1. Space Debris, a Threat to GNSS and its
Applications to Civil Aviation
By Thibaut LABARRE
Student from the ENAC
 Current Situation
 Threat to Satellites
 Influence on GNSS Reliability
 Solutions
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2. History of Collisions
 24 July 1996:
Cerise Ariane V16 (debris)
 17 January 2005:
Thor (Stage) rocket CZ­4 (debris)
 December 1991 (collision identified in 2005):
Cosmos 1934 Cosmos 926 (debris)
 12 February 2009:
Iridium Cosmos 2251
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3. Current Situation (1/4)
 Evolution of the number of debris (>10 cm) from
1960 to 2008
(1 centimeter = 0.393700787 inch)
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4. Current Situation (2/4)
 GEO Space Debris 2008
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5. Current Situation (3/4)
 Since 1957 :
 4000 launches
 More than 200 fragmentations of orbiting objects
• 12,000 objects bigger than 10 cm
(referenced)
• 200,000 objects sizing between 1 and 10 cm
(not referenced)
fragments
• 35,000,000 objects smaller than 1 cm operating satellites
(not referenced) unoperating satellites
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operational debris

6. Curent Situation (4/4)
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7. Threat to Satellites (1/3)
 Probability of collision depends on
 Size of satellite
 Time spent in space
Collision probabilities for one year
 Flux of debris >0.1 mm >1 mm >1 cm >10 cm
Space Station (h=400 km, S=500 1 1 10-2 2 10-4
m2)
SPOT (h=800 km, S=20 m2) 1 0,5 3 10-3 2 10-4
Constellation (h=1,500 km,S=16 m2) 1 3 10-1 10-3 10-4
GALILEO (h=23,222 km,S=3 m2 body
+ 16 m2 solar arrays)
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8. Threat to Satellites (2/3)
 Consequences of an impact
 Caracteristics of a space impact
 Kinetic energy is linked to speed
 Orbital speeds are very high
 Aluminium sphere at 10kmps
 A 1mm chip → an average .22 long rifle bullet at gunpoint
 A pea­sized ball → 180 kg safe travelling at 100 kmph
 A tennis ball­sized sphere → 25 sticks of dynamite
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9. Threat to Satellites (3/3)
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Part of a solar array of the Hubble Space Telescope

10. Influence on GNSS Reliability (1/4)
 What is GNSS?
 Global Navigation Satellite System
 Allows users to determine precisely where they are
on earth
 What are its applications to Civil Aviation?
 Free Flight
 Landing procedures
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11. Influence on GNSS Reliability (2/4)
 Projected development of GNSS
 GPS 1995
 GLONASS 2009
 GALILEO 2013
 COMPASS 2015
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12. Influence on GNSS Reliability (3/4)
 MEO (GNSS orbits) still relatively spared
Payloads Rocket Bodies Operational Debris Breakup Debris Anomalous Debris Totals
LEO 1612 758 651 3232 119 6372
MEO 126 28 2 0 0 156
GEO 587 116 1 2 0 706
Elliptical 249 515 135 167 0 1066
Unknown 171 120 185 0 0 476
Totals 2745 1537 974 3401 119 8776
 But debris will accumulate
 Operating lifespan of satellites : around 10 years
 Orbiting lifespan of satellites : millions of years
 Exponential growth due to fragmentation
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13. Influence on GNSS Reliability (4/4)
 Civil aviation imperatives for GNSS
 Accuracy
 Availability
 Continuity
 Orbital debris endanger the last 2 imperatives
 ABAS technologies require more satellites to work
 The loss of a satellite during a critical phase of a
flight can have catastrophic consequences
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14. Solutions (1/3)
 Armor for GNSS satellites
 Pros
 Enhances lifespan of satellites
 Cons
 Expensive (in terms of weight)
 Covers only a fraction of the risk
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15. Solutions (2/3)
 Dodging the debris
 Pros
 Enhances lifespan of satellites
 Cons
 Every debris trajectory has to be tracked
 Fuel consumption increases
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16. Solutions (3/3)
 Disposal orbits for failed GNSS satellites
 Pros
 Technically feasible
 Cheap
 Applicable to previous satellites
 Cons
 GPS, GLONASS, GALILEO, COMPASS will all have
different orbits
 Disposal orbits may vary and become elliptical (due to
influence from the sun and the moon), interfering with
operating satellite orbits
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17. Conclusion
 All the solutions are only partial and will not
solve the problem
 Cooperation: IADC, COPUOS, ISO
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18. Thank you for listening!
Any questions?
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19. References
 /Les débris spatiaux : une pollution sous
surveillance/, Lecture by Fernand Alby, Director
of the CNES Space Debris Lab., ENAC
Aerospace Challenges, jan. 2009
 http://www.pollutionissues.com/Re­Sy/Space­
Pollution.html
 http://www.aerospace.org/news/newsitems/proc
edures­030702.html
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