China's CROWN/Apophis Mission to Observe Asteroid Apophis in 2029

China is preparing to closely observe the asteroid Apophis during its significant Earth flyby in 2029 with a mission named CROWN/Apophis. This initiative is a key component of China's expanding planetary defense strategy, aimed at enhancing its capabilities in detecting and tracking near-Earth objects.

The CROWN/Apophis mission plans to deploy a main spacecraft and two small satellites into a halo orbit around the Sun-Earth Lagrange point 1. From this vantage point, they will maneuver to intercept Apophis shortly after its close encounter with Earth on April 13, 2029. The asteroid is expected to pass within approximately 31,600 kilometers of Earth's surface, marking the closest known approach by an asteroid of its magnitude in recorded history. Apophis, measuring about 340 meters in diameter, will be visible to the naked eye from Earth, particularly in the Eastern Hemisphere. While the 2029 approach poses no danger, it will alter the asteroid's orbit from an Aten-class to an Apollo-class trajectory and is expected to cause geological changes on its surface.

The main spacecraft, weighing 44 kilograms, will be equipped with combined chemical and ion propulsion systems. Its scientific payload includes a narrow-angle camera, a microwave ranging/Doppler system, a formation monitoring camera, and low-frequency radar. An accompanying 8-kilogram cubesat will carry similar instrumentation to work in concert with the main spacecraft for comprehensive data collection.

This mission aligns with China's broader commitment to planetary defense, which includes a planned kinetic impact demonstration mission. Wu Weiren, chief designer of China's lunar exploration program, announced this demonstration will test the feasibility of altering an asteroid's trajectory through impact using a "fly-along-impact-fly-along" model. China has also been actively building its planetary defense infrastructure, initiating recruitment for a dedicated planetary defense force in February 2025 to focus on monitoring near-Earth asteroids and developing early warning systems.