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s HMM Assessment Study Report: CDF-20(A) February 2004 page 102 of 422 • Cabin atmosphere toxicity, contaminant and hazardous substance concentrations are potential toxic threats in the recycling of breathable habitat atmospheres, water recycling systems, and solid waste handling and recycling systems; bio-hazards; deterioration of electrical insulation of wires; thermal insulation; seal deterioration; food spoilage, potable water contamination…etc • Protection against space radiation hazards; several effects of changes in gravity forces and physiological/psychological risks of extended confinement and hazardous operations. EVA safety. Design of a safe haven. Pathologies to be considered and relevant medical care are a main concern too. 2.9.5 Technical risk assessment scope Within the risk assessment process, available risk information is produced and structured, facilitating risk communication and management decision making. The results of risk assessment and reduction and the residual risks are communicated to the project team for information and follow up. This is a very preliminary top-level analysis, aimed at identifying first-risk trends: • Earth Operations and software risks are not assessed. • Legal & Programmatic risks are not assessed. • Human errors are not assessed. 2.9.5.1 Assessment process Step 1. Identification of hazardous/failure conditions. (what can go wrong…) Step 2. Identification of failure scenarios and their consequences. (when…) Step 3. Categorisation of the scenarios according to their consequence.(what if…) Step 4. Analysis of likelihood and uncertainties of risks. (how likely…) Step 5. Identification and ranking of risk contribution of individual scenarios. Safety hazards Examples I. Contamination/ corrosion Moisture, oxidation… II. Electrical Discharge/ shock Static discharge, short, corona… III. Environmental/weather Fog, vacuum, sand/dust, temperature extremes… IV. Fire/explosion Chemical change, high heat source… V. Impact/collision Meteoroids, rotating equipment… VI. Loss of habitable environment Contamination, toxicity… VII.Pathological/ physiological/ psychological Illness, excessive workload… VIII. Radiation Electromagnetic, radioactive element… IX. Temperature extremes High/low, variations… 2.9.6 Abort possibilities Table 2-38: Technical risk assessment Thorough investigations of Martian mission risks have not yet been performed. Acceptable risks can be achieved if abort options are designed into the mission for all phases. The abort option requirement eliminates mission profiles involving very fast and energetic trajectories, as shown in Table 2-39.

s HMM Assessment Study Report: CDF-20(A) February 2004 page 103 of 422 Phases Options Earth Departure Return to Earth possible Early Part of Transfer to Mars Quick return to Earth usually possible for about the first 75 days Later Part of Transfer to Mars Mars swing-by (gravity assist) return to Earth via opposition-like trajectory Mars Orbit • Early: Return to Earth opposition-like trajectory • Later: Wait for normal Earth return opportunity Mars Descent (not present in the Separate ascent stage and crew module; abort to Mars present mission, but recommended) orbit Surface Operations Use Mars ascent stage; if it is inoperable there is no abort Mars Ascent No practical abort scheme Trans-Earth Injection No practical abort if main propulsion fails Transfer to Earth Continue normal return to Earth 2.9.7 Risk acceptability Table 2-39: Abort possibilities The purpose of this is to analyse the acceptability of risks and risk reduction options according to the risk management policy and to determine the appropriate risk reduction strategy. The results of the preliminary technical risk assessment indicate where the first risk reduction efforts should be made. Main risk contributors at this stage are shown in Figure 2-58, but the maximum concern is risks to the crew. Human factors are extremely important for the mission success. Large uncertainties exist in this context regarding physiology and psychology of the crew due to the lack of previous experience and information available and the preliminary definition of the design. This is expected to improve with the availability of more information and optimisation of the vehicles design, particularly with reference to the failure detection, warning, caution and recovery systems definition. The public safety of people on Earth is also of concern.

s<br />

HMM<br />

Assessment Study<br />

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

February 2004<br />

page 102 of 422<br />

• Cabin atmosphere toxicity, contaminant and hazardous substance concentrations are<br />

potential toxic threats in the recycling of breathable habitat atmospheres, water recycling<br />

systems, and solid waste handling and recycling systems; bio-hazards; deterioration of<br />

electrical insulation of wires; thermal insulation; seal deterioration; food spoilage, potable<br />

water contamination…etc<br />

• Protection against space radiation hazards; several effects of changes in gravity forces<br />

and physiological/psychological risks of extended confinement and hazardous operations.<br />

EVA safety. Design of a safe haven. Pathologies to be considered and relevant medical<br />

care are a main concern too.<br />

2.9.5 Technical risk assessment scope<br />

Within the risk assessment process, available risk information is produced and structured,<br />

facilitating risk communication and management decision making. The results of risk assessment<br />

and reduction and the residual risks are communicated to the project team for information and<br />

follow up.<br />

This is a very preliminary top-level analysis, aimed at identifying first-risk trends:<br />

• Earth Operations and software risks are not assessed.<br />

• Legal & Programmatic risks are not assessed.<br />

• Human errors are not assessed.<br />

2.9.5.1 Assessment process<br />

Step 1. Identification of hazardous/failure conditions. (what can go wrong…)<br />

Step 2. Identification of failure scenarios and their consequences. (when…)<br />

Step 3. Categorisation of the scenarios according to their consequence.(what if…)<br />

Step 4. Analysis of likelihood and uncertainties of risks. (how likely…)<br />

Step 5. Identification and ranking of risk contribution of individual scenarios.<br />

Safety hazards Examples<br />

I. Contamination/ corrosion Moisture, oxidation…<br />

II. Electrical Discharge/ shock Static discharge, short, corona…<br />

III. Environmental/weather Fog, vacuum, sand/dust, temperature<br />

extremes…<br />

IV. Fire/explosion Chemical change, high heat source…<br />

V. Impact/collision Meteoroids, rotating equipment…<br />

VI. Loss of habitable environment Contamination, toxicity…<br />

VII.Pathological/ physiological/ psychological Illness, excessive workload…<br />

VIII. Radiation Electromagnetic, radioactive element…<br />

IX. Temperature extremes High/low, variations…<br />

2.9.6 Abort possibilities<br />

Table 2-38: Technical risk assessment<br />

Thorough investigations of Martian mission risks have not yet been performed. Acceptable risks<br />

can be achieved if abort options are designed into the mission for all phases. The abort option<br />

requirement eliminates mission profiles involving very fast and energetic trajectories, as shown<br />

in Table 2-39.

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