Satellites

[ddtim]

not entirely sure that this is the correct place to put this, but it is an issue. radio waves move in straight lines, and while it is possible to bounce signals off the ionosphere, you do not have much choice of where the signals end up. While it would be possible, with the late 1920s tech base that would arise after a collapse (based partly on your book and partly on the limits to growth study) to build very light and small heavier than air craft, they, and ships in the pacific and southern indian oceans, would need a dependable radio signal.
And so I come to the main point of the post; is 1920s technology sufficient, and is an economy of that sort of size large enough, to support a constellation of small satellites for communications with ships and planes far from land?
Certainly there were would be[url] transistors[http://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld/url], and possibly solar panels http://en.wikipedia.org/wiki/Cadmium_te ... tovoltaics. Rockets should also be around; Goddard was experimenting during the period, and given sufficient time the research would eventually be done again. Incidentally, Goddard also experimented with ion thrusters, so station keeping should be possible. But how to fuel the rockets? Goddard used KEROLOX, but there would be little to no available petroleum; but while KEROLOX is great as a fuel for its density, the specific impulse is not as great as HYDROLOX. But there is a fuel/oxidiser mix that falls neatly between the two; METHALOX. Methane would be abundantly available from anaerobic digesters.
So, the satellites would be feasible, and the rockets would have reasonably cheap fuel, but what of the rockets themselves? Alumium-copper alloy would be the easiest tankage material to make, given the comparative scarcity of lithium. Aluminium alloys can also be used in the engines, apparently http://www.nasa.gov/vision/earth/techno ... dient.html

But can anyone actually pay for it?
the total budget for NASA in 1966, the highest funding they ever had, was 39.3 billion 2009 dollars. to compare, the GDP of the US in 1923 was 867 billion 2009 dollars. this makes an equivalent program approximately 4.5% of the GDP of the US in 1923. It would probably cost less, but these are intended to be conservative estimates.
In conclusion, not only would it be possible for a post collapse society to set up a satellite network (assuming a sufficiently large population for the purposes of taxation and skill specialisation), it may also be possible to have a manned space-flight program.

[Strongbow]

Nice post.
Would it be possible to have pre=planned apocalypse communication satellites? Something that would use solar power, with a view for long term use, which only came on during certain times of the day so as to conserve power? It could give international live time comms by acting as a relay station?

[ddtim]

Nice post.
Would it be possible to have pre=planned apocalypse communication satellites? Something that would use solar power, with a view for long term use, which only came on during certain times of the day so as to conserve power? It could give international live time comms by acting as a relay station?

Well, that depends. if you mean prepositioned, that would require knowing when exactly the apocalypse would occur. if you mean creating a design ahead of time to be deployed rapidly... it really depends what you have to work with. When are you expecting them to be built? if it's before, during or slightly after the flying-pig flu crisis, then you could use satellites very similar to the ones in use today, albeit with much more redundancy in the communications gear and increased fuel. If you are acting as the duly designated representative of the provisional government, then you could commandeer any remaining ICBMs to place them into orbit. If, say, 100 years have passed, then it would be trickier.
Early transistors were fairly hard against radiation (but microchips are easily damaged; that's why you don't see state of the art electronics on the ISS, the chips need to be hardened). However, the additional weight of these, and the other components that would be less capable than those currently used (solar panels especially), would increase the weight considerably. the Ariane 5 Vulcain engine has a thrust of 960-1390 kN (SL to Vac). Copenhagen Suborbital (copsub.com/technology-2/liquid-rocket-engines/) are currently working towards a 260kN engine (ALCOLOX). If that it what can be done by a dozen people in a shed with off the shelf parts, then a dedicated effort could probably do better.
Depending on what orbit the satellite goes into, the amount of sunlight it receives would change. out at geosynchronous, there is sunlight almost all the time. The main issues with longevity on station seem to be fuel and redundant electronics. Not much can really be done about the fuel other than sending up more (unless the EM drive turns out not to be hokum), and the more redundant pathways in the electronics, the heavier it would be.
Still, one never truly knows until it is tried. If you have any friends in the aerospace industry, see if you can get them interested; even if nothing happens, the design may be useful to any developing nations that want to develop a national aerospace industry.

[steve]

Any discussion of satellites should probably include some consideration of Kessler Syndrome https://en.wikipedia.org/wiki/Kessler_syndrome

[steve]

Both the US and China have tested their ability to destroy satellites.

China's test in 2007 was "the largest recorded creation of space debris in history with at least 2,317 pieces of trackable size (golf ball size and larger) and an estimated 150,000 debris particles." 4 years later it passed within 4 miles of the international space station.

https://en.wikipedia.org/wiki/2007_Chin ... ssile_test
http://edition.cnn.com/2011/US/04/05/sp ... index.html