On testing laser ablation processes for asteroid deflection

Gibbings, A., Hopkins, J.M., Burns, D., Vasile, M. and Watson, I. (2011) On testing laser ablation processes for asteroid deflection. In: IAA Planetary Deference Conference, Bucharest, Romania, 9-12 May 2011,

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Asteroids represent both an opportunity and a risk. Their pristine environment captures the early formation of the solar system; while their impact potential could result in the mass extinction of life. Amongst the many possibilities to deflect Near Earth Asteroids, laser ablation has been shown to be theoretically one of the most effective cases. However, to have full confidence in this approach current assumptions must be verified and fundamental questions answered. Current models assume that the asteroid’s body is a dense, non porous, homogenous structure. Forsterite is typically used to represent asteroids. However asteroids exist over an extended range of material compositions, initial rotational rates and surface features. Models must therefore be advanced to represent the diversity within the asteroid population. The nature, composition and geometry of the ejecta plume also requires accurate modelling. The affect of porosity on the expansion of the ejecta gas remains unknown. Existing models of contamination, particularly on the optical elements are limited to the rocket-engine equivalent model. Therefore to successfully assess the effectiveness and efficiency of the laser ablation technique a detailed understanding of each of these parameters is required. Supported by the Planetary Society and the Institute of Photonics, a series of self contained experiments were conducted that assessed the formation of the ejecta plume - gas, dust and other particles - and the rate of optical contamination for several different laser ablation events. This was a product of asteroid analogue target material(s) –dense, porous, and inhomogeneous -, surface geometry and laser beam characteristics. Each test occurred within a vacuum and was supported by a complementary in-situ monitoring system. High resolution, high speed cameras enabled reconstruction of the ejecta plume and flow field. Coupled with a thermal camera this enabled plume specific issues - geometry, ejection velocities, temperature profiles and the contamination flow to be examined. Highly polished mirrors were also used to collect the contaminated particles and assess the rate of degradation. This paper will therefore present the design and methodology, experimental considerations and results of the laser ablation experiments. All collected data has been compared against the theoretical prediction. This permitted the calibration of the current analytical modelling technique. Ultimately the experiment provided a detailed insight into the effectiveness of the laser system, and the laser ablation potential as a viable method of deflecting Near Earth Asteroids.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Watson, Dr Ian and Vasile, Dr Massimiliano
Authors: Gibbings, A., Hopkins, J.M., Burns, D., Vasile, M., and Watson, I.
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
College of Science and Engineering > School of Engineering > Systems Power and Energy

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