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Basically, how to make modern weapon systems, specifically, tanks and planes, work in all environments.

Background

I'm currently putting together a role-play setting, which is fair high tech. The setting is limited to all planets in the solar system. Anything that can be terraformed, has had chunks of it terraformed. Jupiter houses multiple 'Gas Cities.'

The setting takes place on the moon. Using purchased military hardware, which is meant to be all purpose.

The moon is being fought over by private military contractors, funded by two brothers, each of whom wants the other's inheritance. Both sides have access to the same suppliers, and gear. Both sides have fortunes to spend.

The problem, in hindsight, was obvious.

Tanks don't work on the moon. Nor would a jet fighter, at least not how it was designed to.

Clarifcation

What, exactly, would they need to have to operate in various space environments? What kind of traits, and difficulties would they face?

Edit: The answers so far have said something I overlooked. An one for all system, is useless. To make it more practical, what about a modular system. Specifically, a mass produced skeleton, with multiple modular parts for varying environments.

To limit the environments, only the Moon, Venus, Mars, Jupiter.

What would those modules be?

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  • $\begingroup$ You might be interested in milscifi literature, e.g. Hammer's Slammers $\endgroup$ – dot_Sp0T Oct 23 '19 at 16:54
  • $\begingroup$ What do the phrases "stellar environment" and "interstellar environment" mean in this question? They do not seem to have the ordinary meaning. For example, normally "interstellar environment" is understood to mean the hard vaccuum between stars. $\endgroup$ – AlexP Oct 23 '19 at 16:55
  • $\begingroup$ Excuse that mess up. Got my words all tangled up. $\endgroup$ – Rosegold Oct 23 '19 at 16:58
  • $\begingroup$ What’s wrong with Transformers? They have done this already. I used to play Battletech which did everything your trying to do. $\endgroup$ – Vogon Poet Oct 23 '19 at 18:27
  • $\begingroup$ Frame Challenge: Why are people fighting over any moon when they have the ability to freely engineer the environment of any celestial body? Why are people even concerned about large celestial bodies? $\endgroup$ – Frostfyre Oct 23 '19 at 20:32
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Complete rewrite

In general, one-size-fits-all approach is not good. Instead, same basic vehicles will be customized for a given environment, just like RL tanks and airplanes are customized for terrain where they operate (heating and no-freeze lubricants for Arctic, AC and dust control for Iraq).

First, you need to keep the crew supplied with air. So air-tight interior, and/or personal air masks in case of breaches. Luckily, airplanes come with breathing masks, and tank crews members stay in the same seat most of the time.

Then, you need energy source. Could be electricity if you have a major break-through on batteries. Otherwise, you are back to chemical fuels. On Earth, you have a tank of carbohydrates (e.g. gas) and use oxygen from atmosphere. On Jupiter outdoors, you have a tank of oxygen and use hydrogen from atmosphere. On Moon, you have to carry both fuel and oxygen, reducing how far you can drive on a single charge.

Then there are environmental hazards. On Mars and beyond, you will need serious heating. On Venus, you will need cooling. On Moon, you need to keep the abrasive dust from chewing through metal parts, meaning more seals, which would melt on Venice, and freeze and crack on Jupiter. Jupiter requires anti-acid coating, which will be scrapped off by dust storms on Mars.

You can have features for every environment built into a single vehicle, but it will be too heavy, too expensive and too easily broken. If your opponent has vehicles specialized to a given environment, they will be faster, more reliable and more numerous.

So you can have vehicles moved between planets, but you will need to spend some time to refit them.

Also, given the cost and time it takes to move heavy military hardware between planets, it might be cheaper and faster to make new hardware on the target planet.

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  • $\begingroup$ Not just the moon. They're buying military gear designed for nearly most environments. From Mars, to Jupiter. That has to effect design more than 'make it air-tight.' Unless I am mistaken? $\endgroup$ – Rosegold Oct 23 '19 at 17:01
  • $\begingroup$ in what sense is a tank on Jupiter different from a plane on Jupiter? There's no ground for the tank to drive on. $\endgroup$ – Ryan_L Oct 23 '19 at 17:02
  • $\begingroup$ Observing how much tanks "flinch" on shooting a shell, in moon gravity - wouldn't they just flip over backwards? $\endgroup$ – BLT-Bub Oct 23 '19 at 17:03
  • $\begingroup$ There's ground on a gas city. It's a floating city. It has streets. Thus, tank. As Smell asked, that's the kind of stuff I'm looking for. $\endgroup$ – Rosegold Oct 23 '19 at 17:05
  • $\begingroup$ @ 011358 smell tanks can do have muzzle breaks to reduce recoil. They can be made bigger. The mass ("inertia") of the tank remains same, and will continue to absorb most of recoil. Finally, tank geometry makes it very hard to flip. $\endgroup$ – Bald Bear Oct 23 '19 at 17:12
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Some key features that would need to be taken into account are: The presence or absence of gravitational acceleration The presence or absence of an atmosphere at a range of compositions and pressures The possibility of encountering and moving in liquids such as water and methane A wide range of operating temperatures

Some limitations that must be recognised Temperature and pressure limits must be imposed (some areas of the sun and planets are not accessible and are unlikely ever to become accessible in the future). Reaction mass will be required for mobility and there are many unavoidable trade-offs that must be made between size, speed, manoeuvrability, range and endurance.

Some aspects that would need to be built in Flows of liquids in engines would need to be pumped as gravity flow could not be relied upon. The structure of the platform itself would need to be very robust to ensure that it could withstand high pressure environments. A high energy power source such as a fusion reactor would be needed to power the platform and especially to provide mobility. Mobility itself would be a particular problem with many variables such as how long does the platform needs to operate independently before re-tanking, how manoeuvrable does it need to be and how far/fast does it need to travel in which environments? There would be multiple trade-offs here which are unavoidable and large quantities of reaction mass would likely be needed. Rejection of waste heat would be an issue and multiple systems would be needed depending on the environment. Multiple engines of different types would be best for different environments such as chemical rocket engines and nuclear electric rocket engines.

In summary what you are asking for is too open ended to provide a definitive answer. It depends on the detailed limits you want to impose. If the answer is that you do not wish to impose any limits then no such platform is possible as no vehicle or platform could survive the pressures deep within Jupiter’s atmosphere to name but one location that is problematic.

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TL;DR: Don't do it. People think nothing of having different equipment and training for use in air, on the ground, on water and underwater. Cryonic and roasting atmospheres, super high pressures, vacuum and microgravity conditions are different environments and you should equip and train your warfighters appropriately for each.


Lets have a think about the range of environments in the solar system.

  • Surface gravity: <0.00001g to 1g
  • Surface air pressure: 0 to 9.3MPa
  • Water pressure: 0 to 260MPa
  • Surface temperature: 33K (vacuum)/98K (atmosphere) to 700K (vacuum)/735K (atmosphere)
  • Solar irradiation: 0 to 9082W/m2
  • Particle radiation: ~0 to >5Sv/day (continuous background radiation)

There's more awkward stuff to quantify, like strongest winds, strongest magnetic fields, cryogenic rain, radiation levels of solar proton events, scale height of terrain features... the list goes on and on.

Even seemingly simple things like the design of a wheel has to change in non-trivial ways for different planetary surfaces, and complex things like wings are more difficult again... especially if you want to be able to manoever in those alien skies. You might need different jet engines for each atmosphere.

What will happen, if you try to make one thing that can survive all these conditions, is that it will end up carrying a load of dead-weight useless equipment in any of these conditions. Weapons that work in one environment can be utterly useless in another... are you going to carry four different types of gun, and four different types of self-propelled projectile, knowing that you can only use one of each in any given situation? All that wasted weight would be better spent as armour, or weapons, or ammunition, or fuel, or greater safety margins.

Your all-conditions compromise war vehicles will simply get wasted by specialist vehicles that are appropriately adapted to and armed for the conditions and not burdened with useless crud. Those specialists are likely to be vastly cheaper than your ridiculous boondoggle, so you'll be outnumbered into the bargain.

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