THE PLAN FOR SUSTAINABLE SPACE DEVELOPMENT
- a proposal for America’s space program during the current administration -



INCREASING EARTH INDEPENDENCE

From the very start, a major objective of the lunar telerobotic and crew operations would be to reduce the cost of follow-on missions by reducing the mass needed to be shipped to the base. A very rough estimate of the mass by category needed to depart from the Earth-Moon gravitational balance point in order to support a permanent base is as follows:

  • 45% - Descent propellant
  • 23% - Ascent propellant
  • 10% - Water
  • 5% - Inflatable habitat material
  • 5% - Gross metal parts
  • 4% - Food
  • 2% - Paper goods
  • 2% - Crew
  • 2% - Materials made from organic chemistry (e.g. plastics)
  • 2% - Clothing & furnishings
  • 1% - Precision metal parts
  • 1% - Electronics
This provides a useful check-off list as to what items should be the priority for recycling and local production.

ICE PRODUCTION AND PROCESSING
Clearly, if we can harvest and process water starting with the use of telerobotics, we can reduce the cost of launch substantially by reducing the amount that needs to be launched and hence the number of launches. If water ice (and the organics it contains) is being produced and processed at propellant-quantity levels then this could be used to produce propellant, water for drinking, sanitation, & food, paper goods (growing fibers), clothing and furnishings, and the materials made from organic chemistry. Together, the rough estimate indicates that about 88% of the total payload mass would no longer have to be shipped from Earth because these things were being produced on the Moon. This is huge and it could be an early outcome. It may be possible to achieve ice harvesting and processing telerobotically even before the crew arrives. The crew may (or may not) be necessary to produce the items derived from organic chemicals. But these processes are sufficiently well-known such that we could expect the initial crew of eight to achieve them.

METALS
The Apollo program found that dirt in the highland areas of the Moon contain about 1% by mass of iron-nickel micrometeorite bits. These are unoxidized metals which can be magnetically separated from the dirt, melted using concentrated sunlight, the dross removed, cast, and machined into gross metal parts. Although gross metals make up a small portion of the overall mass budget, they are the majority components of telerobots. Those telerobots in turn produce propellant from the ice which is the major component of the mass budget. So, bulky metals indirectly represent a large portion of the mass budget.

Precision metal components such as step motors, reliable valves, etc may not be able to be easily produced on the Moon. They may also require specific alloys with metals not easily extracted from lunar rocks. For a period of time these parts will be shipped from Earth. But they are less massive than the bulky metal parts (e.g. wheels, chassis, limbs, equipment housing, frames, etc).

RECYCLING
The impact of recycling on a permanent base is perhaps not sufficiently appreciated. If one is able to recycle a material and use it twice, it is as though one has cut the amount of its mass that needs to be shipped in half. In fact, there's a formula for how this works:

Total amount = 1/(1/r)
Where r = how efficient each recycling cycle is.

On the International Space Station, they are recycling their water at about 93% efficiency for each cycle. This means that if they start with a liter of water (1,000 g), after recycling, they have 9,300 g of water that they can reuse. But, after use, that 9,300 g of water can again be recycled resulting in 8,649 g of reusable water (9,300 g x 93%). And so on. So, it turns out that having a 93% efficiency of recycling results in the equivalent of having shipped 14.3 liters of water. That's a huge savings.

EARTH INDEPENDENCE
How independent the lunar base / settlement can be measured based upon the degree to which it is mass independent of the Earth. That is to say, if a base is producing or recycling so much such that only 10% of the mass needs to be launched from Earth than compared with a base that is totally dependent upon the Earth then we can say that the base is now 90% Earth independent.

SUFFICIENTLY SUPPLIED
The goal of course, is to achieve 100% Earth independence if possible. There is an interim step in which a base can be considered to have achieved Earth independence even if it is not yet producing all of its needs. This happens when the base has been supplied with enough of the hard-to-produce parts such that one has bought the base an amount of time in which it is not needing to be replenished. If, during that period of time, technology protocols could be implemented to produce the harder-to-produce parts then the base will never have to be replenished from Earth and that base will have been completely Earth independent. Producing the most up-to-date CPUs is very challenging and requires major infrastructure with a lot of industrial support and rare materials. However, telerobots may not need the latest CPUs but have simpler, more easily-produced electronic components that would be "good enough".

POLITICAL INDEPENDENCE
If one looks far enough in the future, one could imagine that people living off Earth may, one day, wish to create their own nations separate from Earth. A suggestion could be that this potential be planned for and encouraged. People tend to want to organize themselves according to things that they share in common such as language, ethnicity, or religion. It is likely that this will continue. So, instead of trying to force people to a single political entity or allowing difference to grow until something happens, perhaps there could be a rule whereby, when an area grows to a certain number (say 50,000), then the people there will be able to vote for independence and their own constitution.

IMPLICATIONS
Achieving Earth independence is a major goal of space settlement. This page argues that and Earth-independent colony need not wait until there is a huge space economy, with huge cities but rather is a project that can be pursued in the near-term. Indeed, this is a project that could be started with an analog base here on Earth.

Achieving a small, Earth-independent colony is potentially a near-term, achievable project.



Next: Watching the crew