On the Consequences of a Fragmentation due to a NEO Mitigation Strategy
- Paper number
IAC-08.C1.3.10
- Author
Mr. Joan Pau Sanchez Cuartielles, University of Glasgow, United Kingdom
- Coauthor
Dr. Massimiliano Vasile, United Kingdom
- Coauthor
Dr. Gianmarco Radice, University of Glasgow, United Kingdom
- Year
2008
- Abstract
The threat that asteroids pose to life on Earth has for long been acknowledged (L.W.Alvarez et al.;1980). Many techniques to deviate threatening asteroids have been proposed in the last three decades. Some of these techniques propose the application of a very low acceleration on the asteroid, while others use a high speed impact or an explosion to produce an impulsive change in linear momentum. If an impulsive deviation technique is applied to an asteroid, and the energy delivered by the deviation method is above a limit threshold (Eileen V.Ryan and H.J.Melosh;1998; K.A.Holsapple;1993), a catastrophic fragmentation, i.e., fragmentation such that the largest fragment contains less than half the mass of the original asteroid, is likely to occur. Few studies have classified, evaluated and compared the existing techniques in terms of deviation efficiency (J.P.Sanchez et al.;2008; Thomas J.Ahrens and Alan W.Harris;1992), but little was done on the analysis of a possible fragmentation. This paper examines the consequences of a catastrophic fragmentation due to an impulsive deviation strategy. In particular, we consider the minimum level of energy (collisional energy) required to deviate the asteroid by more than two Earth radii at the Minimum Interception Distance from the Earth, which is a function of the warning time, i.e. time available before the impact of the asteroid with the Earth. The collisional energy is then compared with the predicted specific energy required to completely fracture the asteroid. As will be shown in the paper, for some warning times the collision energy can rise well above the theoretical catastrophic fragmentation limit. As a consequence the asteroid can fragment in an unpredictable number of pieces having different mass and velocity. The velocity associated to each piece of the asteroid uniquely determines its future trajectory. In the paper, we consider two possible cases: the fragmentation being the desired outcome of the deviation strategy or the undesired product of a mitigation mission. In the latter case we will analyse the evolution of the cloud of fragments and the probability of the bigger pieces in the cloud impacting the Earth. In the former case, we will investigate some possible strategies that allow us to minimize the risk of impact from the bigger pieces in the cloud. Fragmentation is here considered as a stochastic process, using different probability distribution functions for both fragment size and velocity. The evolution in time of the cloud of fragments is computed using Liouville’s theorem and considering a two body dynamics. A number of illustrative examples with asteroids of different size and orbital characteristics will be presented.
- Abstract document
- Manuscript document
IAC-08.C1.3.10.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.