1. National Aeronautics and Space Administration AIAA: Annual Technical Symposium May 9, 2008 Special Acknowledgement to The Orbital Debris Program Office at NASA/JSC For more information: http://orbitaldebris.jsc.nasa.gov/index.html Presenter: Heather Rodriguez 1,2 1 ESCG, 2 University of Houston Orbital Debris: Past, Present, and Future

2. National Aeronautics and Space Administration 2 Orbital Debris Time Machine Prepare to travel back to 1957 and watch the space environment change right before your eyes

3. National Aeronautics and Space Administration 3 Cataloged objects (>10 cm diameter) represented by white dots (not to scale) Before 1957 = 0 objects Orbital Debris Growth

4. National Aeronautics and Space Administration 4 Cataloged objects >10 cm diameter 1960 = 10+ objects Orbital Debris Growth

5. National Aeronautics and Space Administration 5 Orbital Debris Growth Cataloged objects >10 cm diameter 1970 = 1400+ objects LEO GEO ring, Molniya, Polar orbit, GTO

6. National Aeronautics and Space Administration 6 Orbital Debris Growth Cataloged objects >10 cm diameter 1980 = 3700+ objects LEO GEO ring, Molniya, Polar orbit, GTO

7. National Aeronautics and Space Administration 7 Orbital Debris Growth Cataloged objects >10 cm diameter 1990 = 6000+ objects LEO GEO ring, Molniya, Polar orbit, GTO

8. National Aeronautics and Space Administration 8 Orbital Debris Growth Cataloged objects >10 cm diameter 2000 = 8900+ objects LEO GEO ring, Molniya, Polar orbit, GTO

9. National Aeronautics and Space Administration 9 Growth of the Earth Satellite Population Cataloged objects >10 cm diameter April 2008 = 12,000+ objects LEO GEO ring, Molniya, Polar orbit, GTO

10. National Aeronautics and Space Administration 10 Orbital Debris Background Space Surveillance Network (SSN) routinely tracks targets >10 cm –Catalogued objects: objects with multiple detections, orbits established (~12,500) –Tracked objects: detected at least once, may not be included in catalogue ( ~17,000) Orbital Debris = all space objects non-functional and human-made –First launch in 1957 started growth of the orbital debris population (R/B from Sputnik Launch = SSN 1) –First satellite break-up in 1961 –Low Earth Orbit (LEO) debris can travel at speeds of ~7 km/s and ~3 km/s in Geosynchronous Earth Orbit (GEO)

11. National Aeronautics and Space Administration 11 Other Ground-Based Sensors Ground-based remote systems able to detect objects as small as 2 mm in LEO and 10 cm in the GEO regime ESA 1m telescope Goldstone- 70m dish located in Barstow, CA MODEST ( 0.6 Schmidt) located near La Serena, Chile at the Cerro Tololo Inter-American Observatory Haystack and HAX radars located in Tyngsboro, MA Cobra Dane radar located on Shemya Island, AK 3.67 m Advance Electro-Optical System (AEOS) telescope, Maui, Hawaii

12. National Aeronautics and Space Administration 12 Orbital Debris Seen From LMT

13. National Aeronautics and Space Administration 13 Orbital Debris Population Breakdown 10  m100  m 10 cm 1 m 10 m 1 mm 1 cm Size (diameter) NF S/Cs, R/Bs Breakup Fragments Mission-related Debris Al 2 O 3 (slag) Al 2 O 3 Meteoroids NaK Paint Flakes

14. National Aeronautics and Space Administration 14 Sample of Mission-Related Orbital Debris Astronaut Ed White on the first EVA during the Gemini 4 mission in 1965

15. National Aeronautics and Space Administration 15 Sources of the Catalogued Population Approximately 4500 launches conducted worldwide since 1957 Known breakups = 197 –Major events: (number of catalogued fragments, YYYY) Titan Transtage (473, 1965) – U.S. Agena D stage (373, 1970) – U.S. COSMOS 1275 (309, 1981) – Russia Ariane 1 stage (489, 1986) – Europe Pegasus HAPS (709, 1996) – US Long March 4 stage (316, 2000) – China PSLV (326, 2001) – India Fengyun 1C (>2500 a, 2007) – China Briz-M (>1000 b, 2007) – Russia a on-going; b initial report

16. National Aeronautics and Space Administration 16 1996 Major Break-Up

17. National Aeronautics and Space Administration 17 Principal Orbital Debris Data Sources Potential Shuttle Damage

18. National Aeronautics and Space Administration 18 Cumulative Catalogued Population Breakdown FY-1C

19. National Aeronautics and Space Administration 19 On-Orbit Collisions Three accidental collisions between cataloged objects have been identified –1991: Russian Sat (launched in 1988)  Russian fragment –1996: French Sat (launched in 1995)  French fragment (1986 explosion) –2005: U.S. R/B (launched in 1974)  PRC fragment (2000 explosion) CERISE (1996) DMSP R/B 775 km by 885 km 99.1 deg inclination CZ-4 Debris 700 km by 895 km 98.2 deg inclination Collision Altitude: 885 km Geometry of the 2005 on-orbit collision

20. National Aeronautics and Space Administration 20 The Environment in LEO Regime Threat Regime

21. National Aeronautics and Space Administration 21 Window pit from orbital debris on STS-007. Hazards/Risks? Crewed Missions –On average, two shuttle windows are replaced per mission –Seven ISS collision avoidance maneuvers conducted since 1999 –Small debris particles could pose a danger to EVAs –Possibility of impact to sensitive areas on crewed missions Satellites –Avoidance maneuvers –Possible loss of mission –As debris flux increases, need for more effective shielding Need more, improved measurements and modeling for cost-effective mitigation measures and shielding designs An impact that completely penetrated the antenna dish of the Hubble Space Telescope. Orbital debris damage seen during Hubble Space Telescope repairs. 1 mm

22. National Aeronautics and Space Administration 22 Hazards/Risks? Prior to the most recent break-ups, explosions were the biggest concern; future worries focus on collisions. Debris left in orbits > 600 km normally fall back to Earth within several years. At altitudes of 800 km, the time for orbital decay is often measured in decades. Above 1,000 km, orbital debris will normally continue circling the Earth for a century or more. The smaller the particle, the higher the potential for collision. –Smaller particles outweigh the largest particles in population. Kinetic Energy relation. –A 1 kg object in LEO involved in a collision with an object traveling at 10 km/s will have the same impact energy as a fully loaded 35,000 kg truck traveling at 190 km/h.

23. National Aeronautics and Space Administration 23 Assessing the Problem: Involvement  U.S.: U.S. Government Orbital Debris Mitigation Standard Practices NASA Procedural Requirements (NPR) and NASA Technical Standard (NS) on Orbital Debris  IADC: ASI (Agenzia Spaziale Italiana) BNSC (British National Space Centre) CNES (Centre National d'Etudes Spatiales) CNSA (China National Space Administration) DLR (German Aerospace Center) ESA (European Space Agency) NSAU (National Space Agency of Ukraine) ISRO (Indian Space Research Organisation) JAXA (Japan Aerospace Exploration Agency) NASA (National Aeronautics and Space Administration) ROSCOSMOS (Russian Federal Space Agency)  COPUOS: United Nations Committee on Peaceful Uses of Outer Space Started in 1959, currently has 69 member states worldwide Albania, Algeria, Argentina, Australia, Austria, Belgium, Benin, Bolivia, Brazil, Bulgaria, Burkina Faso, Cameroon, Canada, Chad, Chile, China, Colombia, Cuba, Czech Republic, Ecuador, Egypt, France, Hungary, Germany, Greece, India, Indonesia, Iran, Iraq, Italy, Japan, Kazakhstan, Kenya, Lebanon, Libyan Arab Jamahiriya, Malaysia, Mexico, Mongolia, Morocco, Netherlands, Nicaragua, Niger, Nigeria, Pakistan, Peru, Philippines, Poland, Portugal, Republic of Korea, Romania, the Russian Federation, Saudi Arabia, Senegal, Sierra Leone, Slovakia, South Africa, Spain, Sudan, Sweden, Switzerland, Syrian Arab Republic, Thailand, Turkey, the United Kingdom of Great Britain and Northern Ireland, the United States of America, Ukraine, Uruguay, Venezuela & Viet Nam  ISO: The International Standards Organization Technical Committee "Aircraft And Space Vehicles" Sub-Committee "Space Systems And Operations" (known as ISO TC20/SC14) Development of standards to address implementation of measures associated with debris mitigation The orbital debris issue is being addressed at national and international levels

24. National Aeronautics and Space Administration 24 How Does NASA Work to Control and Identify Orbital Debris? Measurements –Radar Data Processing and Analysis –Optical Data Collection, Processing, and Analysis –In Situ Measurements and Analysis –Object detection/correlation –Debris size estimation Radar Cross Section=Projected cross section x Reflectivity x Directivity Optical reflected solar brightness –Orbit determination –Radar range-rate info –Photometric and spectral measurements –Surface material identification –Chemical composition of impactor (In-situ impacts ) Hax and Haystack MODEST and 0.9 m LDEF

25. National Aeronautics and Space Administration 25 How Does NASA Work to Control and Identify Orbital Debris? Modeling –Long-Term Environment Modeling –Engineering Modeling Predicting impacts risks for ISS, STS, and other S/C –Based on measurements and helps better define environment –Debris characteristics as functions of time, altitude, and orbital parameters –Number, type, size distribution, material, spatial density distribution, velocity distribution, flux, etc.) –Fragment characterization based on break-up experiments Ground based break-up experiment

26. National Aeronautics and Space Administration 26 How Does NASA Work to Control and Identify Orbital Debris? Reentry Analysis –Object Reentry Survival Analysis and Risk Assessment Safety Standards and Policies –Mission compliance with NASA Safety Standards HITF: Hypervelocity Impact Technology Facility –Conduct hyper-velocity impact tests, provide damage assessments for ISS/STS, and help design effective shielding for spacecraft January 1997, Georgetown, TX January 2001, Saudi Arabia

27. National Aeronautics and Space Administration 27 The Question  How Bad Is It? Has the current LEO debris population reached the point where the environment is unstable and population growth may be inevitable? Pre-1957 2008 2208

28. National Aeronautics and Space Administration 28 The Growth of LEO Populations (“No Future Launches” Scenario) Starting in 2020 Collision fragments replace other decaying debris through the next 50 years, keeping the total population approximately constant Beyond 2055, the rate of decaying debris decreases, leading to a net increase in the overall satellite population due to collisions SCIENCE 20 January 2006

29. National Aeronautics and Space Administration 29 Viable Solutions? In reality, the situation will be worse than this “no future launches” scenario –Satellites continue to be launched into space –Major break-ups continue to occur (e.g. Fengyun-1c, Briz-M) Postmission mitigation measures (such as passivation and LEO 25-year decay rule) will help, but may not be enough to prevent the self-generating phenomenon from happening To better limit the growth of future debris population, active removal of existing objects from orbit must be considered

30. National Aeronautics and Space Administration 30 Active Debris Removal – The Next Step in LEO Debris Mitigation PMD scenario predicts the LEO populations would increase by ~75% in 200 years The population growth could be reduced by half with a removal rate of 2 obj/year LEO environment could be stabilized with a removal rate of 5 obj/year

31. National Aeronautics and Space Administration 31 Conclusions In order to continue space exploration, the space community must not only be aware but help remediate the orbital debris environment Through ground and in-situ measurements and modeling we can gain knowledge of the population, physical characteristics, and risks of orbital debris The space environment is not owned or used by any one nation; therefore, we all have to work together to preserve the near-Earth space for future generations

32. National Aeronautics and Space Administration 32 Thank you !