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

2. 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:

3. 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

4. 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
55 mph
bowling 300 mph
60 lb 60 mph
Image source:

5. 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)
km = years
km = decades
>800 km = centuries
>36,000 km = forever
Distance relativity:
• km = 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:

6. 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
European Space Agency (ESA) space junk monitoring available at:
Image source:

7. 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,

8. 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:
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.

9. 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:

10. References
Analytical Graphics, Inc. (2010). Iridium 33 – cosmos 2251 collision. Retrieved from European Space Agency. (2010). Space junk. Retrieved from Kessler, D. (2009). The kessler syndrome. Retrieved from Kessler, D., & Cour-Palais, B. (1978). Collision of artificial satellites: The creation of a debris belt. Journal of Geophysical Research, 83(A6). Retrieved from

11. References
National Aeronautics and Space Administration (NASA). (2009). Orbital debris educational package. Retrieved from National Aeronautics and Space Administration (NASA). (2010). What goes up must come down. Retrieved from