ESA Document - Emits - ESA
ESA Document - Emits - ESA ESA Document - Emits - ESA
s HMM Assessment Study Report: CDF-20(A) February 2004 page 42 of 422 yearly limit is not expected to be exceeded during solar maximum by the GCRs alone, but the limit would be exceeded at solar minimum if inadequate shielding is provided, as shown in Figure 2-16. The skin and ocular dose from solar protons, using the ECSS-E-10-04 recommended 95% confidence level of the dose not being exceeded, with 9 g/cm 2 of shielding is 2 Sv/year. However, inside a storm shelter providing 25 g/cm 2 of shielding a yearly dose of 0.12 Sv could be expected in the eyes and skin tissues, assuming a semi-infinite planar shielding geometry. For the Blood Forming Organs (BFOs) the doses are 5.92 Sv and 0.532 Sv, respectively, assuming a spherical shell shielding geometry and the muscular tissues providing an additional 5 g/cm 2 of shielding in addition to the 25 g/cm 2 of the storm shelter. Dose Eq. Sv/yr 1.000 0.800 0.600 0.400 0.200 0.000 2.6.4.3 Career limit GCR Dose Equiv. as Fn of Water shield Thickness Solar Maximum Solar Minimum BFO Annual Limit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Thickness cm or g/cm2 Figure 2-16: GCR dose equivalent (Sv/year) as a function of shielding thickness All radiation sources contribute to the career limit dose calculation, although the majority of the dose accrued throughout the mission will be from solar proton events and galactic cosmic rays. 2.6.5 Assumptions and trade-offs • 500 km orbit about Mars – leads to reduction of about 25% in GCR flux due to planetary “bulk” shielding. • A minimum shielding of 16 g/cm 2 to be provided by the Martian atmosphere during Martian surface activities. • 25 g/cm 2 of shielding provided by the storm shelter to ensure remaining below the 30 day and 1 year limits.
s HMM Assessment Study Report: CDF-20(A) February 2004 page 43 of 422 • 9 g/cm 2 of shielding provided in habitation module to ensure remaining below the yearly limit and career limits from GCRs. • The BFO doses for solar proton doses have been calculated assuming that an additional 5 g/cm 2 of shielding is provided by surrounding tissue, e.g. muscles, bones, etc. It is possible that this can result in significant errors in the estimation of the solar proton dose, as the calculation is at the limits of both the solar proton models and the radiation transport models used. It is expected that the proton fluence at high energies will be less than currently predicted by the JPL model and so result in an over prediction of the dose estimate. However, the errors in the shielding transport models are likely to result in the under prediction of the dose estimate for the solar proton dose. A more comprehensive review of the models and analysis should be performed in the future. 2.6.6 Budgets Skin and Eye radiation Doses are shown in Table 2-4: Phase Duration (day) Phase start Sv/day Total Sv % Year LEO 2 2033/04/06 0.00077 0.002 0.040 HEO 2 2033/04/08 0.03825 0.077 1.974 Earth->Mars Transfer 215 2033/04/10 0.00085 0.184 4.736 Mars Orbit 100 2033/11/11 0.00064 0.064 1.643 Surface Activities 30 2034/02/19 0.00016 0.005 0.126 1.454 Mars Orbit 403 2034/03/21 0.00064 0.257 6.620 1.555 Mars->Earth Transfer 213 2035/04/28 0.00085 0.182 4.692 0.868 Solar Proton Dose 965 3.108 80.170 Total 965 2035/11/27 3.877 Table 2-4: Skin and eye radiation doses Blood Forming Organ (BFO) Doses are shown in Table 2-5: Phase Duration (day) Phase start Sv/day Total Sv % Year LEO 2 2033/04/06 0.00077 0.002 0.040 HEO 2 2033/04/08 0.03825 0.077 1.974 Earth->Mars Transfer 215 2033/04/10 0.00064 0.138 3.550 Mars Orbit 100 2033/11/11 0.00048 0.048 1.231 Surface Activities 30 2034/02/19 0.00016 0.005 0.126 0.329 Mars Orbit 403 2034/03/21 0.00048 0.192 4.961 0.263 Mars->Earth Transfer 213 2035/04/28 0.00064 0.136 3.517 0.174 Solar Proton Dose 965 0.834 4.357 Total 965 2035/11/27 1.430 2.6.7 Conclusions Table 2-5: Blood forming organs radiation doses To ensure that the astronauts do not receive a 30-day dose in excess of the limits, it will be necessary to include a storm shelter with at least 25 g/cm 2 of shielding to protect against solar
- Page 1 and 2: s HMM Assessment Study Report: CDF-
- Page 3 and 4: s STUDY TEAM HMM Assessment Study R
- Page 5 and 6: s T A B L E O F C O N T E N T S HMM
- Page 7 and 8: s HMM Assessment Study Report: CDF-
- Page 9 and 10: s L I S T O F F I G U R E S HMM Ass
- Page 11 and 12: s HMM Assessment Study Report: CDF-
- Page 13 and 14: s HMM Assessment Study Report: CDF-
- Page 15 and 16: s L I S T O F T A B L E S HMM Asses
- Page 17 and 18: s HMM Assessment Study Report: CDF-
- Page 19 and 20: s 1 INTRODUCTION 1.1 Background HMM
- Page 21 and 22: s 2 GENERAL ARCHITECTURE 2.1 Study
- Page 23 and 24: s HMM Assessment Study Report: CDF-
- Page 25 and 26: s 2.2.4.2 Accelerations HMM Assessm
- Page 27 and 28: s 2.2.4.4 Temperature and relative
- Page 29 and 30: s HMM Assessment Study Report: CDF-
- Page 31 and 32: s HMM Assessment Study Report: CDF-
- Page 33 and 34: s Figure 2-10: Trajectory Overview
- Page 35 and 36: s 2.4.3.5 TEI and planetary protect
- Page 37 and 38: s HMM Assessment Study Report: CDF-
- Page 39 and 40: s HMM Assessment Study Report: CDF-
- Page 41: s HMM Assessment Study Report: CDF-
- Page 45 and 46: s Mars Excursion Vehicle Transfer H
- Page 47 and 48: s 2.7.5.1 Mission elements dry mass
- Page 49 and 50: s 2.7.5.8 MEV release The MEV is re
- Page 51 and 52: s Total mission time (days) 1200 10
- Page 53 and 54: s HMM Assessment Study Report: CDF-
- Page 55 and 56: s HMM Assessment Study Report: CDF-
- Page 57 and 58: s stack 9 Propellant mass of the ne
- Page 59 and 60: s HMM Assessment Study Report: CDF-
- Page 61 and 62: s HMM Assessment Study Report: CDF-
- Page 63 and 64: s HMM Assessment Study Report: CDF-
- Page 65 and 66: s The core supporting structure has
- Page 67 and 68: s 2.7.7.1.3 Mars excursion module S
- Page 69 and 70: s 2.7.7.1.4 Earth return capsule HM
- Page 71 and 72: s Mission Phase Description Event s
- Page 73 and 74: s Mission Phase Description Event s
- Page 75 and 76: s 2.7.10 Mission performance Table
- Page 77 and 78: s Days on Martian surface 450 400 3
- Page 79 and 80: s HMM Assessment Study Report: CDF-
- Page 81 and 82: s HMM Assessment Study Report: CDF-
- Page 83 and 84: s Maximum manoeuvre duration 6 mont
- Page 85 and 86: s % of loss from baseline 20 18 16
- Page 87 and 88: s 2.7.15 Sensitivity analysis HMM A
- Page 89 and 90: s 2.7.15.4 Influence of the mass of
- Page 91 and 92: s HMM Assessment Study Report: CDF-
s<br />
HMM<br />
Assessment Study<br />
Report: CDF-20(A)<br />
February 2004<br />
page 43 of 422<br />
• 9 g/cm 2 of shielding provided in habitation module to ensure remaining below the yearly<br />
limit and career limits from GCRs.<br />
• The BFO doses for solar proton doses have been calculated assuming that an additional 5<br />
g/cm 2 of shielding is provided by surrounding tissue, e.g. muscles, bones, etc. It is<br />
possible that this can result in significant errors in the estimation of the solar proton dose,<br />
as the calculation is at the limits of both the solar proton models and the radiation<br />
transport models used. It is expected that the proton fluence at high energies will be less<br />
than currently predicted by the JPL model and so result in an over prediction of the dose<br />
estimate. However, the errors in the shielding transport models are likely to result in the<br />
under prediction of the dose estimate for the solar proton dose. A more comprehensive<br />
review of the models and analysis should be performed in the future.<br />
2.6.6 Budgets<br />
Skin and Eye radiation Doses are shown in Table 2-4:<br />
Phase Duration (day) Phase start Sv/day Total Sv % Year<br />
LEO 2 2033/04/06 0.00077 0.002 0.040<br />
HEO 2 2033/04/08 0.03825 0.077 1.974<br />
Earth->Mars Transfer 215 2033/04/10 0.00085 0.184 4.736<br />
Mars Orbit 100 2033/11/11 0.00064 0.064 1.643<br />
Surface Activities 30 2034/02/19 0.00016 0.005 0.126 1.454<br />
Mars Orbit 403 2034/03/21 0.00064 0.257 6.620 1.555<br />
Mars->Earth Transfer 213 2035/04/28 0.00085 0.182 4.692 0.868<br />
Solar Proton Dose 965 3.108 80.170<br />
Total 965 2035/11/27 3.877<br />
Table 2-4: Skin and eye radiation doses<br />
Blood Forming Organ (BFO) Doses are shown in Table 2-5:<br />
Phase Duration (day) Phase start Sv/day Total Sv % Year<br />
LEO 2 2033/04/06 0.00077 0.002 0.040<br />
HEO 2 2033/04/08 0.03825 0.077 1.974<br />
Earth->Mars Transfer 215 2033/04/10 0.00064 0.138 3.550<br />
Mars Orbit 100 2033/11/11 0.00048 0.048 1.231<br />
Surface Activities 30 2034/02/19 0.00016 0.005 0.126 0.329<br />
Mars Orbit 403 2034/03/21 0.00048 0.192 4.961 0.263<br />
Mars->Earth Transfer 213 2035/04/28 0.00064 0.136 3.517 0.174<br />
Solar Proton Dose 965 0.834 4.357<br />
Total 965 2035/11/27 1.430<br />
2.6.7 Conclusions<br />
Table 2-5: Blood forming organs radiation doses<br />
To ensure that the astronauts do not receive a 30-day dose in excess of the limits, it will be<br />
necessary to include a storm shelter with at least 25 g/cm 2 of shielding to protect against solar
Change language