A Bellucci JF Goester P Omaly S Christy F Delmas CONTEXT TIANGON1 REENTRY FOLLOWUP BY CNES 2 7th International Conference on Astrodynamics Tools and Techniques Oberpfaffenhofen ID: 1032031
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1. TIANGON-1 RE-ENTRY FOLLOW-UP BY CNESA. Bellucci, J.F. Goester, P. Omaly, S. Christy, F. Delmas
2. CONTEXTTIANGON-1 RE-ENTRY FOLLOW-UP BY CNES27th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018Re-entry safety requirements2010French Space Operation Act(FSOA)CNES tools to evaluate safety requirementsRe-entry of Chinese space station Tiangon-1Simulates the ablation of debris from a spacecraft after its destruction during re-entry into the atmosphereEstimates human casualty risk during launch and controlled or uncontrolled re-entry.Operational orbit determinationOperational monitoring and studies of an high risk re-entryCONTEXT
3. TIANGON-1 RE-ENTRY FOLLOW-UP BY CNES37th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018Orbital decay with random attitude 1st aerodynamic stress: appendices loss (solar arrays…)Main fragmentationThermal ablation+ secondary fragmentations
4. TIANGON-1 RE-ENTRY FOLLOW-UP BY CNES47th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018Simulations of the ablation of debris from a spacecraft after its destruction during re-entry into the atmosphereCombination of models for :aerodynamic (Cd computation)aerothermodynamic (heat flux computation)thermal model (heat transfer on objects’ surfaces)Ablation model (estimation of material loss)Evolution of each element characteristics (T, mass, S…)95 km : loss of solar panels78 km : Satellite fragmentationResults on ground (kinetic energy, casualty area…)Altitude+ list or surviving fragmentsModelling of spacecraft using simple shapesoriented object codes
5. ELECTRA Overview5The probability of incurring at least a victimThe expected value of the number of victimsIn case of:a propulsion failureDuring a launch: RL modeDuring a de-orbit maneuver: RC modeAn uncontrolled re-entry :Random re-entries mode : RA modeFinal orbits re-entry : RF modeground impacts of the fragments casualty areaConsideration of the population inside the fallout areaVulnerability of the population Probability of a propulsion failureD BodyRqdebrisD = 0,677mAcComputation of the risk for population during space operations :Risk componentsRL modeRC modeTrajectories simulated with dispersionsFragmentation altitudesdebris impacts (*)Launch Failure or premature stop of boost(*) : without taking into account ablation/melting
6. TIANGON-1 re-entry contextTIANGON-1 RE-ENTRY FOLLOW-UP BY CNES67th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018Mission factsChinese Space Station (Norad 37820)Launch : Sept 29th, 2011Altitude ~ 370 km, inc ~ 42 °2016 : loss of control link ► end of Mission ► Uncontrolled object with decaying altitude due to atmospheric dragRe-entry factsMass ~ 8 tons ► Heavy ?lighter than MIR (124 t)lighter than ATV (~13 t for re-entry) which is not a stationBut uncontrolled re-rentry High risk re-entry International interestCNES mobilization :Flight dynamic technical expertiseObservation means (national and international cooperation)Operational tools ► Prediction of date and location of re-entry ► Estimation of the risk for population
7. Modelling of Tiangon-1TIANGON-1 RE-ENTRY FOLLOW-UP BY CNESVery few official informationInternal knowledge Analogy & scaling with similar vehicles77th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 201810,4 m3,35 mAle=5mm183 independent objectsDebrisk modellingModel3,1 m10 mAft service module : silver-zinc batteries10,4 m3,35 m2,5 mHabitation orbital module :15m3 pressured volume1mTransition section : steel alloy gas tanks with O and N, Water storage tanks8506 kg
8. Orbital parameters :TLE issued on March 18th +extrapolation until T-72h, T-48h, T-24h, T-12h (T= Timpact)Orbit determination on March 26thAblationTIANGON-1 RE-ENTRY FOLLOW-UP BY CNES87th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018V2.10 advanced mode (Cnes internal version)MSIS86/CIRA88 atmosphereJ2 component of Earth potentialMain Fragmentation alt =78 kmBirth T° of fragment = 300 KAlways 90 surviving fragments Total CA ~ 129 m2Orbit computed from TLE issued on March 19th T-72hT-48hT-24hT-12hOrbit determination March 26th, 2018Casualty area (m2)129,03 127,87129,5128,93129,09Not necessary to update fragments list after each new orbit.
9. Uncontrolled re-entry riskTIANGON-1 RE-ENTRY FOLLOW-UP BY CNESLong term => Only RA mode for ELECTRA :Unknown fallout zone not known ► surface on Earth included between +/- i (orbit inclination)Computation by bands of latitude relative to a population data base K bands of latitude [1, 2], probability to fall in the band of latitude [1, 2]Risk computed using the mean density of the population inside the band of latitudeNo risk per country97th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018GPW v4 UN-adjustedExtrapolated by Sertit laboratory90 surviving fragments Probability of victim without protection :2,51 x 10-3
10. ELECTRA : Final re-entry mode (RF)TIANGON-1 RE-ENTRY FOLLOW-UP BY CNES107th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018The initial re-entry points are initialized by a pre process considering only dispersion on the orbital ballistic coefficient (Cb)Short term : estimate the risk a few hours or days before an uncontrolled re-entryRe-entry conditions distributed on a limited amount of orbits Set of probable re-entry points ~ failure instant in RC or RL mode ► same method for risk computation.Evenly distribution of the impact points not to miss to densely inhabited areaInhabited areaCb +y%Cb +z%Cb 0%Cb +x%Circle-equidistant probable re-entry points defined by : date, position, velocity and ballistic coefficientat an identical geodetic altitude of re-entry (around 85 km), associated to an occurrence probability (uniform or Gaussian repartition of Cb)
11. Operational orbit determination : middle-termTIANGON-1 RE-ENTRY FOLLOW-UP BY CNESMiddle term (< 2 months) atmospheric re-entry predictionData : TLE distributed by USSTRATCOM through Spacetrack websiteProcess by OPERA software included in JOCC (OCC flight dynamic system) 117th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018TLE HistoryExpected re-entry date T+uncertaintyOrbital parameters at T-72h, T-48h, T-24h, T-12hStudy with Debrisk (Cf before)Optimization of Electra configuration : fine configuration for accurate risk estimation in a reasonable time for operational monitoringOrbit propagation
12. Risky Re-entries ProcessTIANGON-1 RE-ENTRY FOLLOW-UP BY CNES127th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018Dedicated CNES CellOther agenciesIADCFrench AuthoritiesTLE + Ephem SPRe-entry estimationsMeasurementsMonge + DGA RadarEUSSTSATAM RadarsGraves RadarOrbit DeterminationRe-entry window computationMail & Report generationEUSST Users Of RE serviceUS Radars(sometimes)JAXA RadarKSGC(sometimes)
13. Impact date estimateTIANGON-1 RE-ENTRY FOLLOW-UP BY CNES137th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018TLE dateImpact date estimateRe-entry window durationMarch 19thApril 3rd - 19:39March 20thApril 3rd - 01:06Orbit determination dateMarch 26th 14h30April 1st - 01:5142h10March 27th 14h00April 1st 06:3736h07March 28th 14h00April 1st 04:4952h37March 30th 9h00April 1st 19:0424h34March 31st 08h26April 2nd 00:0616h32April 1st 07h51April 2nd 01:497h08April 1st 15h04April 2nd 01:243h591st risk estimation with Electra RF mode
14. Orbit determination : March 30th, 9h0014Impact date estimate :04/01 19:04Probability of victim :2.835e-03
15. Orbit determination : March 31st, 8h2615Impact date estimate :04/01 23 :24Probability of victim :3.643e-03
16. Orbit determination : April 1st, 7h5116Impact date estimate :04/01 00 :35Probability of victim :3.237e-03
17. Orbit determination : April 1st, 15h0417Impact date estimate :04/01 00 :19Probability of victim :2.813e-03
18. Impact map18CNES Impact date estimate :04/01 00 :19Jspoc Impact date estimate :04/01 00 :16Luckily fall-out in the SPOUA,= Targeted area for controlled reentry► No victims
19. ConclusionTIANGON-1 RE-ENTRY FOLLOW-UP BY CNESTiangon-1 re-entry : opportunity to combine CNES operational means, expertise tools and various teams for efficient and successful monitoring :Station model and Debrisk ablation computationUses in Electra for risk computation using « Final re-entry mode » (1st operational use)All computations relying on daily orbit determination by OCC using various radar observationsDaily evolution of risk per countryPredictions very similar to other agencies197th International Conference on Astrodynamics Tools and Techniques, Oberpfaffenhofen, Germany, 6-9 November 2018
20. THANK YOU FOR YOUR attentionQuestions?