ESA-JAXA Ramses Spacecraft Switched On Ahead of Historic Apophis Encounter

The European Space Agency and Japan Aerospace Exploration Agency have reached an important milestone in their joint planetary-defence effort after the Ramses spacecraft was switched on for the first time.

The spacecraft is being developed for the Rapid Apophis Mission for Space Safety, known as Ramses. Its mission will be to rendezvous with asteroid 99942 Apophis and observe the space rock during its unusually close passage by Earth in April 2029. ESA reported the first switch-on milestone on September 23, 2026, describing it as an important step in the mission’s accelerated development schedule.

Preparing for a Rare Asteroid Encounter

Ramses is scheduled for launch in 2028 so that it can reach Apophis before the asteroid makes its close approach to Earth. The spacecraft is expected to arrive around February 2029, giving scientists an opportunity to observe the asteroid before, during and after its encounter with Earth’s gravitational field.

Apophis is approximately 375 metres across. On April 13, 2029, it will pass within about 32,000 kilometres of Earth’s surface. Despite the dramatic closeness of the encounter, scientists have ruled out an impact with Earth for at least the next century based on radar observations and improved orbital calculations.

The event is nevertheless scientifically significant because an asteroid of this size coming so close to Earth is an exceptionally uncommon occurrence.

Earth’s Gravity Will Become Part of the Experiment

One of the central objectives of Ramses is to observe how Apophis responds as it passes through Earth’s gravitational field.

The planet’s gravity is expected to alter the asteroid’s trajectory and may affect its physical characteristics. Strong tidal forces could potentially produce surface changes such as landslides or disturbances and could also influence the asteroid’s rotation.

Ramses will collect measurements that can help scientists compare Apophis before and after the encounter. Researchers hope to improve their understanding of the asteroid’s shape, surface, mass, density, internal structure, rotation and other physical properties.

Why the Mission Matters for Planetary Defence

Studying Apophis is not only about understanding one asteroid. The information gathered could contribute to future planetary-defence research.

Scientists need to understand how asteroids respond to external forces before they can accurately assess possible techniques for changing the trajectory of an object that might someday pose a threat to Earth. Ramses will therefore provide an opportunity to study an asteroid under naturally occurring gravitational forces rather than relying entirely on simulations or laboratory experiments.

The mission also reflects the growing international cooperation surrounding planetary defence. ESA is leading the Ramses mission, while JAXA is contributing important spacecraft technologies, including lightweight solar arrays, an infrared imaging instrument and launch support through Japan’s H3 rocket.

A Fast-Moving Space Mission

Ramses is being developed under an unusually demanding schedule because the spacecraft must reach Apophis before its 2029 flyby.

ESA awarded a contract to OHB Italia in February 2026 for the spacecraft’s development, construction, assembly and testing. The contract followed the mission’s critical design review, which confirmed that the spacecraft design had reached the required level of maturity for construction.

The first switch-on now marks another step in moving from design and preparation toward an operational spacecraft.

A New Opportunity to Study an Ancient Space Rock

Asteroids are remnants of the early Solar System and preserve information about conditions that existed billions of years ago. Observing Apophis at close range could therefore provide valuable information beyond planetary defence.

During its mission, Ramses will use scientific instruments to document the asteroid and monitor changes associated with its Earth encounter. The resulting observations could improve scientific understanding of asteroid composition, structure and behaviour.

The 2029 encounter is also expected to attract worldwide attention because Apophis will briefly become visible to the naked eye from parts of Europe, Africa and Asia under suitable observing conditions.

With the Ramses spacecraft now switched on for the first time, ESA and JAXA have moved another step closer to an extraordinary rendezvous with Apophis. The mission could provide a rare combination of asteroid science and planetary-defence research while demonstrating how international space cooperation can prepare humanity to better understand objects that pass through Earth’s cosmic neighbourhood.