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Modelle Und Methoden Zur Abwendung Von Kollisionen Von Asteroiden Und Kometen Mit Der Erde

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Modelle Und Methoden Zur Abwendung Von Kollisionen Von Asteroiden Und Kometen Mit Der Erde Modelle und Methoden zur Abwendung von Kollisionen von Asteroiden und Kometen mit der Erde von Diplom-Ingenieur Ralph Kahle aus Dresden von der Fakultät V - Verkehrs- und Maschinensysteme - der Technischen Universität Berlin zur Erlangung des akademischen Grades Doktor der Ingenieurwissenschaften - Dr.-Ing. - genehmigte Dissertation Gutachter: Prof. Dr.-Ing. K. Brieß Gutachter: Dr. E. Kührt Tag der wissenschaftlichen Aussprache: 1. August 2005 Berlin 2005 D 83 Zusammenfassung In der Arbeit werden verschiedene Aspekte der Abwendung der Kollision eines Asteroiden oder Kometen mit der Erde untersucht. Hierzu wird zunächst eine künstliche Population von Kollisionsobjekten definiert, welche die gegenwärtig bekannten physikalischen und dyna- mischen Objekteigenschaften repräsentiert. Ausgehend von der numerischen Modellierung der interplanetaren Objektbahnen unter Berücksichtigung der Störeinflüsse der Planeten und von Modellrechnungen zum atmosphärischen Eintritt wird das Schadenspotential einer Kollision quantifiziert. Für die Kollisionsabwendung werden primär die Objektbahnbeeinflus- sung unter Einsatz eines neuen Verfahrens zur Bestimmung der optimalen Bahnänderungs- geschwindigkeit in einer N-Körperumgebung und sekundär die Objektzerstörung analysiert. Als Ergebnis von Systemstudien zu diversen Technologien eignen sich besonders der Projektilbeschuss und die nukleare Sprengung zur Bahnbeeinflussung von Asteroiden mit einem Durchmesser D < 500 m und < 8 km, respektive. Der Einsatz von Antriebstechnolo- gien oder eines Sonnenspiegels verspricht ein geringeres Antriebsvermögen und beinhaltet erhebliche technologische Schwierigkeiten. Kometen können aufgrund der Bahnunsicherheit infolge der nicht-gravitativen Kraft nicht ausreichend abgelenkt werden. Sie können jedoch für D < 2 km durch eine nukleare Explosion zerstört werden. Die Anwendung numerischer Methoden zur impulsiven Gravity-Assist- sowie kontinuierlichen direkten Transferbahnbe- stimmung zeigt die generelle Erreichbarkeit der Modellobjekte durch konventionelle Raum- fahrzeuge sowie die Durchführbarkeit der Kollisionsabwendung bei einer Vorwarnzeit von 10 bis 30 Jahren. Diese ist jedoch mit den heutigen Suchprogrammen besonders für Objekte mit D < 250 m noch nicht gegeben, so dass trotz verfügbarer Technologien zur Kollisions- abwendung kein sicherer Schutz vor einer Asteroiden- oder Kometenkollision existiert. Abstract The work analyses various aspects on preventing the collision of an asteroid or comet with the Earth. For this purpose an artificial population of colliding objects is defined, which reflects current knowledge on their physical and dynamical properties. Based on numerical models describing interplanetary trajectory and atmospheric entry of an object the damage potential by a collision is evaluated. Collision avoidance is investigated primary in terms of orbit deflection, where a novel method for the determination of optimal change of orbital velocity within an n-body environment is applied, and secondary in terms of object destruction. From system analysis of different technologies it is found that spacecraft projectile and nuclear explosion are suitable for deflecting the orbit of asteroids with diameters D < 500 m and < 8 km, respectively. The application of propulsion systems and solar collectors results in a smaller deflection capability and further leads to significant technological problems. The sufficient orbital deflection of comets is hampered by orbital uncertainties caused by the non-gravitational force. Instead, comets with D < 2 km can be destroyed by means of nuclear explosion. The application of numerical methods for trajectory computation by means of impulsive gravity-assist as well as continous direct transfers reveals that the model objects can generally be reached by conventional space- craft technology, and collision avoidance is feasible if 10 to 30 years of warning time apply. But, the latter can not be guaranteed by current search programmes especially for objects with D < 250 m. Thus, although technology for collision avoidance is available, a sufficient protection from asteroid or comet collision does not exist. Danksagung Die vorliegende Arbeit entstand während meiner Tätigkeit als Doktorand am Institut für Planetenforschung des Deutschen Zentrums für Luft- und Raumfahrt e.V. (DLR) in Berlin- Adlershof. Während dieser Zeit erhielt ich sehr viel Unterstützung, ohne die ich dieses Projekt nicht hätte bewältigen können. Ich danke Herrn Dr. Ekkehard Kührt und Herrn Dr. Gerhard Hahn (DLR-BA) für die Betreuung, die ständige Diskussionsbereitschaft und die vielen wertvollen Ratschläge, die zum Gelingen dieser Arbeit erheblich beitrugen. Außerdem danke ich Herrn Dr. Kührt sowie Herrn Prof. Dr. Klaus Brieß (TU Berlin) für die Begutachtung dieser Arbeit. Herrn Dr. Christian Gritzner (TU Dresden), Herrn Prof. Dr. Gerhard Neukum (FU Berlin) und Herrn Dr. Michael Reichert (DLR-KP) danke ich für ihr Engagement bei der Einrichtung meiner Promotionsstelle am DLR-BA. Herrn Prof. Dr. Stefanos Fasoulas (TU Dresden) danke ich für die interessanten Diskussionen und wertvollen Hinweise zu bahnmechanischen Problemen. Herrn Dr. Jörg Knollenberg (DLR-BA) danke ich für wichtige Anregungen auf dem Gebiet der Kometenphysik. Herrn Prof. Dr. Uwe Motschmann (TU Braunschweig) danke ich für den Austausch zu magnetoplasmadynamischen Antrieben. Herrn Detlef DeNiem (DLR-BA) danke ich für die interessanten Ausführungen zur Einschlagskratermodellierung. Herrn Dr. Steve Chesley (NASA-JPL) danke ich für die zur Verfügungstellung der Bahndaten von ca. 58.000 virtuellen potentiell gefährlichen Asteroiden. Herrn Prof. Dr. Jay Melosh (University of Arizona) und Herrn Hans Krüger (TU Dresden) danke ich für die interessanten Diskussionen zum Sonnenspiegel. Herrn Sebastian Kern (TU Dresden) danke ich für die innovativen Gedanken zur in-situ Ressourcennutzung. Herrn Dr. David Dearborn (Lawrence Livermore National Laboratory) danke ich für die hilfreichen Kommentare zu Technologien der Bahnbeeinflussung. Herrn Mathias Grafe (TU Dresden) danke ich für die Unterstützung bei der Bestimmung von Transferbahnen für kontinuierliche Antriebe und Herrn Prof. Dr. Cristof Bueskens (TU Bremen) für die zur Verfügungstellung einer Rechenlizenz für NUDOCCCS. Außerdem möchte ich mich bei allen nicht namentlich genannten Freunden und Kollegen für die zahlreichen Diskussionen und Anregungen bedanken. Schließlich gilt mein Dank meiner Frau Astrid und meiner Tochter Lena, die zu oft auf ein gemeinsames Wochenende verzichten mussten. Eidesstattliche Erklärung Hiermit erkläre ich, die von mir dem Promotionsausschuss der Fakultät V - Verkehrs- und Maschinensysteme - der Technischen Universität Berlin zur Erlangung des akademischen Grades „Doktor der Ingenieurwissenschaften“ (Dr.-Ing.) vorgelegte Dissertation zum Thema „Modelle und Methoden zur Abwendung von Kollisionen von Asteroiden und Kometen mit der Erde“ vollkommen selbstständig verfasst zu haben. Es wurden keine anderen als die angegebenen Quellen und Hilfsmittel benutzt. Zitate wurden kenntlich gemacht. Berlin, den 8. April 2005 Ralph Kahle Inhaltsverzeichnis 1. EINLEITUNG...................................................................................................................................8 1.1 ASTEROIDEN UND KOMETEN – ENTSTEHUNG, DYNAMISCHE EVOLUTION UND GEFAHR...................................8 1.1.1 Asteroiden, Kometen und Übergangsobjekte........................................................................................8 1.1.2 Erdnahe Objekte.................................................................................................................................11 1.1.3 Gefahr durch Asteroiden und Kometen..............................................................................................14 1.2 BISHERIGE ARBEITEN UND ZIELSETZUNG DIESER ARBEIT........................................................................16 2. MODELLPOPULATION GEFÄHRLICHER ASTEROIDEN UND KOMETEN.................19 2.1 BAHNEIGENSCHAFTEN.......................................................................................................................19 2.2 WEITERE EIGENSCHAFTEN.................................................................................................................23 2.2.1 Objektgröße und Häufigkeit................................................................................................................23 2.2.2 Wahl der Kollisionszeitpunkte............................................................................................................25 2.2.3 Spektraltypen.......................................................................................................................................26 2.2.4 Innere Struktur....................................................................................................................................28 2.2.5 Rotationsperiode und Objektform.......................................................................................................29 2.2.6 Festigkeit.............................................................................................................................................31 2.2.7 Dichte und Porosität...........................................................................................................................32 2.3 VORWARNZEIT................................................................................................................................32 2.4 ZUSAMMENFASSUNG DER MODELLPOPULATION......................................................................................34
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