the Power Conditioning and Distribution Unit for delivering power throughout the spacecraft, and multiple Remote Terminal Units that convert instrument outputs into digital data for the computer. Specialist OHB Italia teams installed the units and harness while maintaining the rigorous schedule.

Ramses lead engineer Ingo Gerth said the units had previously been tested individually in isolation, but now the team could perform real integrated functional testing in unison with other equipment on the satellite, sending commands via the computer to each subsystem to verify performance. Functional architect Arnaud Bourdoux noted that these are the same system-critical units that will be turned on when Ramses is on the launch pad to begin its journey, while OHB Italia project manager Guiseppe Filomeno called the first integrated switch-on an important milestone that provides the first tangible confirmation the integrated systems are working together as intended. ESA project manager Paolo Martino said the moment marks a completely new phase: everything beforehand was paper calculations, simulations or unit tests, but now there is an actual spacecraft ready for full-scale integrated system testing.