A proposal for monitoring potentially dangerous near-Earth asteroids

An enormous number of near-Earth asteroids (NEAs) orbit the sun, and among them 2,072 NEAs are listed in the Minor Planet Center (MPC) database as potentially dangerous near-Earth asteroids (PHAs). These PHAs often come close to Earth orbit and hence the danger posed by PHAs is still a very real and pervasive threat. Given potential threats from PHA impacts, asteroid defense has been discussed with growing interest. Monitoring and early warning of these PHAs is the premise of planetary defense.

In a recent research paper in Space: Science & TechnologyXiangyu Li from the School of Aerospace Engineering, Beijing Institute of Technology, and co-authors propose the novel concept of a monitoring constellation of heterogeneous Wide-Field Near-Earth Asteroid (NEA) Asteroid Surveyors (CROWN), in which six space-based surveyors would loosely deployed in Venus-like orbits to detect the NEAs along the direction of the sunlight.

The authors discuss the concept and overall design of the NEA monitoring constellation. In general, an asteroid defense system should obey the circle of OODA, which includes observation, orientation, decision, and action.

The proposed CROWN would be a key element of the asteroid defense system, primarily responsible for observation and orientation, i.e. detecting and early warning of the PHAs, and tracking and determining the target’s orbit (OD). The surveillance constellation would include a mother ship and six daughter surveyors (space-based optical telescopes).

The mothership would provide the maneuverability required for transfer and deployment. Six daughter surveyors would be loosely deployed in Venus-like orbits and equipped with telescopes pointing backwards toward the Sun to detect NEAs approaching from the direction of the Sun.

In addition, the methods and aspects to evaluate the performance of the proposed CROWN are presented. In general, the performance of a surveillance constellation can be evaluated in terms of the constellation, the surveyor, and the payload. For each aspect, both capability and cost are considered.

For the constellation, the capabilities include surveillance convergence and OD performance. The cost of the constellation would include the power needed for transmission, deployment and maintenance. The performance of an individual appraiser could be evaluated based on the life cycle costs and the relatively favorable cost-benefit ratios. Payload performance metrics include sensitivity, accuracy, power consumption, and price.

Finally, the authors present the CROWN’s overall mission, which comprises four phases.

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