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SPACE DEBRIS

PRESENT SITUATIONF.ALBY

CENTRE NATIONAL D’ETUDES SPATIALES

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 2

Cataloged objects >10 cm diameter

1960

POPULATION ORBITING THE EARTH

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 3

1965

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 4

1970

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 5

1975

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 6

1980

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 7

1985

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 8

1990

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

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1995

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 10

2000

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 11

2005

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

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April 2008

POPULATION ORBITING THE EARTH

Cataloged objects >10 cm diameter

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operational

satellites

5% abandoned

satellites

20%

upper stages

14%

operational

debris

8%

fragments

53%

SITUATION

Since 1957 -more than 4500 launches

-about 200 fragmentations in orbit

12 600 objects > 10 cm

(catalogued objects)

300 000 objects between 1 and 10 cm

(non-catalogued objects)

135 000 000 objects between 0,1 and 1 cm

(non-catalogued)

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ORBITAL DISTRIBUTION

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LIFETIME

The in-orbit lifetime is limited by residues of atmosphere

atmospheric drag, velocity decrease, reentry on Earth

risks:

low Earth orbit reentry on Earth, risk of victims on ground

high altitude orbit important lifetime: in-orbit collision risk

Examples:

Space Station 400 x 400 km 6 months-1 year

SPOT 825 x 825 km 200 years

GEO transfer orbit 200 x 36000 km about 10 years

GEO transfer orbit 600 x 36000 km 10 000 years

geostationary orbit 36000 x 36000 km millions of years

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 16

EVOLUTION: NUMBER OF CATALOGUED OBJECTS

(source NASA)

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ON-ORBIT RISKS

■On-orbit objects have huge kinetic energy

■Even a « small » debris can inflict important damages

■There is no shielding able to resist to particles larger than 2

cm (ISS example)

■Example: aluminium sphere Φ=1 mm at 10 km/s

->perforation of a 4 mm aluminium thick plate

■Probability of collision (Spot):

Probability of collision in 1year with objects

Size of the objects >0,1 mm >1 mm >1 cm >10 cm

probability 1 0,5 3 10-3

2 10-4

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ON-ORBIT RISKS

examples

Cerise (24 July 1996)

first confirmed collision

between 2 catalogued objectsSolar panels of the Hubble Space

Telescope: more than 5000

impacts visible to the naked eye

International Interdisciplinary Congress on Space Debris, 7-9 May 2009, McGill University, Montreal, Canada 19

ON-ORBIT RISKS

example: Space Shuttle

Impact on the wing’s

leading edge

Window impact STS 92

10 mm, depth 2mm

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RISKS ON GROUND

■Atmospheric reentry of a space object:

Very high velocity ~ 8 km/s

Important heating, most of materials melt

Aerodynamic loads

Fragmentation or explosion of the vehicle around 75-80 km altitude

Some materials survive to reentry: steel, titanium, composites,…

20 to 40 % of the initial mass reach the ground

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Example: Delta II upper stage

1997, Georgetown, Texas

engine combustion

chamber

Thermal

protectionHigh pressure vessel

(30 kg)250 kg stainless steel tank

RISKS ON GROUND

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•Increasing number of man-made objects orbiting the Earth

•Critical evolution if nothing is done

•Debris represent a risk to space missions in case of collision

•Debris represent a risk on ground in case of uncontrolled reentry

•Mitigation and remediation are necessary

SUMMARY