1. Space Junk © 2011 Project Lead The Way, Inc.Aerospace Engineering

2. 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

3. Space Junk Increasing 1967 2007

4. 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

5. 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

6. 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

7. 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

8. 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

9. Space Junk Reduction Limit creation Limit explosions with better equipment Graveyard orbit above popular geosynchronous orbit (GEO) Clean up mess

10. References Analytical Graphics, Inc. (2010). Iridium 33 – cosmos 2251 collision. Retrieved from http://www.agi.com/media- center/multimedia/current-events/iridium-33-cosmos- 2251-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

11. 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/k- 4/home/F_What_Goes_Up_K-4.html