High Energy Laser Launcher (H.E.L.L., HELL I SAY!) and the lightcraft and solar moth.

 

High Energy Laser Launcher (H.E.L.L., HELL I SAY!) and the lightcraft and solar moth.

Light-Craft Surface to Orbit Laser Launcher Cargo Delivery

Space programs do not all have to take the same form. Some space programs were rocket oriented, because of a strong need for rockets for other applications such as military. Mostly missiles for blowing stuff up in case you needed it spelled it out. The need for a strong air force was also very influential.

Araxes has different needs, particularly wanting to limit excessive heating of the atmosphere, all of which would affect how its space program manifested.

The use of the Laser Launcher and the Lightcraft originated during the early colonization period before the Araxes Desertborn were fabulously wealthy. Attention was given to Do It Yourself and self-sustainability. We are still very economical and ecological minded, it is just ingrained into us as a cultural virtue.

We are mostly considering options (1.) Surface to orbit and (2.) orbit to Asteroid Belt

Luckily, cast aluminium, the pulsed laser, and basic computing power are all available at even the technical and resource capabilities of small single clan seeqs.

I had been exploring the Solar Sail, the Electric Sail, the Mag-Sail, the High Energy Laser Launcher (Hell), the Solar Moth and the Light-Craft; all of which within local manufacturing infrastructure, and locally available labor and materials of even small single clan seeqs.

Rockets and more complex propulsion require a much more substantial mining and manufacturing infrastructure. Rockets especially, particularly manned rocket ships also not particularly energy efficient.

Rockets are less efficient because you have to carry the fuel, power plant, reaction mass, and a lot more hull than you would need, especially if it is a manned mission, then you have a lot of mass not related to your final payload.

Our solution was the High Energy Laser Launcher (H.E.L.L., great acronym, wish I had thought of it). Keep the fuel and power planet on the ground in the form of the surface based laser launcher. You also don’t have to have as much hull to contain them, saving even more mass. The Laser Launcher aims at the bottom side of the launch vehicle, each pulse (250 pulses per second) rapidly vaporizes the reaction mass (water) which then propels the ship. By carefully aiming the laser launcher, you can steer the light-craft. All of the energy comes from the surface laser launch station, no actual reactor or engine is needed on the light-craft; there is only the hull, reflector, water as propellant and the cargo payload itself.

The Light-Craft base weighs about 23.3 kilograms, plus another 119 kilograms of hull and can push about 200 kilograms of payload with just air. The actual main hull is 1.75 meters diameter and can hold a single cube-shaped crate 1-meter on a side. The original idea is that the Light-Craft would contain no fuel or reaction mass, a 700 megawatt pulsed laser launcher explosively vaporized the air that comes in via the waist air vents which then propels the ship. Obviously, this only works in the atmosphere, for the same reason why commercial aircraft stay below a certain altitude. Araxes’ famously thin atmosphere, operating on just air as propellant is extremely limiting.

One great advantage of the laser launcher is the simplicity of the cargo-capsule. It can be made from cast aluminium with technology available since TL5.

When I adjusted for the air density at different altitudes, the light-craft could not by itself get the payload to orbit with any acceleration short of 437 Gs. Imagine hitting a solid steel wall at twice the speed of sound, that amount of force for 7 seconds. It is also way beyond the maximum dynamic pressure (called Max-Q for some reason) of any reasonable material the hull would be made from. Forget considering the 865 Gs needed to get to escape velocity. The hull and the cargo would likely be severely damaged.

Humbled by the shortcomings of the original concept, we modified the idea and use a version which contained some propellant mass. In this case, while the ship is still technically a light-craft, but now it is closer to a laser thermal rocket. The shape of the light-craft is unchanged, instead we just have water as a propellant that emits at a given rate thru the waist vents to be evaporated by the Pulsed Laser Launcher.

My first hope is that I could launch using just air and then switch over to the reaction mass, but it just wastes the laser launcher. The numbers worked out that unless you are on a planet with as dense of an atmosphere as Titan and as low of gravity, you are better off using water or ammonia as reaction mass. By the way, gravity and atmospheric density on Titan is such that a mainstream humani can strap on wings and fly. I use it for many calculations because other that.

In 17 seconds at 300 Gs (which is doable) and you get to 25 kilometres altitude at 2000 m/s; which is also really great as a weapon, but sadly is far short (25%) of orbital velocity. In the same amount of energy/time, but with water as reaction mass, we can get the light-craft to 43 kilometres at 5000 m/s. In 26 seconds, we can get it to Orbital Velocity at 102.5 kilometres (low earth orbit) at 7845 m/s. In 37 seconds, we can get the payload to 202 kilometres at escape velocity of 11,010 m/s.

300 Gs for 17 seconds is really really really painful, not to mention liquefying for passengers and foodstuffs cargo, but this is for cargo, not people. We can talk another time about the virtues of being immersed in non-Newtonian fluid gel to keep your bones from breaking, and breathing oxygen enriched liquid perflourochemicals like the ultra-deep sea divers so your lungs don’t collapse, but that probably will only get you to 20 Gs, nowhere near able to survive 300 Gs.

300 Gs also puts a remarkable strain (maximum dynamic pressure) on the hull for atmospheric operations. It is generally velocity squared times the air density. Most space shuttles try to keep its maximum dynamic pressure to less than 3.5 tons per square meter. But that is for safety margin, they can handle up to 4 tons per square meter short term without major damage. Lots and lots and lots of math, but 300 G’s is more than we should consider. I tried lots of variants, and modifying the acceleration/thrust at different altitudes, basically we decided to keep it to 4Gs and we won’t have to get into exotic materials which we don’t have local access to in Araxes anyway.

4-G’s is good news, it means we can launch passengers without making them breathe oxygenated perflourocarbon liquids while immersed in impact gel coffins.

4-G’s works out to launching 1666 kilograms of payload, plus 119 kilograms of hull, and the 23.3 kilograms of the light-craft 'engine'.

At 4-G’s, 103 seconds (1 minute + 43 seconds) to the edge of space at 160 kilometres (very very low terrestrial orbit LPO) at 3111m/s. 245 seconds (4 minutes + 5 seconds) to orbit at 903 kilometres (still technically low terrestrial orbit LPO) at 7400 m/s. 328.5 seconds (5.5 minutes) to escape velocity at 1629 kilometres (still technically low terrestrial orbit LPO) at 9980 m/s.

Important Note: The 245 second version to 903 kilometres is the lowest stable orbit, you can wait for your launch window to activate the solar moth to the lagrange point stations or other destinations within the system. The edge of space option, 103 kilometres, you will have to hope that its forward velocity and the solar moth opens well enough that it can continue to the launch window point. It is dicier. I am betting the 245 second version has the least losses.

<THE MATH, feel free to skip, school habit to show your work>

The famous Tsilokovsky’s Rocket Equations are complex, but the equations of the Laser Launcher are different:

Δv = sqrt((2 * Bp * Bε) / mDot) * ln[R]

R = e(Δv/sqrt((2 * Bp * Bε) / mDot)

Δv is the change in velocity

Bp is the Beam Power (700 Megawatts for Laser Launcher, 32.7 Megawatts for Solar Standard)

Bε is the efficiency which the engine converts the beam power to kinetic energy, in this case 63%

MDot is the Mass flow in kilograms per second, in this case about 0.42 kilograms per second.

R is the Mass Ratio, Initial Mass divided by Final Mass. The final mass is the mass of the ship after the fuel and reaction mass has been used up.

<END HEAVY MATH, breathe easier now>

Math and many frustrating spreadsheets later, escape velocity requires 187.5 kilograms of reaction mass, resulting in a net of 1478.5 kilograms of net payload to escape velocity of 9980 m/s.

To get to orbit, requires 138.75 kilograms of reaction mass, resulting in a net of 1527.25 kilograms of cargo. About 22.5 tons per hour launch capacity allowing for some cooling down periods.

Notice I say reaction mass and not fuel. Fuel and reaction mass is not always the same thing. In the original light-craft, the reaction mass is merely air. The energy comes from the ground based laser, so you don’t have to carry fuel on board the ship. In this case the reaction mass is water. Water has great specific energy, it absorbs the energy from the laser and expands nicely. Bhoosh! The equivalent of a surprisingly impressive 9000 m/s exhaust velocity.

The energy is spent on the surface. The pulse laser is 700 megawatts and fires for 328.5 seconds to get to escape velocity.

700 megawatts times 328.5 seconds = 230 Gigajoules. About 60 grams of Deuterium equivalent.

We would rather keep the solar power robust and so it can be manufactured, maintained, repaired and the parts replaced using local material resources, labour and infrastructure of even small single-clan seeqs. An aluminium solar reflector to a boiler steam generator is as robust as you can get. Then use whatever excess power production to crack water for hydrogen to run the laser emitter power plant.

It is strange to consider that we could launch to orbit using firewood or coal, and water. Steampunk Lives! Some trillionaire’s kid in the imperium I am sure has done this as a school science faire project.

The Imperium runs on Deuterium (refined hydrogen). Petroleum products costs about 250 Credits per ton netting 46.3 gigajoules, 185 Megajoules per credit. Wood about 10 Credits per ton netting 3 Gigajoules, 300 megajoules per credit. Combustion Grade Hydrogen is 100 credit per ton netting 142 gigajoules, 1420 megajoules per credit. Deuterium is 500 Credits per ton netting 4 petajoules, which is 8,000,000 megajoules per credit. Deuterium (a.k.a. refined hydrogen) is nearly fifty-six hundred of times more net energy per credit than the best combustion grade fuel.

The Laser Launcher uses much less energy than regular rockets (torch ships). An optimized surface to Lagrange point station cargo ship requires 1.2 tons of deuterium fuel to move 71 tons, that works out to 67,450 Gigajoules per ton of cargo. That is 434 times more energy per ton of cargo than the laser launcher. That is just the energy cost, not to mention the much more substantial ship and crew costs.

While solar and wind as viable alternatives, infrastructure costs are high and it is just going to be hard to get under the energy per credit of Deuterium in the Imperium. Despite that, solar and wind is probably a winner for Araxes’ infrastructure, manufacturing, cultural and political climate. It is a robust technology that can be built and maintained locally by small single-clan seeqs. Self sufficiency is a source of great security.

Modern solar photovoltaic cells are cheaper per kilowatthour than solar thermal which I am recommending, but we would have to either import them or create additional manufacturing infrastructure for them. Solar Thermal is also very simple to construct, and very robust with a long service life measured in generations. Araxes already manufactures very efficient solar cell film, but I am trying to figure out a launching infrastructure that even smaller single-clan seeqs can be self sufficient.

Ordinary space craft have to lift the reactor, engine, fuel, plus facilities for crew and extra hull, but the laser launcher provides the energy making the energy and fuel not required. Additionally, the light-craft is an unmanned ship, so it does not need extra room, life support and other facilities for crew, and extra hull to cover all of their related needs. The light craft is just the 142 kilogram cast aluminium shell, about 140 kilograms of water as propellant, the cargo itself, and another 100 kilograms for the solar reflector to maneuver it to the Midway Station orbital capture. The remainder is all on the surface. The light-craft is reusable and has a long service life and is recyclable.

With cool down and maintenance cycles, the laser launcher can reasonably launch up to 22.5 tons of cargo per hour of operation. The net two tons of water as propellant is recaptures in the atmosphere as water vapour, but frankly not even enough to make a decent cloud. Note: a small cloud visible to the naked eye contains about 500 tons of water vapour, the average cloud is half a million tons of water vapour. If operated continuously for 30 years, the entire propellant supply would expel the amount of water vapour equivalent of a single average cloud.

We could build most of this from salvaging most any trade ship that came to Araxes.

1 laser turret.

1 fuel scoop.

1 fuel processor.

1 fuel tank.

Scrap the hull and the decks for the light-craft.

Wires and pipes.

Using the fuel scoop and a fuel processor salvaged from a trade ship, we could filter out waste water, salt water, or marsh water to obtain the heavy water that contains deuterium, and sell the deuterium (refined hydrogen) to visiting ships. This is much less expensive than obtaining the deuterium (refined hydrogen) from the gas Giants.

We use solar to gather the power we need. Instead of the batteries, which have their own series of technical, resource and infrastructure issues, we use any excess power to crack the water into combustible hydrogen which we would burn for the power plant to power the lasers for power on demand. We use graphene sieves (the real name for the hydrogen refining processor) to filter the deuterium (refined hydrogen) from the combustible hydrogen.

A basic solar reflector farm would reflect and concentrate light to a steam turbine generator to provide the energy needed. Excess energy would power basic dialysis to crack the water into oxygen (to sell) and combustion grade hydrogen (to burn), and to crack the heavy water into oxygen and deuterium (refined hydrogen) to sell.

The combustion grade hydrogen would mean that we have a ready supply of energy to supplement operating the generators when the sun and wind are not cooperating, and to have power on demand to operate the laser launcher array.

Burning hydrogen is the cleanest fuel, the exhaust product is water. Very ecologically friendly. As we are powering this using solar, it is a renewable resource. We will however examine wind power at a later time to supplement.

The net mass of a very very basic TL7 CO2 laser emitters is about 20 kilograms per kilowatt, so the entire laser launcher will mass about 14,000 tons, which is a half sphere (parabola actually) about 30 meters in diameter.

A basic ship mounted combat grade pulse laser is about 700 megawatts, takes up only 14 cubic meters (1/1000th the locally constructed version) and costs half a million credits, less if we buy used or get lucky with salvage.

If we had to, we could construct the individual components of the laser array locally, and for the sake of self sufficiency, Most of the materials and equipment required are available at a neon light factory, I made a simple lower powered one as a school project in high school as a proof of concept. Kids, learn from my mistakes, don’t name your school project, 'Homemade Death-Ray'.

The light-craft itself is composed of two modular units which can be cast locally out of aluminium, even recycled. Good local industry, and recycling is economically rewarding and ecologically wise.

The light-craft and the solar farm can be constructed using existing infrastructure, resources and local labour.

Hydrolysis is simple enough that it is a well known middle school science project (and does not cause the school admins to alert security). The facility can be operated by local labour with only minimal training.

While this setup is great for small scale cargo, especially delivering liquefied fuel, or air, and other sundries, it is not suitable at this scale for large cargo containers (the standard 14 cubic meters or also standard 15.625 cubic meters); it is designed for roughly 1 cubic meter, and if not cube shaped, up to 2 cubic meters bulk cargo if can fit into a half sphere.

The Laser Launched Light-Craft is not designed to launch people into orbit, or Lagrangian Point Midway Station. Although 4 Gs of acceleration for just over 4 minutes is tolerable, 40-80 hours enclosed in a 2 cubic meter space might not be. While this would be tolerable in stasis, this would below steerage class. Bear in mind, the interior height and diameter of the capsule is only about 5 and a half feet, so most people would neither be able to stand upright or lay down outstretched.

Making a larger capsule would require enlarging the energy supply, and we are gearing this towards using the lowest range laser turret which is easy to come by salvage.

Picking up fuel from gas giants conservatively means fuel will be much more expensive than traders are used to; making it cheaper for larger ships to bring their own fuel with them, but either way that cuts into their profits and reduces how much net cargo they can bring. Making the fuel on the surface and launching to jump point and Midway Station means the traders do not have to bring excess fuel for the return trip nor take extra time to find, scoop and process fuel for themselves. This means they can bring more trade goods at lower costs. A win for everyone.

Only idiots would be against it, I have a list of names.

The ability to receive good in orbit, or at the Lagrangian point midway station saves visiting ships a great deal, instead of taking their entire ship to the surface, they can park in orbit, moor at the jump points, or dock at Midway Station and either shuttle down or take the tram. Shuttles weigh as little as a few tons and uses a lot less fuel than a 12000 tons ship with 1000 tons of cargo travelling to and from the jump point and fighting the planetary gravity well both ways.

The Laser Launched Light-Craft Facility makes Araxes more hospitable for traders, attracts more trade, creates local industry, and reduces the number of hulking unregulated nuclear reactors hurtling thru the atmosphere.

Most of what we made, we can construct from salvage or from other resources that are available to us.

Solar Moth/Solar Sail Hybrid

Let’s start with the dimensions of our base cargo-capsule. The light-craft unit, massing 23.3 kilograms is .92 meters high and a diameter of 2.4 meters. The outer hull weighs 119 kilograms, and has an outer diameter of 1.75 meters. The gross payload inside of the hull is 1666 kilograms.

To get to orbit, that gross payload will have to be reduced by 138.75 kilograms which will be consumed with water as reaction mass, leaving 1527.25 kilograms in adjusted gross payload. That took 245 painful (4-Gs) seconds, and the capsule is now in a comfortable orbit at 902.85 kilometers altitude, cruising at a brisk 7400 m/s.

We are going to further reduce that adjusted gross payload by a further 100 kilograms by including The Solar-Moth. The Solar-Moth is a humble but efficient 100 kilogram inflatable reflector, too fragile for atmosphere, but fine now that we are in Low Planetary Orbit (LPO). While you could use the solar sail or solar moth as low as 100 kilometers, errors will be high, 900 kilometers is the safe zone to use the solar moth or a solar sail within probable error.

The Solar-Moth reflects the rays of the sun to the same place that formerly, the laser launcher aimed at. The actual Solar-Moth refers to the 1.75-meter diameter aluminum-coated reflector that concentrates solar radiation onto a window chamber hoop boiler, heating and expanding the propellant through a regeneratively-cooled hoop nozzle. It sounds fancier than it is, a journeyman plumber can build it. The concentrating mirror is one half of a giant inflatable balloon, the other half is transparent (so it has an attractive low mass). Total mass 100 kilograms.

The efficiency of converting the power of the sun to kinetic energy is pretty low, only 63%, efficiencies up to 87% are possible, but at a greater extra cost or greater mass, the numbers didn’t work well. This is a cost benefit analysis not performance optimization. This is build for cost effectiveness, not showing off high performance.

We have to calculate the Beam Power differently than when we used the laser launcher. The solar constant at is 1360.8 watts/m^2. That calculates out to 32.7 MegaWatts instead of the 700 Megawatts with the Laser Launcher. This reduces by a factor of 4 for every doubling of distance from the sun.

<THE MATH, feel free to skip, school habit to show your work>

Δv = sqrt((2 * Bp * Bε) / mDot) * ln[R]

R = e(Δv/sqrt((2 * Bp * Bε) / mDot)

Δv is the change in velocity

Bp is the Beam Power (Now 32.7 Megawatts instead of 700 Megawatts with the Laser Launcher)

Bε is the efficiency which the engine converts the beam power to kinetic energy, in this case 63%

MDot is the Mass flow in kilograms per second, in this case about .44 kilograms per second.

R is the Mass Ratio, Initial Mass divided by Final Mass. The final mass is the mass of the ship after the fuel and reaction mass has been used up.

<END HEAVY MATH, you may resume breathing normally now>

The escape velocity using the Laser Launcher was 9980 m/s. In the case of the Solar-Moth reflectors, we are going to use that as our starting velocity. If we did not use the Solar-Moth, the cargo capsule would arrive at the near approach distance of 0.5 AU in 87 days.

Using a sister of the Laser Launcher, we would reserve an additional 50 kilograms of reaction mass, I am going to use that number to figure out how much faster we can get using the Solar-Moth. Using the solar moth, and not needing the sister Laser Launcher to slow down, the Cargo-Capsule can get to our target 0.5 AU in 44 days instead of 87. It sacrifices the same 50 kilograms it would have to anyway to slow down. The net reduction in cargo is 100 kilograms for the actual Solar-Moth reflectors.

That is 1510.5 kilograms to go 0.5 AU in 44 days, without needed a second laser launcher, nor any additional energy inputs. Nearly half the time for sacrificing only 6.7% from the net cargo, for the same energy input. The Solar-Moth cannot be used for atmospheric entry, it is too delicate. Assume this is surface-to-orbit (and orbit to surface) using the Laser Launcher and the orbit to jump point or orbit to orbit using the Solar-Moth. The moth and cargo capsule is reusable.

I include that for completeness, I am actually only proposing this for getting cargo and supplies to Midway Station.

The Solar-Moth can be used for the orbit to jump point deceleration. Ramping up the Mass Flow, but reducing the actual reaction mass to only 50 kilograms, we can decelerate the Cargo-Capsule in about the 100 diameters, 637,500 kilometers. It will take 39 hours, but it will cost no additional energy, it is unmanned and only reduced the net cargo by 150 kilograms. So now it takes 39 hours to get the Cargo Capsule to the Jump-Point, delivering 1510.5 kilograms to the jump-point from the surface using the Laser Launcher. The Cargo Capsule with the Solar-Moth can be used for the return trip from the Jump-Point to orbital capture using just the Solar-Moth and no additional energy inputs, just an additional 50 kilograms of reaction mass; pump the bilge.

As is, the Solar-Moth enabled Cargo-Capsule is really economical and easy to use for orbit to jump-point and for orbit to orbit of 0.5 AU. The Solar-Moth can be built with the same processes used to make mylar balloons, it is not especially advanced technology.

Reducing net Cargo by 50 kilograms, the Cargo Capsule can go 0.5 AU in 44 days, net cargo 1510.5 kilograms

Reducing net Cargo by 100 kilograms, the Cargo Capsule can go 0.5 AU in 36.2 days, net cargo 1460.5 kilograms

Reducing net Cargo by 200 kilograms, the Cargo Capsule can go 0.5 AU in 29 days, net cargo 1360.5 kilograms

Reducing net Cargo by 300 kilograms, the Cargo Capsule can go 0.5 AU in 25.3 days, net cargo 1260.5 kilograms

Reducing net Cargo by 400 kilograms, the Cargo Capsule can go 0.5 AU in 22.7 days, net cargo 1160.5 kilograms

Reducing net Cargo by 560.5 kilograms, the Cargo Capsule can go 0.5 AU in 19.7 days, net cargo 1000 kilograms

If all you had in the Cargo-Capsule was reaction mass and for some reason wanted to deliver an empty Cargo-Capsule to 0.5 AU, it could arrive in 9.7 days.

44 days is marginally plausible for passenger travel, if you can figure out the life-support and other sundries and equipment you would need for 44 days and keep it and the passenger under 1.5 tons. This is way below low-berth travel. 1 ton for 19.7 days sounds a bit tight to me, but I will figure that out another day. The hull interior is only 343 cubic feet (10 cubic meters) and only 59 square feet (5.5 square meters) of floor space (barely larger than a prison cell), it would barely fit the stasis chamber and related equipment. The base hull interior is about 2.64 meters (8 foot, 8 inches) diameter and about 1.78 meters (5 foot 10 inches) high. You can fit 1.5 tons of cargo plus the reaction mass (remass) in there, but it is not a passenger cabin, except for maybe a stasis chamber. One of these cargo-capsules equals 0.7 displacement tonnage, but only 1.5 mass-tons.

The Solar Moth can be scaled up for larger ships, but the High Energy Laser Launcher is designed for figuring out the cheapest way to put cargo to orbit and possibly to the jump-point, or surface-to-orbit-to-orbit. The Solar-Moth as a passenger capable vessel (for the patient types), it is doable, but for orbit to orbit, not surface to orbit or orbit to surface operations. Nor is it suitable for far out in the solar system. If you really are the patient types, you can operate indefinitely in the Asteroid Belt, collecting reaction mass (remass) in the asteroid belt. Month in stasis, do a little work, month in stasis, do a little more work, etc. Invest in some solar coating to power systems, have some really good recycling. Sounds like the path to madness to me. But, like I said, doable.

From a dead start relative to the destination, the Solar moth can impart a delta-V of 6510m/s. That requires 931 kilograms (optimized amount) of reaction mass. Leaving only 635 kilograms of net cargo. That will get to 0.5 AU in about 133 days with no other assist. This is acceptable for moving ore from the asteroid belt to orbital capture.

When the Solar Moth is out of reaction mass, it is really a solar sail, so we can combine them. The maximum acceleration for the for the optimized solar moth delta V works out to 3m/s^2 for 2170 seconds (36 minutes and change). From there, it is a solar sail vehicle. Starting with a velocity of 6510 m/s, and a mass of 877.3 kilograms instead of 1808.3 kilograms. Twenty Seven days to deliver net 635 kilograms of cargo to 0.5 AU.

Overall, the solar sail is the most energy efficient, but that does not help you to get to orbital or escape velocity first. The best system seems to combine them.

I have to work out deceleration and if using the laser launcher to escape velocity is better than merely orbital velocity and then the solar moth then solar sail from there.

There are other supplemental systems, but would require more engineering and more infrastructure:

1: Railsled and Laser Launcher to a solar moth and solar sail to orbital capture or solar sail or laser launcher to decelerate. It is a very flexible system.

2. The Orbital Ascender Air Vehicle to bring mass to the Space Elevator to then be released either somewhere between orbital capture, geosynch or escape velocity altitudes, then solar moth and solar sail to orbital capture or solar sail or laser launcher to decelerate. Again, a very flexible system.

There are merits for both and no reason not to have both. In this, I am mostly addressing issues related to the quickest, simplest and least expensive surface to orbit, and surface to escape.

For orbit to orbit, solar sails by themselves are pretty energy efficient by themselves. A small boost from an orbital laser launcher is a convenience, but not an energy saver. The Solar Moth is still valuable for being able to steer the capsule more effectively.

Another aspect of the solar moth versus the solar sail is direction. The solar sail is somewhat monodirectional for maximum acceleration, about a third net having to tack against the solar wind. The Solar Moth however, is not diminished by direction, but requires reaction mass. It might be wise to save some reaction mass for steering.

One of the things I was working on was alternate materials for solar sails. At a certain stage, materials became an issue. Reducing the solar moth thickness from 300 millimeters to less than 20 millimeters (7 kilograms), there becomes material degradation from heating. Also, the solar moth reflector at 300 millimeters (100 kilograms) can withstand as close as 0.25AU from the sun, but the 20 millimeters (7 kilograms) thickness version cannot get much closer than 1 AU without strain. It also means that it would not have much tolerance for solar variance, say from solar storms, heliospheric current sheets, flares, solar ejecta, etc.

I am going to stick with the 300 millimeter (100 kilogram) solar moth model for now. There is an aluminium lattice that will be substantially less susceptible to tearing, and we should assume that, but I think we need to keep the net mass for heating purposes. The lattice setup is also optimal for cooling, we can circulate the reaction mass to cool the lattice.

The construction costs for the High Energy Laser Launcher is not substantial. 20% efficient Carbon Dioxide Lasers can be constructed with locally available materials, infrastructure and labour. A basic proof of concept gas laser can be constructed from materials available at a neon lighbulb factory, it is less advanced than it sounds.

Instead of building a giant 700 megawatt laser, which has technical issues of its own, we frequently propose a steerable array of somewhere between 70,000 10-kilowatt laser emitters and sometime even 700,000 1-kilowatt laser element emitter array, which allows for very fine steering of the light-craft. We are building this to move thru air to boil water, not to penetrate armor, so we don’t need massive high megawatts of power, just total net energy output.

If we really wanted to do this on the cheap, we could salvage starship lasers which no longer meet combat technical standards. We mostly just need the emitters.

A basic ship mounted combat grade pulse laser is about 700 megawatts, takes up only 14 cubic meters and costs half a million credits, less if we buy used or get lucky with salvage.

The light-craft itself is composed of two modular units which can be cast locally out of aluminium, even recycled.

If we salvage a fuel scoop and fuel processor, we can filter wastewater, marshwater or saltwater for combustible hydrogen for the laser and deuterium (refined hydrogen) to sell. Otherwise, a full scale fuel scoop costs about a million credits and the fuel processor costs about 50,000 credits. Depending on the labour, infrastructure and distribution setup, that could pay for itself in the first few thousand tons of deuterium (refined hydrogen) sold.

We are recommending solar to gather the power we need. Instead of the batteries, we would use the power to crack the water into combustible hydrogen which we would burn for the power plant to power the lasers for power on demand. We would use the graphene sieve (the real name for the hydrogen refining processor) to filter the deuterium (refined hydrogen) from the combustible hydrogen. The deuterium (refined hydrogen) and oxygen we can liquefy and send as fuel and air replenishment for ships arriving at the jump point and at Midway Station. It can however transport up to 22 tons per hour of operation at a fraction of the cost of a surface to orbit spaceship.

While this setup is great for small scale cargo, especially delivering liquefied fuel and air and other sundries, it is not suitable at this scale for large cargo containers (the standard 14 cubic meters or standard 15.625 cubic meters), it is designed for roughly 1 cubic meter, and if not cube shaped, up to 2 cubic meters if can fit into a half sphere.

Picking up fuel at the gas giants conservative adds between 1000 to 1500 credits per ton to the cost of the fuel. Which means fuel will be 3 to 4 times more expensive than traders are used to. It would be cheaper for larger ships to bring their own fuel with them, but either way that cuts into their profits and reduces how much net cargo they can bring. Making the fuel on the surface and launching to jump point and Midway Station means the traders do not have to bring excess fuel for the return trip nor take extra time to find, scoop and process fuel for themselves. This means they can bring more trade goods and have lower costs.

This saves visiting ships a great deal, instead of taking their entire ship to the surface, they can moor at the jump points or lagrangian point dock at Midway Station and either shuttle down or take the tram. Shuttles weigh as little as a couple tons and use a lot less fuel than a 7000 tonnage ship and 1000 tons of cargo travelling to and from the jump point and fighting the gravity well both ways.

The Laser Launched Light-Craft Facility makes Araxes more hospitable for traders, attracts more trade, creates local industry, and reduces the number of hulking unregulated nuclear reactors hurtling thru the atmosphere.

Most of what we are proposing we can construct from salvage or from other facilities we have available on hand, we mostly wish only the permits to construct and operate and suggestion for a location which is convenient for trade goods to be brought to launch and a conveniently located site for the solar farm and hydrolysis facility.

The Delta V required to launch a mass to Low Terrestrial Orbit (LEO, 50 Kilometers Altitude) is 7800 m/s.

From Low Terrestrial Orbit (LEO) to Terrestrial Geostationary Transfer Orbit (EGTO) is another 2600 m/s Delta-V.

From Low Terrestrial Orbit (LEO) to Terrestrial Geosynchronous Orbit (GEO) is another 3800 m/s Delta-V.

From Low Terrestrial Orbit (LEO) to the L4 or L5 Lagrangian Points is another 4100 m/s Delta-V.

From L4/L5 to Lunar orbits is 700 m/s Delta-V.

From Terrestrial Geostationary Transfer Orbit (GTO) to Lunar orbit is 1600 m/s Delta-V.

From Lunar Orbit to the Moon is 1600 m/s Delta-V.

Using a Midbulk Firefly as my reference using a fairly standard fusion reactor, I get a fuel cost of about 8 times that of the Laser Launcher. I have not priced out what a Firefly should reasonably cost, so I am not including amortization, maintenance, repair and depreciation, just comparing fuel costs.

Without grinding the specific numbers, it is obvious. The transport holds about 150 tons of cargo. To accelerate that payload to Low Terrestrial Orbit, you also have to accelerate 160 tons of the ship itself and 180 tons of fuel. Essentially 541 Gigajoules of Energy per kilogram of cargo.

The Laser Launched Lightcraft has a minimum 150 kilogram hull, no engine, and no fuel, maybe 100 kilograms of water propellant. The energy for liftoff and Delta-V is provided by a ground based laser. About 70 Gigajoules of Energy per kilogram of cargo.

The transport has 10 times more mass carried in the way of the hull, engine and fuel per unit mass of payload than the lightcraft. These cost of these things also has to be paid for and things like the hull and engine have to be maintained and repaired at great cost, even if you amortize the cost.

It is not to say that lightbulk cargo transports are not useful, just that they are not optimal for this purpose.

The Hybrid Stratocraft and the Laser Launched Lightcraft might seem quaintly primitive and retro technologies, but they are huge energy savers, by an order of magnitude. While the price of the energy is not a big deal, it does make the difference between the noontime temperature being 120 and 130. Energy=Heat.

The Laser Lightcraft launching 20 tons of payload to low planetary orbit uses about the same amount of energy as an 18 Wheeler Tractor Trailer hauling 20 tons of cargo for 4 hours at highway speeds. The Stratocraft uses about the same energy as that same big semi but for 10 hours instead of 4.

The solar moth as a near space orbital vehicle

Water has good volumetric expansion as a propellant. The Exhaust Velocity of the Water propellant solar moth is 9000 metres/second, which is impressive. 9000 metres/second is based upon a solar constant of radiation at orbit of about 1360 watts per square metre, which is pretty uniform around the daylight side of our orbital space.

The Solar Moth itself is very lightweight, the mass of the boiler and the reflectors is only 100 kilograms.

The hull of lightcraft, which is only 150 kilograms.

The efficiency of the mirrors is about 65%, although when fancy new they are probably about 85%.

The net reflective surface of the mirrors is about 6000 square metres. Given the solar constant and mirror efficiency, it is a hearty 5 megawatts of power.

Math math math, the thrust to weight ratio of our solar moth is an impressive 4Gs of acceleration empty.

Once we include the mass of the lightcraft, the propellant (water), and the payload (pilot and sundries), the thrust to weight ratio is still a very practical 1G of acceleration.

Tsilikovsky’s rocket equation, math math math, Exhaust velocity times the natural logarithm of the mass ratio, the Delta V (added velocity) of our near orbit solar moth is an not unimpressive 4230 metres per second as the top speed assuming you do not use the propellant to slow down, otherwise half that.

Net result, a brisk and zippy 1 G of acceleration and 4230 m/s of delta-v to work with. That is certainly more than adequate for most mid orbit operation.

You can only really unfurl the solar moth reflectors at an altitude of 1500 kilometres. Below that, you will have to be dependent upon laser launchers boosting directly on your underside. I rated my laser launch system for 1 megawatt, but it would take 8 times that to have the same power as the sun in solar moth mode. 8 megawatts would severely strain the lightcraft’s ability to cool itself. The lightcraft is designed to work in that mode while flying thru the atmosphere, which provides the necessary cooling, in orbital space, that atmospheric cooling is not available. Although the expelling of propellant does move the excess heat away from the craft. Thus, while less than 1500 kilometres, the craft has a lower delta-v.

I enjoy the peaceful sailing than the roar of a rocketship, but maybe more like a racing sailboat with an impressive acceleration and delta-v.