5 LP

Die Überfüllung des erdnahen Weltraums mit Raumflugobjekten (Weltraummüll, Space Debris): ObjektPopulationen, Entstehungsmechanismen, Größenverteilung, zeitliche Entwicklung einer Trümmerwolke, Kollisionen, dynamisches Modell der Gesamt-Population. Elektrische Raumfahrtantriebe und Einsatzmöglichkeiten: Arc-Jets und Resisto-Jets, elektrostatische Triebwerke, elektromagnetische Triebwerke, Einsatz von elektrischen Triebwerken. Nukleare Energieversorgung von Raumflugkörpern.

Vorkenntnisse: keine


Die Vorlesung Raumfahrtrückstände behandelt den Forschungsschwerpunkt Weltraummüll der Raumfahrtgruppe des Institutes für Raumfahrtsysteme. Die Vorlesung ist Teil des Luft- und Raumfahrttechnikstudiums an der TU Braunschweig.

The lecture Spaceflight Technology - Space Debris deals with the main research field space debris of the spaceflight group at the Institute of Space Systems  The lecture is part of the aerospace course of studies at the TU Braunschweig.

Dozent / lecturer
Dr.-Ing. Holger Krag
Dr. Carsten Wiedemann (Institut für Raumfahrtsysteme / Institute of Space Systems)
Umfang / extend

5 ECTS Credits 

Hörsaal / room
HB 35.1 (IFL, Hermann-Blenk-Str. 35)
Zeit / time
Freitag / Friday 16.00 h - 19.00 h,Wintersemester / fall
Samstag / Saturday 10.30 h - 13.30 h,Wintersemester / fall
Termine / dates (dd.mm.yy)

Sa. 24.10.20
Sa. 07.11.20
Sa  14.11.20
Sa. 21.11.20
Sa. 05.12.20
Sa. 19.12.20
Sa. 16.01.21
Sa. 23.01.21
Sa. 30.01.21
Sa. 06.02.21
Sa.  13.02.21

Sprache / language
Deutsch oder englisch / German or English
Literatur / literature
Das Buch zur Vorlesung ist erhältlich.
The book of this lecture is available.
Space Debris - Models and Risk Analysis
Inhalt / content

Introduction: Definition of space debris; indicators of the space debris problem; steps towards a space debris assessment.

Debris & Meteoroid Measurements: Types of Space Object Measurements; Space Surveillance Systems; Phased Array Warning System (PAWS); COBRA DANE and Eglin Phased Array Radars; the SSN Radars Fylingdales and Globus II; Ground -Based Electro-Optical Deep-Space Surveillance; the US Space Surveillance Network (SSN); SSC and the SSN/SSS Space Surveillance Systems; optical and radio windows of the atmosphere; radar observables and power requirements; radar range limitations; range, range-rate, direction angles, and RCS; FGAN tracking of a Cerise boom pass; FGAN imaging of Cerise and its boom; generation of the antenna beam pattern; control of the antenna beam pointing; dish antenna & phased array beam patterns; reduction of signal ambiguity and false alarm rate; false alarm rate and probability of detection; the FGAN Tracking and Imaging Radar (TIRA); the tracking ship "Monge"; the Haystack LRIR and HAX radars; bi-static radar beam-park experiments; the GRAVES electronic fence; design principles of optical telescope systems; telescope design types; photometric sensitivity of optical systems; image processing considerations; ESA SDT and NASA CDT telescope; details of the ESA Space Debris Telescope; NASA Liquid Mirror Telescope (LMT); the ROSACE, SPOC, and PIMS telescopes; GORID and DEBIE in-situ impact detectors; analysis of impacts on LDEF and HST; impact analysis of surfaces returned from space; summary of ground-based debris measurements; summary of in-situ debris & meteoroid measurements; ISS particle fluxes derived from measurement data.

Current Debris Environment: Sources and sinks of man-made space objects; launch activities and the catalog growth; catalog composition by object type & orbit type; spatial distribution of catalog objects; catalog orbit distributions - semimajor axis; catalog orbit distributions - inclination & eccentricity; catalog orbit distributions - apogees & perigees in LEO; launched & on-orbit mass of catalog objects; launched & on-orbit cross-section of catalog objects; on-orbit mass & cross-section by orbit type; decayed mass & cross section of catalog objects; GEO launches and GEO population growth; longitude distribution of GEO objects; precession of the orbit pole of GEO objects; statistics of on-orbit fragmentations; the most severe fragmentation events in history; time-delay and location of fragmentation ; inclination and eccentricity of fragmentation orbits; short-term dispersion of GTO explosion fragments; short-term dispersion of LEO explosion fragments; Gabbard diagrams of fragmentation clouds; long-term dispersion of LEO explosion fragments; inclination & node dispersion of Cosmos-1275 break-up; time dependent node dispersion of fragment clouds; temporal environment variability due to fragmentations; principle of the NASA fragmentation model; structure of the NASA fragmentation model; diameter and area-to-mass spectrum of the NASA Model; mass and ΔV distribution of the NASA model; altitude and inclination distribution of fragments; solid rocket motor slag and dust; solid rocket motor characteristics; solid rocket motor firings; inclination dispersion of SMR slag and dust; eccentricity dispersion of SMR slag and dust; NaK coolant release from RORSAT Reactors; sodium-potassium coolant release; RORSAT reactor core release events; cone ejecta and spallation products; surface degradation products (paint flakes); distribution of surface degradation products; West Ford needles; overview of the debris population sources; size-dependent population contributions to MASTER-2001; spatial densities by source type-large objects; spatial densities by source type-small objects; 3-D spatial density distribution in MEO; 3-D spatial density distribution in GEO.

Current Debris Flux Levels: Mathematical description of impact probability; procedure of collision flux determination; control volume definition for debris flux predictions; volume of a general spherical sector; determination of cell passage events; determination of resident probabilities; cell passage velocity in a horizontal coordinate system; storage format of cell passage events; determination of the approach velocity; determination of the collision flux; mapping of debris fluxes on the ISS geometry; definition of collision flux in target orbit coordinatesmodeling the debris environment with ESA's MASTER model impacts between two circular orbits impacts between circular and elliptical orbits ISS Collision geometry for 10 cm Objects ISS Collision geometry for 1 cm Objects ISS and ERS Collision flux for d >1 cm as fct(ΔV) ERS Collision flux for d >1 cm as fct(ΔV, A) ISS Collision flux for d >1 cm as fct(ΔV, A) ERS Collision flux for d >1 cm as fct(ΔV, i) ISS Collision flux for d >1 cm as fct(ΔV, i) ERS Collision flux for d >1 cm as fct(A, u) ISS Collision flux for d >1 cm as fct(A, u) GTO Collision flux for d > 1 cm as fct(ΔV, h) GTO Collision flux for d > 1 cm as fct(ΔV, i) GTO Collision flux for d > 1 cm as fct(A, u) GEO Collision flux for d > 1 cm as fct(ΔV, A) GEO Collision flux for d > 1 cm as fct(A, h, e) size and mass dependent ISS flux contributions space debris collision flux on typical orbits debris flux and oriented, planar surfaces verification of the MASTER model with PROOF schematic concept of the PROOF software verification of the modeled GEO population verification of the modeled LEO population.

Future Debris Environment Projections: Forecasting the future space debris environment; project BAU collision rates and object counts; discrimination of collision types; projected BAU spatial densities in LEO and GEO; projected BAU object counts by source and orbit; traffic rate effects on future collisions; traffic rate effects on future objects counts; constellation deployments in LEO, MEO and GEO; the GPS, GLONASS and Galileo constellation; constellation deployment plans; constellation deployment effects on future collisions; constellation deployment effects on future objects counts; nano-satellite deployment plans; nano-satellite deployment effects on future collisions.

Debris Mitigation Measures: Background on debris mitigation; reduction of mission-related objects; EOL passivation of spacecraft and upper stages; effectiveness on end-of-life passivation; effectiveness of SMR slag prevention; de-orbiting of LEO objects at end-of-life; requirements for direct EOL de-orbiting; de-orbiting of LEO objects to limited-lifetime orbits; propellant requirements for delayed EOL de-orbiting; effectiveness of delayed and direct EOL de-orbiting; reduction of large fragments by EOL de-orbiting; application of space tethers to EOL de-orbiting; space tether history (1967 -1996); orbit lifetime reduction with conductive tethers; effectiveness of LEO EOL re-orbiting; effectiveness of GEO EOL re-orbiting; re-orbiting of GEO objects at end-of-life; re-orbiting of LEO or GEO objects at end-of-life; GEO drift and libration orbits; recent statistics of EOL GEO Re-orbiting; Astrium concept of a "Robotic GEO Restorer" (ROGER); capture by tethered nets or grippers; ROGER spacecraft design and mission details.

Future Debris Flux Projections: Effects of debris mitigation measures on ISS fluxes; effects of debris mitigation measures on ERS fluxes; effects of debris mitigation measures on GTO fluxes; effects of debris mitigation measures on GEO fluxes; build-up of critical LEO concentrations for BAU.

Debris Mitigation Guidelines: Overview of existing debris mitigation guidelines; US Governmental compliance with mitigation standards; European and international debris mitigation standards.

Re-Entry Risk Assessment: Re-entries of risk objects; typical Delta-II re-entry survivor objects; methods for long- and short-term re-entry predictions; effects of perturbations on a satellite orbit; variation of air density and temperature profiles; solar and geomagnetic activity and the causes; sunspot characteristics; Variation of aerodynamic cross-section; long-term prediction of the natural decay of Mir; modeling of the final re-entry and break-up; re-entry orbit and attitude dynamics; re-entry aerodynamics; re-entry aerothermal and thermal analysis; spacecraft model definition; disintegration, demise and ground impact; identification of potential re-entry survivor objects; dispersion of ATV survivor fragments on ground; re-entry casualty cross section; the world population density distribution; re-entry casualty probability assessment; global re-entry risk distribution; medium- and short-term risk analysis & management; re-entry patterns of Skylab and Mir/Salyut-7; unsuccessful Salyut-7/K-1686 risk management; Skylab short-term risk management strategy; controlled Mir de-orbiting operations; Mir re-entry risk management; conclusions on re-entry risk assessment.

On Orbit Collision Avoidance: Background information on collision avoidance; collision between Cerise and an AR-1 V-16 fragment; determination of potential conjunction events; conjunction event frequency for ERS-1 & 2; determination of Collision risk - step 1; determination of Collision risk - step 2; US conjunction avoidance criteria for STS; ESA conjunction avoidance criteria for ERS-1 & 2; typical high risk conjunctions for ERS-1; collision avoidance manoeuvres.

HVI Testing & Modeling: Hypervelocity impact effects; light gas guns -technical concepts; light gas guns - physical principles; HVI effect on a semi- infinite target; HVI accelerator capabilities; HVI damage on single-wall shields; multiple-wall HVI shielding concepts; HVI ballistic limit curves; HVI test and validation concepts; conclusions on HVI testing and shielding.

Near Earth Meteoroid Environment: Meteoroids and meteorites; the terrestrial meteoroid environment; meteoroid model (background and streams); terrestrial meteoroid collision flux; earth shielding and gravitational focusing; major meteor streams in 2001; prediction of the Leonid stream activity 2000 -2002; prediction of the Leonids in 2001.

NEO Risk Assessment: Background on near-earth objects (NEOs); major terrestrial meteorite impact craters; NEO statistics and mean time between impacts; recent impacts and atmospheric entries; classification on meteorites; historic and future close approaches by NEOs; risks levels and consequences of NEO impacts; impacts of comet Shoemaker-Levy 9 on Jupiter; impact features of Shoemaker-Levy 9 on Jupiter.

Space Nuclear Reactor Systems: Neutron spectra; design of reactor assemblies; control: absorption of neutrons; control: reflection of neutrons; reactor design; SNAP-10A; control: reflection of neutrons; control: absorption of neutrons; thermoelectric energy conversion; thermionic energy conversion; TOPAZ; ITR concept; Buk reactor; charged particles in the earth's magnetic field; reactor powered spacecraft concepts.

Electric thrusters: Electrothermal propulsion; arc-jets; resisto-jets; electrostatic propulsion; ion thruster; Kaufman-thruster; high frequency thruster; electromagnetic propulsion; jxB-thruster; application of electric thrusters; north-south correction on GEO; transfer from LEO to GEO; recovery of the satellite ARTEMIS.

Fig. 1. Fragment of the Cluster-1 satellites, retrieved after failure of launch
Ariane-501 at CSG/Kourou on June 4, 1996
Fig. 2. Inspection of meterite samples of stony and nickel-iron type
Fig. 3. Inspection of meterite samples of stony and nickel-iron type Fig. 4. Sample of an Aluminium block of 18 cm diameter and 8.2 cm thickness that
was impacted by a 1.2 cm Aluminium sphere at a velocity of 6.8 km/s, causing
a crater of 9 cm diameter and 5.3 cm depth, and a rear wall spallation of 9.2
cm diameter.
Fig. 5. Part of a Hubble Space Telescope solar array that was retreived from
space on March 3, 2002, after almost 8 years and 3 months in orbit. The
sample shows several impacts from sub-mm objects.
Fig. 6. Explanation of the physical principles that led to the damage observed
for the hypervelocity impact sample in Fig. 4.
Fig. 7. Samples of dual-wall Whipple shields, and explanation of the underlying
protection concept.
Fig. 8. Close-up of stony and nickel-iron meteorite samples ranging from 10 grams
to 8 kilograms, including a cut (bottom left) that displays Widmannstätt