www.strath.ac.uk/spacespace@strath.ac.uk

Synergistic Approach of Asteroid Exploitation and

Planetary Protection

From Threat to Action

9-12 May 2011

Joan-Pau Sanchez

2011 IAA Planetary Defense Conference

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

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.

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:

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

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

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?

Thank you!Contact email:

jpau.sanchez@strath.ac.uk