Failure of the settlement

A complete failure of the settlement would mean the evacuation or death of all settlers. Possible causes can be human failure, technical failure and acts of nature beyond control. It could take decades or centuries before a subsequent colonization attempt is started. This article wants to collect situations, incidents, precautions and mitigations.

Destruction of life support

Oxygen and CO2

On Earth Free Oxygen comes from plants, bacteria and other life forms. However, if the plants die, they no longer produce oxygen or remove CO2, that will accumulate and eventually reach poisonous levels. Dust storms have been know to block out 95% of the light, and last for weeks. In such cases, plants may no longer be able tp play their part in a purely biological life support system. It is safer, for all but the largest colonies, to have backup systems to treat the CO2 and free the oxygen back into the settlement's atmosphere. Numerous chemical processes will reduce CO2 and produce oxygen for the base at a lower energy cost than plants.

Temperature

If heating systems fail, the temperature in on-surface buildings may drop rapidly and destroy equipment and plants. Humans may freeze to death.

Precaution: Underground parts of the settlement draw benefit from the high heat capacity of the surrounding rock, which keeps the temperature for a long time. The interior of the settlement rooms can be optimized to store large amounts of warmth. Big water tanks have a high heat capacity. Effective thermal insulation can reduce heat loss to very low levels.

Water

Early exploration missions will bring their own water, if only for life support during the trip. However, water will be extracted locally, and the presence of water or ice is likely to be a primary condition in the selection of the base/settlement location.

Water is common as permafrost, even approaching the equator. (A meteorite impact 35 degrees from the equator threw up chunks of ice.) Geothermal energy plants may produce huge amounts of water. Water shortages might be caused by water leaking, freezing, or subliming if the habitat is exposed to vacuum.

• Having water requires planning (to make sure enough water is brought, or the settlement grows slower than water is 'mined'), and care of life support and maintenance to make sure it is not wasted or lost thru emergencies.
• Humans are 'aquatic apes'. A swimming pool would be a luxury which would also provide an emergency source of water.
• Water is an excellent radiation shield, so water far in excess of the habitats needs, might be mined and stored as ice (outside the habitat), or as liquid (near the walls) for this reason.
• Water is also the source of hydrogen for fuel and food production, so large quantities of water will be required for any settlement with in situ fuel or food production.

Contamination of air or food

... with radioactive, chemical or bacteriological substances

• Risk: Intoxication, injury
• Precaution: If dangerous substances are not produced, they can not pose a threat. If such substances are unavoidable, they should be produced, used and stored in a separated part of the colony, where no other vital system can be affected in case of an incident.

Destruction or contamination of greenhouses

• Severity: Vital.
• Risk: Starvation and suffocation of the settlers.
• Mitigation: Redundancy. Separation of zones.

Disconnection or destruction of energy network

• Severity: Vital.
• Risk: If the energy network is poorly designed, the energy supply for the colony can break down completely by a defect in any of the single points of failure.
• Mitigation: Decentralization of the network. Make sure that any remaining part of the network continues to function locally. This concept involves a structural redundancy of all vital parts and sub-parts.

Disconnection or destruction of telecommunication network

• Severity: Non-vital.
• Risk: Supervision of remote parts of the colony may gets lost.
• Mitigation: Redundancy.

Explosion, causing drop in air pressure

• Severity: Vital.
• Risk: Suffocation of the settlers. Dissolution of the greenhouse plants.
• Mitigation: Several zones of living space, separated by bulkheads.

Destruction of transportation means

... that are needed to reach peripheral sites of the colony

• Severity: Non-vital.
• Risk: Growing of the colony is interrupted.
• Mitigation: Keep all vital stuff in a Recycling loop.

Biological

The human metabolism needs a great variety of substances. The full complexity of all interactions is not fully understood. If there is a shortage or an excess of some unexpected, the health might be seriously affected. In worst case the ability to work and maintain the vital parts of the colony falls below a required minimum. Such substances may possibly produced by some sort of germs that are omnipresent on Earth, but are not in the Martian colony.

The immune system may get out of balance, since the ensemble of germs around and inside of the settlers will be different or narrowed. If, unlike in the ISS, the bacteriological profile is not updated frequently, some vital germs might become extinct.

Mitigation: A garden with soil is a living ground for many microbes and germs.

Social

The settlement might also fail socially. If the settlers lose interest, or if their descendants decide to return to the Earth. If the cost of maintaining the settlement is too high and the settlers lose heart, the settlement will be destroyed, although not catastrophically. The end of immigration combined with a birth rate below the replacement rate of the population would end the settlement, possibly with a long drawn out agony, or with a resettlement program. This has happened in a number of 'ghost towns' throughout the history of the Earth, and on every continent. Mining communities are particularly susceptible.