SPACE DEBRIS Fernand ALBY What is the situation in-orbit? What are the possible actions?

SPACE DEBRIS

Fernand ALBY

What is the situation in-orbit?

What are the possible actions?

1date

2

Cataloged objects > 10 cm

1960

Number of objects

3

1965


Number of objects

4

1970


Number of objects

5

1975


Number of objects

6

1980


Number of objects

7

1985


Number of objects

8

1990


Number of objects

9

1995


Number of objects

10

2000


Number of objects

11

2005


Number of objects

12

April 2008


Number of objects

13

January 2009


Number of objects

14

Origin of the debris

1-what is the situation in orbit ?

Status of the population

Risks in orbit

Risks on ground

15

SITUATION IN ORBIT

since 1957:

5% 8%14%

20%

53%

Several tens of millions of objects between 1mm and 1 cm(not cataloged)

about 5 000 launches

more than 220 on-orbit fragmentations

20 000 objects > 10 cm (15 000 in the public catalog)

500 000 objects between 1 and 10 cm(not cataloged)

16

Ariane V16

Fengyun 1C

Iridium-CosmosSource NASA

Nu

mb

er o

f o

bje

cts

Evolution Number of cataloged objects

17

Consequences in orbitRisks of collision

The objects are not floating in space…They are orbiting the EarthTheir velocity is around 8 km/s (in LEO)

Very large kinetic energyExample : aluminum sphere =1 mm at 10 km/s

->perforation of a 4 mm-thick aluminum wall

Even « small » debris may produce important damages

No shield can protect against particles > 2 cm (example ISS)

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Hubble Space Telescope

Exampleof impacts on HST solar panels

19

Example: Hubble Space Telescope

Deployment of the solar panels at ESTECMore than 5000 impacts visible to the naked eye

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Exampleof impacts on HST solar panels

21

Space Shuttle

Impact HublotImpact on a window

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Hublot

Space Shuttle

Bord d’attaque des ailes

window

Wing leading edge

23

International Space Station

24

Cerise

24 July 1996

25

10 February 2009

Iridium 33Cosmos 2251

26

10 February 2009

Iridium 33Cosmos 2251

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Very high speed ~ 8 km/s.

Important heating, fusion of most of materials

Aerodynamic loads.

Fragmentation or explosion of the vehicle

around 75-80 km altitude.

Some materials may survive to the reentry :

Stainless steel, titanium, ceramics,…

20 to 40 % of initial mass reach the ground

Atmospheric reentry of a space object:

Consequences on ground Risk of debris fall

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Atmospheric reentries

One or several manoeuvresselection of reentry time and positionSelection of debris impact zone (ocean)

Uncontrolled reentries

Atmospheric densitydragaltitude decrease

Random fall in the latitude band corresponding to the inclination

Debris impact zone unpredictable

Controlled reentries

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Thermal protection

Combustion chamber

High pressure tank (30 kg)

250 kg stainless steel tank

Delta II upper stage, Texas (1997)

Example of uncontrolled reentry

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SPOUA

10-5 FOOTPRINT

10-2 FOOTPRINT

Example of controlled reentryATV Automated Transfer Vehicule

29 September 2008

31

to better know the situation

2-what are the possible actions ?

to protect against debris

to limit the debris creation

to clean space

32

TO BETTER KNOW THE SITUATION… SPACE SITUATIONAL AWARENESS

Objective: knowledge of population of objects orbiting the Earth

Needs: Military Civilian: prevention of collisions, prediction of reentries

Principle: « small » debris: statistical knowledge (flux models) « large debris »: deterministic knowledge (catalogues)

Facilities: Detection radars Tracking radars Telescopes: detection and tracking

low altitude

High altitude

Dual activity

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About 15 000 objects in the public catalog

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Bi-static radar Developed by ONERA Operated by Air Force (CDAOA)

■ Emission: 4 panels (phased array antennas) Field of view 180° towards South

■ Reception: Field of omnidirectional antennas Narrow beam formed by computation Angular and doppler measurements

■ goal: catalog satellites in low Earth orbit

RADAR GRAVES

APTBLP

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■Radars SATAM (French Air Force): located at: Suippes Captieux Solenzara

■DGA radars:Le Monge:

Armor x 2 Normandie

ToulonQuimper

TRACKING FACILITIES

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■Radar TIRA (Tracking and Imagery Radar)Located near Bonn, belongs to FHR (Fraunhofer Institut)

diameter 34 m

Accurate tracking and imagery

■Telescopes TAROT (CNRS)Detection and tracking of objects (0,5-1m) in GEO

Observatoire de la Côte d’Azur and Chili

Computation by CNES

OTHER FACILITIES

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TO PROTECT AGAINST DEBRIS… PREDICTION OF COLLISION RISKS

■14 civilian and military satellites controlled by CNES in LEO (altitude ~ 600 / 1200 km):

CALIPSO, COROT, ELISA E12, ELISA E24, ELISA W11, ELISA W23, HELIOS2A, HELIOS2B, JASON2, PICARD, PLEIADES 1A, PLEIADES 1B, SMOS et SPOT5.

Corot

Spot 5 Hélios 2aHélios 2b

Jason 2

Calipso

Elisa (4)

Smos

Pléiades 1APléiades 1B

Picard

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Screening

Risk evaluation

Support requests

Manoeuvres proposals

CNES

Risk analysis

CONTROL CENTER

One team per mission :

Coordination

Station keeping

spacecraft

Ground segment

Alerts

ORBIT COMPUTATION CENTER

Le Monge TIRA(Germany)

GRAVES System (CDAOA)

(Pour

A-Train)

JSpOC

Tracking facilities

Military radars

Graves

OPERATIONAL COLLISION RISK MONITORING AT CNES

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TO PROTECT AGAINST DEBRIS… PREDICTION OF ATMOSPHERIC REENTRIES

Difficulties to predict reentry date: Incertitudes on atmospheric density, variability of solar activity Poor knowledge of ballistic coefficient CD, unknown and variable attitude (S/m) Possible lift effect Limited tracking periods (low altitude)

Order of magnitude of accuracy: about 10% of remaining time

Example: 1 week before: 1 day (16 revolutions) 1 day before: 3 hours (2 revolutions) 12 hours before: + ou – 1 revolution

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Mean value:4h05 TU

Observed reentry4h00 TU

EXAMPLEUARS REENTRY 24 SEPTEMBER 2011

B

E

41

TO PROTECT AGAINST DEBRIS…

Shields : Multi layers (Kevlar or Nextel)Effective up to 1 or 2 cm but…

heavy, complex,

expensive, Satellites generally not shielded

HautBas

Risque d’impact

International Space Station:

More than 100 different shields

10% of the mass of the Station

PNP = 0,9 over 10 years

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LEO

GEO

Mitigation measures:

•Limitation of operational debris

•Protection of low Earth orbits : 25-year tule

•Protection of geostationary orbit: graveyard orbit

•Passivation of satellites and launchers at end of mission

TO LIMIT THE DEBRIS CREATION…

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Economical competition: all actors shall use the same rules

need for an international consensus

DIFFICULTIES

Space debris mitigation measures are costly: mass, performances, development, operations

Critical balance to find between : -to do nothing and continue polluting Earth environment -to penalise ourselves when implementing alone constraining measures

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INTERNATIONAL COOPERATION

ISOOrganisation Internationale de NormalisationNorms, standards

IADC Inter Agency Space Debris Coordination CommitteeMitigation Guidelines: technical reference document

COPUOSCommittee on the Peaceful Uses of Outer Space High level principles

Space Agencies :

Countries: United Nations

Industry-Operators

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LEGAL FRAMEWORK

Space Treaties of the United Nations :Liability and responsibility of the launching StateObligation to authorize and to control national space activities carried out by non-governmental entities (article VI Outer Space Treaty 1967)

States shall monitor and control activities of their citizens in space:Regulatory regimes are being implemented: licensing systems or laws

French Space Operations Act voted in June 2008:The associated Technical Regulations contain requirements relative to space debris

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TO CLEAN SPACE

■ Mitigation measures may not be sufficient

■ The number of debris could increase due to collisions between objects

■ Need (to be confirmed): to remove from orbit the largest debris (debris sources)

Chain reaction

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TO CLEAN SPACE

■Many solutions studied:Laser on-ground, airborne, or in-orbitOrbital tugDrag augmentation devices

Inflatable surfacesElectrodynamic tethersHarpoon, net…

■Feasibility to be demonstrated…

Hoyt

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TO CLEAN SPACE

■ Technical: Approach Capture De-orbiting system

■ Economical Cost of such a mission Need to remove several objects Who is going to pay?

■ Legal Rights, obligations, Treaties Debris belong for ever to their launching State

■ Need for further studies on modelling and key technologies

■ Operational service???

Some difficulties…

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Constant augmentation of debris population orbiting the Earth increasing risk to space missions

Critical evolution if nothing is done

No realistic solution, except prevention

Good awareness of the problem at international level: consensus on the necessary mitigation measures

Legal systems are being implemented (license, law)

Need for active debris removal to be confirmed

Conclusions

SPACE DEBRIS Fernand ALBY What is the situation in-orbit? What are the possible actions?

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