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www.strath.ac.uk/[email protected]
Synergistic Approach of Asteroid Exploitation and
Planetary Protection
From Threat to Action
9-12 May 2011
Joan-Pau Sanchez
2011 IAA Planetary Defense Conference
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Introduction
Possible synergies between space systems capable of deflecting realistic impact threat and, at the same time, gravitationally capturing small asteroids for later resource exploitation.• Low-thrust tugboat model as a space system.• Tugboat system attaches to the
asteroid surface and provides continuous thrust.
1. Assessment on the capability of such a system to deflect realisticimpact threats.
2. Statistical population that could bemanoeuvre into Earth-bound orbits.
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
9-12 May 2011 2Joan Pau Sanchez
Source: ESA
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Deflection: Procedure
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
9-12 May 2011 3Joan Pau Sanchez
Earth orbit
NEO orbit
Rendezvous Trajectory
17,518 impactors.
Deflection Action
1. Baseline Design• 5,000 kg wet mass• v∞ of 2.5 km/s•Medium-to-large mission
The objective is to compute the mass of the largest object that the tugboat system could deflect from each one of the impacting orbits.
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Deflection: Set of Virtual Impactors
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
9-12 May 2011 4Joan Pau Sanchez
Set of virtual impactors plotted as dots of size and colour as a function of the relative frequency that should be expected for each impactor.
<p>=1%
<p>=0.2%
<p>=0.05%
<p>=0.01%
<p>≤0.005%
Complete set of weighted impactors:
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Deflection: Planetary Protection
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
9-12 May 2011 5Joan Pau Sanchez
Type of Event Approximate range of Impact Energies (MT)
Approximate Range Size of
Impactor
Airburst 1 to 10 MT 15 to 75 mLocal Scale 10 to 100 MT 30 to 170 m
Regional Scale 100 to 1,000 MT 70 to 360 mContinental Scale 1,000 MT to 20,000 MT 150 m to 1 km
Global 20,000 MT to 10,000,000 MT 400 m to 8 km
Mass Extinction Above 10,000,000 MT >3.5 km
Table 1: Impact hazard categories
Type of Event Lead Time
1 year 2.5 years 5 Years 10 Years 20 years
Airburst 51% 93% 99% 100% 100%
Local Damage 0.01% 1.6% 18% 78% 98%
Regional D. 0% 0% 0% 0% 6%
Continental D. 0% 0% 0% 0% 0%
Global D. 0% 0% 0% 0% 0%
Table 2: Levels of Planetary Protection
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Asteroid Capture Concept
9-12 May 2011 6Joan Pau Sanchez
On the possibility of moving small near Earth asteroids and inserting them onto Earth bound trajectories for later utilization.• How much material could a 5000 kg low thrust spacecraft
transport back to Earth? Low Thrust is a very limiting constraint.
• The final Earth orbit insertion needs to be ballistic or unaided by the propulsion system.
Ballistic capture may be possible for objects with relative velocities v∞ below 1 km/s.
Grazing aero-assisted trajectories may be possible to capture objects with relative velocities v∞ above 1 km/s.• Only aero-braking trajectories are designed so that
maximum dynamical pressure does not exceed material Strength.
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
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Asteroid Capture Concept
Type of Capture
Lead Time
1 year 2.5 years 5 Years 10 Years 20 years
Ballistic >60t(12)
>105t(21)
>220t(44)
>385t(77)
>590t(118)
Dustball Str./10
>170t(34)
>290t(58)
>610t(122)
>1,060t(212)
>1,675t(335)
Dustball Strength
>520t(104)
>915t(183)
>2,130t(426)
>3,820t(764)
>6,420t(1284)
Stony Strength
>2,955t(591)
>4,200t(840)
>8,200t(1640)
>13,140t(2628)
>22,965t(4593)
Iron-Nickel Str.
>6,965t(1394)
>11,490t(2298)
>25,585t(5117)
>40,745t(8149)
>64,710t(12943)
Introduction
Deflection: 1. Procedure
2. Impactors
3. Protection
Asteroid Capture
9-12 May 2011 7Joan Pau Sanchez
Table 3: Largest mass returned to Earth - parenthesis: fraction returned mass compared with the initial wet mass of the spacecraft
How much material could a 5000 kg low thrust spacecraft transport back to Earth?