Solar Sailing KEI Apophis Deflection Mission Solar Sailing Kinetic Energy Impactor (KEI) Bernd Dachwald Ralph Kahle Mission Design Tradeoffs for Impacting and Bong Wie Deflecting Asteroid 99942 Apophis Outline Introduction Mission Design German Aerospace Center (DLR) Mission Operations Section Bernd Dachwald Variation of Oberpfaffenhofen, 82234 Wessling, Germany Mission Design bernd.dachwald@dlr.de Parameters German Aerospace Center (DLR) Summary and Space Flight Technology Section Ralph Kahle Conclusions Oberpfaffenhofen, 82234 Wessling, Germany ralph.kahle@dlr.de Arizona State University Department of Mechanical & Aerospace Engineering Bong Wie Tempe, AZ 85287, USA bong.wie@asu.edu AIAA/AAS Astrodynamics Specialist Conference 21–24 August 2006, Keystone, CO
Solar Sailing Outline KEI Apophis Deflection Mission Introduction Bernd Dachwald Ralph Kahle The Hazard from Near-Earth Objects Bong Wie The Case of 99942 Apophis Outline Kinetic Energy Impactor Deflection Introduction Scenario (I) Kinetic Energy Impacts Mission Design Solar Sail Force Model Variation of Mission Design Simulation Model Parameters Evolutionary Neurocontrol Summary and Conclusions Mission Design Pre-2029-Encounter Impact Scenario (II) Post-2029-Encounter Impact Variation of Mission Design Parameters Sail Temperature Limit Solar Sail Degradation Summary and Conclusions
Solar Sailing Near-Earth Asteroids (NEAs) KEI Apophis Deflection Mission Bernd Dachwald Ralph Kahle ◮ The orbits of NEAs intersect or pass near the orbit of Bong Wie Earth Outline ◮ 838 NEAs with a diameter d � 1 km are currently Introduction known The Hazard from Near-Earth Objects The Case of 99942 ◮ The entire population contains perhaps more than 1 000 Apophis Kinetic Energy Impactor Deflection objects of this size Scenario (I) Kinetic Energy ◮ All NEAs with MOID ≤ 0 . 05 AU and d � 200 m are Impacts Solar Sail Force Model Potentially Hazardous Asteroids (PHAs) Simulation Model Evolutionary ◮ There are currently 790 known PHAs, 161 of them with Neurocontrol Mission Design d � 1 km Variation of ◮ Even asteroids that do not intersect Earth’s orbit may Mission Design Parameters evolve into Earth-crossers, since their orbits are chaotic, Summary and having a relatively short dynamical lifetime Conclusions ( ∼ 10 7 years)
Solar Sailing The Case of 99942 Apophis KEI Apophis Deflection Mission ◮ In June 2004, a NEA with a diameter of about 320 m was Bernd Dachwald Ralph Kahle discovered (firstly designated 2004 MN4 and later 99942 Bong Wie Apophis) Outline ◮ Very close encounter with Earth on 13 Apr 2029 Introduction The Hazard from ◮ With a non-negligible probability subsequent very close Near-Earth Objects The Case of 99942 Apophis encounter or even impact on 13 Apr 2036 or later Kinetic Energy Impactor Deflection ◮ Currently estimated probability that Apophis impacts the Scenario (I) Kinetic Energy Impacts Earth in 2036 is 1 / 45 000 Solar Sail Force Model ◮ Earth impact velocity of about 12 . 6 km / s Simulation Model Evolutionary Neurocontrol ◮ Released energy would equal about 875 Megatons of TNT Mission Design Variation of ◮ Whether or not Apophis will impact the Earth in 2036 or Mission Design later will be decided by its close encounter in 2029. (If the Parameters asteroid passes through one of several so-called “gravitational Summary and Conclusions keyholes” ( ∅ ≈ 600 m), it will get into a resonant orbit and impact the Earth in one of its later encounters, if no counter-measures are taken)
Solar Sailing Solar Sail Kinetic Energy Impactors (KEIs) KEI Apophis Deflection Mission (Multiple) KEIs impact Apophis at perihelion from a trajectory that is Bernd Dachwald retrograde w.r.t. Apophis’ orbit ( ⇒ v imp ≈ 75 km / s) Ralph Kahle Bong Wie Outline Introduction The Hazard from Near-Earth Objects The Case of 99942 Apophis Kinetic Energy Impactor Deflection Scenario (I) Kinetic Energy Impacts Solar Sail Force Model Simulation Model Evolutionary Neurocontrol Mission Design Variation of Mission Design Parameters Summary and Conclusions
Solar Sailing Scenario I KEI Apophis Deflection Mission (fictional) Bernd Dachwald Ralph Kahle 1. In 2013 (very favorable radar and optical observations), it is found Bong Wie that in its 2029-encounter Apophis is likely to fly through the 2036-keyhole ⇒ resonant return to hit the Earth in 2036 Outline Introduction 2. At 01 Jan 2020, a solar sail KEI is launched from Earth The Hazard from Near-Earth Objects ◮ 160 m × 160 m, 168 kg solar sail assembly The Case of 99942 Apophis ◮ 150 kg impactor Kinetic Energy Impactor Deflection ◮ a c = 0 . 5 mm / s 2 Scenario (I) Kinetic Energy ◮ T lim = 240 ◦ C Impacts Solar Sail Force ◮ C 3 = 0 km 2 / s 2 Model Simulation Model Evolutionary 3. After having attained a trajectory that is retrograde to Apophis’ Neurocontrol orbit, the solar sail KEI is brought onto a collision trajectory, from Mission Design where it can impact Apophis in 2026 in the case that Apophis is Variation of Mission Design still likely to fly through the keyhole Parameters Two kinds of collision trajectories are investigated: Summary and Conclusions ◮ A trajectory that maximizes v imp ◮ An exactly retrograde orbit (ERO) that encounters Apophis at every perihelion and aphelion passage
Solar Sailing Scenario I KEI Apophis Deflection Mission (fictional) Bernd Dachwald Ralph Kahle 1. In 2013 (very favorable radar and optical observations), it is found Bong Wie that in its 2029-encounter Apophis is likely to fly through the 2036-keyhole ⇒ resonant return to hit the Earth in 2036 Outline Introduction 2. At 01 Jan 2020, a solar sail KEI is launched from Earth The Hazard from Near-Earth Objects ◮ 160 m × 160 m, 168 kg solar sail assembly The Case of 99942 Apophis ◮ 150 kg impactor Kinetic Energy Impactor Deflection ◮ a c = 0 . 5 mm / s 2 Scenario (I) Kinetic Energy ◮ T lim = 240 ◦ C Impacts Solar Sail Force ◮ C 3 = 0 km 2 / s 2 Model Simulation Model Evolutionary 3. After having attained a trajectory that is retrograde to Apophis’ Neurocontrol orbit, the solar sail KEI is brought onto a collision trajectory, from Mission Design where it can impact Apophis in 2026 in the case that Apophis is Variation of Mission Design still likely to fly through the keyhole Parameters Two kinds of collision trajectories are investigated: Summary and Conclusions ◮ A trajectory that maximizes v imp ◮ An exactly retrograde orbit (ERO) that encounters Apophis at every perihelion and aphelion passage
Solar Sailing Scenario I KEI Apophis Deflection Mission (fictional) Bernd Dachwald Ralph Kahle 1. In 2013 (very favorable radar and optical observations), it is found Bong Wie that in its 2029-encounter Apophis is likely to fly through the 2036-keyhole ⇒ resonant return to hit the Earth in 2036 Outline Introduction 2. At 01 Jan 2020, a solar sail KEI is launched from Earth The Hazard from Near-Earth Objects ◮ 160 m × 160 m, 168 kg solar sail assembly The Case of 99942 Apophis ◮ 150 kg impactor Kinetic Energy Impactor Deflection ◮ a c = 0 . 5 mm / s 2 Scenario (I) Kinetic Energy ◮ T lim = 240 ◦ C Impacts Solar Sail Force ◮ C 3 = 0 km 2 / s 2 Model Simulation Model Evolutionary 3. After having attained a trajectory that is retrograde to Apophis’ Neurocontrol orbit, the solar sail KEI is brought onto a collision trajectory, from Mission Design where it can impact Apophis in 2026 in the case that Apophis is Variation of Mission Design still likely to fly through the keyhole Parameters Two kinds of collision trajectories are investigated: Summary and Conclusions ◮ A trajectory that maximizes v imp ◮ An exactly retrograde orbit (ERO) that encounters Apophis at every perihelion and aphelion passage
Solar Sailing Potential Trajectory for a Pre-2029-Impact KEI Apophis Deflection Mission Trajectory that maximizes v imp Bernd Dachwald Ralph Kahle Bong Wie Launch at Earth Sail Temp. [K] Outline 520 Introduction 500 450 The Hazard from Apophis orbit Near-Earth Objects 400 The Case of 99942 350 Apophis 300 Kinetic Energy Impactor Deflection Scenario (I) Kinetic Energy Impacts Solar Sail Force Model Simulation Model Evolutionary Earth orbit Neurocontrol Mission Design Retrograde Apophis impact Variation of Mission duration: 6 years Mission Design Parameters Impact velocity: 75 . 4 km / s Summary and Conclusions
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