On April 13, 2029, the asteroid Apophis, with a diameter of approximately 340 meters, will pass by Earth at an altitude of 32,000 km. This marks the first time in recorded history that an asteroid of this size—around 300 meters in diameter—has come this close to Earth; such an event is said to occur only once every several thousand years.
The RAMSES (Rapid Apophis Mission for Space Safety) project aims to capitalize on this rare opportunity by sending a probe to rendezvous with Apophis before, during, and after its closest approach to Earth. Through high-resolution observations, the mission will study changes in the asteroid’s physical properties caused by Earth’s tidal forces.
ESA will develop the spacecraft system in a short timeframe by making full use of the legacy gained from the Hera (Double Asteroid Exploration Mission) project. JAXA will provide three key components: lightweight solar array wings (SAWs), an infrared camera (TIRI: Thermal InfraRed Imager), and a launch opportunity aboard the H3 rocket. RAMSES is scheduled to launch in fiscal year 2028 as a dual launch with DESTINY+ (Deep Space Exploration Technology Demonstrator), arrive at Apophis at the end of February 2029, and pass near Earth while continuing observations while in rendezvous with Apophis.
For Japan, participation in the RAMSES project presents an opportunity to generate scientific results through direct observations of Apophis, while also providing an opportunity to enhance international competitiveness and build trust in the industries producing lightweight solar array wings and the H3 rocket. This collaboration, spanning all three key elements—observation instruments, bus systems, and launch vehicles—is a first-of-its-kind endeavor. Furthermore, the development of RAMSES will serve as a demonstration of planetary defense activities—specifically, the ability to rapidly develop and launch a probe through international cooperation in the event of a future asteroid impact on Earth.
The current close cooperative relationship between ESA and JAXA began with the BepiColombo mission and is the result of the trust fostered through that joint development. The RAMSES mission will lay the foundation for future international planetary defense activities.
（Image Credit: ESA）
