Alison Gibbings and Massimiliano Vasile, aerospace engineers at the University of Strathclyde, UK, new solution is a 500-kilogram swarm of fingernail-sized spacecraft would, they calculate, deflect a fast-moving, 250-metre asteroid by nearly 35,000 kilometres – easily enough to avoid a collision, provided the swarm hits eight years, or about three orbits, before the expected Earth impact. A swarm could be launched from Earth in a single rocket. After release, pebbles could harness the thrust provided by reflected sunlight to steer themselves into a tight cloud directed at the asteroid.
Initially adapted from kinematic impactors and ion beaming, this paper presents a novel concept for the successful deflection and mitigation of asteroids. By releasing and subsequently impacting an asteroid with a large, dense cloud of low mass, high velocity, nano-size smart spacecrafts, significantly high rates of deflection can be achieved. This is known as the Smart Cloud approach to deflection. Each particle within the cloud consists of a passively operated, microchip that together provides hundred to thousands of individual impact points on the asteroid. The impact energy of each microchip is significantly lower than the asteroid’s distribution limit of fragmentation. This is advantageous as it eliminates the possibility of any unwanted and uncontrollable fragmentation of the asteroid. This might otherwise occur with the impact of a monolithic spacecraft and/or projectile.
For analysis the Smart Cloud approach as been compared to two other deflection methods. This includes the ion beam shepherd and the low thrust tug. The deflection potential for each technique has been examined for both deep and shallow crossing asteroids. All assessment has been made relative to the mass efficiency of each deflection method. This is defined by the fraction of spacecraft mass dedicated only to the deflection mission, relative to the total mass of the spacecraft. The evolution of the Smart Cloud has also been assessed. The maximum diameter of the Smart Cloud currently coincides with the maximum diameter of the asteroid. This is distributed over an extended region of space.
The results demonstrated that the Smart Cloud is highly effective for the deflection and mitigation of deep crossing asteroids. This occurs when the mass of the Smart Cloud is equivalent to the propellant mass used in the ion beam shepherd approach. The Smart Cloud approach also reduces the system mass and complexity of the overall spacecraft. The high impact velocities are not provided by a dedicated acceleration system. But are instead the result of the relative motion of the Smart Cloud and the asteroid on their respective orbits. This paper will therefore present the comparison between the Smart Cloud, the low thrust tug and the ion beam shepherd. The Smart Cloud’s deflection methodology and spacecraft design is also given in more detail. This includes the design and integration of each microchip.