Idobox

For insulation: Wood looks cool, but is very heavy. If you want insulation inside the pressurized capsule, plant fibers or even wool might be a better solution. Astronauts wearing furs! But really, having a second layer outside with a vacuum in between (easy in space), is technically the best option, and completely possible with Victorian technology and science. I assumed you were talking of orbit, and thus didn't talk about life support (if the flight is short enough, you don't need it). We already talked about temperature. Food and water are not particularly difficult to store for a week or two, it leaves us mostly with atmosphere. CO2 is known since the XVII century, and had already been liquefied and frozen by the early 1800s. I'm not sure how well its chemistry was known in the era, but activated charcoal or concentrated caustic soda solutions can be use as scrubbers. I'm sure there are plenty of other simple reactions that could be used. That leaves us with oxygen. Commercial production of liquid oxygen started in 1895 in the real world, so a simple vat is an acceptable option. Peroxyde has already been proposed, but it is unstable and liquid, and also likely expensive with steampunk technology. Modern oxygen generators often use sodium chlorate, which turns into salt and oxygen when heated above 300°C, and was industrially produced in 1892, although I'm not sure they were aware of the oxygen production properties by then.

You can use RF two ways to do that. The cheap way is to use measure power: Put an emitter on the person, for example a phone with bluetooth, put a receptor on the drone, measure power, which is proportional to 1/r², get distance. With off the shelf components, the signal might too powerful at this kind of range to be measured accurately, and require an attenuator (can be done with resistors). With two or more receptors, you'll know in what direction to move, with one, you will to "wiggle" to find out. A variant is to use a RFID reader and passive tags, and measure RSSI (return signal strength intensity). You would have to use UHF, 2.4GHz or higher, because lower frequencies use magnetic coupling, which for a number of reasons, would be a nightmare to use on a drone (think contactless cards or NFC phones). The advantage over the previous is that passive tags are pretty much just stickers, which might be handier than a active radio source. The issue is that it would be more expensive, and not all RFID readers have RSSI. The second option, which is a bit more complex, is to measure phase, ie time of flight. To do that, the easiest way is to put an emitter on the drone (let's say 13.56MHz, free frequency) and a frequency doubler on the target (can be as simple as a diode with an antenna). You then measure the phase difference (can be done with a XOR gate) between the 27.12MHz signal that rebounds from the target to one you generate on board of the drone (using a diode again). At 27.12MHz, the wavelength is about 10m, so if you get a phase difference of 2*pi/10, it means the signal traveled 10m/10 = 1m, and since the signal traveled form the drone to the target and then back, the distance is 0.5m. The first solution is simpler, but a lot less accurate. Antennas don't transmit with the same strength in all directions, so if you tilt the drone or the beacon, the system will detect a change in distance even if it doesn't happen. Also, as the components heat up, the calibration will change a little bit, and cause a small error. The second solution is a lot more accurate, but a little bit more technical. Calibration isn't much of an issue: you are comparing two signals coming from the same source, so you only need a stable frequency source, which costs a few $.

Nitrocellulose was invented in 1862, so definitely fits the steampunk theme, and is an actual rocket propellant. The sprint antimissiles are fueled by nitrocellulose with zirconium layers (that one isn't very steampunk) and gellified nitroglycerine, and accelerates at 100g. SRB is the steampunk way of doing rockets. Guns, despite what Verne wrote, can't work with that technology. Ram accelerators and multi-charge guns are an actual option today, but the technology is more dieselpunk/atompunk. Hybrid or liquid fuel rockets without turbopumps are a decent option for circularisation and other orbital maneuvers, with their good isp and low TWR. Cold gas RCS and gyroscopes are also available technologies. A story about a space race between Great Britain and France in Victorian times (I can't think of any other power willing to invest the absurd sums required at the time, but if you feel like adding USA, Russia or Austria, it's your choice) would be amazingly enjoyable. Fighting in the colonies to get suitable launch sites, oversized steam boats carrying giant SRBs, engineers devising mechanical "flight computers" to keep the rocket pointing the right way, discovering hypersonic aerodynamics, reentry heat, cosmic rays, that natural rubber is crap in a vacuum, that copper and glass don't like 400°c thermal cycles, etc... I imagine it could start with single stage suborbital rockets with simple aerodynamic stabilization could be used in the beginning, with mechanical scientific tools on board, like pressure and temperature loggers. Steel would be the material of choice for most of the rocket. Explosive bolts and electric systems might be possible, but coolness requires hydraulic or wire systems for the control surfaces and stage separation. In particular, for the stages, I imagine two concentric rings, with a number of cylinders in the radial direction, a bit like the big bank safe doors. Once shock heating is discovered, transpiration cooling using water would probably be one of the first proposed ideas. Ablative heatshields could also be made of a variety of low tech materials, including cork or leather. Thermal amplitude and airtightness would be trickier. Dewars were invented in 1892, and are a very good option for insulation. They would just require one airtight capsule surrounded by a thin metallic shell and a few spacers between the two. The lower tech option is to increase thermal inertia, IE bring a big chunk of ice. The best material for the capsule would be metal, since they knew how to make boilers. Riveted steel sheet would be a material of choice, but copper or brass might be viable options. For joints, I would have them use resin or asphalt first, before discovering they're crap for space, and moving to soft metals like lead or tin, and designing the capsule so that internal pressure keeps the joints tight. And also, I'd expect a few catastrophic failures before they give up on glass windows, and even doors.

Although proper stealth would be almost impossible, decoys and blinding could be rather easy. The whole argument is that hiding your IR signature is almost impossible, unless you're actually a rock, and even then, you might be detected. But launching a few hundred very hot but small decoys would be a viable strategy. The enemy would know you're up to something, but they would have a lot of trouble identifying the actual target. Of course, unless you're very close, they will also have lot of time to find out which one is the relevant target, and also send a counter-attack weeks, months or even years before you reach them. The other option is to blind their detectors. A focused beam of strong IRs targeted at your enemy's bases would blind its telescopes while you do your burn. If you can emit it continuously, or at least quite frequently, they couldn't know when you did your burn, or even if one happened. The weaponized version of that uses a stronger IR beam, possibly pulsed, to deplete the coolant used on their telescopes, rendering them unusable. The blinding solution of course works only for burns close to your emitter, logically close to your planet/base or main fleet. You will still need to find a way to hide your waste heat during the actual transfer. The only type of mission it would make sense for would be spying/infiltration. For actual warfare, shooting first from far away would be a safer option, especially if you have access to lasers, particle beams or relativistic projectiles (basically weapons that give only seconds or minutes between the moment firing is detected by the target, and the moment the target is rendered unable to detect anything ever again, even less retaliate).

Let me develop on that. The limit on how much energy you can store in a capacitor is the breakdown voltage, where the insulator stops insulating, and you get a nice spark usually accompanied by smoke. This breakdown voltage is a function of insulator material and thickness. If you use a thicker insulator, you get a higher breakdown voltage, but also a lower capacitance. in the end, the quantity of energy you can store is proportional to the volume of insulator used. As said, superinsulators will leak less, but keeping a capacitor charged for hours is already possible. What you want for better capacitors are materials with very high breakdown voltages.

I don't think so. Friction of the projectile with the rails is probably more significant than air resistance at those speeds. Given the time scales, an ion engine would be much better. You could also imagine putting solar sails. They might have terrible TWR, but you could use mass from phobos to build them, and over thousands of years, they'll provide a significant deltaV.

A nuclear ramjet/NERVA wouldn't be ideal on Earth, for the same reason air-augmented rockets are not used: the air breathing part of the flight would be quite short, and wouldn't justify the extra-weight. Plus all the issues with nukes. Now, for a Venus or Titan probe, it's a completely different story. You could use the NERVA for the transfer and different orbital manoeuvres, then aerobrake, use the jet mode in the atmosphere to go around, land and take off again. Because the atmosphere on Venus is so thick, you get to use the jet mode a lot longer than on Earth.

I'm pretty sure AAR and solid fuel ramjets (not that different) are used on air to air missiles. That's because they stay in places where the atmosphere is thick, and don't try to go anywhere near orbital speed. I can see them being used on SRB. Of course, TWR is very important for a SRB, more than ISP, but it could make sense to use it for the first minute or so.

If you use a flat enough reentry angle, and have enough drag, the impact velocity will be the same you would get from dropping it by plane. For a skydiver, terminal velocity is about 200km/h, a cake delivery package could easily be around 100km/h or less. If we assume the max deceleration a cake can survive is about 10g (imagine putting 15kg on top of it), and terminal velocity is 30m/s, it would take about 5m to brake. That's far too much to use bubble wrap or equivalent, but some kind of long air piston could probably do it.

I don't think you can call urine an object, or say it's been manufactured. But there have been instances of astronauts building stuff out of other stuff, like commander Chris Hadfield showing space darts. I'm not sure when the first one happened, probably very early.

CO2 capture makes sense where there is a lot of it, in the exhaust of some factories or power plants. So, we agree on that point. Now, buying cement or steel from other countries is going to be very expensive. Also, if your politicians play that game, they won't either try capturing CO2, which would increase tax and energy costs, when they could just hope other countries will be greener.

You still need to pump hundreds or thousands of tons of air through your system to extract tons of CO2. And that's expensive, both in term of energy and money. Even if fossil fuel power plants are closed, you could still have biomass power plants and use the CO2 for algae farms. Also, cement and steel production are two of the largest CO2 emission sources, and will keep existing for a long time. But the first step we have to do is to cut our energy consumption. Stop driving cars, use good insulation, live in dense cities and you have solved 70% of the problem. Plant trees every where you can, and you have a massive and cheap carbon sink. Stop eating meat, especially beef, and you're almost there. Then, you can start thinking of how to produce the electricity you need. Trying large scale capture of CO2 before you have done all that is waste of resources, because you would have a larger impact for less cost with any of those.

On the contrary. Solid Oxide Fuel Cells have typical operating temperatures between 800-1000°C, molten carbonate fuel cells work at 650°C, so the 470°C superfluid CO2 would be an excellent cold sink for one. Actually, you could even slap a Peltier elements around the fuel cell to get a few more percent of efficiency. By the way, while looking for fuel cell operating temperatures, I found a bit (but not much) on carbon fuel cells. Apparently, you can use carbon or carbon rich materials in either SOFC and MCFC, which makes fuel storage much easier. I haven't checked, but it might be possible to use with other oxidizers than O2. And then, there's wind.

The temperature is less than 500°C. Sure it's hot, but not crazy hot, most parts of a well built probe can perfectly deal with that. Old dumb steel and copper can, many plastics can, glass can, ceramics won't even notice the difference. Transistors can be made to work at those temperatures, but it would be very difficult to dump heat, which is why I suggest thermionic devices for power applications. The only parts that really need cooling are microelectronics, and maybe some sensors. Keeping them cool with a heat pump is totally feasible. Lajoswinkler, are you suggesting a heat machine as the power source? RTGs, which are the only such power source used for probes, won't have a good efficiency, which is why I spent some time proposing other power sources that won't mind the temperature.

And that's the right approach for many problems, but there is very little CO2 in air, and lots of air, so you need a massive collecting area to do anything meaningful, and a cheap way to concentrate the CO2. And right now, harvesting biomass is the best option. Capturing CO2 straight out of the exhaust of power plants and other big emitters is also an option, and here, big centralized works. But of course, the first thing we have to do is to stop releasing so much CO2 in the atmosphere in the first place.

Believe it or not, plants work internally by chemical processes I think what he meant is that big, localized chemical plants are not the right way to tackle the problem. And until we can have mass produce cheap and small fischer process devices, and handle the logistics of collecting all the "waste", it will be much easier to use biomass. And yeah, harvesting plants and dumping them somewhere is a decent strategy to capture CO2. Harvesting algae might be even more efficient, especially in areas prone to blooms. Some people have also proposed using a LOT of wood in construction. An ideal solution would be to transform a large quantity of biomass into charcoal and dump it in old coal mines. Of course, it would only make sense if we stopped burning coal in the first place.

Doxygen difluoride is for wimps, real rocket scientists use chlorine trifluoride. For the fuel, I propose acetylene, it's not particularly toxic, but it should make a nice boom, and also melt whatever hasn't been eaten by the ClF3. Also, it would release copious amounts of CF4 (a potent greenhouse gas) and more importantly HF, one of the strongest acids around, and terribly dangerous to living things. I can't think of a single structural material that could be used for the chamber and bell, or for the launchpad, but it would be very interesting to watch from a distance, upwind. [EDIT] I've read about FOOF. My bad, ClF3 sounds very safe by comparison. Seriously, who in their right mind looked at the formula of peroxide and thought it was a good idea to replace the hydrogen with fluoride?

Actually, we could have Venus rovers with today's technology, only limited by power supply (probably very little sunlight at the bottom, and RTGs won't be very good there). So why doesn't anybody send some? It doesn't have to be as complex and expensive as curiosity. Also, there is supposedly a lot of wind on Venus, which given the density would be more comparable to strong water currents. I suppose wind power would be an option. I want windmill powered, PTFE coated titanium rovers on Venus.

Titanium, fused quartz glass and PTFE are perfectly good materials to build a Venus lander that would survive for years, no need for unobtainium. You keep the humans in orbit, and send a robotic probe down there. Structural parts will pose no problem, electronics might require some cooling, all power electronics can be done with vacuum tubes and will have no problem with the heat. For power, the best would probably to use fuel cells. Chemical batteries usually don't like high temperatures too much, RTGs get crappy efficiency in hot atmospheres, beta and alphavoltaics just don't have the power density. With today's technology, I would store fuel as metal hydride and for oxygen I would use a gas generator. The ISS uses lithium perchlorate that decomposes around 400°C, so that would be unsuitable, but there is more stable stuff. You could also imagine a fuel cell reacting with atmospheric CO2 or sulphuric acid (more reactive, a lot less concentrated). Even better, you could develop a aluminium/H2SO4 fuel cell on the model of air-metal batteries, using molten salt or something as the electrolyte. To deal with pressure, the best way would be to keep the bare minimum in a pressure vessel, and coat everything else in PTFE or metal fluoride: the pressure can't crush you if it is equalized, and superhot sulphuric acid is not the worst chemical we deal with on industrial scales. Electric motors could not use permanent magnets with the temperature, but once again, copper, titanium and PTFE and perfectly fine in these conditions, and PTFE is an excellent insulator, and also has extremely low friction coefficient, so you could have excellent induction or switched motors. The last issue is the many sensors. But once again, 500°C corrosive and high pressure atmosphere might sound like hell, but many industrial processes have it worse. And if you need some stuff that cannot be done to survive the conditions, you can always encase it and actively cool it.

When I read this, I imagined a ClF3 - LiAlH4 hybrid rocket, and my palms started to sweat. I would feel safer with a lit stick of dynamite. Also, think of the damage to the infrastructure is the thing blows up, and rockets tend to do that. More seriously, mass drivers are an actual option. Ram accelerators and light gas guns have accelerated stuff to orbital speeds in labs before, of course tiny projectiles only, but scaling them up is not that difficult (compared to building SLS or the ISS for example). In particular, a RAM accelerator is more or less a 2km long steel tube filled with an explosive mix of gas, a remarkably simple machine. Of course, the acceleration would be too high for humans or delicate instruments, but smart ammunition go through much worse, so small rockets, electronics, solar panels, antennas, optics, solar sails and inflatable structures could very well survive. Then you have the issue of traveling at 6 or 7km/s in the lower atmosphere. There is remarkably little data about this kind of things, and we can assume there will be loud bang, some serious negative g, and lot of compression heating. The deceleration would probably not be worse than the acceleration, and ablative heatshields could deal with the heat at the cost of mass fraction. The other exciting technology is momentum exchange tethers. Basically you have a station in LEO spinning a long tether. You grab ships on suborbital trajectories (for example one thrown from a mass driver) and release them at a higher velocity, putting them into orbit. By doing so, you slow down your station, so you need to compensate for the lost momentum. This can be done by putting high ISP thrusters, or by slowing down other stuff (stealing their momentum), for example by deorbiting satellites, or by catching and slowing down projectiles sent at very high velocities (from your mass driver). This one is a lot less ready, since we have little experience with long tethers in space (there are concerns about wear due to micro-collisions), and having a rendezvous and docking between a ship on a suborbital trajectory and the end of a fast moving, fast spinning tether would be quite hard. Docking is normally done with ships that are on the same orbit and still takes hours, here your objects would have very different trajectories, and you would have minutes, or maybe even seconds to do it. Still, it's a very exciting prospect.

The RD 180 is an excellent engine, but from what I understand, the main difficulty building them is with metallurgy. They use a LOx rich mix in the turbopump, which gives them their great performances, and that tends to set the metal parts on fire, which is bad. The Chinese will not just need the plans, they will need to be taught the metallurgy too.

About life on Titan, I'd like to point out that there appears to be something consuming hydrogen on the surface (the concentration drops too quickly when going lower in the atmosphere), and we have no idea what does it. There are no known catalysts that could do this at these temperatures, and life has been suggested. Because there are, of course, no signs of military tension between the USA, Russia and China for example. Seriously, not so long ago, both the US and China played at shooting down satellites to show they can, there is east Ukraine, the south China sea tensions, the sea of Japan tensions, US support to Taiwan, arguing about Libya, Syria and Iran. We need the outer space treaty.

Lasers are very inefficient light sources, and monochromatic, so you'll need at least three to get colour pictures, and a way to "fuse" them, maybe switching from one to another very fast? Expensive video-projectors use 3 optics with DLPs (tiny moving mirrors for each pixel), one for each colour, so that would be easier to adapt with lasers. That being said, using larger lenses would give you equivalent results. Finally, what's the point of projecting a small image to such ranges? Because if you want a very large screen very far away, you just need a more powerful lamp and conventional optics.

There's something everybody overlooked about contamination: If something can survive the sterilization process and the trip to Europe, it could very well survive being ejected from the atmosphere by a meteor impact. Sure, it doesn't happen very often that rocks from one planet en up on one other, but we have several Mars rocks on Earth, so it does happen. It means there must Earth rocks all over the solar system, carrying extremophiles, and some of them have already crashed on Europa. True, most of them will take a lot more than 10 years to get there, since they will require some gravity assist to get the deltaV, but that doesn't sound terribly harsher than what stowaways on a Europa probe would face. Beyond that, I love the idea of a sealed probe that is scorched to insane temperatures. You could also use strong oxidizers like chlorine trifluoride to really be sure.

I just checked the wiki on the gazelle and sprint to try to find out how the hell they managed this kind of acceleration and deltaV. Not a lot of info on the gazelle, but for the sprint they say : "The first stage, Hercules X-265 engine, is believed to have contained alternating layers of zirconium "staples" embedded in nitrocellulose powder, followed by gelatinizing with nitroglycerine, thus forming a higher thrust double-base powder." Nitrocellulose mixed with nitroglycerine is known as smokeless powder, and is the most common type of propellant for guns, from hand guns to naval artillery. And they added zirconium, I suppose because aluminium was not reactive enough. This rocket is pretty much a big bullet with the propellant exploding slowly.