Head-on impact deflection of NEAs: a case study for 99942 Apophis

  • Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value

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Metadaten
Author:Bernd DachwaldORCiD, Ralph Kahle, Bong Wie
Parent Title (English):Planetary Defense Conference 2007
Document Type:Conference Proceeding
Language:English
Year of Completion:2007
Date of the Publication (Server):2022/03/28
First Page:1
Last Page:12
Note:
Planetary Defense Conference 2007, Wahington D.C., USA, 05-08 March 2007
Link:http://spacesailing.net/paper/200703_washington_dachwaldkahlewie.pdf
Zugriffsart:weltweit
Institutes:FH Aachen / Fachbereich Luft- und Raumfahrttechnik
FH Aachen / IfB - Institut für Bioengineering