SPACE DEBRIS Past Present Future Society of Physics
SPACE DEBRIS Past, Present, Future Society of Physics Students Guest Science Speaker Embry-Riddle Aeronautical University Prescott, Arizona Professor Robert D. Culp University of Colorado October, 2016
• The history, causes, and growth of space debris • Current state of space debris hazards • Future prospects for debris growth and mitigation • Sketch of CU Space Debris Group’s research
Ronald A. Madler, Ph. D. thesis “Evolution of the Near-Earth Man-Made Orbital Debris Environment” 1994, University of Colorado One of the pioneers and key researchers in the investigation of the cascade effect Madler’s work contributed significantly to the current acceptance of the inevitable growth of the space debris hazard
The Current Problem More than 17, 000 cataloged pieces The NORAD catalog contains all pieces bigger than 50 cm. , most pieces bigger than 5 cm. Estimated 500, 000 pieces greater than 1 cm. Nearly all pieces between 1 cm and 5 cm are untrackable, uncataloged, yet pose catastrophic consequences to Resident Space Objects (RSO). All pose critical risk to resident space objects Typical relative impact speed is 10 -20 km/s.
Summary of all objects in Earth orbit officially cataloged by the U. S. Space Surveillance Network
Only 1381 Operational Satellites as of December 31, 2015 These 1381 active satellites are divided into the following categories: 37% Commercial 14% Communications (Civil and Military) 14% Earth Observers 12% Research and Development 8% Military Surveillance 7% Navigation 5% Scientific 5% Meteorology
Debris Distribution Bands at altitudes of 800 km, 1500 km, and GEO (35786 km) Both cataloged (large) and untrackable (small) have these altitude distributions. Small debris is distributed evenly longitudinally. Large debris objects, including working satellites, have inclination concentrations.
Large Debris Inclination Concentrations 6000 tons mass in orbit, 99% in large masses At 1000 km, 82 degree inclination, 290 large masses At 800 km, 99 degree inclination, 140 large masses At 850 km, 71 degree inclination, 40 large masses At GEO (35, 800 km altitude) 1200 tons, 520 large masses
Fragmentation: the source of small debris Explosions: rocket bodies, batteries, intentional Collisions, including antisatellite experiments Normal operations Deterioration of satellites and other large bodies
Over 200 Fragmentation Events to Date More than half of cataloged pieces are from fragmentations. Worst: Chinese Fengyun-1 C, (2007) An antisatellite test, intentional collision Second worst: Russian Cosmos 2251 collision with Iridium 33 Accidental collision between two intact catalog objects The only accidental collision between two intact satellites thus far.
Early Fragmentation Events Earliest fragmentations raised the space debris alarm Very first: Transit 4 A Rocket Body, June 29, 1961 Residual fuel explosion Early worst: Ariane Spot 1 Rocket Body, November 13, 1986 Residual fuel explosion. Still the 6 th worst of all time. Notable: 7 Delta Rocket 2 nd Stage Explosions, (1973 -1981) Residual fuel explosions, led to corrective venting of surplus fuel Also, 30 USSR deliberate end-of-life explosions, (paranoia)
Untrackable Debris from Normal Operations Far Less Serious than from explosions or collisions • • • Solid Rocket Effluent (primarily aluminum oxide) Staging and Reentry Events that are Explosive Planned Experiments Waste and Refuse from ISS and Shuttles Deterioration of Large Masses (paint flecks, insulation, atomic oxygen corrosion, small particle abrasion)
Untrackable Debris 1 cm – 5 cm: estimated 500, 000 pieces (potentially catastrophic) 1 mm – 1 cm: millions of pieces (damaging or mission degrading) Untrackable debris can only be defended against by shielding, satellite design, or orbit selection
Debris Cloud Evolution An explosion or collision creates a cloud of fragments. The cloud becomes an ellipsoid following the original orbit for a few revolutions. The ellipsoid elongates along the orbital path until (days) a torus is formed. Cause: differing periods of particles The torus spreads and gradually (months) becomes a belt with the same ground coverage of the original orbit. Cause: differing plane precession of particles
Long-term Debris Cloud Evolution The debris becomes (years) evenly distributed background particles around the same region covered by the belt. For LEO breakups, the debris slowly rains down through lower elevations, beginning at once, continuing for decades. Cause: atmospheric drag, small but still present up through a thousand kilometers.
The Cascade Effect 1978 Paper by Don Kessler and Burton Cour-Palais “Collision Frequency of Artificial Satellites: The Creation of a Debris Belt” Collisions between orbiting objects create large numbers of equally dangerous smaller debris. This greatly increases the threat to other orbiting objects including large satellites. This increasing threat of collisions leads to a chain effect, or cascade effect.
Conclusions from Kessler’s 1978 Paper Collisions between cataloged objects will begin around the year 2000. The hazard to spacecraft from small debris will quickly exceed the hazard from natural meteoroids in low Earth orbit (LEO). Debris flux will increase exponentially from breakup and deterioration of large masses.
Current Results Predictions from 1978, and later confirmations by other researchers (including Madler) have become increasingly accurate. From now on, debris from random collisions between orbiting objects, both cataloged and smaller, will be the dominant source of small debris. This cascade effect, or chain reaction, was called “The Kessler Syndrome” by John Gabbard. Kessler himself is lukewarm to this name!
Predicted Collision Rate between Catalogued Objects Assuming various growth rates in the catalogue From 1978 Kessler/Cour-Palais JGR publication
1978 JGR Predicted Collision Rate Compared to 1991 to 2009 Observed Collision Rate Observed catalogued collisions: Important to short-term environment only (Cosmos 1934, Cerise, Thor-Burner, Iridium) Observed catastrophic collisions: Important to short and long-term environment (Iridium)
The Only Feasible Solution First: Compliance with mitigation guidelines by all space-faring nations. Second: Active retrieval of large orbiting masses at end of usefulness. Otherwise, and perhaps even so, small debris will continue to increase exponentially (the cascade effect). Collision data over the next decade will confirm this prediction.
The Future The world will continue to use space. The cascade effect says the 6000 tons mass currently in space will eventually become a threatening background of untrackable small debris. The FAA expects a five-fold increase in cataloged objects in the next 2 -5 years. Today’s catalog of 15 -20, 000 pieces will grow to 100, 000.
Solutions Some solutions are obvious. Some are yet to be imagined. Solutions will be developed--have faith in our technology. The solutions will differ for tracked and cataloged debris, for small, untrackable debris, and for debris at GEO altitudes.
Large, Trackable Debris Catalog, track, avoid! Space Situational Awareness (SSA) Expand the catalog to track most debris down to 3 cm in size. Expand ability to discover and track debris. Avoid collisions by choosing orbits, and improving conjunction detection. Avoid placing satellites in high debris density regions, provide valuable satellites with maneuvering capability. Remove large masses at end of life. Large masses--the source of small debris Operate responsibly.
Untrackable, Small Debris Improve shielding to protect against debris 1 cm and smaller. Design satellites to be robust against small debris, and to survive for long lifetimes of encountering the abrasive effects of untrackable debris. Choose orbits to avoid predicted high density regions of untrackable debris. Again, remove large masses before they deteriorate.
A Special Problem: the GEO Region In GEO, the problem is worse. There are 1200 tons of mass, 520 satellites in GEO +/- 100 km. Including debris, there are 1400 cataloged objects in this region. Detecting is much more difficult for GEO objects, hence the catalog is less complete than at LEO. There are only about 400 controlled (active) satellites. The rest are drifting. Disposal orbits are only 300 km above GEO.
GEO Difficulties Roger Mc. Namara showed (and Kim Luu confirmed) that the official disposal orbits (GEO + 300 km) are unsafe in the long term due to perturbations and collisions. Removal of large, dead masses in GEO (true removal, not just lifting to disposal orbit) is the most urgent of debris problems.
Obstacles FIRST: Technology—must improve detection, tracking, cataloging, and conjunction analysis (collision prediction). Removal of large masses. All within reach, but expensive. SECOND: Economics—the biggest problem. All of the solutions are expensive. Who will Pay? THIRD: Political realities—newer space-faring nations refuse to take responsibility. They resist deorbiting, ending ASAT and other debris generating experiments, and minimizing operational debris.
A Few Ideas for Large Mass Removal LEO: Drag additive (balloons, sails) Orbit modification using attached rockets or lasers from a distance. All methods have problems: attachment requiring rendezvous and grappling, aim of lasers, hazard of approaching an uncontrolled, spinning large mass… GEO: Only energy change will work: Attach rockets, space-based laser propulsion, tow via nets, bolos, or harpoons. Relative speeds are lower, so rendezvous is simpler, yet still difficult. Unusual example: CU Hans-Peter Schaub and four companies: Touchless reorbiting using an electrostatic tractor force to tow mass to higher orbit.
CU Research in Space Debris In the ‘ 70’s, I was working on debris cloud evolution at the time Kessler raised the alarm. By the early ’ 80’s, I had established the first University Program to study in depth the space debris problem. For two decades, it was the only graduate program in space debris anywhere.
Areas of Research in Space Debris, 1980 -2015 Breakup models—collisions and explosions Environment models—the background debris Debris Cloud Evolution—from breakup to background debris Advanced Computer Visualization—interesting, but was soon discarded Ground-based Hypervelocity Impact Tests—simulating collisions
CU research Areas, continued Advanced Shielding Design—modified Whipple designs and tests SMART Catalog—the seeds of the expanded catalog Size and Radar Cross Section Studies—important for modeling Radar, Ballistic Coefficient, Optical Signature Studies Lethality and Space-based Defense—SDI and ASAT inspired GEO Debris Hazards—perhaps the biggest problem
The Early Leaders of Space Debris Research During the ‘ 80’s, space debris research was led by four key players: Donald J. Kessler, Project Scientist for Space Debris, NASA Johnson Space Center Vladimir A. Chobotov, Manager, Space Hazards Section The Aerospace Corporation Nicholas L. Johnson, Advisory Scientist Teledyne Brown Engineering Robert D. Culp, Professor of Aerospace Engineering Sciences The University of Colorado
The First years of the CU Space Debris Group In 1980 I collaborated with Kessler through NASA research contracts. Darren Mc. Knight was assigned to do a Ph. D under me by the USAF Palace Knight Program. He was at Kirtland AFB for a year awaiting deployment to CU for his graduate work. I sent him material on space debris and asked him to look into it for a thesis topic. He, an energetic self-starter, arrived with ideas about the origin of debris clouds from collisions and explosions.
Darren Mc. Knight—the First Space Debris Ph. D In 1985, Mc. Knight’s thesis detailed an empirical means of distinguishing explosion-caused from collision-caused debris clouds. He put together the SOCIT tests—persuaded the USAF to give us an unused OSCAR satellite. We took the satellite to Tullahoma, TN, to the AEDC test facility, and subjected it to tests in the hypervelocity test range.
The SOCIT Tests at Tullahoma The OSCAR satellite was dismantled and subjected to separate tests on the solar panels, on the bus structure, and on the instruments. Small (0. 5 cm) aluminum pellets were shot at these parts at speeds of 6 -7 Km/s. The data from these SOCIT tests remain today as the best source of information about space debris impact on satellites.
Other Ground Tests of Debris Clouds CU directed and participated in many space debris impact tests at Tullahoma, at NASA JSC, and at other Hypervelocity Test facilities. This included tests of new shield designs at NASA JSC. As our representative, Roger Mc. Namara participated in a productive explosion test in California, and brought back the definitive data on large-scale explosions in space.
The CU Space Debris Graduates After Mc. Knight, the golden years of our research featured a dozen Ph. D graduates and as many outstanding MS graduates. These graduates went on to dominate the space debris discipline for the next twenty years. Many of them continued to work with our research group even after they had other responsible positions in the industry.
Success of Our Graduate Students These graduate students, along with a cadre of MS students, gained a world-wide reputation. Madler and Maclay were welcomed on international and national committees as equals to old, established researchers. All gave papers at international conferences. The following, unreadable slide, lists these Ph. D students and their theses:
Darren S. Mc. Knight, "Simulation of On-Orbit Satellite Fragmentations, "1986 Timothy D. Maclay, “Untrackable Orbital Debris Hazard Assessment and Shield Design for Satellites Operating in Low Earth Orbit”, 1993 Ronald A. Madler, "Evolution of the Near-Earth Man-Made Orbital Debris Environment, " 1994 Roger P. Mc. Namara, "The Investigation of Space Debris Generation and Associated Long-Term Effects in the Geosynchronous Region, " 1995 Ian J. Gravseth, “Determination of the Physical Properties of Artificial Debris Via Remote Observations, ” 1996 Christopher A. Sabol, “A Role for Improved Angular Observations in Geosynchronous Orbit Determination”, 1998 Khanh Kim Luu, “Effects of Perturbations on Space Debris in Supersynchronous Storage Orbits”, 1998 Kira Michelle (Jorgensen) Abercromby, “Using Reflectance Spectroscopy to Determine Material Type of Orbital Debris”, 2000 Brian J. Poller, “The Photometric Detection of Known Sun Occluding Orbital Debris”, 2009
Other Major Achievements by the CU Group Maclay developed and tested innovative shield designs. Madler developed his debris cloud model and published the definitive affirmation of Kessler’s cascade theory. Madler and Maclay led the discipline in estimating and modeling the background debris and the evolution of debris clouds.
More Research Results Dickey and Gravseth completed important work on determining size and composition of space debris via remote sensing—radar cross section, ballistic coefficient (from drag), and optical characteristics. This led to the ODERACS Projects: Orbital Debris and Radar Cross Section Experiment
ODERACS We proposed to NASA that we drop calibrated spheres and dipoles from the Space Shuttle, and take data on RCS, optical albedo, and ballistic coefficient. This was successfully accomplished on two Space Shuttle flights. CU did all the laboratory calibration of RCS and optical signatures of the objects. We received two NASA Commendations for these projects.
Spheres Launched from the Canister
Determining the Mass/Diameter Relation of Space Debris Madler, Maclay, Gravseth, Mc. Namara, and Dickey published definitive methods of determining this relation using remote sensing. The definitive relation, called MAD-CHIMPS in our research papers, is used to this day.
Long-term Hazard from Space Debris During this time, our team (primarily Madler, Maclay, and Mc. Namara) published definitive analyses of the long-term hazard to Resident Space Objects (RSO) from space debris. Madler published the exposition of the long-term evolution of space debris, establishing the cascade phenomena once and for all.
Debris Hazard in GEO Mc. Namara published an historic warning about the space debris hazard in GEO, especially attacking the idea of a super GEO disposal plan. Kim Luu and Chris Sabol, three years later, joined in the GEO analysis and warning regarding the disposal orbits. Mc. Namara showed that collisions of dead satellites in the disposal area, combined with ever-present perturbations, would threaten active GEO satellites over the coming decades.
The EXCALIBIR Experiment A lethality experiment that never happened. Proposed by Mike Dickey: a plan to intercept the discarded external tank from a shuttle launch. The tank reentered above the Pacific ocean, passing over Kwajalein. A missile from Kwajalein would intercept it, and fire a shotgun-like cloud of pellets at the tank. Instrumentation on the tank would telemeter back the effects of the pellet impacts. A cheap experiment to obtain lethality data. Never funded, never happened.
Spectroscopy and Space Debris This is the most recent research by our space debris group. Spectroscopy applied to the detection and identification of space objects including debris. Ian Gravseth and Kira Jorgensen (now Abercromby) were the prime participants. Madler, Maclay, and David Spencer also contributed from their postgraduate positions.
Spectroscopy Results Kira Jorgensen (now Kira Abercromby) arranged a collaboration with the Federal Research Center near Denver. In the Federal Laboratory, she established full spectroscopic optical signatures for hundreds of space materials. This data was used successfully to identify a curious object orbiting the Sun—it was a rocket body from a lunar probe upper stage, long lost. This data base is still the best source of material spectrographic signatures, and is used to help identify unknown objects in space, and space debris.
Questions? Comments? Discussion?
- Slides: 57
