1 ORBITAL DEBRIS: TOWARDS SUSTAINABLE SPACE ACTIVITIES PARIS SPACE WEEK 2015 Christophe BONNAL CNES...

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ORBITAL DEBRIS:

TOWARDS SUSTAINABLE SPACE ACTIVITIES

PARIS SPACE WEEK 2015

Christophe BONNALCNES – Launcher Directorate – Senior Expert

Chairman – Space Debris Committee

International Academy of Astronautics

[email protected]

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CO

NT

EN

T NUMBER OF OBJECTS IN ORBIT UNCONTROLLED REENTRY COLLISION RISKS SOURCES OF ORBITAL DEBRIS POTENTIAL SOLUTIONS MITIGATION RULES SHIELDING COLLISION AVOIDANCE REMEDIATION – ACTIVE DEBRIS REMOVAL

CONCLUSIONS

Christophe BONNAL - Paris Space Week 2015 – 04.02.2015

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Charts from NASA Space Debris Office presenting catalogued objects 10 cm in LEO1 m in GEO

Beware the exaggerated size of the dots…

GROWTH OF THE EARTH SATELLITE POPULATION

Texte1

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Texte1

Texte2

1960

Cataloged objects >10 cm diameterChristophe BONNAL - Paris Space Week 2015 – 04.02.2015

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Texte1

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1965

Cataloged objects >10 cm diameter


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1970



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1975



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1980



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1985



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1990



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1995



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2000



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2005



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2010



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NUMBER OF OBJECTS IN ORBIT

The number of objects in space strongly increases in time:

- Mainly in Low Earth Orbits (Region A = 2000 km, i)- Significant in Geostationary Orbit (Region B = GEO 200 km 15°)

- Despite the reduction in the number of launches compared to 70-80’s

- Despite mitigation rules since 1995 - 2002

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195

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Mas

s in

Orb

it (

mill

ion

s o

f kg

)

Year

Monthly Mass of Objects in Earth Orbit by Object Type

Total Objects

Spacecraft

Rocket Bodies

Fragmentation Debris

Mission-related Debris

Number of successful orbital launches per year

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1961

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1969

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1981

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1993

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2009

2013

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NUMBER OF OBJECTS IN ORBIT

Roughly 23,000 large objects in space:

17,200 catalogued objects

additional 6,000 non catalogued by US but identified

720,000 debris larger than 1 cm

135 million debris larger than 1 mm

U But space is very wide!

At a given time, only 18 large objects above France

Roughly 1000 active satellites (5 %):

450 in GEO 450 in LEO

100 elsewhere

functional satellites

5%non functional

satellites17%

upper stages13%

operational debris13%

fragments52%


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SITUATION IN ORBIT: NUMBER OF CATALOGUED OBJECTS (NASA)Iridium 33 – Cosmos 2251

Fengyun 1C

H8 V16

USA 193

HPAS Pegasus XL

Derival 214 / yr

Derival 1000 / yr


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RANDOM ATMOSPHERIC REENTRY

What goes up will go down: Orbital objects in Low Earth Orbit reenter atmosphere after some time

Residual atmosphere generates a drag which progressively lowers the orbit Atmospheric reentry leads to vaporization of most of the materials

Combination of heat flux and mechanical stresses during reentry

But roughly 10 to 20% in mass survive reentry (refractory materials, dense elements, Russian dolls effect, …)

No way to know with precision where and when an impact will occur High number of reentries:

1 or 2 catalogued objects per day

1 or 2 large integer object (satellite or stage) per week Potential casualty risk


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COLLISION RISKS

Collision risk in Sun Synchronous Orbit today is comparable to the unreliability of the satellite or of its launcher:

Collision occur between debris and operational spacecraft

Can lead to loss of function of an operational spacecraft

Very complex modelling:

steel debris of 1 cm radius = 1 MJ = Large car at 130 km/h aluminum debris of 1 mm radius = 1 kJ = Bowling ball at 100 km/h

Real criteria for catastrophic collision: impact > 40 J/g

Examples:

Probability of mission failure of Spot 5

3 to 5% over lifetime (CNES)

Probability of failure of Sentinel-1 over lifetime

Component loss = 53 %, Mission loss > 3,2 % (TAS-I)


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SOURCES OF ORBITAL DEBRIS

4 main debris sources:

Launches Example of 2014: 92 launches 334 catalogued objects today

Aging of materials (Thermal Protections, electrical cells, Mylars…)

Mainly very small debris

Fragmentations, voluntary or not

280 registered end of 2013

Examples of accidental fragmentation (154):

Upper Stage of Ariane V16 (Spot 1): 796 catalogued debris in 1986Upper Stage of Pegasus XL: 601 catalogued debris in 1996

Examples of voluntary fragmentations (59):

Feng-Yun 1C: 3000 catalogued debris in 2007USA-193 : 500 catalogued debris in 2008, none remaining today

Number is lowering thanks mainly to passivation measures

Collisions 5 official ones, 64 suspected with smaller debris

Example: Iridium 33 – Cosmos 2251 in 2009 2269 catalogued debris todayChristophe BONNAL - Paris Space Week 2015 – 04.02.2015

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COLLISION IRIDIUM 33 – COSMOS 2251 (AGI)


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A chain reaction is feared in Low Earth Orbit:

Two antagonist phenomenon

1. Permanent generation of new orbital objects

2. Natural cleansing of orbits by atmospheric drag

Chain reaction when 1 > 2

The higher the altitude the lower the drag is

but the lower the number of debris is and vice versa…

Known as the Kessler syndrome

Uncontrolled increase if the “collision” part of debris generation becomes lager than the “atmospheric cleansing”

No worldwide consensus yet: very complex studies

Suspected between 700 and 1100 km altitude (and 1500 km TBC)

KESSLER SYNDROME


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DENSITY OF OBJECTS IN LEO(Source NASA)

A-trainEssaim – Demeter

IridiumOrbcomm

SpotRadarsatEnvisat

ERS

Corot

JasonTOPEX/Poseidon

Globalstar

Rapideye

Meteor


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It is fundamental to comply with current mitigation measures:

1. Short term- Minimization of operational debris; no voluntary break-ups,- Systematic passivation to prevent accidental break-ups,- Two protected zones (LEO, GEO): 25 years rule.

2. Long term- Systematic deorbitation or escape.

Very wide number of reference documents:- IADC Guidelines (2002), - UN Guidelines (2007), - National Standards (CNES 1999), ESA Standard (2007)- European Code of Conduct (approved ASI-BNSC-CNES-DLR-ESA 2004),- ISO 24113 standard and second tier standards (under approval),- French Space Law LOS (approved 2008, into force since Dec.2010).

POTENTIAL ACTIONS: MITIGATION RULES


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POTENTIAL ACTIONS: SHIELDING


Satellites can be shielded against small impacts:

Wide variety of shields

Multi-walls concepts

large number of standards

Commonly applied on “manned” satellites (ISS, ATV…)

Typical limitation: 1 or 2 cm

Energy is too high above this limit

Strong impacts on satellite designs:

Thermal control, communications, mass, costs…

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POTENTIAL ACTIONS: COLLISION AVOIDANCE


In some cases, satellites can avoid a collision: Collision avoidance:

An operational satellite is maneuverable

Orbits of large debris can be predicted

Collisions with catalogued objects can be anticipated

A maneuver can be commanded prior to collision

Very complex modelling:

Need to have very accurate orbital parameters

Dedicated sensors are required (radars, telescopes)

Space Surveillance Systems

CNES offers an anti-collision service (CAESAR) to protect active satellites Orbital catalog produced by the radar system GRAVES

Protects collision on operational satellite, but does not prevent collisions between debris

POTENTIAL ACTIONS: COLLISION AVOIDANCE

French Space Surveillance Systems

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POTENTIAL ACTIONS: REMEDIATION – ACTIVE DEBRIS REMOVAL


Situation can be improved if the worst debris are retrieved: Active Retrieval of 5 to 10 debris every year could stabilize population:

Complex modelling: no consensus yet

Could be a long term solution

ADR can take a very wide range of solutions:

Contact-less: laser, electrostatic, ion-beam effect…

Contact without control: harpoon, clamp, net, air-bags, EDT…

Contact with control: robotic arm, tentacles…

Numerous studies at worldwide level

Strong synergies with “On Orbit Servicing”

No clear financial scheme yet Business plan is hard to understand

Legal, insurance, political, military problems

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CONCLUSIONS


Whatever the technical solution, an action shall be undertaken: Poor respect of remediation rules today:

Roughly 50% of the orbited objects cope with the 25-year rule

Numerous orbital objects are not passivated

Significant cost of proposed measures:

No clear conclusions yet

Costly deorbitation at end of life

Impact on design

No business plan for Active Debris Removal

Legal impact of proposed measures

No consensus on situation at worldwide level Actions at UN and IADC level (Inter Agency Coordination Committee)

Need for a revolution in mentalities “Clean” space operations

Long Term Sustainable Activities is questioned

1 ORBITAL DEBRIS: TOWARDS SUSTAINABLE SPACE ACTIVITIES PARIS SPACE WEEK 2015 Christophe BONNAL CNES...

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