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3 Page 3 of 22 TABLE OF CONTENT 1. SCOPE APPLICABLE AND REFERENCE DOCUMENTS APPLICABLE DOCUMENTS REFERENCE DOCUMENTS ABBREVIATIONS MISSION DEFINITION ENVIRONMENT DEFINITION Electrons Protons Trapped protons Solar flare protons Heavy Ions Galactic Cosmic Rays (GCR) Solar Flare Heavy Ions RADIATION EFFECTS Total Ionizing Dose (TID) Non Ionizing Dose (NID, also called displacement damage) Protons in SILICON Electrons in SILICON Protons in GaAs : Electrons in GaAs : NEUTRAL EARTH ATMOSPHERE INTRODUCTION... ERROR! BOOKMARK NOT DEFINED. DOCUMENT CHANGE DETAILS...22

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5 Page 5 of SCOPE This document describes the space environment of concern for Mission; it covers radiation environment in the 5. and 6. while in 7. is depicted the neutral earth atmosphere. The earth s natural radiation environment consists of electrons, protons and heavy ions. These particles are either trapped by the earth s magnetic field (Van Allen Belts) or transiting through the space (solar flare or Galactic Cosmic Ray). These particles can induce two types of degradation: long term degradations and Single Event Effects (SEE). Long term degradations are generated mainly by electrons and protons. This type of degradation occurs following an accumulation of ionizing dose deposition in circuit insulators or by atom displacement (mainly protons). On low altitude orbit (< 1000 km) the long term degradation is expected to be mainly induced by the trapped protons. Protons and electrons spectra expected on orbit are described in Figure 1 to Figure 4. The associated dose-depth and displacement curves are presented in Figure 7 and in Figure 8. Single Event Effects are generated by protons and heavy ions coming from solar flare and galactic cosmic rays. In this case, we consider that only one particle (protons or heavy ion) can induce the degradation by striking a sensitive volume in circuits. For heavy ions interaction, the energy deposition is described in term of Linear Energy Transfer (LET). The LET spectrum for orbit is presented in Figure 5 for galactic cosmic rays and in Figure 6 for solar flare. The proton LET is too low (< 0.1 MeV.cm2/mg) to induce directly SEE. However such events can be triggered indirectly by secondary atom emission issued from nuclear reaction between proton and bulk silicon atom. Such reactions being dependent of proton energy, proton spectrum is presented in term of energy in Figure APPLICABLE AND REFERENCE DOCUMENTS 2.1 APPLICABLE DOCUMENTS Ref. Document name Doc. Ref. AD 1 Radiation Hardness Assurance for Sentinal 5 precursor S5P.RS.ASU.SY REFERENCE DOCUMENTS [RD 1] "The AE8 Trapped Electron Model Environment", J.I. Vette, NSSDC/WDC-A-R&S 91-24, NASA/GSFC, Greenbelt, MD, November, [RD 2] "AP8 Trapped Proton Environment for Solar Maximum and Solar Minimum", D. M. Sawyer and J.I. Vette, NSSDC/WDC-A-R&S, 76-06, NASA/GSFC, Greenbelt, MD, December, [RD 3] "New interplanetary proton fluence model", J. Feynman et al, J. Spacecraft, vol. 27, n 4, p403, July, [RD 4] "Cosmic Ray Effects on Micro-Electronics, part IV," J.H. Adams, Jr, NRL Memorandum report 5901, Naval Research Laboratory, Washington, DC, December, [RD 5] "CREME96 : a revision of the Cosmic Ray Effects on MicroElectronic code", A.J. Tylka et al, IEEE Transaction on Nuclear Science NS-44, , December, 1997.

6 Page 6 of 22 [RD 6] "Updated calculations for routine space-shielding radiation dose estimates: SHIELDOSE-2", Seltzer, S. M., NIST Publication NISTIR 5477, Gaithersburg, MD, December [RD 7] "NOVICE, A Radiation Transport/Shielding Code", T.M. Jordan, E.M.P. Consultants Report, January, [RD 8] "Radiation Engineering Methods for Space application, section 2 : Environment (mission analysis and specification", R. Mangeret, RADECS 2003 short course, ESA-ESTEC, Noordwijk, The Netherlands, September [RD 9] "Damage correlations in semiconductors exposed to gamma, electron and proton radiations", G.P. Summers et al, IEEE Trans. Nuc. Sc. Vol 40, n 6, Dec [RD 10] "The Energy Dependence of Lifetime Damage Constants in GaAs LEDs for 1 to 500 MeV Protons", A. L. Barry et al., IEEE Trans. Nuc. Sc. Vol 42, n 6, Dec [RD 11] "Extension of the MSIS Thermospheric Model into the Middle and Lower Atmosphere.", A. E. Hedin, J. Geophys. Res. 96, 1159, [RD 12] ECSS Space Environment Standard E-10-04, January ABBREVIATIONS Abbrev. AL CCD CREME DD DDC DDEF GCR GSFC JPL LED LEO LET NIEL SEE / SEP TID TNID WC Meaning Anomalously Large event Charge Coupled Device Cosmic Ray Effect on MicroElectronics Displacement Damage Dose Depth Curve Displacement Damage Equivalent Fluence Galactic Cosmic Rays Goddard Space Flight Centre (NASA) Jet Propulsion Laboratory (NASA) Light Emitting Diode Low Earth Orbit Linear Energy Transfer Non Ionising Energy Loss Single Event Effect / Single Event Phenomena Total Ionising Dose Total Non Ionising Dose Worst Case

7 Page 7 of MISSION DEFINITION mission is defined by a design lifetime duration of 7 years. Its orbit is at approx 830 km altitude (837 km apogee and 820 km perigee) and inclination. Estimated launch is ENVIRONMENT DEFINITION 5.1 Electrons Fluxes of electrons that are trapped in Earth radiation belts are modeled through the AE8MAX model (WC) from NSSDC/NASA [RD 1], with Jensen and Cain geomagnetic field model. Corresponding fluxes can be found in Table 1 and in Figure 1. Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) E E E E E E E E E E E E E E E E E E E E E E E E E E E E+00 Table 1 : Trapped electron fluxes, AE8max, orbit 1.E+06 Integral flux (#/cm2/s) >E 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 Trapped electrons 1.E Energy (MeV) Figure 1: trapped electron integral fluxes, AE8max, orbit

8 Page 8 of Protons Protons can be of two origins. There are trapped protons in the Earth radiation belts and solar protons emitted as bursts during solar eruptions Trapped protons Trapped protons are modelled through the AP8MIN model (WC) from NSSDC/NASA [RD 2] with Jensen and Cain geomagnetic field model. No material shielding is considered. Corresponding fluxes can be found in Table 2 and Figure 2. Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+00 Table 2 : Trapped proton fluxes, AP8min, orbit 1.E+04 Integral flux (#/cm2/s) >E 1.E+03 1.E+02 1.E+01 Trapped protons 1.E Energy (MeV) Figure 2 : Trapped proton integral fluxes, AP8min, orbit

9 Page 9 of Solar flare protons For cumulated effect purpose (Total Ionizing and Non Ionizing Dose), solar flare protons fluxes on orbit have been simulated using Feynman (JPL-91) model [RD 3] with a confidence level of 90%. No material shielding is considered. Corresponding fluences can be found in Table 3 and in Figure 3. Energy (MeV) Differential fluence (/MeV/cm 2 ) Integral fluence (/cm 2 ) Energy (MeV) Differential fluence (/MeV/cm 2 ) Integral fluence (/cm 2 ) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+00 Table 3 : Solar proton fluence, JPL-91 model, orbit 1,E+12 1,E+11 flare protons Differential fluence (#/MeV/cm 2 /5years) 1,E+10 1,E+09 1,E+08 1,E+07 1,E+06 1,E+05 1,E Energy (MeV) Figure 3 : Solar proton differential fluence, JPL-91 model, orbit

10 Page 10 of 22 For SEE rate computation purpose, solar flare protons fluxes on orbit have been simulated using October 1989 major flare model. No material shielding is considered. Corresponding flux can be found in Table 3 and in Figure 3. Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) Energy (MeV) Differential flux (/MeV/cm 2 /s) Integral flux (/cm 2 /s) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+03 Table 4 : Solar proton fluence, October 1989 model, orbit 1,E+06 Differential flux (#/MeV/cm 2 /s) 1,E+05 1,E+04 1,E+03 1,E+02 1,E+01 1,E+00 1,E-01 flare protons : Oct. 89 1,E-02 1,E+00 1,E+01 1,E+02 1,E+03 Energy (MeV) Figure 4 : Solar proton flux, October 1989 model, orbit

11 Page 11 of Heavy Ions Galactic Cosmic Rays (GCR) Galactic Cosmic Ray LET spectra were simulated using OMERE software. To calculate SEP rates, the cosmic rays environment will be calculated in terms of integral Linear Energy Transfer (LET) spectrum. The simulations were performed considering the following parameters : Shielding : 1 g/cm 2 Earth Shadow : included Stormy : no Ion species : 1 < Z < 92 The LET spectrum is calculated in Solar minimum activity period (WC). LET fluxes are given in Figure 5 and in tabulated format in Table 5. S5P LET spectra GCR E-05 #/cm2/s 1E-06 1E-07 1E-08 1E-09 1E-10 1E-11 1E E E E E E+02 LET (MeV.cm2/mg) Figure 5 : Integral GCR flux spectrum on orbit, Aluminium shielding 1 g/cm 2

12 Page 12 of 22 LET [MeV.cm 2 /mg] Flux (#/cm 2 /s) > LET LET [MeV.cm 2 /mg] Flux (#/cm 2 /s) > LET 1.00E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-07 Table 5 : Integral GCR flux spectrum on orbit, Aluminium shielding 1 g/cm Solar Flare Heavy Ions Predictions of solar heavy ions flare fluxes on orbit are obtained using the CREME96 suite of programs [RD 5]. To calculate worst-case SEE rates, the solar heavy ion flare environment will be calculated in terms of integral Linear Energy Transfer (LET) spectrum. Shielding : 1 g/cm 2 Earth Shadow : included Stormy : yes Ion species : 1 < Z < 92 The LET spectrum is calculated for the October 1989 large event, worst day flux. LET fluxes are given in tabulated format in Table 6 and in Figure 6 (together with the GCR spectrum):

13 Page 13 of 22 LET flux LET flux [MeV.cm 2 /mg](#/cm /s) > LET [MeV.cm 2 /mg](#/cm /s) > LET 1.00E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-04 Table 6 : Integral solar flare ion flux spectrum based on M=8 in CREME86 for the orbit, Aluminium shielding 1 g/cm 2

14 Page 14 of 22 S5P LET spectra GCR Flare #/cm2/s E-05 1E-06 1E-07 1E-08 1E-09 1E-10 1E-11 1E E E E E E+02 LET (MeV.cm2/mg) Figure 6 : Integral solar flare ion flux spectrum on orbit, Aluminium shielding 1 g/cm 2 comparison with GCR spectrum 6. RADIATION EFFECTS 6.1 Total Ionizing Dose (TID) The solid sphere Total Ionizing Dose depth curve is calculated over a shielding range from 10 µm to 100 mm. This curve has been calculated thanks to SHIELDOSE 2 software [RD 6]. For material degradation purpose, a DDC dealing with lower thicknesses may be available on request. If the Sub-Contractor doesn t use advanced particle/matter interaction simulation tools, the following between in curves shall be used, instead of using directly particle fluxes and/or fluences as an input. The following curve (Figure 7 and associated table) is calculated for an Aluminium Solid Sphere Shielding, with a Silicon Detector located in its centre. It shall be used to perform Ray Tracing Analysis, taking into account the angle of incidence between the ray and the crossed material.

15 Page 15 of 22 1.E+08 1.E+07 1.E+06 1.E+05 Trapped electrons Trapped protons Solar protons Bremmstrahlung Total dose TID[rad(Si)] 1.E+04 1.E+03 1.E+02 1.E+01 1.E Aluminium solid sphere thickness (mm) Figure 7 : TID-depth curve for 7 years mission, Solid Sphere Shielding thickness [mm] TID [rad(si)] Shielding thickness [mm] TID [rad(si)] 1.00E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+02 Table 7 : TID-depth curve for 7 years mission, Solid Sphere

16 Page 16 of Non Ionizing Dose (NID, also called displacement damage) Both protons and electrons can induce displacement damage in semiconductor devices. The part of deposited energy involved in displacement defects creation is called Non Ionising Energy Loss (NIEL). This curve is calculated for aluminium solid spheres shielding of various thickness. The mission TNID-depth curve takes into account the environment defined in previous paragraphs. TNID-depth curve is provided for thicknesses ranging from 1 µm to 50 mm. It is given for GaAs (applicable for example to LED device material) and Silicon (applicable for example to CCD die material) targets, in Figure 8 and in Table 8. 1.E+13 DDEF [#/cm2] for 10MeV protons 1.E+12 1.E+11 1.E+10 Silicon GaAs 1.E Solid sphere Aluminium thickness (mm) Figure 8 : Solid Sphere Non Ionising Dose-depth curve (10MeV protons), GaAs and Silicon targets, 7 years mission

17 Page 17 of 22 Shielding thickness [mm] Silicon 10MeV protons GaAs 10MeV protons Shielding thickness [mm] Silicon 10MeV protons GaAs 10MeV protons 1.00E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+09 Table 8 : Solid Sphere Non Ionising Dose-depth curve, GaAs and Silicon targets, 10MeV protons, 7 years mission Displacement Damage Equivalent Fluence (DDEF) may be derived from TNID curve by help of NIEL tables (provided in Table 9 to Table 12 ) according to the following method: 1- identify the particle type (protons, electrons) and target material (GaAs, Si), 2- identify the particle energy E (MeV), 3- identify the shielding thickness t, 4- Then uses the following relationship : DDEF E, t E TNID t NIEL

18 Page 18 of 22 NIEL values provided in Table 9 to Table 12 are extracted from Summers et al. publication [RD 9] excepted the one used for protons in GaAs that comes from Barry's work [RD 10] Protons in SILICON Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm 2 /g] Table 9 : NIEL values in Silicon as a function of proton energy Electrons in SILICON Energy [MeV] NIEL [MeV.cm /g] Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm /g] Table 10 : NIEL values in Silicon as a function of electron energy

19 Page 19 of Protons in GaAs : Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm 2 /g] Table 11 : NIEL values in GaAs as a function of proton energy Electrons in GaAs : Energy [MeV] NIEL [MeV.cm /g] Energy [MeV] NIEL [MeV.cm 2 /g] Energy [MeV] NIEL [MeV.cm /g] Table 12 : NIEL values in GaAs as a function of electron energy

20 Page 20 of NEUTRAL EARTH ATMOSPHERE The present chapter depicts the neutral earth atmosphere environment. Below 1000 km altitude, a good knowledge of temperature, total density, concentrations of gas constituents and pressure can be important for aerodynamic forces prediction. Especially surface corrosion due to atomic oxygen impingement must be assessed to predict the degradation of sensitive coatings. Reference data for atmosphere come from the MSISE-90 (Mass Spectrometer and Incoherent Scatter Extended 1990) model [RD 11], which is the European reference [RD 12]. MSISE-90 profiles of temperature, number densities, pressure and total density for low activity (F10.7 = (F10.7) avg = 70, Ap = 0), mean activity (F10.7 = (F10.7) avg = 140, Ap = 15) and extremely high activity levels (F10.7 = (F10.7) avg = 300, Ap = 30) Low activity Mean activity High activity T( K) Tot (g/cm 3 ) 2.51E E E-16 He (/cm 3 ) 3.25E E E+06 O (/cm 3 ) 2.83E E E+06 N 2 (/cm 3 ) 3.72E E E+04 O 2 (/cm 3 ) 1.07E E E+02 Ar (/cm 3 ) 5.12E E E+00 H (/cm 3 ) 1.62E E E+03 N (/cm 3 ) 9.92E E E+05 P (Pa) 4.74E E E-07 Table 13: Temperature, total density, concentrations of gas constituents and pressure averaged along orbit

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22 Page 22 of 22 DOCUMENT CHANGE DETAILS ISSUE CHANGE AUTHORITY CLASS RELEVANT INFORMATION/INSTRUCTIONS Initial Issue DISTRIBUTION LIST INTERNAL EXTERNAL M. Sharples ESA Configuration Management Library

SIMULATION OF SPACE RADIATION FOR NANOSATELLITES IN EARTH ORBIT *

Romanian Reports in Physics, Vol. 64, No. 1, P. 302 307, 2012 SIMULATION OF SPACE RADIATION FOR NANOSATELLITES IN EARTH ORBIT * M.F. TRUȘCULESCU 1,2, O. SIMA 1 1 University of Bucharest, Physics Department,