Ramses Asteroid Spacecraft Powers Up for First Time in Milan Cleanroom

The European Space Agency and Japan Aerospace Exploration Agency's Ramses planetary defence spacecraft has been switched on for the first time by its prime contractor, marking a major milestone in the mission's time-critical development schedule. The power-up confirms that the spacecraft's integrated core systems are working together as intended, a concrete sign of progress toward a rendezvous with the asteroid Apophis that cannot be delayed.

Ramses must reach space by spring 2028 to meet Apophis as the cruise-liner-sized asteroid passes Earth on Friday 13 April 2029. That timeline represents less than three and a half years from contract signing to lift-off, a schedule dictated by celestial mechanics rather than program budgets.

The switch-on took place at the Milan cleanroom facility of OHB Italia, where the spacecraft's Core Module containing all its main electronics is being assembled. Key Ramses units have been mounted within the module's U-shaped body and linked together by the spacecraft harness. Power was applied to the On-Board Computer together with its integrated subsystems inside the spacecraft body for the first time.

Those subsystems include the mission's Mass Memory Unit for data storage, the Power Conditioning and Distribution Unit delivering power throughout the spacecraft, and multiple Remote Terminal Units that convert instrument outputs into digital data for the computer. Ramses lead engineer Ingo Gerth explained that while the units had previously undergone individual testing in isolation, this was the first real integrated functional testing, allowing commands to be sent via the computer to each subsystem to verify performance.

Ramses functional architect Arnaud Bourdoux said the switch-on was significant because these are the same system-critical units that will be turned on when Ramses is on its launch pad. Giuseppe Filomeno, Ramses project manager at OHB Italia, said powering up the onboard computer and establishing communication between the connected units provided the first tangible confirmation that the integrated systems are working together. ESA's Ramses project manager Paolo Martino said the moment marks a completely new phase, with everything beforehand consisting of paper calculations, simulations or unit tests, and now an actual spacecraft ready for full-scale integrated system testing.

To save schedule time, Ramses is being assembled in two parts at once. The Core Module in Italy is being built around a dummy version of the spacecraft's central cylindrical core. Meanwhile the spacecraft's Propulsion Module, including its actual carbon-fibre reinforced-polymer core, is being dressed with propellant tanks, sensors, actuators and linking harness at ArianeGroup's Orbital Propulsion Centre in Lampoldshausen, Germany.

The milestone confirms that the integrated systems function together as intended, providing the first tangible evidence that the spacecraft is coming to life at the Milan facilities. It also advances a joint ESA-JAXA effort in planetary defence, with Japan contributing to the mission.

The two modules will be mated next spring at ESA's ESTEC Test Centre in Noordwijk, the Netherlands, beginning the pre-flight testing phase. That testing will reproduce the conditions Ramses will face during launch and operations, including a thermal vacuum test lasting two to three weeks and a mission simulation running a sped-up sequence from lift-off to end of mission. Ramses and its two accompanying CubeSats must be ready for launch on a Japanese H-3 rocket in spring 2028.