The mean atmospheric pressure on Mars is one-thousandth of Earth's. The atmosphere is also toxic, and dangerously dry and dessicating.

Ambient temperatures fluctuate between 20 and -140 Centigrade. Winters are an Earth year long.

Gravity is one-third of terrestrial.

Solar and cosmic radiation is intense. Large solar flares are deadly.
Vehicles need to be fully self-sufficient enclosed environments, providing heat, air, and protection from UV and ionising radiations.

Driving position:
Double-walled pressure-containing viewdome. Boron doped polycarbonate outer shell for impact strength, clarity, and primary radiation protection. Inner shell heavy leaded safety glass, for in-depth radiation absorption. Also filters ultraviolet. Double shell offers thermal insulation, and some added security in the case of micro-meteorite impact.

Main body:
Double-skinned alloy and carbon fibre cylinder, the wall cavity filled with 5mm diameter solid polyethylene balls that provide thermal buffering, absorption of primary radiation from space and scattered secondary radiation from the metal outer skin.

A small storm shelter for major solar flare excursions, is built into the main water tanks for emergencies. Radiation sensors are also fitted on either side of the vehicle.

Accommodation:
On two decks supports three crew members eg: Captain/Specialist
Engineer/Cyberneticist
Navigator/Scientist
––for a number of weeks depending on supplies held in convoy, resupply from the air, or predeployed caches laid enroute beforehand by airship.

Upper observation blister allows eyeball panoramic view of the surrounding terrain without suiting up and going out. Useful for a manual positional star fix in the event of electronic malfunction. Single layer leaded glass for optical clarity, normally sealed off with an airtight steel hatch below for safety. Standard fitting on all vehicles: amber navigation strobe light communicates the visual position of the vehicle at a distance. Solar cell power arrays on the roof augment electrical power demands for cabin heating and air reprocessing. This provides a reliable background energy backup in case of engine failure, so maintaining internal environmental viability, with uninterrupted warmth and clean breathable air. Augmented power also allows communications, electronic systems, and some small equipment to continue failsafe functioning, including the airlock servos and evacuation pumps.

Communications aerials maintain connection with other mobile units, fixed base assets, orbital vehicles and a network of compact satellites providing planet-wide GPS cover for navigation. GPS also tracks individual vehicles and groups, updating positions in real time on all data screen downlinks.

Other services uplinked allow data transfer, including internet and email, locally, and between Mars and Earth.

Fuel:
Water mined from local permafrost domes, or transported by rolling pipeline from the poles as powdered ice, is electrolyzed into hydrogen and oxygen using electricity from solar array farms.

The oxygen is compressed, mixed with nitrogen, and stored ready for use, while the hydrogen is catalyzed in a Sabattier reaction with carbon dioxide drawn from the atmosphere, (or transported in liquid form from the pole), to produce methane.

A byproduct of this process is water which can be recycled or consumed: CO2 + 4H2 = CH4 + 2H20

Methane is a very useful fuel inasmuch it is liquid at non-cryogenic temperatures, and can perform as an atomised gas in ordinary engines, and as a liquid fuel in rockets. This reduces the number of production chains necessary to support a range of transport options.

Reserve methane and nitr-oxy tanks extend the range of the landtrain, or can act as a tanker unit for more than one tractor. Fuel can be drawn continuously when the drive unit is permanently attached through hoses to the trailer, or more simply by topping up periodically on demand with a temporary connection, during a fuelling stop. In wild terrain, unconnected operation is preferred in case of inadvertent trailer detachment. A lesser risk of losing vital gas from sheared hoses. Trailers may also be temporarily parked while reconnaissance on risky ground proceeds separately by tractor alone.

Fuel-air tanks are green. Methane tanks are red. The primary air supply is carried within the tractor unit, the primary methane supply is carried externally, in case of leakage. The trailing unit also includes an auxiliary solar array on top, which is plugged into the tractors main power bus.

Power Unit:
Self-contained breathing, dual diesel engines (or turbines), driving electric generators. Gaseous methane powers the engine units, supplied with an onboard compressed nitrogen/oxygen mix in lieu of an atmospheric supply. The Martian atmosphere is largely carbon dioxide, and unbreathable by man or machine.

Methane burns to give carbon dioxide and water:

CH4 + 2O2 = CO2 + 2H20

The exhaust water not being potable, contaminated with heavy metals, lubricant residues and such, is cycled through the sanitary plumbing. In practice, pure oxygen would burn methane at too high a temperature for the engine, and the mix would be buffered with nitrogen to keep operations cooler, and provide a neutral medium for expansion heating of the gas mix to drive the pistons (or turbine).

 

Drivetrain:
Final drive is accomplished via sealed individual electric traction motors on each wheel. Directional control is by skid-steer adjustment of power to each side as necessary, tank-like, fed unequally to either side drive units as required. This maintains the integral strength of the continuous beam axles, and otherwise reduces the number of external moving parts in a conventional steering linkage, improves reliability kilometres away from the local workshop, and reduces exposure to oxidising dust.

 

Three power driven wheels per side minimises axle collapse in transit due to a single tyre failure, and possible fatal accompanying structural damage. In that case, repositioning wheels would allow running on five only (gaps placed in middle), or four in an emergency, even if all carried spares are depleted.

 

Extra wide wheelbase for maximum stability in isolated and rugged terrain, protecting pressure vessel from local impact.

 

 

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Wide, low pressure tyres spread body weight evenly in low gravity and reduce stress on tyre in low bar atmosphere. Additionally, with the weight loading spread over several wheels, individual tyre pressures can be kept low to aid traction on loose surfaces, and avoid drastic shock from a suddenly depressurising tyre in the low bar ambient air pressure of Mars.

An extra wheel with tyre is carried on the rear of the trailer (as on the tractor unit). Additional trailer units of various types (but not another heavy fuel load) can also be attached to the rear towing rig, for extra spares and supplies.

Supporting Equipment:
Hydraulic arms assist in jacking up and stabilising the vehicle, when removing and rotating around wheels from axle to axle, should the need arise. Can also assist another vehicle to transfer wheels, or with loading and unloading materiel.

Heavy loads can also be lifted to and from the airlock, (including personnel). Each arm can be operated remotely by hand-held electronics (scriber-pads) and is fully cammed to avoid accidental contact, or impact, with the vehicle frame.

A steel girder buffers against collision within rock fields. Winch and towing eyes provide flexibility and mutual assistance where traction is difficult.

Steerable halogen searchlights are designed to be set rigid, steerable, or to be locked onto a target according to need. Independently focusable, one pair usually set to distance, the other pair to the immediate near surface vicinity.

Drive-by-wire control system underpins all hardware operations. The final driver interface operates through digital displays and joystick control, mediated by computer networking throughout the vehicle.

Beyond the forward view, panoramic 360 vision is implemented by the use of CCTV cameras augmenting simple line of sight, also transmitting proxy telepresence images to base stations.

An airlock hatch accommodates one fully suited person at a time. Provision is made to pressure-clean exposed suit fabric by air blast, and filter out any oxidising, and irritant, Martian dust before entering the cabin environment.

The role of the vehicle is to provide a robust, self-contained roving habitat that forms a spearhead for exploring rough terrain, both for scientific purposes, and prospecting for vital resources such as water.

It would be resupplied from the air to extend its range, and followed up by larger landships, for development of useful finds.

© Jan Kaliciak 25-07-05 Landtrain Explorer - 01 - v1.3