REMORA - REndezvous Mission for Orbital Reconstruction of Asteroids: A fleet of Self-driven CubeSats for Tracking and Characterising Asteroids

As of January 2021, our solar system is populated by 24,797 known Near-Earth Objects (NEOs) classified as asteroids (24,684) and comets (113). Asteroids over 140-meter diameter whose trajectories cross the Earth's orbit, represent a threat for our planet and are classified as Potentially Hazardous Asteroids (PHAs) - 2,156 objects. The need to accurately predict the orbit of PHAs emerged as a serious issue in 2004 when investigations into the trajectory of the asteroid Apophis (~350-meter diameter) revealed a high impact probability with Earth in 2029. Further observations concluded that Apophis no longer posed a risk in 2029 but it could now impact the Earth in 2036. Apophis serves to highlight the current limitations in observations to accurately predict asteroid orbits and their potential impacts. Moreover, PHA mitigation became a priority only in 2013 when an asteroid of ~20-meter diameter caused approximately 1,600 injuries in Chelyabinsk (RU). As the asteroid's trajectory placed it in the Earth's daytime sky, it was undetected by ground-based telescopes, therefore no warning was given to the local population. The Chelyabinsk incident revealed that impacts of relatively small asteroids can pose a significant threat. Given that such events could occur in the future, with the potential to cause severe injuries/loss of life, economic disruption, and material damage, how can the next generation of space-based technology overcome the limitations of telescopes to systematically track and characterise PHAs?

REMORA - REndezvous Mission for Orbital Reconstruction of Asteroids: A fleet of Self-driven CubeSats for Tracking and Characterising Asteroids explores a new mission idea, inspired by the symbiotic relationship between remora fish (i.e., CubeSats, 10x10x10 cm and 1.35 kg per unit) and sharks (i.e., target asteroids). As remoras attach to sharks using them for food and free transportation, similarly, a fleet of CubeSats tagging asteroids will provide high accuracy in orbital determination.

Asteroids are, small (1m-100km), inactive, celestial bodies orbiting the Sun. The gravitational forces of the Sun and larger planets alter their orbits, and thus, their motion is not reliably predictable many years into the future (e.g., Apophis) without precise observations and tracking. Moreover, asteroids who orbit in the day-side of the sky are less likely to be discovered (e.g., Chelyabinsk). Therefore, a PHA's physical characteristics and orbit cannot be precisely determined unless a spacecraft rendezvous with it and analyses the asteroid. There is a lack of readily available technology proven to be effective in altering an asteroid's orbit. Before mitigation designs are developed for deflecting a PHA's orbit, it is vitally important to characterise PHAs sufficiently.

REMORA will fill the 'gaps' between the limitation of current asteroid observations and the design of future mitigation techniques in response to an imminent PHA threat. Sending a fleet of space sensors, CubeSats, throughout the solar system to rendezvous with asteroids will allow for key orbits to be permanently and accurately tracked and we will move a step forward in defending our planet. Moreover, asteroids are rich in water, a key element for supporting human spaceflight and for enabling in-space construction and reducing costs in spaceflight. Indeed, water is essential for life support, radiation shielding for astronaut safety and in-space manufacturing of rocket fuel for oxygen and hydrogen. In the long-term, unlocking asteroid resources will lead to the development of the asteroid mining industry. Ultimately, REMORA will lay the foundation for a CubeSat's onboard algorithm (i.e., NEAR tool) that will be capable of executing their own mission without ground support - reducing the costs for running deep space programs and enabling flexible, large-scale, and multi-mission architecture (i.e., a fleet).