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

Space Junk What is space junk? Statistics Natural Artificial Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 Earth image is an artist’s impression of space junk orbiting the Earth. Satellite image is of Vanguard satellite which was US first satellite. Launched in 1958. Image source: http://orbitaldebris.jsc.nasa.gov/photogallery/beehives/LEO1280.jpghttp://www.nasa.gov/audience/forstudents/k-4/home/F_What_Goes_Up_K-4.htmlhttp://orbitaldebris.jsc.nasa.gov/model/modeling.html

Space Junk Increasing 1967 2007 Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Space Junk Increasing 1967 2007 View these videos in order: Space Objects in 1967 Video Space Objects in 2007 Video Satellite History Video

Space Junk Impact Danger? Low Earth Orbit (LEO) debris Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 Image source: http://ares.jsc.nasa.gov/ares/exploration/HITF/problem.cfm

Space Junk Impact How long will it orbit? Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 Distance relativity: • 250-600 km = 150-375 miles (lower Earth orbit where the shuttle and space station are located) • 20,000 km = 12,500 miles (distance to Global Positioning Satellites (GPS)) • 36,000 km = 22,500 miles (distance to Geosynchronous Satellites which are used for communication and television broadcasts) Image source: http://www.orbitaldebris.jsc.nasa.gov/library/EducationPackage.pdf

Space Junk Tracking Spacecraft measure objects sized < 0.1 cm Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 There are several tools used to track objects. Monitors onboard spacecraft can track objects <0.1 cm in size of which there are millions ech with the potential to cause significant damage to spacecraft. Telescopes and radar track more than 100,000 objects which measure over 0.5 cm in size. Optical tools can track objects larger than 10 cm of which there are 11,000. More information about space junk tracking efforts: NASA Orbital Debris Program Office available at http://orbitaldebris.jsc.nasa.gov/ European Space Agency (ESA) space junk monitoring available at: http://www.esa.int/esaKIDSen/SEMESIXJD1E_Liftoff_0.html Image source: http://orbitaldebris.jsc.nasa.gov/photogallery/beehives/LEO1280.jpghttp://www.nasa.gov/audience/forstudents/k-4/home/F_What_Goes_Up_K-4.htmlhttp://orbitaldebris.jsc.nasa.gov/model/modeling.html

Space Junk Impacts Incidents CERISE, 1996: Briefcase size 31,500 mph Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 Impress upon students that risks are low to individuals: • risk is 1 in a trillion of injury from orbital debris • risk due to lightning strike is 1 in 1.4 million (annual risk in the US) • one person known to be struck by debris but not hurt Image source: Shuttle Window Strike - STS-94, http://www.orbitaldebris.jsc.nasa.gov/library/EducationPackage.pdf http://orbitaldebris.jsc.nasa.gov/photogallery/beehives/LEO1280.jpghttp://www.nasa.gov/audience/forstudents/k-4/home/F_What_Goes_Up_K-4.htmlhttp://orbitaldebris.jsc.nasa.gov/model/modeling.html

Kessler Syndrome Donald Kessler journal publication in 1978 Presentation Name Course Name Unit # – Lesson #.# – Lesson Name 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 At the end of presenting this slide, pause the presentation and play the Iridium and Cosmos Collision Debris video. This is also available for download at the multi media page by AGI: http://www.agi.com/media-center/multimedia/current-events/iridium-33-cosmos-2251-collision/ On February 10, 2009 the Iridium 33 and Cosmos 2251 satellites collided with a velocity of ll.6 km/sec, at an altitude of 790 km. The collision was catastrophic, likely producing hundreds of fragments large enough to catastrophically breakup other satellites, and tens of thousands of fragments large enough to damage other satellites. This is the first clear example of what was predicted in 1978. Iridium and Cosmos Collision Debris Video description Satellite collision with an Evolve-based, statistical break-up model This 1-minute video demonstrates the approach trajectories of the two satellites prior to impact, as well as a statistical break-up model with an example of propagated debris. This is a 1000 object statistical sample of more than 2,600 fragments predicted using a modification of the NASA Evolve debris model. This model abstracts structural and material fragmentation physics. Outcomes depend on the degree of contact between the two satellites, distinguishing between portions totally involved and those outside the contact area. This depiction uses initial on-orbit masses of 685 Kg for Iridium and 900 kg for Cosmos 2251 and assumes 30% direct contact for each object. The model can also release instantaneous energy stored in unexpended propellants, although that capability was not used in this case.

Space Junk Reduction Limit creation Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Space Junk Reduction Limit creation Limit explosions with better equipment Graveyard orbit above popular geosynchronous orbit (GEO) Clean up mess Image depicts an impact risk model of the International Space Station (ISS). Image source: http://www.orbitaldebris.jsc.nasa.gov/library/EducationPackage.pdf

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%20Frequency.pdf

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