So, to start the question, I want to have a small assumption here:

Let us assume that we are an interplanetary civilisation. We have spammed much of the Solar System, but it is not all sunshine and flowers (if it was, I would not be asking this question). According to Atomic Rockets, the first two steps for a Space Force are strategic assumptions and goals, which I will provide an example for very soon. But first some more context on the assumptions for this situation.

You have a growing insurrection on Mars, the Belt, the Galilean Moons and the Saturn Moon System, with Mars having a population more than 700 million, the Belters having 160 total colonies, which combined make up a population of 40 million, while the combined Outer Solar System populations are basically around 100 million.

Now, the problem is......those 840 million colonists are NOT wanting to stick with the 12.9 billion people on Earth, mainly due to growing secessionist sentiment, Earth getting desperate for phosphorus deposits on Mars, Deimos and other C-type asteroids, which are controlled by various large corporations, whom also dominate other industries, in addition to the mining of phosphorus, a growing cultural divide, and failed negotiations between the UN, its member states and autonomists.

We also have a combined threat of "pirates" in Cislunar Space, Martian orbital space and the Trojans, which also host a lot of black market activity and is often a terrorist haven.

And finally, we have the problem of spacecraft permits, since civilians can now get their own spacecraft, albeit with some degree of expense, not to mention bureaucracy.

This gives the UN's space forces four key priorities:

  1. Protect commerce to keep the phosphorus flowing to Earth.
  2. Enforce the laws and regulations of the UN's member states and UN treaties on international law.
  3. Ensure that asteroids are not able to smash Earth.
  4. Power Projection to crush any potential uprisings.

Another thing I should point out is that most UN space force assets are contributions from UN member states, with it only being mandatory in the event of an emergency (such as the ongoing uprising), while the UN itself keeps a small directly controlled cluster, and three Espatier divisions (Espatiers are basically space marines) to deal with goals 2 and 3 (at least for now).

To be clear, the UN's member states of the planet with settlements and thus, space forces by order of interplanetary influence are:

  1. United States
  2. China
  3. European Union (mainly British, French, German and Italian, with the ocassional settlement by other EU member states)
  4. Japan
  5. Korea
  6. India
  7. Russia
  8. Israel
  9. The Gulf States (under the Islamic Space Alliance, led by Saudi Arabia)
  10. Latin America (under the Pan American Space Organisation, led by Brazil)
  11. ASEAN (led by Indonesia)
  12. Nigeria
  13. South Africa

These nations and space alliances all have space forces, and can enforce laws and regulations within the colonies, so long as they comply with international treaties, even though the UN member states have fought armed conflicts against each other in space via proxy prior to 2367, but since then, the UN has been more influential.

As for the UN member states, I should point out that although they all have national interests at heart, they do agree that independence for the colonies in a total sense could spell disaster, especially the Big 5 (previously, the Big 6), even though they also have autonomist sympathisers, though mainly moderate autonomists. This proved to be a factor in failed negotiations with the autonomists, which in turn, led to hostilities becoming more official as secessioonists became more and more radicalised. However, since we are focusing on both the unofficial and official state of hostilities, we need to account for the autonomists playing a role.

Given that, will the capabilities of the UN space force be efficient in performing the specified goals, especially with the basis of its assumptions (both in terms of security and fiscal environments), especially goals 1 and 4, as the undeclared war becomes less and less undeclared and more official? More importantly, how can it operate efficiently under its security concerns and fiscal restraints?


This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See the tag description for more information.

closed as too broad by Aify, Ash, L.Dutch, Azuaron, Hohmannfan Sep 13 '17 at 20:55

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  • $\begingroup$ The question looks very vague. If there is a problem with law enforcement, additional forces may be brought in, If there is a movement towards independence, empire should give it proper consideration. I can imagine a brave settler who desperately tries to warn his fellow Martians: "The Earthlings are coming!" $\endgroup$ – Alexander Sep 13 '17 at 16:33
  • 1
    $\begingroup$ @Alexander "One if by Rocket, Two if by Asteroid!" sort of thing? $\endgroup$ – Paul TIKI Sep 13 '17 at 16:40
  • $\begingroup$ They would need a variety of ships. Fast but well armed ones to respond to distress calls from trade ships. Local police are probably best for point 2. Some powerful long-range missiles and an early warning system should fix point 3. Point 4 could be solved by huge battleships hovering over each colony to show the UN's power and/or WMDs that can be fired at uprisings. $\endgroup$ – Bellerophon Sep 13 '17 at 16:46
  • $\begingroup$ @Alexander. I can fix that. $\endgroup$ – Future Historian Sep 13 '17 at 17:41
  • $\begingroup$ Done! Well....sort of. $\endgroup$ – Future Historian Sep 13 '17 at 17:41

Capabilities and missions

Logistics! Even on the earth the old saying is that amateurs study tactics professionals study logistics. The capability to supply and reinforce would be critical. (Supply as in additional missiles, fuel and similar).

Transport capacity especially propulsion technology and the ability to reach destinations quickly with a large payload.

Redundancy in units and systems

Landing ability: hover duration time, surface hugging capability, landing in deficit terrain, specialist units to deal with different atmospheric compositions.

Armament type and amount especially missile and anti-missile technology.

Presence (or not) of human troops and the quantity required.

Sensing equipment for offensive and defensive purposes especially missile detection.

Attack and destroy surface and space based installations or threaten to do so.

Gather intelligence by monitoring of communications and tracking space vehicles.

Law enforcement policing operations where limited unrest has broken out.

Landing armed forces to overpower and take control of surface installations.

Assumptions Resource availability or funding for the forces Lots of money and resources spent on the military would allow larger more impressive forces, more attack options, multiple redundancy and the capacity for units to carry out many different mission types. It would also enable a greater involvement of human personal and troops which might be necessary in some circumstances. Less money and resources would tend to favour more limited automated robotic systems such as guided missiles operated remotely and fewer options for human troop actions.

Time scales and preparation How long does it take the situation to evolve: Months, years, or decades? The longer the time span the better adapted the infrastructure and counter measures would likely be (subsurface installations etc). If the situation arises rapidly then neither side would be well prepared. If one side had planned and prepared extensively in advance then it would have a big advantage.

The unknown nature and extent of retaliatory action by the other side Space based and to a lesser extent asteroid and atmosphere-less moon based infrastructure would be very vulnerable to attack so should be relatively easy to destroy in any armed conflict. For example many relatively small very fast stealth missiles fired at a target in a salvo would be very difficult to detect and destroy before impact.

Very vulnerable space based systems would also be present in earth orbit which could be relatively easily destroyed. For example a missile packed with millions of small ball bearings fired into retrograde geostationary orbit and then blown up would effectively destroy all geostationary satellites within hours and would make geostationary orbit unusable for a very long time.

Notes I would have thought that it would be far cheaper and easier to retrieve phosphorous from earth source even if dilute, than to find process and ship phosphorous from the asteroid belt. Some other material might be a more suitable for trading.

Smashing the earth with asteroids would require large amounts of energy and orbital changes both of which should be easy to detect remotely and allow counter measure to be taken such as missile attack before the orbit had been sufficiently changed.

With 700 million on Mars I would assume that Mars would be completely self-sufficient in almost all commodities. The other 120 million spread over more than 160 instances would not be self-sufficient except in the basic necessities so there might be scope for “blockade” type threats.


This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See the tag description for more information.

  • $\begingroup$ Interesting. I do want to point out that Mars has had some terraforming efforts in the times since the initial colonisation waves of the mid-late 21st and early 22nd Centuries, and the efforts had to be an international cooperation initiative. By the time conflict erupts in 2392 (at least officially, even though the conflict has been an undeclared war for 20 years at this point), Mars is capable of sustaining human life without EVA suits, though genetic engineering is somewhat common enough that humans can adapt to lower gravity and the like. $\endgroup$ – Future Historian Sep 13 '17 at 18:39
  • $\begingroup$ And.....need I remind you that there is no stealth in space? ;) As a hard science fiction setting, I should point out that even with nuclear pulse fusion engines (and their antimatter-catalysed versions), travel time in the Inner Solar System could take months at best, and further out, into the Galilean Moons and Saturn Moon System, it could take a year or two tops from Earth. From each other, more or less ~7 years for a Hohmann transfer to get there. $\endgroup$ – Future Historian Sep 13 '17 at 18:40
  • $\begingroup$ And besides. I already pointed out the UN member state contribution system. The UN has a small cluster of armed military spacecraft, mostly to deal with any "pirates", along with three Espatier Corps divisions, though most of its assets are from the contributions of national space forces, which are going to be mandatory in the event of an emergency such as.......say....I do not know....official hostilities erupting between Earth and the colonies. $\endgroup$ – Future Historian Sep 13 '17 at 18:44
  • $\begingroup$ And.....I should probably put all this information in the main question, hmmmm? $\endgroup$ – Future Historian Sep 13 '17 at 19:30
  • $\begingroup$ Also, a slight correction: 140 million in 272 locations, with 160 of them being asteroids in the Belt, and an extra 20 million people in 100 Jupiter Trojans, and the remaining objects being Europa, Ganymede, Callisto, Titan, Enceladus, Mimas, Iapetus, Rhea, Ceres, Dione, and Hyperion respectively. There are also some UN military outposts in orbit around Io, Tethys, Thebe, and Amalthea, with a scientific outpost being on Triton, though this is later turned into a criminal haven while the UN is busy fighting the colonists. $\endgroup$ – Future Historian Sep 13 '17 at 19:39

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