Space Junk Space Junk What is space junk

Space Junk

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 • Telescopes and radar see > 0. 5 cm – >100, 000 objects • Spacecraft measurement < 0. 1 cm – Millions of objects • Optical and radar 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 -cosmos 2251 -collision/ European Space Agency. (2010). Space junk. Retrieved from http: //www. esa. int/esa. CP/index. html Kessler, D. (2009). The kessler syndrome. Retrieved from http: //webpages. charter. net/dkessler/files/Kes. Sym. html Kessler, D. , & Cour-Palais, B. (1978). Collision of artificial satellites: The creation of a debris belt. Journal of Geophysical Research, 83(A 6). Retrieved from http: //webpages. charter. net/dkessler/files/Collision%20 Fr equency. pdf

References National Aeronautics and Space Administration (NASA). (2009). Orbital debris educational package. Retrieved from http: //www. orbitaldebris. jsc. nasa. gov/library/Education. Pa 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