Apophis Cratering Experiment Mission Concept

Apophis is set to become one of the most extensively studied asteroids in history thanks to the detailed observation campaign of OSIRIS-APEX during its 2029 and 2030 extended mission to the near-Earth object, alongside Ramses which is expected to launch in 2028. To supplement those missions, we propose the Apophis Cratering Experiment (ACE), an impactor mission that leverages OSIRIS-APEX or Ramses as a dedicated observer, during and after the collision, to maximize scientific return at a low cost. In addition to providing significant science return, the mission offers a low-cost opportunity to demonstrate novel SmallSat technologies in deep space as non-critical payloads to increase the momentum transfer to the asteroid. There are several low-C3 (< 5 km2/s2), ballistic transfer opportunities in 2029 and 2030 that impact Apophis at velocities of 4 to 6 km/s after the OSIRIS-APEX science campaign. At these speeds, the proposed 85 kg ACE spacecraft will create a crater 20-50 m in diameter and 2-8 m deep, far below depths explored by previous missions. At the same time, the impact is “assuredly safe” and will not increase the risk of a future Apophis-Earth encounter. This mission concept study introduces the mission objectives and ties them to high-level spacecraft and mission requirements. We present a preliminary mission design, including several options for launch periods, and one resonant transfer that offers multiple opportunities to impact Apophis. Preliminary spacecraft requirements are presented, with summaries of the subsystems and optical navigation strategy for targeting impact. The mass of ACE is driven by the primary science objectives, rather than the spacecraft subsystems. An 85 kg spacecraft is required to create a large crater and transfer a significant amount of momentum to the asteroid. Rather than flying inert ballast, this mass requirement offers an opportunity to fly a variety of SmallSat technology demonstrations in deep space at a low cost, without relying on them for mission success.