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s Figure 2-57 shows that: 2.8.4 Options HMM Assessment Study Report: CDF-20(A) February 2004 page 100 of 422 • With the present mission configuration the minimum assembly time found would be 4.6 years • This is strongly dependent on the launcher selection and the associated launch rate. If the launch rate of Energia is 4 times per year the assembly time is longer than 6 years • The need for manned operations in the assembly sequence and their associated launches increases significantly the assembly time, reliant on the shuttle availability • A launch for the refuelling of the cryogenic stage may be required The above scenario minimises the cryogenic boil-off but has the disadvantage of maximizing the flight life of the habitation volumes because these modules are launched at the beginning of the sequence. The assembly sequence can be modified so that the assembly of the habitation modules occurs last in the sequence. The resulting sequence and the effect on the result are shown in Table 2-36: Element Name Mass Cryo Stage? Launch Sequence Checkout time of composite Launcher Type Docking Arm required? Type Connections Robotics or EVA required? PS TEI + Service Platform 1 80,000 No 1 30 ENERGIA N/A No N/A No PS MOI 1 80,000 No 2 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS MOI 2 80,000 No 3 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS MOI 3 50,000 No 4 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS MOI 4 50,000 No 5 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PM Central Structure 1 and 2 20,000 No 6 30 Proton Capture & Berthing Yes Berthing/Docking No PM Central Structure 3 + Service Platform 2 20,000 No 7 30 A5 Capture & Berthing Yes Berthing/Docking No PS TMI 1 80,000 Yes 8 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 2 80,000 Yes 9 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 3 80,000 Yes 10 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 4 80,000 Yes 11 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 5 80,000 Yes 12 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 6 80,000 Yes 13 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 7 80,000 Yes 14 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 8 80,000 Yes 15 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 9 80,000 Yes 16 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 10 80,000 Yes 17 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 11 80,000 Yes 18 30 ENERGIA Capture & Berthing Yes Berthing/Docking No PS TMI 12 80,000 Yes 19 30 ENERGIA Capture & Berthing Yes Berthing/Docking No Node 1 + Airlock + Service Platform 3 20,000 No 20 90 Proton Capture & Berthing Yes External cable(s) Yes Habitation module 50,000 No 21 90 ENERGIA Capture & Berthing Yes External cable(s) Yes Node 2 + Cupola + Servive Platform 4 20,000 No 22 90 Proton Capture & Berthing Yes External cable(s) Yes ERC + SA + Antennas 15,000 No 23 90 A5 Capture & Berthing Yes External cable(s) Yes TV Supply 20,000 No 24 30 A5 Dock only No N/A No MEV 46,500 No 25 0 ENERGIA Dock only No External cable(s) Yes 1,511,500 25 Table 2-36: Modified assembly sequence The resulting assembly time becomes: Main Outputs Description Days since start Years since start Date Remarks Phase A start of first element -2920 -8.0 24/12/2020 Assuming development/integration of 8 years/element First launch 0 0.0 22/12/2028 Last element launched 1293 3.5 07/07/2032 Last EVA/Shuttle launch 1155 3.2 20/02/2032 End of assembly (no margin) 1306 3.6 20/07/2032 End of assembly 1486 4.1 16/01/2033 Includes Overall margin of 180 days Crew Launch 1546 4.2 17/03/2033 LV: 1 Shuttle Start of commissioning 1486 4.1 16/01/2033 Departure 1576 4.3 16/04/2033 Commissioning duration of 60 days Description Value Unit Total mass launched 1,511,500 kg Prop mass loss due to boil-off 28,210 kg Nr of launches 25 Nr of launches for EVA/robotics 2 Nr of Crew launches 0 Total number of launches 27 Remark Includes service Platforms Mass lost until launch window and is launched as last PS Includes launch of all elements and relaunch due to boil-off Shuttle launches for EVA/arm 1 Shuttle (Could also be 2 Souyz) Table 2-37: Modified assembly results

s HMM Assessment Study Report: CDF-20(A) February 2004 page 101 of 422 Table 2-37 shows that the overall assembly time does not alter. The change in the assembly sequence only affects the amount of cryogenic boil-off. The effect of delaying the assembly of all habitable modules until the end of the sequence, increases the boil-off by about 7.85 tonnes. When considering the in-orbit assembly sequence, the determining factors will therefore be the ‘operational life’ of the (habitable volume) equipment for the mission as a trade-off against the amount of fuel boil-off considered acceptable (mainly in the cyrogenic tanks launched first in the sequence) and also whether a refuelling launch shall be considered. 2.9 Safety/risk assessment 2.9.1 Mission-specific characteristics The driving characteristics of this mission are: • It falls within the category of Human Space Flight, including EVA activities. • It is an inter-planetary mission with sample return, therefore the Interplanetary Protection Rules and the UN treaties are applicable. 2.9.2 Definition of “safety and mission success” The first step in the risk assessment process is to establish the mission success definition and to set the safety goals of the mission: • Mission success: to bring a crew of 6 members to Mars and return them safely to Earth. • Safety goal: to identify all possible safety hazards, to eliminate/control them to an acceptable level during all the phases of the mission. • Probabilistic goals (overall safety & mission success risks): Human Spaceflight statistics show a 5% risk of losing the crew. Any next-generation system for transporting astronauts to Mars will be probably designed to a risk requirement much lower than that, e.g 0.5%. 2.9.3 Safety requirements: • Double & Single Failure/Fault/Operator error tolerance to catastrophic & critical events; safety margins • Fail safe: This is the capacity of the system to remain in a safe condition when a failure occurs or to skip directly into another safe condition 2.9.4 Mission factors/issues: Throughout the mission design the following factors are important: • Mission abort/ rescue capabilities. (Acceptable risks can be achieved if abort options are designed into the mission for all phases except for those for which it is impossible • Greater reliability and / or redundancy of systems. (e.g. Common Mode/Common Cause failures) • Preventive and/or corrective maintenance strategy (e.g. robotics, spares, aged equipment control, caution and warning system) • Capability to monitor/ detect and assess effects of slow events such as: metal fatigue, cracks; dust, corrosion and rust

s<br />

Figure 2-57 shows that:<br />

2.8.4 Options<br />

HMM<br />

Assessment Study<br />

Report: CDF-20(A)<br />

February 2004<br />

page 100 of 422<br />

• With the present mission configuration the minimum assembly time found would be<br />

4.6 years<br />

• This is strongly dependent on the launcher selection and the associated launch rate. If<br />

the launch rate of Energia is 4 times per year the assembly time is longer than 6<br />

years<br />

• The need for manned operations in the assembly sequence and their associated<br />

launches increases significantly the assembly time, reliant on the shuttle availability<br />

• A launch for the refuelling of the cryogenic stage may be required<br />

The above scenario minimises the cryogenic boil-off but has the disadvantage of maximizing the<br />

flight life of the habitation volumes because these modules are launched at the beginning of the<br />

sequence.<br />

The assembly sequence can be modified so that the assembly of the habitation modules occurs<br />

last in the sequence. The resulting sequence and the effect on the result are shown in Table 2-36:<br />

Element Name Mass Cryo Stage?<br />

Launch<br />

Sequence<br />

Checkout<br />

time of<br />

composite<br />

Launcher<br />

Type<br />

Docking<br />

Arm required? Type<br />

Connections<br />

Robotics or EVA<br />

required?<br />

PS TEI + Service Platform 1 80,000 No 1 30 ENERGIA N/A No N/A No<br />

PS MOI 1 80,000 No 2 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS MOI 2 80,000 No 3 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS MOI 3 50,000 No 4 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS MOI 4 50,000 No 5 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PM Central Structure 1 and 2 20,000 No 6 30 Proton Capture & Berthing Yes Berthing/Docking No<br />

PM Central Structure 3 + Service Platform 2 20,000 No 7 30 A5 Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 1 80,000 Yes 8 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 2 80,000 Yes 9 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 3 80,000 Yes 10 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 4 80,000 Yes 11 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 5 80,000 Yes 12 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 6 80,000 Yes 13 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 7 80,000 Yes 14 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 8 80,000 Yes 15 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 9 80,000 Yes 16 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 10 80,000 Yes 17 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 11 80,000 Yes 18 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

PS TMI 12 80,000 Yes 19 30 ENERGIA Capture & Berthing Yes Berthing/Docking No<br />

Node 1 + Airlock + Service Platform 3 20,000 No 20 90 Proton Capture & Berthing Yes External cable(s) Yes<br />

Habitation module 50,000 No 21 90 ENERGIA Capture & Berthing Yes External cable(s) Yes<br />

Node 2 + Cupola + Servive Platform 4 20,000 No 22 90 Proton Capture & Berthing Yes External cable(s) Yes<br />

ERC + SA + Antennas 15,000 No 23 90 A5 Capture & Berthing Yes External cable(s) Yes<br />

TV Supply 20,000 No 24 30 A5 Dock only No N/A No<br />

MEV 46,500 No 25 0 ENERGIA Dock only No External cable(s) Yes<br />

1,511,500<br />

25<br />

Table 2-36: Modified assembly sequence<br />

The resulting assembly time becomes:<br />

Main Outputs<br />

Description<br />

Days since<br />

start<br />

Years since<br />

start<br />

Date<br />

Remarks<br />

Phase A start of first element -2920 -8.0 24/12/2020 Assuming development/integration of 8 years/element<br />

First launch 0 0.0 22/12/2028<br />

Last element launched 1293 3.5 07/07/2032<br />

Last EVA/Shuttle launch 1155 3.2 20/02/2032<br />

End of assembly (no margin) 1306 3.6 20/07/2032<br />

End of assembly 1486 4.1 16/01/2033 Includes Overall margin of 180 days<br />

Crew Launch 1546 4.2 17/03/2033 LV: 1 Shuttle<br />

Start of commissioning 1486 4.1 16/01/2033<br />

Departure 1576 4.3 16/04/2033 Commissioning duration of 60 days<br />

Description Value Unit<br />

Total mass launched 1,511,500 kg<br />

Prop mass loss due to boil-off 28,210 kg<br />

Nr of launches 25<br />

Nr of launches for EVA/robotics 2<br />

Nr of Crew launches 0<br />

Total number of launches 27<br />

Remark<br />

Includes service Platforms<br />

Mass lost until launch window and is launched as last PS<br />

Includes launch of all elements and relaunch due to boil-off<br />

Shuttle launches for EVA/arm<br />

1 Shuttle (Could also be 2 Souyz)<br />

Table 2-37: Modified assembly results

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