Site Selection

This article is a topic of debate. Please feel free to jump in with a constructive contribution.

First Lunar Settlement Site Selection
And, the Great Instant Science Head Butting

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A great contest is shaping up over the selection for the first, and quite likely only site for a long time, for a human settlement on the Moon. Later there will surely be many lunar settlements, but for right now we need to focus on where to place the very first settlement using the information and technologies that will be available to us in the 2020 time frame.

NASA chose a site, Crater Shackleton, for planning purposes in NASA_Exploration_Strategy but claimed the choice was only "Notional" (meaning speculative; not based on fact). Currently available data is not adequate to definitively pick the true best location. Soon, enough new data will be available from missions like LRO to nail down the choice.

Right now, this very minute, somebody should organize a contest between the different parties supporting specific sites. Maybe that somebody should be Lunarpedia.

Activity Zones as Site Selection Criteria

A good lunar settlement site must have a number of areas for specific activities. In designing a space settlement, these areas are called activity zones. Each of these activity zones will have very demanding requirements and can serve as a good basis for judging the relative merits of various sites. A good settlement site will rate high in a number of activity zones, but need not be at the top of every one.

Good travel routes and communications lines will be needed connecting each of the zones to allow people, robots, and information to travel freely. Some of the most important activity zones include:

Habitation Zone

This zone has most of the buildings for human occupancy and needs to be fairly flat and smooth. It should be away from other sites that represent dangers, like the Landing Zone, and away from activities that will seriously kick up dust, like the industrial zones. For some sites, such as scientific instrument locations, this zone will be of only short term importance as there will be no permanent habitation.

Landing and Launch Zone

You land and launch spacecraft from this zone. It needs to be flat and smooth. You cannot land a spacecraft in a field of boulders. We nearly lost one or two Apollo missions to this problem. This zone must also be separated from other zones by some distance (one kilometer has been suggested) so that a misfire does not drop a spacecraft into an occupied building. This zone must have good access to stable lunar Orbits. It must also support successful response in emergencies. Spacecraft that have near landing misses must have a good chance of landing safely in alternative areas and the crews being rescued. This is a difficult requirement to meet in the lunar South Polar Region. Equatorial regions have the best and safest access to orbit.

Earth Communication Zone

This zone must have an unrestricted view of the Earth at all times for microwave antennas and laser communications telescopes. Even a glancing path near the lunar horizon could be a problem. This zone covers most of the lunar hemisphere facing the Earth.

There is a thin libration zone near the lunar limb where the Earth will dip above and below the horizon, or where local terrain could obstruct the line of sight. In these areas there may be peaks with good Earth views close to valleys with good Earth shielding. Such a site would be ideal for a number of types of scientific instruments.

Solar Power Zone

This zone should have an unrestricted view of the Sun for as large a percentage of the time as possible. For most of the Moon the Sun is below the horizon 14 days per lunar month, but there are areas several hundred kilometers around the lunar poles where the Sun is visible from high ground most of the time. All sites will loose direct Sun from time to time; during eclipses if at no other time.

All significant lunar solar power systems (above 100 Watts) will have to track the Sun so that they can present their maximum collection surfaces to the Sun. Solar tracking is far easier to do at all sites on the Moon than on Earth.

At polar sites, the Sun goes round and round the sky and may from time to time dip below the horizon. Here the interruptions may be only a few hours depending on the site latitude and altitude. Some polar peaks approach 100% sun, but may be difficult to access. Such sites may be described as “broad sunlight uplands” (Churchill) or “Peaks of Eternal Sunlight” (J. R. R. Tolkin?).

At equatorial sites, the Sun follows a path across the sky similar to what we normally experience on Earth, only very slowly. The 14 Earth-day long lunar night is difficult to deal with and will require effective power storage. A number of recent breakthroughs of batteries for electric cars promise considerable help on this problem in the near term. Eventually, nuclear power or rectennas could be used to avoid the limitations of solar power. Current Lunar analogue station mission plans efforts center on simulating periodic availability of power.

Industrial Zone, Sunny

This zone must be suitable for large solar powered industrial actives such as volatiles mining and be suitable for industrial scale operations (see Sandworms). These zones will have abundant solar power, but may not have the greatest concentrations of volatiles. These operations may kick up a lot of dust and therefore need to be at a distance from the Habitation Zone. This is the type of operation described by Harrison Schmitt, in "Return to the Moon".

Industrial Zone, The Cold and the Dark

This zone only applies to near polar sites and would be in one of the many permanently dark craters within a few hundred kilometers of either lunar pole. There is good evidence for significant concentrations of volatiles in these locations. If these deposits can be verified by LRO then mining them will be a major source of volatiles for all future space activates. This is a prize well worth going after.

Unfortunately, due to the very nature of these locations, no solar power is available here. Also the ground temperature is at cryogenic levels of about 100 K. Industrial equipment for this type of mining operation will be completely different from the equipment needed for the sunny zones so the two types of zones must be considered separately.

The possibility of this supply of volatiles is one of the most powerful arguments for a polar settlement site. It could also turn out that either the volatiles are not there or they cannot be efficiently mined.

Scientific Interest zones

There should be zones near the settlement that contain features of scientific interest and zones favorable for doing scientific experiments or placing instruments. Areas of interest include volcanic vents, lava tube, and permanently dark areas. Sites for instruments include areas shielded from Earth noise, low in human activity, and with excellent views of the universe. The majority of such sites are in the equatorial regions.

Special Site Considerations

Some sites have special features that will strengthen their case for selection over other sites:

High KREEP Mare Sites

The optimum terrain for refining nuclear fuel, potassium, phosphorus, rare earth elements, and titanium will be located in maria where native basalts are enriched in KREEP and Ilmenite.

Ilmenite Access Settlement Sites

Ilmenite is one of the few obvious ores to collect on Luna.

Lagrange Access Sites

The optimal place to install a beanstalk to its corresponding Lagrange Point

Lava Tube Sites

The most valuable terrain on Luna is underground, and nowhere is there easier and more plentiful access than inside a structurally stable lava tube. Lunar lava tubes are expected to be far larger than their terrestrial counterparts -- large enough for pressurized cities. Development without such advantageous terrain is likely to be far more expensive, especially with any scaling of population.

Several organizations have worked on the problem of locating and using lava tubes and a lava tube mockup is one of the features of NASA's CoLab effort in Second Life.

Polar Sites

Polar sites offer locations with dark areas that can provide constant extreme cold and may also provide volatiles such as Hydrogen, and also peaks that are at least partially lit most or almost all of the time.

Volcanic Gas Access Settlement Sites

Any reliable volcanic gas vents are a likely source of valuable volatiles. Crater Aristarchus is a known site of gas venting (see below).

Specialty Maps

Rating various proposed settlement sites will require analysis of a lot of scientific data. Some of the data is available now. Some of it can be calculated with existing computers and software. And, some of the data will be taken by lunar missions over the next few years. Effective presentation of supporting data is critical to building a case for a specific settlement site.

One of the best ways to organize such a large amount of data is in the form of maps. Here are a few maps that are critical to selecting a site that might not be obvious or of interest for other activities:

Slope

This is not the altitude but is a contour map of the absolute value of the rate of change of the altitude. All activities will have serious limitations as the amount of surface slope they can tolerate. For example, Apollo rovers were limited to a slope of 35 degrees in the extreme. All the settlement areas must be connected by ground transportation, therefore all areas must be connected by slope contours below the limits of our new rover designs. Areas not so connected might as well be on the far side of the Moon. We await the LRO data for this map.

Roughness

Many areas on the Moon are strewn with boulders and are therefore very rough. This type of train is unacceptable for landing sites and difficult to use for most other functions such as habitat or industry. You would need to put out a lot more energy and effort just to move the boulders off a site before it could be used. Roughness can be measured by radar reflection from Earth.

Percent Sun

This map is critical both for sighting solar power stations and for locating industrial activities requiring large amounts of solar power. This map can be calculated with existing software, but more precise altitude data will make improved maps possible.

Percent Earth view

This map is critical for communication with Earth. The problem is not important for equatorial locations, where the Earth is always high in the sky, but is critical in polar and limb sites. Microwave links that even pass near to the lunar surface experience considerable interference. The Earth view map can be calculated with existing software, but much improved detail will follow from the altitude data from LRO.

Science interest

This map can be a photographic one but must be supported with a detailed list of areas accessible from the site that have particular scientific interest or that would be good sites for setting up scientific instruments.

Mineral concentrations

This will be a series of maps showing the concentrations of valuable minerals in the area of the site. Of particular interest are the Volatiles, Ilmenite, and titanium. Rough versions of these maps can now be assembled from satellite data, but more detailed information of specific sites will be need in situ measurements.

Average and extreme ground temperature

One of the most difficult problems for a lunar settlement is how to get rid of waste heat. This heat must be radiated to the sky but the radiator panels also see large areas of the lunar surface. The average ground temperature strongly affects the power required for life support. Sites with surface temperatures significantly above room temperature for many hours during the lunar day, as is the case in equatorial regions, will make waste heat radiation difficult.

At the opposite end, sites with very low temperatures will make maintaining survival temperatures at night difficult, particularly in emergencies. This argues against low lying polar sites.

Instant Science

Some time in 2009, the LRO data will start to flow. The American public will want instant science (they always do). They are paying the bills so they are entitled to some consideration no mater how much the scientists hate to be pinned down for instant science.

One way to handle this problem is to embrace it.

We could set up a contest between various interested groups who would champion various sites for a lunar settlement. Each group would partially build the case for a specific site with all available data. The groups could be in high schools, universities, industry, technical societies, or Internet groups anywhere on Earth.

When the LRO data goes public, it will already be in the form of sophisticated maps. The software that generates the standard maps will also be capable of generating specialty sight selections maps with only a small additional effort.

The game then becomes one of watching the LRO data like a hawk to find the times new data on your particular site will first become available. Then jumping on your data within minutes to provide new support for your site and move it forward in what will best be described as a horse race.

One special parameter to map is slope. Americans love their cars. They may not have a great interest in science but they will be fascinated by a lunar map lying out in what areas they could drive cars, what areas would require off-road vehicles, and what areas are just plain clefts you would drive off. It will also give the news people something they can deal with in the otherwise incomprehensible flow of data. This would be a reasonable accommodation to the special interests of the American people.

To make this work, Lunarpedia will really need to find somebody to put up some real prize money. Lunarpedia could make this happen.

A few Possible Sites

Here are a few sites that have already been put forward. You can make the case for your favorite site here:

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Crater Aristarchus

This site is known to experience frequent volatile outgassing events. There is good potential to trap valuable gases which could enable setting up lunar settlements.

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Crater Shackleton

This site is located almost on top of the lunar South Pole and has outstanding access to the cold and the dark. This site is detailed in NASA_Exploration_Strategy.

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Mount Malapert

This site is about 125 kilometers Earthward from the lunar South Pole. It features a peak with eternal sunlight and good access to the cold and the dark. For more details see Malapert Park and [[1]] Malapert in Wikipedia.

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Mare Anguis

Northeast of Mare Crisium and referred to by many as Angus Bay,, this site has been deemed likely to be surrounded by multiple lava tubes and was selected for the Artemis Project reference mission. A great deal of work on a planned mission there is the cornerstone of the Artemis Data Book.

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Sinus Medii

An equatorial location near the center of the Moon's Earth facing hemisphere.

From Sinus Medii a microwave rectenna can deliver many times more electrical power per square kilometer than solar power, via beaming power from Solar Power Satellites. Rectennas are also many times lighter per kilowatt than solar cells, therefore much cheaper to land on to the surface of the Moon. Furthermore, rectennas can deliver electrical power continuously, on a 24/7 basis, whereas most of the Moon is in darkness for 14 days per 28 day period. Unlike solar panels, rectennas do not need to be tracked to follow the Sun, so can be cheap passive structures.

Also see: rectenna, Skyhook, tether.

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North Pole

North Pole, the cold and the dark

Mare Tranquillitatis

Equatorial, historic

Aristarchus plateau

Equatorial

Rima Bode

Equatorial, scientific

Oceanus Procellarum

Equatorial, Limb

Mare Smythii

Equatorial, Limb

Oriental Basin floor

Limb

Crater Grimaldi

Limb, science

Central Farside Highlands

Farside, science

South Pole-Aitken Basin Floor

Farside, science, the cold and the dark

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Pick your site now! The best ones will soon be gone!

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Field Trip

In the end we must put a robot rover down on the top two or three sites for a detailed reconnaissance. No amount of orbital readings will replace the need for real ground data.

There is no reason the winning site selection team should not have some input in the commanding of a rover exploring their site and early access to the data.

The More Distant Future

The lessons we learn from establishing our very first lunar settlement will be many, dramatic, and hard. Once these lessons are learned we will be able to pick lunar sites that suit our exact needs and design settlements that are safe and permanent. We will become a space fairing civilization and our actions today are laying the foundation.