The first product of asteroid mining is likely to be rocket fuel. Some asteroids (the carbonaceous type) contain up to 20% water and carbon compounds. This can be processed to Oxygen + Hydrocarbons, which is a common high-thrust rocket fuel. The lifetime mass return ratio of an asteroid tug is ~350:1, and if 20% is usable fuel, then you gain 70:1 just on that one product. Extracting water and carbon compounds only requires kitchen oven level heat, which is easy to do by concentrating sunlight.
There are lots of other products we can potentially extract from asteroids, but that's the easiest and most useful, since most anything you do in space needs some fuel to get where you want to go.
Asteroids did have geological processes, just different ones. The "metallic" type come from protoplanets which melted internally from radioactive decay early in their history. The iron and iron-loving elements sank to the core because they are the densest. Later collisions broke up the protoplanets, exposing their cores. The metallics are a high percentage of iron, nickel, cobalt, and a few other elements. The "stony-irons" come from regions that didn't fully separate the core and rocky layers. They range from low to high percentage iron, with the remainder being rock.
The other process that happened is thermal. Depending how far from the Sun a given asteroid first formed, and later orbit history, certain compounds condensed or not, and then could be baked. Probably the most significant difference is due to the "frost line", the distance at which water ice can remain solid in a vacuum. It happens to be right in the middle of the Asteroid Belt, where Ceres is. Objects beyond that distance tend to have a lot of water. Anything closer tends to have little water, though it can contain "hydrated minerals", where the water is chemically bound.
We actually know quite a bit about the composition of asteroids. Nature delivers samples to Earth in the form of meteorites. We can compare the spectra of meteorites to those from asteroids we get through telescopes, and infer what they are made of. We have flown past or orbited several asteroids, most notably the Dawn mission to Vesta and now Ceres, two of the largest asteroids. Spacecraft carry a larger variety of instruments and can do a better job of telling what the asteroids are made of.
As far as materials processing, we can design machines based on meteorite samples, or simulated samples, since meteorites are rare and valuable. If the Asteroid Redirect Mission that NASA wants to do happens, we would have a sizable boulder to experiment with. After taking science samples, they could try various processing methods on an actual piece of asteroid rock, in zero-g. I don't think we can design serious production units without a a few rounds of trying it on a small scale. For that, we would need at least a small asteroid tug that fetches back chunks from different asteroid types, so we have enough raw materials to experiment on. Most known asteroids are too big to move whole. A 30 meter one is anywhere from 18,000 to 90,000 tons. So for early space mining, we are talking about scraping loose stuff off their surfaces, or grabbing boulders.
my email is the same as my user name here, but lowercase, and add (at)gmail. Feel free to contact me if you want more information. I can point you at sources I have, or send you stuff directly.
So do solar panels. The difference is a rectenna array generates 300 W/m^2 for 24 hours a day, while solar panels generate about 200 W/m^2 from 4-6 hours a day in most decent locations. In crappy locations for solar (Seattle, Germany), the energy per land area is *way* higher for space beamed power.
If a consortium of university libraries demanded open access, the publishers would have to agree. Those libraries are generally the ones who pay for subscriptions.
That's because it doesn't have tilt resistance. On a skateboard with wheels, when you lean, the wheels on that side are compressed, and push back on your feet. The hoverboard doesn't have a restoring force when you tilt it, so you fall over. What they need are two parallel coils, spaced about a foot or more apart, so they have some tilt resistance. What they have now is like a skateboard where all 4 wheels are in a single line.
We just have to punish corporate management as the responsible people when a corporation commits a criminal offense. They would straighten up pretty quick if that happened. Commit mortgage security fraud on a vast scale (Bank of America)? Not just a fine, but all the top people responsible go to jail, for committing fraud.
That's not correct. *Control* of multinationals is by a core of banks and investment houses ( http://arxiv.org/abs/1107.5728 ), which for shorthand we can call "Wall Street". A number of them are based outside the U.S., but pretty much all have an office in the Wall Street area. *Ownership* is distributed more widely. For example, I used to work for Boeing, and I'm vested in their retirement fund. Theoretically the fund holds the assets in trust for the retirees, who are the beneficial owners. The control of the funds, however, is in the hands of whatever fund manager Boeing has hired, which is typically one of the big Wall Street companies. Since the fund assets are over $20 billion, the fund manager has a lot of influence with the various companies whose shares they hold. I have none.
The separation of ownership and control is the trick by which Wall Street exerts undue influence. And they don't even have to collude to get their way. Everyone on Wall Street has the same goal: maximize profits at all costs. So they all use their influence in the same direction to get their way, whether lowering the capital gains tax, extending copyright, etc.
> Bitcoin has no similar intrinsic value that isn't easily copied (and possibly improved upon) by any number of altcoins.
What you are calling "intrinsic value" is more correctly "utility value", the value we put on things for their usefulness. However, it is not an intrinsic property of an object. A gallon of water in the desert when you are thirsty is worth much more than a gallon of water to take a shower at home, when you have it supplied by a water utility at low cost. Both gallons are useful, and people are willing to pay for them, but different amounts.
In the case of bitcoin, it is the Bitcoin Network which gives it usefulness. Without the network, you cannot make transactions, and thus any coins you have are useless (you can't send them to anyone, and thus can't buy anything with them). Bitcoin has by far the largest network of it's kind. It consists not just of the relay nodes that forward transactions, but custom hardware, software applications, merchants who accept it, and users. That network isn't easily copied, it has to grow over time.
With the network, I can pay a programmer in Kiev from Atlanta easily, cheaply, and quickly. That's a pretty useful thing. I can also make payment contingent on a software script written into the transaction, because bitcoin was designed with a scripting language. I cam make my money programmable. That's a whole new useful feature.
Like many other networks, bitcoin responds to Metcalfe's Law. The more people who use it, the more valuable the network becomes. This is also true of fiat currency networks. Lots and lots of people use the US dollar. The dollar is thus highly useful, because you can spend it on lots of things in lots of places. Try spending a Zimbabwean Dollar anywhere, even in Zimbabwe. It experienced 10^25 inflation, and now nobody wants it. So if you have a stack of them, they are useless, except as a collector's item. Even though they were issued by a government, the size of the network that uses the currency trumps that.
> The fishy part has always been that the theft occurred from offline, "cold storage" wallets,
According to a Reddit AMA today from a former Mt. Gox employee (he had kept silent until the arrest, because his testimony was part of the investigation), there were no cold storage wallets. It was total amateur hour on Karpeles' part: no proper security, no proper accounting, customer funds used for business and personal expenses, etc. The likely situation is the "missing" bitcoins never actually existed. Customer accounts were credited with fake coins to cover the fact that their funds were being used for other things. Eventually customer demands for cash or sending out their bitcoins elsewhere could not be met, and they declared bankruptcy.
History of technology is an interest of mine. Pottery is at least 10,000 years old, Wheels about 4,000. The main reason pottery is so old is obviousness. Build a cooking firepit on clay soil, and you just invented pottery. You only have to notice the bowl holds water the next time it rains. From there, it is a short step to doing it on purpose: http://usscouts.org/scoutcraft...
Beamed power for space launch has been discussed for decades - I have several ring binders of data on the subject. Practical depends a lot on your power storage. Space launch of anything larger than a teacup takes a lot of power. For example, the three liquid engines on the Space Shuttle put out a combined 21 GigaWatts of power, of which 156 MegaWatts was just to run the turbopumps to shove the propellants into the main combustion chamber (the turbopumps had their own combustion system to power themselves).
So this launch system seems to have batteries between the power grid and the microwave generators. That makes sense, because you can't suck GigaWatts on demand off conventional grids. Batteries have been improving in cost and performance pretty well recently, so that may have put it in a practical range. I wonder, though, if on-demand turbogenerators might not be cheaper.
The other parts of the system: heat exchanger, phased array, high power microwave amplifiers, are relatively straightforward, you just need a lot of them. What I wonder about is traffic model. High power launch systems like this cost a lot to build. If you only use them a few times a year, that investment has to spread over relatively few launches. You really want to use them a lot, like daily or hourly. But where is the traffic going to space to fill that much capacity?
All rockets heat a propellant, then expand it from a chamber and nozzle to maximize thrust. Conventional rocket heat the propellant by combustion of the propellant itself. But if you have an external energy source, you can heat it that way instead. In this case, the energy source is a microwave beam, and the propellant is Hydrogen gas. Engines like the SpaceX Merlin have exhaust products of CO2 and water, since their propellents are kerosine and oxygen. These have high molecular weights, much higher than for Hydrogen. Lower molecular weight gases have a higher speed of sound at the same temperature. Therefore their exhaust velocity in a nozzle can be higher, and you get more thrust per kg of gas.
This has been known for a long time, the physics of gas expansion are well known. To make a workable space launcher, you need enough MW of microwave energy, accurate focusing and tracking, and a really efficient and lightweight absorber on the vehicle. Power requirements for space launch are surprisingly large. For example, the Space Shuttle carried three liquid engines, which produced 7 GW of exhaust power each. Something that may have made this concept workable is high power, reasonable cost batteries. Gigawatt power levels are more than most electric grids can deliver. So a way to store it up and release in a short time is very helpful. Traditional rockets did it with very big propellant tanks and enormously powerful (70,000 Horsepower) turbopumps to shove the propellants into the engine fast enough.
Launch to orbit is a high energy proposition. Conventional rockets add 50 kW of kinetic energy to each kilogram of payload for 600 seconds. The Tesla Model S car consumes 20 kW for the whole car at highway speed.
You can't troll someone who spent a career in aerospace, and has written a book on space systems engineering [ http://en.wikibooks.org/wiki/S... ] when it comes to space systems design. You especially can't troll me when you are an anonymous coward, and I have the same user name here as on Wikibooks, and can thus prove I wrote that book. Now go away, or I shall taunt you a second time.
> The problem with orbital mining is that it depends on the presence of orbital manufacturing.
I'm sorry, but that's a very confused statement. It is quite possible to build a space tug that mines rock from an asteroid, and delivers it to another orbit where it is needed. If the need is for radiation shielding, then no manufacturing steps are required. The more general flow of industry goes:
Extraction -> Raw Materials Processing -> Ready to Use Materials -> Parts Fabrication -> Assembly
Using steel as an example, iron ore, coal, and limestone are extracted at their respective mines. They are combined in a blast furnace to process them into iron. The iron is further processed into a particular alloy of steel, in a useful shape (sheet, bar, rod, etc). This is the ready to use material. The steel is fed to machine tools to make finished parts, which are then assembled into some kind of machine, like a car engine.
Parts fabrication and assembly are together called manufacturing, but they are not necessary if your space product is usable as a material. For example, some asteroids contain hydrated minerals. If you heat them to 200-400C, the hydrates will decompose to water + a different mineral. The water can then be used as water by human crew, or further processed to oxygen and hydrogen by electrolysis for rocket fuel. The dehydration furnace and electrolysis units can come from Earth, ready to use. In fact, the Space Shuttle used the reverse process in a fuel cell, combining H2 and O2 to make water and electricity.
Shielding, water, and fuel are commonly needed items in space, so it makes sense to bring up equipment to produce them, if you can produce more than their weight in products. The actual return ratios are in the range of 100:1, meaning for each 1 ton of asteroid tugs and furnaces, you eventually get 100 tons of products. When launch costs are high, it makes a lot of sense to do that. More complicated manufacturing, like turning metallic asteroids into parts and machines, will come later, if it makes economic sense.
The cycling orbit space habitat mentioned in the article is almost the answer. You add to it asteroid mining from nearby orbits. That gives you radiation shielding and a source of fuel, oxygen, food, etc. Now you can send lots of people to Mars without having to use a big rocket each time.
More details:
The Earth-Mars space is full of small asteroids. 12,750 have been found so far. Some of them will be a small delta-V (velocity change) from a transfer orbit that goes from Earth to Mars and back. So you send a space tug ahead of time to one of them, grab a few hundred tons of rock, and move it to the desired orbit. Later you launch a crew habitat surrounded by empty storage lockers. You stuff the rock into the lockers, and now you have radiation shielding for the crew.
On the repeating trip to Mars, your crew in transit can process the rock to extract water, oxygen, carbon, and other useful items. This is both supplies for the transit crew, and forward supplies to deliver to Phobos. If you run low on raw rock, you send your space tug out to fetch some more. Eventually they can install a greenhouse and start growing their own food too.
Eventually you carry a habitat module to Phobos, and repeat the mining operation, because Phobos is a great big asteroid. Build up enough fuel and supplies, and send a lander down to the surface. Compared to bringing everything from Earth with a Big Fucking Rocket, this is way way cheaper.
NASA probably would not be in the business of fixing satellites for other people, just their own. Once the technology is available, other people will likely take it up as a profit-making business. Not having to write off $300 million satellites when they break is worth billions a year. The most qualified "satellite repair dudes" will be the original satellite makers, since they know the most about them in the first place.
The satellite maintenance we have studied and performed (Hubble, and the Space Station) always assumed the satellite was designed for it. That means a "grapple fixture" (a hard point designed for grabbing), and provisions to change out equipment or refuel. Most satellites today are not designed for maintenance, because there is no way to do it. Hubble and the Station have access to robot arms, EVA humans with tools, etc. Satellites in GEO don't.
Once a service station is available (and an orbital tug to bring satellites to it), you can be sure the design of satellites will be changed to use it. Right now a single part breaking, or running out of fuel makes you write off a $300 million satellite. That's a hell of an incentive to make it fixable.
Messing with someone else's satellite is highly illegal, and sure to be noticed. Multiple nations can track satellites, so it's not like you can sneak up on it. Snagging an uncooperative or dead satellite is more like a salvage operation. You are likely to damage delicate parts like solar arrays or antennae. You might get some useful parts out of it, but not likely a fully functioning satellite, because it wasn't designed to be taken apart and put back together. Second-hand satellite parts, and reducing future orbital debris hazards might be enough reason to do it, with permission of the owners, if you can do it cheaply enough.
> The solar industry will continue to tout capacity rather than actual generation because most folks don't understand the difference.
The solar industry reports capacity because the whole electrical industry uses that to size their wires, from transmission lines to the wiring in your house. Every electrical device you plug into the wall outlet has peak power draw listed in Watts or Amps. That's so you don't overload the circuit (typically 20 Amps or 2400 Watts). In the same way, transmission lines that carry power from plants to cities have a maximum capacity, and the grid operator has to know what peak power level each source can provide.
What you are calling "actual generation" is just "energy", or power x time. For a power plant, it's typically listed as "Peak capacity (MW) x capacity factor (%) x 8766 hours (in a year) = Energy output (MWh)". The capacity factor is the average output divided by the peak output. It varies from 90% for nuclear, to as low as 15% for solar in a bad location like Seattle (not recommended). Every power plant, without exception, has less than 100% capacity factor, although the reasons vary. A hydroelectric dam might theoretically run nearly all the time, since individual turbines can be shut for maintenance. But that does not account for weather. During a drought, there may not be enough water behind the dam to keep running at full power.
The job of a grid operator is to have enough power sources and transmissions lines to meet demand every minute of every day. That demand varies all the time: daytime vs night and weekends, seasonal cycles, weather variations. They prefer to use generating plants with the lowest operating costs first. So solar, wind, hydro, etc. that don't burn fuels are the preferred choice when available. They also prefer to use long-running plants like nuclear for "base load", the demand at the lowest point of the day, because they are slow to start and stop. "Dispatchable" plants (like Hydro), which can be turned on and off quickly are preferred to adjust supply to match demand as it varies. It's not as simple as "X is better than Y"
The grid operator also has to have enough reserve capacity for when something unexpected happens. A severe storm could knock out a bunch of demand (by downing distribution lines, or people are snowed in and don't go to work, thus businesses stay closed). A power plant can shut down unexpectedly, and other sources have to fill in. A heat wave or cold snap could drastically affect demand.
> It will stop once they realize that all crypto currencies are in fact traceable via their block chain.
No, they are not. There are such things as "paper wallets" (containing the private key to a bitcoin address). You can hand over such a wallet to another person, without creating a transaction on the block chain. There are also services built on top of the block chain - ChangeTip ( https://www.changetip.com/ ) is an example. People can send tips to each other, and it is internal to ChangeTip's books until you want to withdraw. Finally, there are more than one cryptocurrency. If you privately exchange bitcoins for litecoins, you break the traceability, because there is nothing to show that the two transactions, which happen about the same time, are connected. On a single chain they are, because balances explicitly are sent from one address to another.
> because smart people do not seek government employ.
That's a simplification. Smart people are discouraged from government employ because the pay scale is low. The Federal general salary (GS) scale tops out at 100-130K per year. However, other factors, like job security, not having to work very hard, or power over other people's lives can compensate for the low pay. A really interesting job can also attract smart people. Civilian U.S. astronauts are on the GS scale, and thus they top out at the same salaries as other federal employees. But they have a *really* interesting job, and I think all of them are pretty smart (I've met and worked with half a dozen or so).
Slashdot Mirror
I've been working on a textbook about Space Systems Engineering: http://en.wikibooks.org/wiki/S...
In section 4.9 I do the numbers for orbital mining: https://en.wikibooks.org/wiki/...
The first product of asteroid mining is likely to be rocket fuel. Some asteroids (the carbonaceous type) contain up to 20% water and carbon compounds. This can be processed to Oxygen + Hydrocarbons, which is a common high-thrust rocket fuel. The lifetime mass return ratio of an asteroid tug is ~350:1, and if 20% is usable fuel, then you gain 70:1 just on that one product. Extracting water and carbon compounds only requires kitchen oven level heat, which is easy to do by concentrating sunlight.
There are lots of other products we can potentially extract from asteroids, but that's the easiest and most useful, since most anything you do in space needs some fuel to get where you want to go.
Asteroids did have geological processes, just different ones. The "metallic" type come from protoplanets which melted internally from radioactive decay early in their history. The iron and iron-loving elements sank to the core because they are the densest. Later collisions broke up the protoplanets, exposing their cores. The metallics are a high percentage of iron, nickel, cobalt, and a few other elements. The "stony-irons" come from regions that didn't fully separate the core and rocky layers. They range from low to high percentage iron, with the remainder being rock.
The other process that happened is thermal. Depending how far from the Sun a given asteroid first formed, and later orbit history, certain compounds condensed or not, and then could be baked. Probably the most significant difference is due to the "frost line", the distance at which water ice can remain solid in a vacuum. It happens to be right in the middle of the Asteroid Belt, where Ceres is. Objects beyond that distance tend to have a lot of water. Anything closer tends to have little water, though it can contain "hydrated minerals", where the water is chemically bound.
We actually know quite a bit about the composition of asteroids. Nature delivers samples to Earth in the form of meteorites. We can compare the spectra of meteorites to those from asteroids we get through telescopes, and infer what they are made of. We have flown past or orbited several asteroids, most notably the Dawn mission to Vesta and now Ceres, two of the largest asteroids. Spacecraft carry a larger variety of instruments and can do a better job of telling what the asteroids are made of.
As far as materials processing, we can design machines based on meteorite samples, or simulated samples, since meteorites are rare and valuable. If the Asteroid Redirect Mission that NASA wants to do happens, we would have a sizable boulder to experiment with. After taking science samples, they could try various processing methods on an actual piece of asteroid rock, in zero-g. I don't think we can design serious production units without a a few rounds of trying it on a small scale. For that, we would need at least a small asteroid tug that fetches back chunks from different asteroid types, so we have enough raw materials to experiment on. Most known asteroids are too big to move whole. A 30 meter one is anywhere from 18,000 to 90,000 tons. So for early space mining, we are talking about scraping loose stuff off their surfaces, or grabbing boulders.
my email is the same as my user name here, but lowercase, and add (at)gmail. Feel free to contact me if you want more information. I can point you at sources I have, or send you stuff directly.
So do solar panels. The difference is a rectenna array generates 300 W/m^2 for 24 hours a day, while solar panels generate about 200 W/m^2 from 4-6 hours a day in most decent locations. In crappy locations for solar (Seattle, Germany), the energy per land area is *way* higher for space beamed power.
The fact that he helps run the U.S.'s largest ground solar installer isn't a conflict of interest?
If a consortium of university libraries demanded open access, the publishers would have to agree. Those libraries are generally the ones who pay for subscriptions.
> that allows people within the company
JPL is a NASA center managed by CalTech. Neither is a company.
That's because it doesn't have tilt resistance. On a skateboard with wheels, when you lean, the wheels on that side are compressed, and push back on your feet. The hoverboard doesn't have a restoring force when you tilt it, so you fall over. What they need are two parallel coils, spaced about a foot or more apart, so they have some tilt resistance. What they have now is like a skateboard where all 4 wheels are in a single line.
We just have to punish corporate management as the responsible people when a corporation commits a criminal offense. They would straighten up pretty quick if that happened. Commit mortgage security fraud on a vast scale (Bank of America)? Not just a fine, but all the top people responsible go to jail, for committing fraud.
That's not correct. *Control* of multinationals is by a core of banks and investment houses ( http://arxiv.org/abs/1107.5728 ), which for shorthand we can call "Wall Street". A number of them are based outside the U.S., but pretty much all have an office in the Wall Street area. *Ownership* is distributed more widely. For example, I used to work for Boeing, and I'm vested in their retirement fund. Theoretically the fund holds the assets in trust for the retirees, who are the beneficial owners. The control of the funds, however, is in the hands of whatever fund manager Boeing has hired, which is typically one of the big Wall Street companies. Since the fund assets are over $20 billion, the fund manager has a lot of influence with the various companies whose shares they hold. I have none.
The separation of ownership and control is the trick by which Wall Street exerts undue influence. And they don't even have to collude to get their way. Everyone on Wall Street has the same goal: maximize profits at all costs. So they all use their influence in the same direction to get their way, whether lowering the capital gains tax, extending copyright, etc.
> Bitcoin has no similar intrinsic value that isn't easily copied (and possibly improved upon) by any number of altcoins.
What you are calling "intrinsic value" is more correctly "utility value", the value we put on things for their usefulness. However, it is not an intrinsic property of an object. A gallon of water in the desert when you are thirsty is worth much more than a gallon of water to take a shower at home, when you have it supplied by a water utility at low cost. Both gallons are useful, and people are willing to pay for them, but different amounts.
In the case of bitcoin, it is the Bitcoin Network which gives it usefulness. Without the network, you cannot make transactions, and thus any coins you have are useless (you can't send them to anyone, and thus can't buy anything with them). Bitcoin has by far the largest network of it's kind. It consists not just of the relay nodes that forward transactions, but custom hardware, software applications, merchants who accept it, and users. That network isn't easily copied, it has to grow over time.
With the network, I can pay a programmer in Kiev from Atlanta easily, cheaply, and quickly. That's a pretty useful thing. I can also make payment contingent on a software script written into the transaction, because bitcoin was designed with a scripting language. I cam make my money programmable. That's a whole new useful feature.
Like many other networks, bitcoin responds to Metcalfe's Law. The more people who use it, the more valuable the network becomes. This is also true of fiat currency networks. Lots and lots of people use the US dollar. The dollar is thus highly useful, because you can spend it on lots of things in lots of places. Try spending a Zimbabwean Dollar anywhere, even in Zimbabwe. It experienced 10^25 inflation, and now nobody wants it. So if you have a stack of them, they are useless, except as a collector's item. Even though they were issued by a government, the size of the network that uses the currency trumps that.
> The fishy part has always been that the theft occurred from offline, "cold storage" wallets,
According to a Reddit AMA today from a former Mt. Gox employee (he had kept silent until the arrest, because his testimony was part of the investigation), there were no cold storage wallets. It was total amateur hour on Karpeles' part: no proper security, no proper accounting, customer funds used for business and personal expenses, etc. The likely situation is the "missing" bitcoins never actually existed. Customer accounts were credited with fake coins to cover the fact that their funds were being used for other things. Eventually customer demands for cash or sending out their bitcoins elsewhere could not be met, and they declared bankruptcy.
10 year treasuries have averaged ~2.5% over the last 5 years:
http://data.cnbc.com/quotes/US...
Median CPI, before fiddling, has average about 2% over the last 5 years
So over that period, the estimated real return is 0.5%
Right. I guess that's why the largest bank in France and the largest mutual fund operator in the US are testing out bitcoin/cryptocoins:
http://www.ibtimes.co.uk/frenc...
http://i.imgur.com/yfKkhRu.png
Oh, and the NASDAQ is already using blockchain technology for their private market:
http://money.cnn.com/2015/05/1...
History of technology is an interest of mine. Pottery is at least 10,000 years old, Wheels about 4,000. The main reason pottery is so old is obviousness. Build a cooking firepit on clay soil, and you just invented pottery. You only have to notice the bowl holds water the next time it rains. From there, it is a short step to doing it on purpose: http://usscouts.org/scoutcraft...
IAARS (I am a rocket scientist) (see my wikibook if interested: https://en.wikibooks.org/wiki/... )
Beamed power for space launch has been discussed for decades - I have several ring binders of data on the subject. Practical depends a lot on your power storage. Space launch of anything larger than a teacup takes a lot of power. For example, the three liquid engines on the Space Shuttle put out a combined 21 GigaWatts of power, of which 156 MegaWatts was just to run the turbopumps to shove the propellants into the main combustion chamber (the turbopumps had their own combustion system to power themselves).
So this launch system seems to have batteries between the power grid and the microwave generators. That makes sense, because you can't suck GigaWatts on demand off conventional grids. Batteries have been improving in cost and performance pretty well recently, so that may have put it in a practical range. I wonder, though, if on-demand turbogenerators might not be cheaper.
The other parts of the system: heat exchanger, phased array, high power microwave amplifiers, are relatively straightforward, you just need a lot of them. What I wonder about is traffic model. High power launch systems like this cost a lot to build. If you only use them a few times a year, that investment has to spread over relatively few launches. You really want to use them a lot, like daily or hourly. But where is the traffic going to space to fill that much capacity?
It is listed in my space transportation wikibook: https://en.wikibooks.org/wiki/...
All rockets heat a propellant, then expand it from a chamber and nozzle to maximize thrust. Conventional rocket heat the propellant by combustion of the propellant itself. But if you have an external energy source, you can heat it that way instead. In this case, the energy source is a microwave beam, and the propellant is Hydrogen gas. Engines like the SpaceX Merlin have exhaust products of CO2 and water, since their propellents are kerosine and oxygen. These have high molecular weights, much higher than for Hydrogen. Lower molecular weight gases have a higher speed of sound at the same temperature. Therefore their exhaust velocity in a nozzle can be higher, and you get more thrust per kg of gas.
This has been known for a long time, the physics of gas expansion are well known. To make a workable space launcher, you need enough MW of microwave energy, accurate focusing and tracking, and a really efficient and lightweight absorber on the vehicle. Power requirements for space launch are surprisingly large. For example, the Space Shuttle carried three liquid engines, which produced 7 GW of exhaust power each. Something that may have made this concept workable is high power, reasonable cost batteries. Gigawatt power levels are more than most electric grids can deliver. So a way to store it up and release in a short time is very helpful. Traditional rockets did it with very big propellant tanks and enormously powerful (70,000 Horsepower) turbopumps to shove the propellants into the engine fast enough.
Launch to orbit is a high energy proposition. Conventional rockets add 50 kW of kinetic energy to each kilogram of payload for 600 seconds. The Tesla Model S car consumes 20 kW for the whole car at highway speed.
> I'll believe in people settling Mars at about the same time I see people setting the Gobi Desert
Nomadic herders have lived there for a long time. Lately they are building a massive copper and gold mine:
https://en.wikipedia.org/wiki/...
So I expect there is a pretty big mining town to support the mine. You believe in Mars colonies now?
> No one's mining asteroids or setting up camp on Mars.
Half a dozen billionaires are trying to prove you wrong. How many companies have you started?
You can't troll someone who spent a career in aerospace, and has written a book on space systems engineering [ http://en.wikibooks.org/wiki/S... ] when it comes to space systems design. You especially can't troll me when you are
an anonymous coward, and I have the same user name here as on Wikibooks, and can thus prove I wrote that book. Now go away, or I
shall taunt you a second time.
> The problem with orbital mining is that it depends on the presence of orbital manufacturing.
I'm sorry, but that's a very confused statement. It is quite possible to build a space tug that mines rock from an asteroid, and delivers it to another orbit where it is needed. If the need is for radiation shielding, then no manufacturing steps are required. The more general flow of industry goes:
Extraction -> Raw Materials Processing -> Ready to Use Materials -> Parts Fabrication -> Assembly
Using steel as an example, iron ore, coal, and limestone are extracted at their respective mines. They are combined in a blast furnace to process them into iron. The iron is further processed into a particular alloy of steel, in a useful shape (sheet, bar, rod, etc). This is the ready to use material. The steel is fed to machine tools to make finished parts, which are then assembled into some kind of machine, like a car engine.
Parts fabrication and assembly are together called manufacturing, but they are not necessary if your space product is usable as a material. For example, some asteroids contain hydrated minerals. If you heat them to 200-400C, the hydrates will decompose to water + a different mineral. The water can then be used as water by human crew, or further processed to oxygen and hydrogen by electrolysis for rocket fuel. The dehydration furnace and electrolysis units can come from Earth, ready to use. In fact, the Space Shuttle used the reverse process in a fuel cell, combining H2 and O2 to make water and electricity.
Shielding, water, and fuel are commonly needed items in space, so it makes sense to bring up equipment to produce them, if you can produce more than their weight in products. The actual return ratios are in the range of 100:1, meaning for each 1 ton of asteroid tugs and furnaces, you eventually get 100 tons of products. When launch costs are high, it makes a lot of sense to do that. More complicated manufacturing, like turning metallic asteroids into parts and machines, will come later, if it makes economic sense.
The cycling orbit space habitat mentioned in the article is almost the answer. You add to it asteroid mining from nearby orbits. That gives you radiation shielding and a source of fuel, oxygen, food, etc. Now you can send lots of people to Mars without having to use a big rocket each time.
More details:
The Earth-Mars space is full of small asteroids. 12,750 have been found so far. Some of them will be a small delta-V (velocity change) from a transfer orbit that goes from Earth to Mars and back. So you send a space tug ahead of time to one of them, grab a few hundred tons of rock, and move it to the desired orbit. Later you launch a crew habitat surrounded by empty storage lockers. You stuff the rock into the lockers, and now you have radiation shielding for the crew.
On the repeating trip to Mars, your crew in transit can process the rock to extract water, oxygen, carbon, and other useful items. This is both supplies for the transit crew, and forward supplies to deliver to Phobos. If you run low on raw rock, you send your space tug out to fetch some more. Eventually they can install a greenhouse and start growing their own food too.
Eventually you carry a habitat module to Phobos, and repeat the mining operation, because Phobos is a great big asteroid. Build up enough fuel and supplies, and send a lander down to the surface. Compared to bringing everything from Earth with a Big Fucking Rocket, this is way way cheaper.
NASA probably would not be in the business of fixing satellites for other people, just their own. Once the technology is available, other people will likely take it up as a profit-making business. Not having to write off $300 million satellites when they break is worth billions a year. The most qualified "satellite repair dudes" will be the original satellite makers, since they know the most about them in the first place.
The satellite maintenance we have studied and performed (Hubble, and the Space Station) always assumed the satellite was designed for it. That means a "grapple fixture" (a hard point designed for grabbing), and provisions to change out equipment or refuel. Most satellites today are not designed for maintenance, because there is no way to do it. Hubble and the Station have access to robot arms, EVA humans with tools, etc. Satellites in GEO don't.
Once a service station is available (and an orbital tug to bring satellites to it), you can be sure the design of satellites will be changed to use it. Right now a single part breaking, or running out of fuel makes you write off a $300 million satellite. That's a hell of an incentive to make it fixable.
Messing with someone else's satellite is highly illegal, and sure to be noticed. Multiple nations can track satellites, so it's not like you can sneak up on it. Snagging an uncooperative or dead satellite is more like a salvage operation. You are likely to damage delicate parts like solar arrays or antennae. You might get some useful parts out of it, but not likely a fully functioning satellite, because it wasn't designed to be taken apart and put back together. Second-hand satellite parts, and reducing future orbital debris hazards might be enough reason to do it, with permission of the owners, if you can do it cheaply enough.
> The solar industry will continue to tout capacity rather than actual generation because most folks don't understand the difference.
The solar industry reports capacity because the whole electrical industry uses that to size their wires, from transmission lines to the wiring in your house. Every electrical device you plug into the wall outlet has peak power draw listed in Watts or Amps. That's so you don't overload the circuit (typically 20 Amps or 2400 Watts). In the same way, transmission lines that carry power from plants to cities have a maximum capacity, and the grid operator has to know what peak power level each source can provide.
What you are calling "actual generation" is just "energy", or power x time. For a power plant, it's typically listed as "Peak capacity (MW) x capacity factor (%) x 8766 hours (in a year) = Energy output (MWh)". The capacity factor is the average output divided by the peak output. It varies from 90% for nuclear, to as low as 15% for solar in a bad location like Seattle (not recommended). Every power plant, without exception, has less than 100% capacity factor, although the reasons vary. A hydroelectric dam might theoretically run nearly all the time, since individual turbines can be shut for maintenance. But that does not account for weather. During a drought, there may not be enough water behind the dam to keep running at full power.
The job of a grid operator is to have enough power sources and transmissions lines to meet demand every minute of every day. That demand varies all the time: daytime vs night and weekends, seasonal cycles, weather variations. They prefer to use generating plants with the lowest operating costs first. So solar, wind, hydro, etc. that don't burn fuels are the preferred choice when available. They also prefer to use long-running plants like nuclear for "base load", the demand at the lowest point of the day, because they are slow to start and stop. "Dispatchable" plants (like Hydro), which can be turned on and off quickly are preferred to adjust supply to match demand as it varies. It's not as simple as "X is better than Y"
The grid operator also has to have enough reserve capacity for when something unexpected happens. A severe storm could knock out a bunch of demand (by downing distribution lines, or people are snowed in and don't go to work, thus businesses stay closed). A power plant can shut down unexpectedly, and other sources have to fill in. A heat wave or cold snap could drastically affect demand.
> It will stop once they realize that all crypto currencies are in fact traceable via their block chain.
No, they are not. There are such things as "paper wallets" (containing the private key to a bitcoin address). You can hand over such a wallet to another person, without creating a transaction on the block chain. There are also services built on top of the block chain - ChangeTip ( https://www.changetip.com/ ) is an example. People can send tips to each other, and it is internal to ChangeTip's books until you want to withdraw. Finally, there are more than one cryptocurrency. If you privately exchange bitcoins for litecoins, you break the traceability, because there is nothing to show that the two transactions, which happen about the same time, are connected. On a single chain they are, because balances explicitly are sent from one address to another.
> because smart people do not seek government employ.
That's a simplification. Smart people are discouraged from government employ because the pay scale is low. The Federal general salary (GS) scale tops out at 100-130K per year. However, other factors, like job security, not having to work very hard, or power over other people's lives can compensate for the low pay. A really interesting job can also attract smart people. Civilian U.S. astronauts are on the GS scale, and thus they top out at the same salaries as other federal employees. But they have a *really* interesting job, and I think all of them are pretty smart (I've met and worked with half a dozen or so).