1. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de 106-25-2008 Assessment of PWT Conditions for the STARDUST Post-Flight Analysis Ricarda Wernitz, Markus Fertig, Georg Herdrich, Stefan Löhle, Michael Winter, Hans-Peter Röser Speaker: Sebastian Lein

2. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis206-25-2008 Contents  STARDUST reentry observation campaign  STARDUST observation campaign  SLIT experimental set-up  Data reduction and evaluation  Results  IRS Plasma Wind Tunnels  Characterization of plasma conditions for experimental rebuilding of STARDUST reentry in PWK 1

3. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis306-25-2008 Sample return from comet Wild 2 Fastest re-entry ever of an artificial object 15.1.06, 1:56:42 a.m. Ablative heat shield PICA (phenol impregnated carbon) No instrumentation on board Mass45.8 kg Diameter0.811 m Velocity12.8 km/s Angle of entry8° STARDUST Sample Return

4. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis406-25-2008 STARDUST Sample Return Mission, Comet Wild 2: Fastest Re-entry Ever (12.8 km/s)

5. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis506-25-2008 NASA Observation Campaign DC8 at 14 km flight altitude International Participation (USA, Japan, Germany) IRS SLIT experiment: Emission spectrometry in near UV Advantages: Fixed wavelength range, comparatively high spectral resolution But: Difficult tracking due to small angle of vision SLIT

6. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis606-25-2008 SLIT Experimental Setup - Spectrometer Spectrometer Fiber orientation at spectrometer entry FO bundle 50x100µm Fiber orientation telescope EMCCD camera telescope angle of vision 0,45° Exposure time: 0.2 s 250 to 2500 photons/pixel at telescope entrance Full vertical binning

7. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis706-25-2008 Tracking camera SLIT Experimental Setup - Tracking Angle of vision Spectrometer 0.45° Intensifier: angle of vision 20° grid glued to intensifier screen lens system (telescope)intensifiervideo camera

8. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis806-25-2008 Video

9. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis906-25-2008 Evaluation of SLIT Data: Data Reduction  Background radiation, cosmic rays and atmospheric absorption (ModTran)  Wavelength and intensity calibration  Allocation of time and space  Distance and orientation of the DC8 (GPS)  Separation of Planck (heat shield) and plasma radiation  Heat shield temperatures  Analysis of plasma radiation

10. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1006-25-2008 Evaluation of SLIT Data: Data Reduction  Background radiation and cosmic rays  Wavelength and intensity calibration  Allocation of time and space  Distance and orientation of the DC8/SRC  Separation of Planck (heat shield) and plasma radiation  Heat shield temperatures  Analysis of plasma radiation

11. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1106-25-2008 Separation of Planck and Plasma Radiation Decreasing sensitivity towards UV → higher simulation temperature preferable Spectra fit at two different temperatures:  T=50K lower temperatures at smaller wavelengths Possible inaccuracies: scattered light assumption of linear temperature distribution along capsule

12. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1206-25-2008 Heat Shield Temperatures  Maximum temperature at peak heating (64 km) 2850 K  Upper limit for heat shield temperatures Thermal radiation of ablation particles not taken into account Linear temperature distribution along capsule assumed

13. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1306-25-2008 Fitting measured and simulated spectra  temperatures at best agreement Molecular Temperatures Satisfactory agreement. Not every peak simulated. Spectra simulated using PARADE Varying rotational and vibration temperatures Obtaining molecular temperatures via best fitting simulations to experimental data

14. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1406-25-2008 Fitting measured and simulated spectra  temperatures at best agreement Molecular Temperatures Satisfactory agreement, not every peak simulated. 62 km ~ Peak heating

15. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1506-25-2008 Fitting measured and simulated spectra  temperatures at best agreement Molecular Temperatures Agreement between simulation and experiment increases with decreasing altitude

16. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1606-25-2008 Evaluation of SLIT Data Molecular temperatures:  Fit to simulated spectra (PARADE)  Data base for CN and N2+ generated for T rot < 10000 K and T vib < 15000 K  T vib,CN decreases from > 15000 K at 75 km to 8000 K at 50 km  T vib,N2+ increases with decreasing altitude  T vib,N2+ higher than 15000 K (max. simulated temperature) in a wide range  Both rotational temperatures do not exceed 10000 K

17. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1706-25-2008 PWT: Experimental Entry Simulation Arc-driven thermal plasma generator (TPG) Specific enthalpy: 1-30 MJ/kg Pressure: 1-1000 hPa Gases: N 2 +O 2, Ar, Ar+O 2, N 2, H 2, N 2 +CH 4, Ar+CO 2 H 2 +O 2, He RB3 (PWK4) IPG3 (PWK3) Inductively heated plasma generators (IPG) Magnetoplasmadynamic generators (MPG) Specific enthalpy: 1-80 MJ/kg Pressure: 1-15 hPa (Luft) / 50 hPa (O 2 ) Gases: arbitrary, e.g. N 2, O 2, Ar, H 2, CO 2 or any combination thereof Specific enthalpy: 2-150 MJ/kg Pressure: 1-100 hPa Gases: N 2 +O 2, Ar, Ar+O 2, N 2, H 2, N 2 +CH 4, Ar+CO 2, He RD5/7 (PWK1/2)

18. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1806-25-2008 Plasma Conditions for Experimental Rebuilding

19. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis1906-25-2008 Experimental Rebuilding: Axial Profiles of Heat Flux and Total Pressure Max. heat flux at x=177 mm from nozzle: 12.1 MW/m 2 147 V, 1483 A, p amb =27 hPa 13.85 g/s N 2, 4.21 g/s O 2, 0.49 g/s Ar Total pressure 38 hPa Maximum heat flux of STARDUST reproduced

20. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis2006-25-2008 Experimental Rebuilding: Characterization of Plasma Conditions Increasing current at x=197 mm from plasma source: Increasing current from Test1: 1433 A to 1730 A Test2: 1421 A to 1967 A Max. heat flux at 197 mm from nozzle: Test2: 14 MW/m 2 151 V, 1965 A 13.67 g/s N 2, 4.2 g/s O 2, 0.49 g/s Ar 38.7 hPa

21. www.uni-stuttgart.de INSTITUT FÜR RAUMFAHRTSYSTEME www.irs.uni-stuttgart.de Session VI Extreme Environments – Assessment of PWT Conditions for STARDUST Post-Flight Analysis2106-25-2008 Summary  Preliminary post-flight analysis of STARDUST reentry  Data acquisition and reduction  Numerical simulation of emission spectra → identification of plasma species → identification of Planck, rotational and vibration temperatures  Characterization of plasma conditions  Heat fluxes of up to 14 MW/m 2 reproduced  Maximum heat flux of STARDUST reproduced