They can try, but once people can make their own stuff using automation, they won't need jobs, and therefore won't pay income taxes. Governments can then pass all the laws they want, but without money they can't pay the Men With Guns to enforce them, and so become irrelevant. If they try to collect taxes/goods by force by coming to your door, it will become increasingly obvious they are just organized crime with paperwork. You can tell your computer driven machines to make weapons and then tell the government enforcers to get the hell out.
Once we have enough factories that have grown to full capacity, we tell them to build rocket factories and launch pads, and send new seed factories into space:
That's why you want to build in high orbit *near* the Moon, and not *on* the Moon.
The three main types of asteroids (chondrite, stony, and metallic) are all different from each other, and from the Moon, because of their origins and history. In particular, the chondrites have up to 20% water and carbon compounds. You can deliver asteroid rock to high orbit using solar-electric propulsion, which is very efficient. You can deliver Lunar materials to orbit with an electric centrifuge, also very efficient. In high orbit you get sunlight 100% of the time to power your equipment. The Lunar surface only gets sunlight 50% of the time, and the gaps are two weeks long, which is annoying.
> After all, Moon is made basically of the same material that the Earth was formed with.
They started out similar because the Moon is made from debris from the Theia-Proto Earth collison. But the Moon remained hot for a long time due to original collision energy, later bombardment, radioactive decay, and tidal heating when it was much closer to Earth. Because of the Moon's smaller size, it lost most of the "volatile" compounds (anything with a vapor pressure at lava temperatures). They either escaped directly, or were stripped by solar wind particles. So the Earth and Moon are fairly different today.
That's where self-bootstrapping automated production (seed factories) come in.
You build the first ones here on Earth. That's my day job, by the way - building prototype seed factories. The first generation factories are built in moderate environments, like Atlanta where we are working. They produce parts for more equipment, eventually growing to industrial size. They also produce useful products to pay for their upkeep. Eventually you send new seed factories to more difficult locations, like the oceans, ice caps, and deserts. Finally, you tell your collection of factories to build rocket factories and launch pads, and off you go to space.
The starter sets (seed factories) won't be free, but they will be low cost because they are small. They pay their own way after that, by making things people need and want.
> but you need to claw out of a really deep gravity well to get that stuff to the Moon
The actual escape energy from Earth is 62.5 MJ/kg = 17.375 kWh/kg = $1/kg at wholesale electric rates, about what I pay for potatoes. We just have been terribly inefficient about how we get to space.
In any case, water, carbon, and electrolytes are available in the Chondrite type asteroids ( http://www.sciencedirect.com/s... ), so at most you would have to supply trace nutrients.
Space industry as of 2015 was $335 billion in economic activity ( see page 7 of http://www.sia.org/wp-content/... ), with about 1400 operational satellites in total. We don't have a way to effectively repair or refuel these satellites. When they stop working, we have to replace them at great expense. Saving money or increasing profits provides plenty of "will and commitment" to build the first generation of space mining and production. This would start with propellants, since just about every satellite uses them, and they are a simple product to make.
> we don't know where (or even if) the needed resources exist in viable quantities or concentrations
On the contrary, nearly all satellites operate on solar energy, so we know that is feasible. The total solar flux passing closer than the Moon is equal to the whole world's fossil fuel reserves *every minute*. That's more energy than we know what to do with, provided we can tap it economically.
Meteorites are pieces of asteroids that hit the Earth and survived re-entry. So we are able to examine those in detail, and then infer the composition of asteroids still in space by comparing spectra. For a handful of asteroids, and the Moon, we have visited by scientific missions, or in person, and gotten more direct information. So, for example, we have detailed geologic maps for the Moon ( http://www.lpi.usra.edu/resour... ) and are building up our knowledge of other bodies.
> human colonies are a death sentence to anyone living there permanently
I will set aside the fact that the human condition has a 100% mortality rate so far, and that a minor oops driving to work will kill you on Earth. But I helped design and build the Space Station, and it's been occupied for 15 years now. Think of it as a proof of concept. A space colony in orbit or on the surface can deal with gravity by rotation. On the ground that means a merry-go-round or racetrack setup that people use for as many hours as required to maintain health. Bulk rock is easy for surface locations, and not so hard for orbital ones. Enough thickness will provide good shielding. Most illustrations of space colonies are "artist's concepts" and don't address safety in the way engineers building bridges and skyscrapers have to. A real colony would have multiple layers of pressure shell, compartmentalization, emergency shelters, and other safety provisions. Yes, accidents and failures will happen, but we live with fires and natural disasters on Earth. The question is can you bring the risks down to a comparable level as on Earth. I think the answer is yes.
> at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that.
We are installing over a hundred billion watts of solar and wind capacity worldwide this year. Coal use has dropped by a third in the US in the last 10 years. Things could move faster, but when oil states like Saudi Arabia and Dubai are installing renewables, it should be obvious change is happening ( http://www.pv-tech.org/news/sa... )
I'm part of a project to build this kind of self-bootstrapping Seed Factories, for Earth first, then later in space. There's a report on applying the concept to space at:
I've corresponded with Metzger, and agree with his general idea, but disagree about placing the seed factory on the Lunar surface. The surface only gets sunlight half the time, while in high orbit you can get sunlight 100% of the time. The Moon is severely depleted in volatile compounds because it was baked for hundreds of millions of years, and is too low mass to hold on to easily vaporized materials. Near Earth Asteroids complement the Moon in terms of ore types, and the optimum place to bring everything together is a high orbit near, but not on, the Moon.
No, they are quite sane when viewed from the right perspective. Over 85% of Google's revenue comes from ads, but more and more people are using ad-blockers. This is a threat to their existence. So the purpose of Alphabet is to find something, anything, to fill in when ad revenue declines. Some of their projects are pretty conservative, like high speed broadband, wireless, and cloud services. Other companies already make billions a year on them. Others are riskier, but you never know when one could turn out to be a hit. After all, search wasn't that big a market until Google made it one. They have so much cash piled up, it makes sense to throw some of it around in the hopes of another hit.
Taco delivery is just a feasibility test. The real underlying service is last-mile delivery of small packages. Right now, a car, van, or UPS truck does that. Imagine a Google self-driving electric delivery van that has several variously sized drones on the roof. They can fly off and do multiple deliveries in short range of the van, then fly back to recharge their batteries. That kind of system would be way more efficient in making deliveries around town than a truck with a human driver. None of the pieces for such a delivery system are ready yet, but they are working on it.
Banks insure depositors by paying into the FDIC insurance fund. Most of the time when a bank goes belly-up, the insurance covers it. It's only when many banks get in trouble at the same time, as happened during the Financial Crisis a decade ago, that the Federal Reserve and Treasury stepped in to bail them out.
As of July 2016, The Treasury's Troubled Asset Relief Program (TARP) has collected about $8 billion more than it paid out, representing about a 2% profit on the $400 billion disbursed. The program isn't over yet, so we don't know the final impact on taxpayers, but they haven't lost *yet*
> I am not sure what is driving the increased price/market cap,
That's pretty simple. Bitcoin has a hard cap on block size of 1 MB. This was originally put in many years ago by Satoshi Nakamoto to limit spam attacks that would DDOS Bitcoin nodes. By the middle of this year actual user transactions were pushing the 1 MB cap, and the developers of the "Core" version of Bitcoin have refused to raise it. There are various theories about *why* they refuse to raise it (stupidity, financial conflicts of interest, etc.), but for discussing the impact on other cryptocurrencies it doesn't matter. Only the existence of the limit matters.
In order to get into the limited space for new transactions, people have had to raise the transaction fee they offer. In turn, this has made alternate currencies cheaper to use, although Bitcoin still benefits from being the first mover and the network effect (more users, more apps and tools to use it). The alternate currencies are worth more now because traders predict a shift in usage if the cap on Bitcoin remains in place for long. At the same time, the majority of users are getting fed up with with a network limited to 14.4K dialup speeds (1 MB/10 minutes = 13,333 bits/second), so there are efforts to fork the Bitcoin software (it's open source) to something less restrictive. There still needs to be some kind of limit, because network nodes have to be able to relay and verify transactions in real time, but 1 MB/10 minutes isn't it.
I use No Script + Ublock Origin, and can see the content just fine. Some sites I have to tweak which scripts I allow. If it requires too much fiddling to strike a balance between seeing what I want and getting too many ads, I just move on to the next site. Advertisers don't seem to get this. In the days of paper newspapers and magazines, you got nothing without someone paying for it. Sometimes you got lucky and the previous reader left it behind for you to read, but usually you had to pay for it yourself. With the Internet, there is *always* another website to look at, and you pay a flat monthly fee to your service provider to deliver all of it.
> if they're just testing the engines why did it need the payload in place ?
They're not just testing the engines. They are testing everything on the rocket, including communications and power to the satellite. It would be embarrassing if they forgot to charge the satellite's battery (it has to use one before the solar arrays open up). Basically this is a dress rehearsal for launch, where they do everything except let go of the rocket from the pad. Assuming everything went well, it would shut down the engines after a few seconds, then fuel up and launch for real a few days later.
I should like to make a few comments on your post:
* There have been a number of small scale "space tether" experiments. These bear about the same relation to a full space elevator as flying a kite across a river does to a suspension bridge across that river. We have long way to go before we are ready to build a functioning space elevator.
* The popular image of a space elevator (a 60,000 km vertical cable attached to the ground) is based on a 121 year-old thought experiment by space pioneer Konstantin Tsiolkovsky. That design is laughably impractical, and nothing like what a modern version would be like.
* A space elevator is a transportation infrastructure project, like a bridge or an airport. We don't build that kind of infrastructure for a few tens of vehicles a year, neither would we build a space elevator. The economics would make no sense.
These comments should not be taken as implying I am against the idea. On the contrary, I think space elevators will be very important at some point in the future, and therefore I and many others have done work on the concept. But the time is not yet ripe for them to be built.
Bruce, as a space systems engineer, I can tell you it's all about fatigue life. Materials like aluminum and titanium have a finite number of load cycles they can withstand as a function of the stress level - more stress, less cycles. A 737 is designed to fly around 25,000 times, so the stress has to be low enough to allow that. Traditional expendable rockets literally evolved from ICBM's, and by their nature ballistic missiles are one-use products. So they can be used at higher stress, and therefore lighter weight.
The Space Shuttle orbiters flew about 25 times each, and the structural parts had no problem doing it, because they were designed for it and had lower stress. All SpaceX has to do is lower the loads enough, and the parts should last for many flights. This makes the rocket a little heavier, but for a first stage that only gets to 20% of orbit velocity, 6 extra pounds translates to about 1 pound of lost payload. They compensate by using dense fuel (kerosene/oxygen), so can use smaller and lighter tanks, and by having dramatically light engines for their thrust level.
> Then again, part of the reason that you spent 100m$ on building the cargo, is that the launch was been so darn expensive.
Having worked in Boeing's space system division, this is explicitly a trade-off we do and understand. You can spend more engineering effort to make a satellite lighter. This allows you to pack in more transponders or fuel, increasing the revenue the satellite can earn. Lighter happens from better solar arrays, TWT amplifiers, structural materials, and propulsion systems. These cost money to develop and optimize. The point at which you stop optimizing for weight is when the next 1% in spending no longer buys you a 1% improvement in revenue. Spending includes launch cost, satellite cost, and insurance cost. So cheaper launch will affect the optimum design towards cheaper and heavier satellite.
As a side note, Boeing is a partner in ULA, which makes rockets, but they also build satellites. It turns out that over the last 15-20 years you could get "more bang for the buck" by making the satellite more efficient. That's why solar arrays are now 30% efficiency vs 12%, and ion engines are standard equipment (~7 times better fuel efficiency). A better rocket would have required a lot more spending. The 35 acre ULA rocket factory in Decatur, AL ( http://www.madeinalabama.com/2... ) was the last major investment of it's type, and factories that large are pretty expensive compared to the ones for satellite parts.
Note: Huntsville, AL, where I used to work, is the major aerospace town in the area. There is a NASA center and the Army Missile command, and most major companies have buildings in the area. Decatur is the next town over, and on the Tennessee River. The rockets are so large they have to be shipped by barge to the launch site, so that's why the plant is there instead of in Huntsville.
This is very far from the facts. Satellite TV alone is six times NASA's budget, and twice all of US government programs (NASA, DOD, weather satellites). Worldwide, the satellite industry is 2/3 of the total of space-related GDP, and government funding 1/3.
SES, which is SpaceX's customer for the used rocket, operates *40* communications satellites. They are the largest private satellite operator, which is why they are willing to take the risk. First, if the rocket blows up, it was insured, and only represents 2.5% of their fleet. Second, since they need a lot of launches, they potentially save a hell of a lot if the cost comes down.
There is already approximately one firearm per adult in the US. They are not evenly distributed though, some people have several, some people have none. I don't think we need to sell any more to provide an anti-drone deterrent.
Me, I have lots of trees on my property, so a drone operator will have to fly very carefully, or just stay higher than the 120 ft pine trees.
According to the Minor Planet Center ( http://minorplanetcenter.net/ ) there are 717,000. A planet being anything that orbits the Sun. They come in three sizes, major planet, dwarf planet, and minor planet. There used to be only two sizes, but we added a new one to accommodate recent discoveries.
Major planets are round, and dominate their orbit. Pluto doesn't qualify, because it's orbit crosses Neptune, which is 8,500 times more massive. In fact, Pluto is Neptune's bitch, being locked into a 3:2 orbital resonance with Neptune. There are thus 8 major planets.
Dwarf planets are round, but don't dominate their orbit. There are about half a dozen of them found so far. Roundness matters because they are no longer in their original form. Some combination of radioactive decay, collision heating, and gravity caused heating, separation by density, and other changes.
Minor planets are everything else, not round, and don't dominate their orbit. They may still be in their original form, unaltered. This matters for science, because they preserve the early history of the Solar System.
If you are not a scientist, you can call Pluto whatever you want, a Disney character for all I care. But scientists will create categories that make sense to them, for their own work, and these are what they have come up with.
The unobtainium is called "Near Earth Asteroid materials", from the almost 15,000 known objects. Whatever orbit you want to go into, there will be some asteroids "near" in velocity terms. So you scrape some rock and dust off the surface of the asteroid, and use it to shield your "transit habitat" on the way to Mars or the Belt. The habitat doesn't stop, but goes in a repeating orbit, picking up new crew each time. During the trip, you process some of the rock into useful products, like fuel, oxygen, water, and metals. If you run low, you send your asteroid tug to get more rock.
And before you call me a "space nutter", my office was on the factory floor where the Space Station modules were built, and I'm working on a textbook for the next generation of space systems engineers ( http://en.wikibooks.org/wiki/S... ), so I do have a clue what I'm talking about.
Since the turn of the century, the number of known NEA's has increased 15-fold, electric propulsion has increased exhaust velocity ten-fold, and solar arrays have tripled power/mass ratio. It's a different world than the one you probably think exists.
> IIRC, KSR depicted the colonized solar system as being dependent on resources from Earth, and workers on outer planets regularly returned to Earth to maintain their health.
With respect to Mr. Robinson, he's just wrong. There is 7 times as much solar energy in high orbit as the average location on Earth, because there is no atmospheric absorption, night, or weather. Even at larger distances from the Sun, you can collect lots of energy using lightweight reflectors. With sufficient energy, you can process raw materials into whatever you need, including more power supplies.
As far as health, with rotating habitats and enough shielding, there should be no reason people cannot live in them full time.
> Because physics tells us that the energies need to accelerate a starship to any fraction of c is something we cannot generate and sustain.
Fortunately the Sun puts out 3.8 x 10^26 W, and we can also use it as a gravitational lens to focus a beam generated by tapping a fraction of that power. Once we develop self-bootstrapping space factories, we can use them to build a giant solar-powered laser. I don't minimize the challenge of doing it, but it is not beyond known physics.
Never is a long time. The fastest we can go with *current* technology is about 200 km/s, or 1/1500th c. (the speed you quoted as fastest is 1 mile/second, so there was a math error). Current technology is defined as a plasma or ion engine powered by a nuclear reactor, all of which currently exist, just not put together on a spaceship.
Assuming at some point we build self-replicating factories in space, we can eventually use them to make a very powerful laser powered by the Sun, and use the Sun as a gravitational lens to focus the beam. In that case the upper limit is set by other things than the propulsion system. If the beam is used to power a particle accelerator, your exhaust can be near c, and your exhaust mass can be much larger than the original fuel in your tanks, due to relativistic mass gain. So the usual rocket equation is not applicable, and the total energy is not limited to mc^2, because it is coming from outside the vehicle. Simply point the particle accelerator the other way to slow down.
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They can try, but once people can make their own stuff using automation, they won't need jobs, and therefore won't pay income taxes. Governments can then pass all the laws they want, but without money they can't pay the Men With Guns to enforce them, and so become irrelevant. If they try to collect taxes/goods by force by coming to your door, it will become increasingly obvious they are just organized crime with paperwork. You can tell your computer driven machines to make weapons and then tell the government enforcers to get the hell out.
It's not. That's why we are building the first self-bootstrapping automated factories here on Earth:
https://en.wikibooks.org/wiki/...
Once we have enough factories that have grown to full capacity, we tell them to build rocket factories and launch pads, and send new seed factories into space:
https://en.wikibooks.org/wiki/...
That's why you want to build in high orbit *near* the Moon, and not *on* the Moon.
The three main types of asteroids (chondrite, stony, and metallic) are all different from each other, and from the Moon, because of their origins and history. In particular, the chondrites have up to 20% water and carbon compounds. You can deliver asteroid rock to high orbit using solar-electric propulsion, which is very efficient. You can deliver Lunar materials to orbit with an electric centrifuge, also very efficient. In high orbit you get sunlight 100% of the time to power your equipment. The Lunar surface only gets sunlight 50% of the time, and the gaps are two weeks long, which is annoying.
> After all, Moon is made basically of the same material that the Earth was formed with.
They started out similar because the Moon is made from debris from the Theia-Proto Earth collison. But the Moon remained hot for a long time due to original collision energy, later bombardment, radioactive decay, and tidal heating when it was much closer to Earth. Because of the Moon's smaller size, it lost most of the "volatile" compounds (anything with a vapor pressure at lava temperatures). They either escaped directly, or were stripped by solar wind particles. So the Earth and Moon are fairly different today.
That's where self-bootstrapping automated production (seed factories) come in.
You build the first ones here on Earth. That's my day job, by the way - building prototype seed factories. The first generation factories are built in moderate environments, like Atlanta where we are working. They produce parts for more equipment, eventually growing to industrial size. They also produce useful products to pay for their upkeep. Eventually you send new seed factories to more difficult locations, like the oceans, ice caps, and deserts. Finally, you tell your collection of factories to build rocket factories and launch pads, and off you go to space.
The starter sets (seed factories) won't be free, but they will be low cost because they are small. They pay their own way after that, by making things people need and want.
> but you need to claw out of a really deep gravity well to get that stuff to the Moon
The actual escape energy from Earth is 62.5 MJ/kg = 17.375 kWh/kg = $1/kg at wholesale electric rates, about what I pay for potatoes. We just have been terribly inefficient about how we get to space.
Who needs Brawndo, when you can have Pussy in orbit ( https://www.amazon.com/Pussy-N... )? :-)
In any case, water, carbon, and electrolytes are available in the Chondrite type asteroids ( http://www.sciencedirect.com/s... ), so at most you would have to supply trace nutrients.
I think you are being too pessimistic, Barbara.
Space industry as of 2015 was $335 billion in economic activity ( see page 7 of http://www.sia.org/wp-content/... ), with about 1400 operational satellites in total. We don't have a way to effectively repair or refuel these satellites. When they stop working, we have to replace them at great expense. Saving money or increasing profits provides plenty of "will and commitment" to build the first generation of space mining and production. This would start with propellants, since just about every satellite uses them, and they are a simple product to make.
> we don't know where (or even if) the needed resources exist in viable quantities or concentrations
On the contrary, nearly all satellites operate on solar energy, so we know that is feasible. The total solar flux passing closer than the Moon is equal to the whole world's fossil fuel reserves *every minute*. That's more energy than we know what to do with, provided we can tap it economically.
Meteorites are pieces of asteroids that hit the Earth and survived re-entry. So we are able to examine those in detail, and then infer the composition of asteroids still in space by comparing spectra. For a handful of asteroids, and the Moon, we have visited by scientific missions, or in person, and gotten more direct information. So, for example, we have detailed geologic maps for the Moon ( http://www.lpi.usra.edu/resour... ) and are building up our knowledge of other bodies.
> human colonies are a death sentence to anyone living there permanently
I will set aside the fact that the human condition has a 100% mortality rate so far, and that a minor oops driving to work will kill you on Earth. But I helped design and build the Space Station, and it's been occupied for 15 years now. Think of it as a proof of concept. A space colony in orbit or on the surface can deal with gravity by rotation. On the ground that means a merry-go-round or racetrack setup that people use for as many hours as required to maintain health. Bulk rock is easy for surface locations, and not so hard for orbital ones. Enough thickness will provide good shielding. Most illustrations of space colonies are "artist's concepts" and don't address safety in the way engineers building bridges and skyscrapers have to. A real colony would have multiple layers of pressure shell, compartmentalization, emergency shelters, and other safety provisions. Yes, accidents and failures will happen, but we live with fires and natural disasters on Earth. The question is can you bring the risks down to a comparable level as on Earth. I think the answer is yes.
> at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that.
We are installing over a hundred billion watts of solar and wind capacity worldwide this year. Coal use has dropped by a third in the US in the last 10 years. Things could move faster, but when oil states like Saudi Arabia and Dubai are installing renewables, it should be obvious change is happening ( http://www.pv-tech.org/news/sa... )
I'm part of a project to build this kind of self-bootstrapping Seed Factories, for Earth first, then later in space. There's a report on applying the concept to space at:
* https://en.wikibooks.org/wiki/... (part 1)
* https://en.wikibooks.org/wiki/... (part 2)
I've corresponded with Metzger, and agree with his general idea, but disagree about placing the seed factory on the Lunar surface. The surface only gets sunlight half the time, while in high orbit you can get sunlight 100% of the time. The Moon is severely depleted in volatile compounds because it was baked for hundreds of millions of years, and is too low mass to hold on to easily vaporized materials. Near Earth Asteroids complement the Moon in terms of ore types, and the optimum place to bring everything together is a high orbit near, but not on, the Moon.
...be called CmdrTaco?
No, they are quite sane when viewed from the right perspective. Over 85% of Google's revenue comes from ads, but more and more people are using ad-blockers. This is a threat to their existence. So the purpose of Alphabet is to find something, anything, to fill in when ad revenue declines. Some of their projects are pretty conservative, like high speed broadband, wireless, and cloud services. Other companies already make billions a year on them. Others are riskier, but you never know when one could turn out to be a hit. After all, search wasn't that big a market until Google made it one. They have so much cash piled up, it makes sense to throw some of it around in the hopes of another hit.
Taco delivery is just a feasibility test. The real underlying service is last-mile delivery of small packages. Right now, a car, van, or UPS truck does that. Imagine a Google self-driving electric delivery van that has several variously sized drones on the roof. They can fly off and do multiple deliveries in short range of the van, then fly back to recharge their batteries. That kind of system would be way more efficient in making deliveries around town than a truck with a human driver. None of the pieces for such a delivery system are ready yet, but they are working on it.
Banks insure depositors by paying into the FDIC insurance fund. Most of the time when a bank goes belly-up, the insurance covers it. It's only when many banks get in trouble at the same time, as happened during the Financial Crisis a decade ago, that the Federal Reserve and Treasury stepped in to bail them out.
As of July 2016, The Treasury's Troubled Asset Relief Program (TARP) has collected about $8 billion more than it paid out, representing about a 2% profit on the $400 billion disbursed. The program isn't over yet, so we don't know the final impact on taxpayers, but they haven't lost *yet*
https://www.treasury.gov/initi...
> I am not sure what is driving the increased price/market cap,
That's pretty simple. Bitcoin has a hard cap on block size of 1 MB. This was originally put in many years ago by Satoshi Nakamoto to limit spam attacks that would DDOS Bitcoin nodes. By the middle of this year actual user transactions were pushing the 1 MB cap, and the developers of the "Core" version of Bitcoin have refused to raise it. There are various theories about *why* they refuse to raise it (stupidity, financial conflicts of interest, etc.), but for discussing the impact on other cryptocurrencies it doesn't matter. Only the existence of the limit matters.
In order to get into the limited space for new transactions, people have had to raise the transaction fee they offer. In turn, this has made alternate currencies cheaper to use, although Bitcoin still benefits from being the first mover and the network effect (more users, more apps and tools to use it). The alternate currencies are worth more now because traders predict a shift in usage if the cap on Bitcoin remains in place for long. At the same time, the majority of users are getting fed up with with a network limited to 14.4K dialup speeds (1 MB/10 minutes = 13,333 bits/second), so there are efforts to fork the Bitcoin software (it's open source) to something less restrictive. There still needs to be some kind of limit, because network nodes have to be able to relay and verify transactions in real time, but 1 MB/10 minutes isn't it.
I use No Script + Ublock Origin, and can see the content just fine. Some sites I have to tweak which scripts I allow. If it requires too much fiddling to strike a balance between seeing what I want and getting too many ads, I just move on to the next site. Advertisers don't seem to get this. In the days of paper newspapers and magazines, you got nothing without someone paying for it. Sometimes you got lucky and the previous reader left it behind for you to read, but usually you had to pay for it yourself. With the Internet, there is *always* another website to look at, and you pay a flat monthly fee to your service provider to deliver all of it.
> if they're just testing the engines why did it need the payload in place ?
They're not just testing the engines. They are testing everything on the rocket, including communications and power to the satellite. It would be embarrassing if they forgot to charge the satellite's battery (it has to use one before the solar arrays open up). Basically this is a dress rehearsal for launch, where they do everything except let go of the rocket from the pad. Assuming everything went well, it would shut down the engines after a few seconds, then fuel up and launch for real a few days later.
Dear Mr 3208 (if I did the binary conversion right),
I taught a class on space elevator design last year:
Notes: https://en.wikibooks.org/wiki/...
Slides: http://imgur.com/a/cCTY5
I should like to make a few comments on your post:
* There have been a number of small scale "space tether" experiments. These bear about the same relation to a full space elevator as flying a kite across a river does to a suspension bridge across that river. We have long way to go before we are ready to build a functioning space elevator.
* The popular image of a space elevator (a 60,000 km vertical cable attached to the ground) is based on a 121 year-old thought experiment by space pioneer Konstantin Tsiolkovsky. That design is laughably impractical, and nothing like what a modern version would be like.
* A space elevator is a transportation infrastructure project, like a bridge or an airport. We don't build that kind of infrastructure for a few tens of vehicles a year, neither would we build a space elevator. The economics would make no sense.
These comments should not be taken as implying I am against the idea. On the contrary, I think space elevators will be very important at some point in the future, and therefore I and many others have done work on the concept. But the time is not yet ripe for them to be built.
Bruce, as a space systems engineer, I can tell you it's all about fatigue life. Materials like aluminum and titanium have a finite number of load cycles they can withstand as a function of the stress level - more stress, less cycles. A 737 is designed to fly around 25,000 times, so the stress has to be low enough to allow that. Traditional expendable rockets literally evolved from ICBM's, and by their nature ballistic missiles are one-use products. So they can be used at higher stress, and therefore lighter weight.
The Space Shuttle orbiters flew about 25 times each, and the structural parts had no problem doing it, because they were designed for it and had lower stress. All SpaceX has to do is lower the loads enough, and the parts should last for many flights. This makes the rocket a little heavier, but for a first stage that only gets to 20% of orbit velocity, 6 extra pounds translates to about 1 pound of lost payload. They compensate by using dense fuel (kerosene/oxygen), so can use smaller and lighter tanks, and by having dramatically light engines for their thrust level.
> Then again, part of the reason that you spent 100m$ on building the cargo, is that the launch was been so darn expensive.
Having worked in Boeing's space system division, this is explicitly a trade-off we do and understand. You can spend more engineering effort to make a satellite lighter. This allows you to pack in more transponders or fuel, increasing the revenue the satellite can earn. Lighter happens from better solar arrays, TWT amplifiers, structural materials, and propulsion systems. These cost money to develop and optimize. The point at which you stop optimizing for weight is when the next 1% in spending no longer buys you a 1% improvement in revenue. Spending includes launch cost, satellite cost, and insurance cost. So cheaper launch will affect the optimum design towards cheaper and heavier satellite.
As a side note, Boeing is a partner in ULA, which makes rockets, but they also build satellites. It turns out that over the last 15-20 years you could get "more bang for the buck" by making the satellite more efficient. That's why solar arrays are now 30% efficiency vs 12%, and ion engines are standard equipment (~7 times better fuel efficiency). A better rocket would have required a lot more spending. The 35 acre ULA rocket factory in Decatur, AL ( http://www.madeinalabama.com/2... ) was the last major investment of it's type, and factories that large are pretty expensive compared to the ones for satellite parts.
Note: Huntsville, AL, where I used to work, is the major aerospace town in the area. There is a NASA center and the Army Missile command, and most major companies have buildings in the area. Decatur is the next town over, and on the Tennessee River. The rockets are so large they have to be shipped by barge to the launch site, so that's why the plant is there instead of in Huntsville.
This is very far from the facts. Satellite TV alone is six times NASA's budget, and twice all of US government programs (NASA, DOD, weather satellites). Worldwide, the satellite industry is 2/3 of the total of space-related GDP, and government funding 1/3.
SES, which is SpaceX's customer for the used rocket, operates *40* communications satellites. They are the largest private satellite operator, which is why they are willing to take the risk. First, if the rocket blows up, it was insured, and only represents 2.5% of their fleet. Second, since they need a lot of launches, they potentially save a hell of a lot if the cost comes down.
There is already approximately one firearm per adult in the US. They are not evenly distributed though, some people have several, some people have none. I don't think we need to sell any more to provide an anti-drone deterrent.
Me, I have lots of trees on my property, so a drone operator will have to fly very carefully, or just stay higher than the 120 ft pine trees.
According to the Minor Planet Center ( http://minorplanetcenter.net/ ) there are 717,000. A planet being anything that orbits the Sun. They come in three sizes, major planet, dwarf planet, and minor planet. There used to be only two sizes, but we added a new one to accommodate recent discoveries.
Major planets are round, and dominate their orbit. Pluto doesn't qualify, because it's orbit crosses Neptune, which is 8,500 times more massive. In fact, Pluto is Neptune's bitch, being locked into a 3:2 orbital resonance with Neptune. There are thus 8 major planets.
Dwarf planets are round, but don't dominate their orbit. There are about half a dozen of them found so far. Roundness matters because they are no longer in their original form. Some combination of radioactive decay, collision heating, and gravity caused heating, separation by density, and other changes.
Minor planets are everything else, not round, and don't dominate their orbit. They may still be in their original form, unaltered. This matters for science, because they preserve the early history of the Solar System.
If you are not a scientist, you can call Pluto whatever you want, a Disney character for all I care. But scientists will create categories that make sense to them, for their own work, and these are what they have come up with.
The unobtainium is called "Near Earth Asteroid materials", from the almost 15,000 known objects. Whatever orbit you want to go into, there will be some asteroids "near" in velocity terms. So you scrape some rock and dust off the surface of the asteroid, and use it to shield your "transit habitat" on the way to Mars or the Belt. The habitat doesn't stop, but goes in a repeating orbit, picking up new crew each time. During the trip, you process some of the rock into useful products, like fuel, oxygen, water, and metals. If you run low, you send your asteroid tug to get more rock.
And before you call me a "space nutter", my office was on the factory floor where the Space Station modules were built, and I'm working on a textbook for the next generation of space systems engineers ( http://en.wikibooks.org/wiki/S... ), so I do have a clue what I'm talking about.
Since the turn of the century, the number of known NEA's has increased 15-fold, electric propulsion has increased exhaust velocity ten-fold, and solar arrays have tripled power/mass ratio. It's a different world than the one you probably think exists.
> IIRC, KSR depicted the colonized solar system as being dependent on resources from Earth, and workers on outer planets regularly returned to Earth to maintain their health.
With respect to Mr. Robinson, he's just wrong. There is 7 times as much solar energy in high orbit as the average location on Earth, because there is no atmospheric absorption, night, or weather. Even at larger distances from the Sun, you can collect lots of energy using lightweight reflectors. With sufficient energy, you can process raw materials into whatever you need, including more power supplies.
As far as health, with rotating habitats and enough shielding, there should be no reason people cannot live in them full time.
> Because physics tells us that the energies need to accelerate a starship to any fraction of c is something we cannot generate and sustain.
Fortunately the Sun puts out 3.8 x 10^26 W, and we can also use it as a gravitational lens to focus a beam generated by tapping a fraction of that power. Once we develop self-bootstrapping space factories, we can use them to build a giant solar-powered laser. I don't minimize the challenge of doing it, but it is not beyond known physics.
Ignore him. Go look at my space systems engineering book ( http://en.wikibooks.org/wiki/S... ) for a survey ot propulsion methods.
Never is a long time. The fastest we can go with *current* technology is about 200 km/s, or 1/1500th c. (the speed you quoted as fastest is 1 mile/second, so there was a math error). Current technology is defined as a plasma or ion engine powered by a nuclear reactor, all of which currently exist, just not put together on a spaceship.
Assuming at some point we build self-replicating factories in space, we can eventually use them to make a very powerful laser powered by the Sun, and use the Sun as a gravitational lens to focus the beam. In that case the upper limit is set by other things than the propulsion system. If the beam is used to power a particle accelerator, your exhaust can be near c, and your exhaust mass can be much larger than the original fuel in your tanks, due to relativistic mass gain. So the usual rocket equation is not applicable, and the total energy is not limited to mc^2, because it is coming from outside the vehicle. Simply point the particle accelerator the other way to slow down.
Because she's ugly :-).