Railroading on Moon and Mars

by Peter Kokh

Most of us are familiar with the critical role that railroads played in opening up the American West. The story was repeated, with some differences, in Canada and Australia. And with the railroads came the benefits of the Industrial Revolution. The railroads extended communications (telegraph) and by providing access to the territory they passed through, predeveloped the land.

How railroads can help

On the Moon and Mars, we aren’t going to find building materials that we can “throw together” to provide shelter from the cosmic elements. We will need pressurized structures. Pressurized modules made in a first quickly industrializing settlement can be shipped by the railroads to points along the route to provide the nucleus of new settlements. Pressurized modules have to be handled with care. Try to haul them overland on unimproved roads and the stresses of bouncing around are going to compromise seals and maybe open cracks. Rails on the other hand will provide a smooth low-friction ride to a prepared siding complex where they can be dropped off and docked with one another to provide an instant starter outpost. Such new “town starters” might even be called “sidingments” or “sidlings” instead of settlements. Every new train could bring another module or two including ready to plug in “container factories.”

Now it is going to take some time before we are building pressurized modules on the Moon. Until then, inflatable modules will cost significantly less to produce and ship from Earth, and the railroads could carry these to desired locations as well. Clearly railroads could establish chains of interconnected settlements much faster than by any other option. That goes for the Martian frontier as well.

If the human frontier on Mars advances this way from one point of origin, we won’t have the problem of distant settlements isolated from one another. But if we are going to open Mars by railroading, we need to do some homework first. Top priority is production of a high vertical resolution map of Mars so that we can plot logical rail corridors where along which grade changes are slow. We may soon have a good start on such a map from altimetry data from the present and planned fleet of orbiters. We need to look for the elevation change pinch points are located. On Earth, these are straights and passes through which traffic funnels. Those will be critical anchors along proposed routes.

Between such narrow points the doable routing options are greater, and attention can be paid to scenic areas that would draw tourist traffic, for example. Scenic and Geological treasures along the selected route would go to the top of the list for boundary determination, and for location of adjacent visitor concession areas to set the stage for tourist and excursion companies, serving Mars pioneers.

Next we need to really work to define a useful “economic geography” of Mars. That’s a map that shows where “all” the critical resources are to be found, and in what degree of concentration. Where the elements from which building and manufacturing materials can be made are found to cluster, we have potential new industrial centers. Feasible routes that do not connect resource clusters would be options for development at a later date. These considerations are to the point on both worlds.

Routine aviation on Mars may be further in the future

Why take the train when we can fly on Mars? I do believe that we can, but I also think that aviation on Mars will be uncomfortably pushing the envelop and that because of that, it may be risky for some time.

On the one hand, we are confident that flight is possible at 125,000 feet on Earth, and perhaps that has already been demonstrated. But no one has ever demonstrated take off and landing at that altitude. The suggestion is to design Mars planes like Harrier VTOL fighters.

It still has to be demonstrated. And unless we are to be flying only at the Mars version of sea level, say within the northern ocean-sized basin or within Hellas, and if we are not going to just skim just over the surface, Mars aircraft are going to have to be stable at pressures a lot thinner than that at 125,000 feet on Earth.

Another thing I have never heard a Mars aviation fan (other than myself) concede is that the equivalent of 125,000 feet on Earth only describes the situation in spring and fall when much of the polar carbon dioxide snow over both polar caps is vaporized. As we go into either summer or winter, a significant part of the atmosphere, as much as 30%, will freeze out over one or the other poles. If Mars flight is possible only seasonally, it will not become the backbone of transportation on Mars. Another question is to what extent will dust storms that can last months, make flight dangerous.

Now maybe we can fly even when the atmosphere is at its thinnest. I hope so, but do we know? And more to the point, will we be able to hoist heavy cargo by air? I believe that railroads on Mars will become the backbone of global transport in the early decades

Mars-Specific Design Challenges

Seasonal thermal extremes on Mars (from just over the freezing point of water to temperature lows far below the lowest ever reached in Antarctica, means that tracks must be designed for thermal contraction and expansion. Now on the Moon, the challenge is greater. It gets just as cold on the Moon as in the Martian winter, and in-between far hotter than the highest temperatures ever experienced on Earth on a monthly schedule. On the Moon we may have to shade the rails somehow. unless we can find an alloy with a very low coefficient of thermal expansion. The same will hold true of whatever we come up with to keep the lateral rail-rail separation within close tolerances: a functional equivalent of our railroad “ties.”

On Mars we must use elevation contour maps to identify locked, no outlet basins, which could, in a terraformed future Mars become lakes or small seas. No sense pushing tracks through such depressions, no matter how conveniently smooth.

On both worlds, we have to design out the possibility of derailment that would involve upturned cars losing pressurization with a total loss of life. We will be dealing with lower gravities while momentum and mass remain the same. Very wide gauges (rail to rail separation) and very low centers of gravity, even some amount of banking of curved track sections may be part of the answer. But perhaps the best approach would be to take a page from modern all steel roller coasters with wheels above and below the rails so that the cars cannot come off the track.

If we have to complicate rail design to meet these constraints, then track switching becomes more complicated as well. But there should be ways to do it other than the roundtable.

For passenger trains, there is another issue. On Earth our passenger cars are “vestibulated.” They have flexible accordion like passageways above the couplings that allow protected access between cars. On Moon and Mars it is unlikely that flexible corridors could long be maintained without a pressure loss.

There would seem to be at least two ways around this problem.

(1) Restrict car to car (in Europe, wagon to wagon) passage to periods when the train is at the depot, or otherwise parked on straight level track sections. While so parked, the cars could snuggle up to one another, effectively docking as we do in space. For breathing purposes, Mars might as well provide a high vacuum, as does the Moon.

(2) There is another option. As the railroads will be pushed through new unoccupied lands with no in place transportation infrastructures in place, there will be as yet no overhead clearances to observe. Nor will the rights of way be expensive to acquire. Mars, and the Moon, are virgin territories and the railroads will have the chance to set both rail gauge and clearances.

There is no reason why a Mar/Moon passenger car/wagon could not be double the width, double the length, and double the height (two floors) able to carry as many passengers as a Jumbo jet. Not that traffic will mandate such jumbo one-car trains at first, but the point is we should design the system so that in the future, when and if traffic warrants, we could build such capacious cars. The word “train means an coupled row of cars, one following the other, pulled/pushed by an engine car.

On the new frontiers of Moon and Mars, we have the option of starting with a clean slate blackboard, and we should take the opportunity to design for a more densely populated frontier with many major settlements. Now most people are not thinking that far ahead, but if we don’t, then we risk making a slew of unnecessary, stupid, contraceptive dead-end decisions.

The Railroad as Land Developer

Another thing worth paying attention to well in advance of the time when we starting to expand out of an initial outpost, is the role the railroad land grant system in place when railroads opened the American rest. What were the good points? What points were not so good.

The Martian (and Lunar) railroads could be a major force in developing the strips of land that they passed through. This is too significant an opportunity to ignore. We will need to get it right.

Many more issues

How will railroads be powered? Nuclear power is an option that was taken quite seriously back a few decades ago by the Norfolk and Southern running between Cincinnati, Ohio, and Norfolk, Virginia. I am not sure how far along that brainstorming effort got before being abandoned. If we can make a nuke sized to run a submarine, then why not a railroad? But they are heavy units requiring water for cooling.

The tops could be paneled with photovoltaic cells. The railroad could be paralleled with communication and electric power cables. On Mars, there is another option. A small nuke on board could process methane fuel from the atmosphere as the train travels! This is an option not available on the Moon. This system would be self-contained, ideal for day-night, all-season operation through territories without any other infrastructure.

Choosing between options

Some options will be realizable and practical before others. Yet if the most desirable option will save many headaches down the road, it’s worth predeveloping. The bottom line is what percentage of the various options involves the least mass to be shipped from Earth – Earth sourcing is by far the most expensive option of all.

So we need to design a railroad system that has a lot of features with no guarantee that they will all be ready on time:

# Lowest total component mass to be upported out of Earth’s deep gravity well

# Highest percentage of component mass that can be manufactured on location (English for technospeak “in situ”) in time to start building the system

# Most rugged in terms of wear and tear, but also with respect to constant exposure to the Moon’s naked (Mars almost naked) cosmic environment.

# Overall architecture that best supports spread of settlements as well as route-side development

# The system is the most rugged and least prone to degradation and early repair or replacement.

# The system design that best supports quick deployment of new settlements (sidingments)

So if this article intrigued you, whether or not you have always been a train buff or a model railroader or you have simply enjoyed train travel, and if you enjoy a engineering challenge, why not join our brand new design brainstorming group:

Calling all railroad buffs, model railroad fans, systems architects, 3-D modelers, systems integration experts, and anyone else who would like to get in on the ground floor of creating these different but yet similar ready-to-go transportation architectures for Moon and Mars.

We need your help. Let’s collaborate across disciplines to give railroading a special future on the space frontier.

We will be uploading more files to this site, so visit often.

This is a joint initiative of the Moon Society and MarsDrive and is cosponsored by The Lunar Reclamation Society and Wisconsin Mars Society.

More cosponsors welcome. Help spread the word. We plan on inviting railroad buffs and model railroaders, people who may never have thought of the Moon and Mars as human frontiers, much less as settings for extra-terrestrial railfoads!