[Spaceships] Antimatter Factory
 

We can mine and refine anything, but how do we make antimatter?

ANTIMATTER FACTORY (TL9) [ANY!]
This is an industrial collider capable of producing and storing antimatter. The $/hr entry on the table shows the value of antimatter produced each hour (antimatter is worth $10B per pound). Antimatter is used in Antimatter Reactors (p. SS20), certain reaction masses (p. SS46), and in antimatter warheads (p. SS47). An antimatter factory might explode if disabled or destroyed (see Volatile Systems, p. SS62).

Option: May be High-Efficiency (double $/hr and power point requirement, multiply cost by 4).

Antimatter Factory Table

Re: [Spaceships] Antimatter Factory
 

Design Notes
The Antimatter Factory system is based on the Industrial Antimatter Factory (IAF) from the GURPS Ultra-Tech Designer's Notes. The IAFs produce antimatter at different rates and costs depending on TL, while GURPS Spaceships seems to assume a constant cost for antimatter fuels (p. SS46) at all TLs (but maybe not for antimatter warheads, p. SS47). The Antimatter Factory system is based on the TL11 IAF's capabilities because it best matches the cost of antimatter given in GURPS Spaceships:

Matter/antimatter reaction fuel costs $10T per ton (p. SS46). Assuming the cost of the matter is trivial compared to the antimatter (and the antimatter makes up one-half of the reaction mass), that means the antimatter is valued at $10B per pound, or $22 per microgram. This is comparable to the $25 per microgram cost for TL11 IAF production and for TL11 antimatter explosive in GURPS Ultra-Tech (p. 88).

No weights are given for IAFs so I assumed 200 tons, the same as the Vatfac (p. UT91) – not that they're similar, it just seemed a reasonable size for a "factory" (if this value is incorrect it will just move the stats up or down the SM scale, but won't change the ratio of Cost to $/hr). Since the TL11 IAF costs $1B and produces 100,000µg per day, this yields a cost for the Antimatter Factory system of $5M per ton (for example, a 5-ton Antimatter Factory costs $25M) and a production rate of 500µg per day per ton, or $459 worth of antimatter per hour per ton (for example, a 5-ton Antimatter Factory produces $2,294 worth of antimatter per hour, which I've rounded down to a GURPS Spaceship-convenient $2,000 per hour).

The High-Efficiency option is based on the mention in the Designer's Notes of optimizing an IAF for high-power locations such as close to the sun.

It would take the Antimatter Factory of a single SM+15 ship 2,250,000,000 hours (257,000 years) to produce the 6,750 tons of antimatter required to fuel a Dirac-Class Exploration Cruiser (pp. SS5:11-12).

Return on Investment: An Antimatter Factory system requires 12,500 hours to produce an amount of antimatter worth the cost of the system itself (i.e, a $25M system requires 12,500 hours to produce $25M worth of antimatter; 25,000 hours for a High-Efficiency system). This compares to 1,667 hours for a Fabricator or Robofac system producing small goods (with 40% input cost; 40,000 hours for large goods, 400,000+ hours for goods requiring assembly off the production line), or 200 hours for a Nanofactory system producing small goods (with trivial input cost; 4,800 hours for large goods, 48,000 hours for goods requiring assembly off the production line).

GMs might want to set a minimum size for Antimatter Factories. I suggest SM+9 at TL9 (150 tons), SM+6 at TL10 (5 tons), and no limit at TL11+.

Re: [Spaceships] Antimatter Factory
 

Amazing. You're like a machine!

One thing that would be useful to have in the table would be how long the antimatter factory would take to produce one fuel tank's worth of the three different antimatter engine types.

Edit: I've added a link from my post in this thread:http://forums.sjgames.com/showthread.php?t=71263

Re: [Spaceships] Antimatter Factory
 

Added. A bit ugly, does it make sense?

Re: [Spaceships] Antimatter Factory
 

ANTIMATTER PRODUCTION FACILITY, LEVEL 1 (TL9)

This facility can produce $7.2M worth of antimatter every day, enough to supply 360 tons of antimatter-catalyzed hydrogen or water or 1,200 pounds of antimatter-boosted hydrogen or water. Supplied with raw materials, it can also fabricate goods up to 600 pounds (SM+1) at $150K/hr, or ships and products up to 100 tons (SM+6) at $15K/day plus 1 ton/day assembly time. Given adequate demand for its products it can earn back its cost in under two years.

tabFront Hull: [1] Steel Armor (dDR 7); [2-6!] Antimatter Factories ($60K antimatter per hour each).
tabCentral Hull: [1] Steel Armor (dDR 7); [2-6] Solar Panel Arrays (one power point each); [core] Control Room (C6 computer, comm/sensor Level 7, 6 control stations).
tabRear Hull: [1] Steel Armor (dDR 7); [2] Open Space (0.1 acres farmland); [3] Habitat (10 luxury cabins); [4] Habitat (4 luxury cabins, 2 sickbays, 2 offices, gym, lounge, briefing room, fabricator minifac, 10 tons cargo); [5] Solar Panel Array (one power point); [6] Hangar Bay (100 tons capacity); [core!] Fabricator ($150K/hr production capacity).
tabFeatures: Spin Gravity (0.15G). Crew: 6 control crew, medic, 2 administrators, 3 technicians. Statistics: TL9, SM+9, $4.1161B.
tab

Re: [Spaceships] Antimatter Factory
 

Sure. Even better.

Re: [Spaceships] Antimatter Factory
 

I'm not sure that's realistic, with such a huge RoI.

Re: [Spaceships] Antimatter Factory
 

By comparison, Class IV and Class V Orbital Spaceports (p. SS6:10) earn back their cost in three months producing small goods (SM+1 or smaller; including 40% input cost and crew salaries)*, 6 years constructing and repairing small ships on production lines (SM+8/9 or smaller; same), or 60 years constructing and repairing large ships in hangar bays (SM+11/12 or smaller; same). So the Antimatter Production Facility falls in the middle category of those break-even points (years, not months or decades), though admittedly on the shorter end of the category.

If you think an antimatter factory should have break-evens more like a spaceport working on large ships than a spaceport working on small ships, consider basing its stats on a TL10 Industrial Antimatter Factory which produces antimatter at 1/10 the rate and five times the cost as the TL11 IAF (giving a break-even of about 80 years for the Antimatter Production Facility), though the assumption for the TL10 IAF is that antimatter costs 100 times as much.

* The Space Industrial Park (p. SS6:8) and Space Factory (p. SS6:9) also have break-even points under three months.

Re: [Spaceships] Antimatter Factory
 

Those ridiculous RoIs are why SS7 has the 'slower production speed' design switch, which I highly recommend in any even semi-plausible setting. It divides production speed by 24 (by making those per-hour rates be per-day).

I'd also alter the rules for production of large objects that were in SS6 to remove the stupid 'large vessels take weeks instead of hours to construct' rule or whatever it was, because they make no economic sense - time on a fabricator costs how much time on a fabricator costs, no matter if you're making a ton of really small objects or one really big object. In order to reconcile SS6's rules with any sort of economic reality, you'd need to multiply ship purchase costs significantly to reflect the lost opportunity cost of the fabricator building spaceships instead of smaller components.

Re: [Spaceships] Antimatter Factory
 

There are situations where a RoI of 70% is reasonable, but the production of a product that is by its nature generic is usually* not one of them; a more typical RoI would be 5-10%. Note, however, that's the return above and beyond operating costs; in many cases, operating costs are considerably higher than profits.

*If the value of the product is dropping extremely fast, high ROI is appropriate; for example, RAM chips are a generic product but your production lines had better pay off fast.

Re: [Spaceships] Antimatter Factory
 

Okay, I only naively compared fabrication/production rates to the facility's construction cost. Let's see what else there might be.

GURPS Spaceships 2 has some sections on operating costs, though they are mainly geared at traveling spaceships rather than installations. Operating expenses for an industrial facility might include:

• Bank Payments (p. SS2:29) -- SIGNIFICANT. If you paid for construction with a loan then your final cost will be higher (because of interest) and it will thus take longer to break even. The "quick-and-dirty" interest calculations on p. SS2:27 mean your final cost will be 144% of the basic cost (1 to 2% of the facility's cost per month, for 12 or 6 years respectively).
• Crew Salaries (p. SS2:29) -- NOT SIGNIFICANT. I'm not sure how factory workers work with GURPS Spaceships. Can a non-automated factory (such as a Fabricator) be run by someone in a Control Room control station, or does it require additional actual bodies in the factory? If the latter, how many machinists are required to operate, say, an SM+15 factory at full capacity? The Work Shack and Space Industrial Park both mention construction and factory workers (p. SS6:7-8), who are in addition to the crew needed to run the ships; the Space Factory and Class III and Class IV Orbital Spaceports only mention technicians (who are already required to maintain the systems); and the Class V Spaceport mentions that its technicians double as factory workers when needed (is that when additional workers are needed, or when any workers are needed?). Despite the questions above, even if all the occupants of the entire ship are being paid to work in the factory, crew salary won't be a significant expense compared to the fabrication rate. At TL9, most crew will earn $3,600 per month (p. SS2:30) or $20.45/hr at 22 days/month, 8 hours/day. If a Class V Orbital Spaceport employed all of its potential 31,000 occupants, at $698K/hr (90% workers at $20.45K/hr, 10% supervisors at $40.91/hr), that would be only 0.5% of the factory's production capacity ($150M/hr). If we assume a factory requires as many workers as workspaces, then it's only $6.7K/hr.
• Consumables (Fuel and Provisions, p. SS2:30) -- NOT SIGNIFICANT. If the factory is powered by a fueled power plant, you'll have to pay for more fuel on some regular basis. Unless you're running a chemical power plant, this is unlikely to be a significant expense compared to fabrication rate. Anyway, all of the factories use Solar Panel Arrays.
• Repair and Maintenance (p. SS2:31) -- NOT SIGNIFICANT. The rules for maintenance in the Basic Set (p. B485) produce maintenance costs greater than GURPS Spaceships 2 lists for cheap or very cheap ships (pp. SS2:27-28), so I'm going to assume those aren't the correct rules to use and that there are no maintenance costs for a spaceship in good condition.
• Taxes (p. SS2:32) -- SIGNIFICANT. Taxes are 10% of profits for most businesses, 5% for government-subsidized businesses.
• Insurance (p. SS2:32) -- MODERATELY SIGNIFICANT. Hull and Machinery Insurance is 0.1% of the ship's cost per month, doubled if it has volatile systems (and I realize now that an Antimatter Factory should be considered a volatile system -- I'll add a mention of that above).

So a Class V Orbital Spaceport (p. SS6:10) costs $180.32B and its factory has a production capacity of $150M/hr (minus 40% input cost). It can generate a gross profit of $64.8B/month worth of small items ($/hr rate), +$2.7B/month on its in-factory production lines ($/day rate), or less than $270M/month assembling ships off of the production line ($/day rate, ×1/10). With a 2%/month loan payment, the spaceport runs in the red for the first 6 years ($2.7B - $3.6B loans - $1.2M salaries - $270M taxes - $180M insurance = -$1.36B per month), but makes $2.25B/month after that (16.6%/year ROI), breaking even in its tenth year. With a 1%/month loan payment, the spaceport makes a profit from year one: $445M/month for the first 12 years, $2.25B/month after that. If the spaceport is financed in-house (no loan payments), then it simply takes 6.7 years to break even. Once the spaceport has paid off its loan (or construction cost) it can choose to make only $61.5M/month profit (1/36th of in-factory profit) assembling ships off of the production line (0.41%/year ROI).

The Antimatter Production Facility can make a $106M/month profit for the first 6 years with a 2%/month loan payment (31%/year ROI) or $147M/month for 12 years with a 1%/month loan payment (43%/year ROI), then $189M/month after that (55%/year ROI). Financed in-house, it takes 1.8 years to break even. Those ROIs do seem high. Dividing antimatter production rates by 2 or 3 produces ROIs more in line with the spaceport, but maybe high ROIs are not inappropriate for a facility composed 25% of volatile systems which might cause the whole thing to explode!

Re: [Spaceships] Antimatter Factory
 

I found this post to be super-helpful!! Thanks munin!!

I included it in my ship designs and formatted your post nicely into a sheet.

This is so wonderful.

Re: [Spaceships] Antimatter Factory
 

I think that an Antimatter Factory should just be a specialized version of Factory that produces a value of antimatter equal to the value of the products of a standard Factory. The difference should be that an Antimatter Factory should require two Power Points and should be a volatile system.

Re: [Spaceships] Antimatter Factory
 

Interesting. That would more than double the output!

I made an optional rule for my setting that TL10 AMFs produce 10x the output. This allows the creation of anti-matter boosted H2 in a time period I thought was reasonable (1000 hours to create 50K tons of ambH2, or about 42 days). So, the ship I created could continually refine and boost H2 with the on-board factories/mining/refinery and provide on going fuel for the attached explorer craft and various small worker/miners.

It's all somewhat superscience, so I don't feel TOO guilty tossing in this one ^ tech in my otherwise "realistic" TL10 setting. :D

I am having a blast making these Spaceships with the GURPS spaceships system. Just the perfect amount of detail and customization. I would really love to see another 50+ page book in the series with TONS (pun intended!) of design options. I'm like having 13-year-old-me giddy fun with this.

Re: [Spaceships] Antimatter Factory
 

If we look to this thread from a few years ago, we find a very reasonable estimate of Power Points as 1PP = 50kW per ton of ship.

This puts an absolute upper bound on antimatter production of 50kW * 1 day / c^2 = 48 micrograms per day per ton of ship mass for a system drawing one Power Point. That's about $1,000 of antimatter per day at Spaceships prices.

Of course, that absolute upper bound means 100% efficient conversion of energy into antimatter, which is probably a ludicrous idea! As far as we currently understand these things, matter and antimatter must be created in equal amounts, which automatically halves our efficiency — 24 µg/day/PP/ton.

As stated earlier, Spaceships AM costs match the TL11 figures from the Designer's Notes, which pin that to a factory producing 100,000 µg/day for an installation cost of $1B and a production value of $100,000/hour. A hundred thousand micrograms per day suggests a single system on board a 2,000-ton ship at that impossible 100% efficiency. The only slightly less-impossible 50% efficiency would mean a single system on a 4,000-ton ship, which matches up exactly with the table in the original post.

I would suggest 20% efficiency, meaning 10,000 tons or a SM+10 ship, as a very reasonable non-superscience TL11 figure. That would mean a table like this would fairly closely match the figures in the Designer's Notes, assuming the efficiency scales roughly with the cost at each TL:

At TL9, divide production by 100 and multiply cost by 25.
At TL10, divide production by 10 and multiply cost by 5.
At TL11, use the listed figures.
At TL12, double production and divide cost by 20.

Alternatively for TL12, multiply production by 10 and divide cost by 5, but a non-superscience system requires 5 PP!

Re: [Spaceships] Antimatter Factory
 

I derive PP from the Weapon Battery Outputs. If we assume that effective laser weapons have a 50% efficiency (otherwise the waste heat would broil the occupants of the spacecraft), then a SM+10 Major Battery would require 300 MW of energy (2 × (3 GJ/20 seconds)). The end result would be around 30 kW per metric ton of spacecraft (I just convert tons 1:1 to metric tons because there is no way that any reasonable spacefaring civilization will not use metric units).

Since antimatter production has a realistic maximum efficiency of 50% (half of the energy produces antimatter and half the energy produces matter), the maximum amount of energy for realistic production would be 30 kW per metric ton (assuming 2 PP). With 90 TJ required per gram of antimatter (E=mc^2), the maximum possible realistic production would be 12 micrograms per hour per metric ton of spacecraft (120 milligrams per hour for an SM+10 spacecraft). From the cost of antimatter given in Ultratech, we can calculate maximum efficiency, meaning that a TL12 civilization produces antimatter at a 41.67% efficiecy, TL11 8.33%, TL 10 0.0833%, and TL9 0.00833%. An SM+10 factory would produce 100 milligrams per hour at TL12, 20 milligrams per hour at TL11, 200 micrograms per hour at TL10, and 20 micrograms per hour at TL9.

Re: [Spaceships] Antimatter Factory
 

This is awesome. So now I ask you gents to help me tune up my implementation.

Goal: to have factory facilities on board my space station/craft that serves as a base of operations for long-term exploration missions.

My setting is TL10.

The factory is in a SM+15 ship.

I have two anti-matter plasma torch engines with two fuel tanks (150K of fuel).

Based on your suggestions (aka "how you would do it"), how long would it take to make 150K tons of anti-matter boosted H2?

Would that take about 300K tons of ice (comets, asteroids, etc.)? More?

I appreciate your thoughts!!

Re: [Spaceships] Antimatter Factory
 

Antimatter-boosted hydrogen uses grams of antimatter per ton of hydrogen. So 150K tons of fuel needs 0.15 tons of antimatter.

Celti's table says 400 µg per hour at TL10, so that's roughly 43 thousand years.

Re: [Spaceships] Antimatter Factory
 

Much more. Ice is roughly eight parts oxygen to one part hydrogen by weight. Call it 1.5 million tons of ice in round figures. However, that's only a block 100 x 100 x 150 metres, which is a fairly small comet.

Re: [Spaceships] Antimatter Factory
 

The problem with antimatter-boosted hydrogen is that its price in Spacecraft is 0.1% of the TL 10 price of the requisite antimatter in Ultra-Tech, so it should cost $12 billion per metric ton at TL10 rather than $12 million per metric ton presented in Spacecraft. It would have to use milligrams of antimatter per ton for the price given in Spacecraft to be economically correct at TL10.

Re: [Spaceships] Antimatter Factory
 

Which is not practical. So, why would we have anti-matter plasma torches without anti-matter production? I guess you build some giant solar powered monster station on Mercury and ship the fuel everywhere? :D

Huh. I'm going to keep my stats. Working at 10x the rate listed in Munin's table, I can refine 50K of ambH2 in 1000 hours (about 42 days). Not exactly as efficient as I would imagine but certainly reasonable from a "make fuel as we need it" - in a quasi-realistic TL10 universe.

I feel like we could use a real Anti-Matter Factory that is configurable to setting "switches". Maybe a switch like "super efficient anti-matter production"?

Re: [Spaceships] Antimatter Factory
 

Even 50% efficient isn't possible. So going beyond that is already fully into superscience. But dials for plausible, technically possible, order of magnitude superscience, and gonzo technobabble superscience is always a good idea, IMO too.

I always assumed antimatter production is for when energy is free and needs to be "moved". Though really for when no other fuel would work. Such as for superscience drives or realistic drives where performance is needed and money is no object... like some military vehicles.

Re: [Spaceships] Antimatter Factory
 

Eeeeh... >50% would be limited superscience, in my amateur opinion. The entire existence of the problem of baryon asymmetry suggests that it at least was possible to produce unequal amounts of matter and antimatter at some point in time.

This is pretty much true, yeah. If you need to refuel en-route, you don't use an antimatter rocket, you use a fusion rocket and tank up on remass twice as often.

Re: [Spaceships] Antimatter Factory
 

What is ambH2?

Re: [Spaceships] Antimatter Factory
 

antimatter-boosted H₂ (hydrogen).

Re: [Spaceships] Antimatter Factory
 

Whatever caused the ever so slight initial asymmetry has not been shown in modern antimatter production, so it must be negligible for our purposes. 50% antimatter production would require literal perfect 100% efficiency due to the other half being matter production.
Some things can approach near perfect efficiencies, but many technologies simply can't without assuming superscience or other major hand-waving.

Re: [Spaceships] Antimatter Factory
 

The problem with antimatter is that it is that there really isn't any reason to use it. If you really need a highly efficient fuel, just use a pure He-3 mixture, the products of which can be converted very efficiently into propulsion. Since 1 gram of antimatter possesses the same cost of 1 metric ton of He-3 in most settings, you are just better off using He-3. D-He-3 mixes never work out well because the D burns at much lower temperatures and pressures than He-3 (if you look at the fusion rates, the temperature/pressure required to burn 1 He-3:1 D will end up burning around 200 D, so what you end up with is all of the D burning off, leaving a mixture with a proportion of 5 He-3:1 T:1 p:1 n).

If you really want to make antimatter affordable though, you need to make energy very cheap and the process very efficient. Right now, the wholesale cost of electricity is $30/MW-h (3.6 GJ), so the electricity required to make one gram of antimatter at 50% efficiency (the hypothetical maximum efficiency) would cost $750,000. At TL9, the efficiency is only 0.00833%, meaning that the electricity cost should actually be around $9 billion per gram (the cost is $25 billion per gram in Ultra-Tech, but I think that the electricity is the majority of the 'materials' for the productive formula). In order to make it as affordable as in Spaceships, you would need to either increase the efficiency by 32X and decrease the cost of electricity by 32x.

Re: [Spaceships] Antimatter Factory
 

That's essentially what I do in Wives and Sweethearts (TL11 with mild superscience): antimatter factories as close to the star as they can be put and still survive, and freighters that shift the stuff around to where it's needed. Most systems have their own factories.

Re: [Spaceships] Antimatter Factory
 

An automated orbital platform orbiting Sol at 0.1 AU would receive around 100 PP per Solar Panel Array, translating to 30 GW per Solar Panel Array for an SM+10 spacecraft. If an SM+10 spacecraft possessed 10 Solar Panel Arrays and 5 Antimatter Production Facilities, it could produce 10 milligrams of antimatter per hour at TL9. Of course, it would also suffer 100x as much radiation from solar storms and would have problems storing that much antimatter. Even with that level of production, the price would not drop quickly because of the enormous maintenance cost (you would likely be capturing only 1% of the antimatter produced, meaning that the remaining 99% is turning the facility to Swiss cheese), which would likely be 1% of the facility cost every eight hours.

Re: [Spaceships] Antimatter Factory
 

Why would there be any more trouble storing 10mg than 1mg? Or 1g or 100g? Pretty sure you just need a magnetic bottle.
Production is the yield of antimatter produced and stored by the factory, by definition. It would be very bad design to build a leaky antimatter factory that releases 99% of its production to its environment. Even a-m that couldn't be captured inside the factory would be directed to absorber shields of some sort.

Maintenance would be a problem for being so close to the Sun, not from containing a-m factories.

Re: [Spaceships] Antimatter Factory
 

I think of this as the "standard" way of making antimatter in quantity when there isn't blatant superscience. I first encountered it in Vernor Vinge's novel Marooned in Realtime (1986), but it may be older.

Re: [Spaceships] Antimatter Factory
 

The 25 billion is the "retail" price so it should include things like the transport and guarding of the dangerous material to the point of sale and of course profit for the maker and seller. So on that it seems fairly reasonable with the given production price.


It should be noted that in Space ships the highest energy production/dollar put into production machinery is achieved with TL8 fission. The more advanced systems costs more/power point.

So taking a say SM 11 fission reactor for $100 million, and the 1.5% costs for maintenance, bank loans and other costs makes the costs $1.5 million/month.

SM 11 power point seems to be 10 GJ weapon shot every 20 seconds for normal weapon and one every 10 seconds for improved, so assuming normal is 25% efficient and improved 50%, that is 40 GJ/20 seconds or 2GW.

So the power plant would produce 24*30*2 GW-h/month= 1440GW-h or 1.44 million MW-h for that 1.5 million cost. So one on site power production using space ships prices would give a cost of just over $1/MW-h.

So that is a *30 improvement in cost for the electricity, we would then only need additional efficiency to cover the cost of the AM production facility, profit, transporting and such over your 0.00833% efficiency to reach spaceship prices. Say an efficiency increase of order of magnitude *2 to *8 maybe.

Re: [Spaceships] Antimatter Factory
 

Energy is insanely cheap in Spaceships. The price of the fission reactor is $0.1/W, which is ridiculous cheap, considering that non-mobile fission reactors are 10/W. Solar panels are also laughably cheap at $0.16/W, considering that they cost $5/W before you subtract an average of $3.50/W in grants and tax incentives given by the federal, state, and local governments in the USA. In reality, SM+10 fission reactors should cost $3 billion, not $30 million, and solar panels should have a cost $1.5 billion at SM+10, if you do not receive subsidies and grants.

Re: [Spaceships] Antimatter Factory
 

If you use the posters' estimates of power points, then you hit the problem of solar panels producing far more energy as would be realistically available. They're obviously written to make them slightly competitive with fission reactors, etc.

Re: [Spaceships] Antimatter Factory
 

The power to weight ratio isn't absurd -- it's probably easier to get 1 kW/kg out of solar than it is out of nuclear. The problem is size. A SM +5 ship (30 tons, 1,500 kW) needs at least 1500 square yards for 1 pp. The actual cross-section of a SM +5 ship is probably something like 75 square yards, to get 1500 square yards you need to go up to SM +9, and realistic efficiencies result in it being about SM +11. This gets worse as you go up SMs -- a decent rule of thumb would be to multiply SM by 1.5 and then add 4, rounding up, for the SM of the solar array.

Re: [Spaceships] Antimatter Factory
 

If we use an estimate of 30 kW of electricity production per metric ton of spacecraft mass per power point, the minimum realistic size of a solar panel would be around 120 square meters per metric ton of spacecraft per power point at TL8 (assuming 19% efficiency) or 60 square meters per metric ton of spacecraft per power point at TL9+ (assuming 38% efficiency). If we also assume a minimum mass of 0.75 kg per square meter, the minimum mass for a SM+10 solar panel should be around 900 metric tons at TL8 (two components per power point) or 450 metric tons at TL9+ (one component per power point). Anything less robust than 0.75 kg per square meter (75 milligrams per square centimeters or the same mass as a postage stamp per area) will probably not survive any meaningful acceleration.

Re: [Spaceships] Antimatter Factory
 

But that comparison is a little like comparing the price of getting elemental aluminum in 2018 to the price of in Napoleon's time. Relative costs change as technology advances.

Re: [Spaceships] Antimatter Factory
 

This is missing a core problem with solar in Spaceships (though Anthony skirted around it).

Spaceships' adoption of mass as its' sole significant measurement makes the fuel/delta-V issues work out right for realistic drives. However no formula basing solar power generated on mass will work out right. Solar power should be based on surface area and not mass.

As ships get larger their ratio of surface area to mass will shrink so attempts to use solar power will require increasingly large arrays added on. Historical/Real World spacecraft have relied on unfolded arrays anyway rather than panels covering only the outside hull.

As with most of Spaceships realism issues it arises out of trying to extend a marginal/niche real world technology to give it general usefulness. Most users would never encounter the problems.

Re: [Spaceships] Antimatter Factory
 

I always assume that Solar Panel Array are deployable arrays that retract during combat and planetary operations.

Re: [Spaceships] Antimatter Factory
 

What would the vessel do for power then?

<shrug> I went back and checked and all the basic rules text says is that a Solar Panel Array is an exposed system and is not protected by armor. There certainly didn't seem to be anything about it changing the vehicle's SM.

So not a fantastically realistic design option and I wouldn't use it as a source for hard numbers.

Re: [Spaceships] Antimatter Factory
 

Solar arrays aren't for realistic combat capable ships anyway.
I'd probably want retractability for safety's sake, but only for "large" accelerations then unfurl for coasting.

Re: [Spaceships] Antimatter Factory
 

Exposed systems — including solar panels and sails — are targeted at the ship's SM+3 per Spaceships 1, p. 66.