A semi autonomous colony on Mars lives basically on its own production of energy, food and air, provided by imported technology from Earth. All vital systems are lo-tech and can be maintained from local resources. Additional goods are regularly imported from Earth:
- Complicated medical equipment
- Drugs for medical treatment
- Luxury foods
- Non-vital hi-tech equipment (e.g. computers)
As part of a colonization strategy it may be an advanced step in the colonization program.
Limitations of shipping
Shipping to Mars with current launcher technology is expensive. Cheaper commercial launchers must be developed if continued shipping is to be a reality. Although landing large payloads on the surface is difficult, this could be done with technology designed for the original construction of the colony. The limitations on shipping, however, mean that any large settlement will be fairly close to an autonomous colony.
What if support from Earth stops?
However, if the shipments were to stop, the colony might be able to sustain itself for the long run, based upon the lo-tech equipment. Some people may then choose to return to Earth if space access is possible.
As an alternative to a low tech society, a reasonable precaution would be for the settlement to stock a strategic amount of supplies of essential elements or equipment. The stockpile should be sufficient for the settlement to have the time required to develop local sources for the supplies. For example, digging for cobalt on Mars might be uneconomical compared to shipping from Earth. But if shipping from Earth stops, the settlement would develop local mines, whatever the cost, as they would become essential. This way a higher technology settlement could be maintained.