Its not like not having the cable prevents from exploiting space based industries, we just haven't come up with the value of the proposition
Space will be economically uninteresting until somebody manages to drop the price-per-pound by a few orders of magnitude, and then an awful lot of things becoming economically interesting. A viable space elevator might just accomplish that.
I can't see the cost of delivering and supporting humans in space dropping below the cost of, say, delivering and supporting humans underwater in SCUBA gear. Living in a space hab is like living in a deep-sea hab in many logistical ways (including no need for decompression time).
The only major uses of SCUBA I'm aware of are 1) the military; 2) mineral exploration; and 3) tourism. Is there really any reason to think there will be "an awful lot" of other economically interesting things to do in space?
Mine some asteroids for iron, carbon, silicon, water. Now you have the raw materials for the biggest solar powerplant ever made. Ship the power down the space elevator and you have cheap renewable energy without the downsides of it being earthbound. Ship any excess ores down to earth for more profit. Some of those asteroids could have billions, if not trillions of tons of raw materials ready to use.
It's a bit far out there as ideas go, but so was visiting the moon at one point!
But you don't have to send people. There's lots of stuff in space that can be done by robots. Easier than in the deep sea, because of easier communicaton.
And if you're not talking about the deep sea, but fairly shallow seas, then doing things there isn't really all that expensive at all, and driving the costs of operating in space down to that level is going to be incredibly attractive.
But with 22k miles (3x earth diameter) of transmission losses.
First, each molecule has a specific set of frequencies where photons are "easy" to absorb because they correspond to transitions between quantum states. Any system whose goal is to deliver energy wirelessly through the atmosphere will obviously not use those frequencies.
The other way for a photon to lose energy to the medium it's traveling through is, if the medium contains molecules like water that have different parts with positive and negative charges, the electromagnetic wave will move the differently charged parts in opposite directions. The energy to do that is lost [1].
[1] "Lost" is an application-specific notion. This mechanism is also how a microwave heats food, and in this case the energy imparted to the water molecules in the food can't be considered "lost" because it's supposed to go into the food!
On the contrary, getting rid of heat in a vacuum is easier than getting rid of heat in an atmosphere. Here's a diagram of human heat loss at the surface:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/coobod.htm...
According to this source, at the surface of earth, under the atmosphere, a person loses:
Perspiration: 17 watts
Conduction: 11 watts
Radiation: 133 watts
Without an atmosphere, the direct radiation of heat energy into space becomes more efficient (no greenhouse effect), and it's always the most efficient way to radiate heat.
It is the efficiency of direct radiation of heat energy that explains why objects at the surface can fall below air temperature overnight under a clear sky, as they surely do.
I think some of the confusion arises because of vacuum thermos bottles, which are really efficient at holding onto their heat. But how they work is a bit complicated. They deal with conduction and convection losses by having the vacuum barrier between the contents and the outside. As to radiation, they rely on a reflector that's part of the vacuum bottle, which has the effect of greatly slowing the rate of heat loss by radiation.
So the vacuum thermos avoids radiation heat loss, not because of the vacuum, but with a reflector. That works in space too -- many orbiting telescopes use reflectors to keep the sun's heat energy from heating up the sensors and spoiling their performance.
But a vacuum is a pretty good medium for heat loss by radiation. The moon's surface, heated to several hundred degrees Celsius during the lunar daytime, drops to 26 Kelvins after a few (earth) days of darkness (26 degrees above absolute zero). That's a new figure, lower than had been realized, and seven degrees colder than the surface of Pluto.
I do recall someone explicitly stating that radiation is a poor means of losing heat compared to convection and conduction - which seems to just be wrong.
Yes -- it's a common belief, and it's wrong. Under clear skies after dark, objects on the surface that are convectively coupled to the atmosphere will quickly fall below air temperature because of radiation heat loss, which can produce what is called "radiation fog", so named because it's caused by the air being cooled by the ground, which in turn has been cooled by direct radiation into space.
Not quite so simple. If we're talking about a cable near the earth, where the sun sometimes shines, there are always two heat paths -- from the sun to the cable, and from the cable to deep space. It's not easy, nor is a way self-evident, to make the cable fall to deep space temperatures at a reasonable cost, given that the sun is providing heat energy that must be diverted.
It's really easy to send stuff from orbit to Earth. The trick is keeping it from burning up on the way in.
Imagine a base runner in baseball after a home run. Spends half the time on the far side of the pitcher from the homeplate umpire, but he is only occluded from the homeplate umpire by the pitcher for a very short amount of time. That's (very!!) roughly the scales involved here.
I think it would mainly be useful for people either launching/maintaining a lot of satellites, or living in Earth orbit. Or if someone is producing energy or material in space (orbital solar power stations?) and they want to easily transmit it back to Earth, an elevator would probably be more efficient than weekly collection runs.
That's not true at all. The vast majority of the energy cost of going to another planet is incurred just getting into earth orbit. A space elevator radically improves the economics of interplanetary travel.
In fact, you can get certain transfer orbits "for free" by just extending your tether a bit beyond geosynchronous orbit and using it to fling bulk payloads to Mars, etc.
In "Blue Mars" by Kim Stanley Robinson, we get to a point where travel between Earth and Mars is faster than the elevator ride from the top of Earth's elevator to the bottom.
I could see Space Tourism taking off though. Taking space jet skis out for a spin round the moon and back that kind of thing. Perhaps some exclusive space hotel.