Space Junk
Aerospace Engineering
© 2011 Project Lead The Way, Inc.
Space Junk
• What is space junk?
– Natural
• Comets, asteroids
– Artificial
• Satellite break up
• Paint flakes, tools, and thermal blankets
• Human refuse
• Statistics
– 28,000 objects created since 1957
– 9,000 still in orbit (550 are useful)
– 75 launches per year
Space Junk Increasing
1967
2007
Space Junk Impact
• Danger?
– Low Earth Orbit (LEO) debris
• 7 km/s = 18,000 mph
• Energy
– Car @ 55 mph
– bowling ball @ 300 mph
– 60 lb safe @ 60 mph
Space Junk Impact
• How long will it orbit?
<200 km = days (LEO for space shuttle)
200-600 km = years
600-800 km = decades
>800 km = centuries
>36,000 km = forever
Space Junk Tracking
• Spacecraft measure objects sized < 0.1 cm
– Millions of objects
• Telescopes and radar tracking (> 0.5 cm)
– >100,000 objects
• Optical tracking (> 10 cm)
– 11,000 objects
• Multi-national effort
– NASA Orbital Debris Program Office
– European Space Operations Centre
• Advise orbit changes
Space Junk Impacts
• Incidents
– CERISE, 1996: Briefcase size 31,500 mph
– South African land strike
– Texas, 1997
– South Africa, 2000
– Satellite and shuttle windshield strikes
Kessler Syndrome
• Donald Kessler journal publication in
1978
• Satellite collision generates fragments
• Fragments cause exponential increase in
collisions
• Growth of debris belt
• Potentially blocks other craft from that
altitude or above
• Example: Iridium 33 and Comos 2251
collision in 2009
Space Junk Reduction
• Limit creation
• Limit explosions with better equipment
• Graveyard orbit above popular
geosynchronous orbit (GEO)
• Clean up mess
References
Analytical Graphics, Inc. (2010). Iridium 33 – cosmos 2251
collision. Retrieved from http://www.agi.com/mediacenter/multimedia/current-events/iridium-33-cosmos2251-collision/
European Space Agency. (2010). Space junk. Retrieved
from http://www.esa.int/esaCP/index.html
Kessler, D. (2009). The kessler syndrome. Retrieved from
http://webpages.charter.net/dkessler/files/KesSym.html
Kessler, D., & Cour-Palais, B. (1978). Collision of artificial
satellites: The creation of a debris belt. Journal of
Geophysical Research, 83(A6). Retrieved from
http://webpages.charter.net/dkessler/files/Collision%20Fr
equency.pdf
References
National Aeronautics and Space Administration (NASA).
(2009). Orbital debris educational package. Retrieved
from
http://www.orbitaldebris.jsc.nasa.gov/library/EducationPa
ckage.pdf
National Aeronautics and Space Administration (NASA).
(2010). What goes up must come down. Retrieved from
http://www.nasa.gov/audience/forstudents/k4/home/F_What_Goes_Up_K-4.html