SPACE TUBE

Patent Application Number 2009761.4

BACKGROUND

At present, the only way we can get into space is with space rockets which are extremely expensive and dangerous. For this reason people are looking for alternatives and one of the most outrageous ideas is the Space Elevator. The idea being to lower a cable down from a geostationary satellite (35,786 km or 22,236 miles high) so space cargo can climb up this cable. The problem is that it is totally unpracticable with today’s technology as you need a cable so long 62,000 miles,100,000 km to go to a counter weight, beyond geostationary orbit, that it will break under its own weight.

Some people have proposed building a building a tower up into space but it would be a gigantic project that would be as difficult as the Space Elevator. As you will have to deal with tremendous compression forces and made it extremely wide at the base, at least 10 miles (16 kilometres) or more, to prevent it toppling over or being blown down by the wind. But this is only true, if conventional building methods are used.

Then there is the proposed ThothX Tower which is just a giant balloon 12 mile high. It would be so large that a runway can be built on top of it, but the design has problems with strong winds and 12 miles high is still well short of what is needed.

There are also space companies who are attempting to launch space rockets from aircraft. The problem with this is that the highest an aircraft can take a space rocket is about 7 miles. Whereas most satellites orbit the Earth between a 120 to 200 miles high. So 7 miles up is not a big advantage and this is why many space organizations don’t consider an air-launch.

A tube or mast would be a lot smaller and cheaper than a massive tower but the objections to this, is that a mast has to be held up with guy cables to prevent the wind blowing it over, and there is a limit in how high you can take them. The highest was the Warsaw Radio Mast which was 646 meters, or 0.4 of a mile in height.

Then there still be a problem of compression forces that will bend and buckle the mast if it goes up too high. Nowadays we have light materials like carbon fibre. Though it will be epoxy resin that is mixed with carbon fibre, that will be taking the compression load, and manufacturers claim it can be made harder than concrete. Then there are lighter materials like graphene which hasn’t been mass produced yet. Although many pressure vessels are made from composite material like steel or aluminium reinforced by carbon fibre. Metals have the advantage of being as strong in tension as they are in compression.

But this is not the only problem, any slight bend in the tubes, will be made far worse by the compression forces bearing down on it. Then there is the problem of the tube from being blown over by strong winds like gales and hurricanes.

It is these problems that need to be solved, to make a Space Tube possible.

ABSTRACTION

Pressurised tube

All the problems of a space tube that can reach up into space, can be solved with a pressurised tube, lighter building materials and active support. Although the pressure in a pressurised tube can help resist downward compression forces and buckling the walls of the tube. It still has the weight of an extremely long tube bearing down on it. But the pressurised air in the tube can also provide sideways and upwards force to keep the tube vertical and counter compression forces. It is this that will take the place of guy cables to keep the tube upright. So how high can something like this go? It seem it can go up a very long way.

Nowadays people can buy compressors and pressure tanks for air-guns and scuba gear that compress air up to 4,500 psi or 300 bars. As normal air pressure at sea level is about 14.5 psi, or 1 bar, if the tube at ground level is pressurised by compressors, then it will be possible to keep high air pressure a long way up an extremely long tube.

The troposphere is about 7 miles or 12 kilometres high, so in theory if the tube at the base is pressurised to 4,500 psi or 300 bars, the troposphere could be extended up in the tube, 300 times that height, which will be 2,100 miles or 3,600 kilometres high. This is as high as geostationary orbit. Though the pressure at the top of the troposphere and therefore the tube, will be about only 10% of the air pressure at sea-level.

But industry uses pressure vessels with far greater air pressure, for instance, titanium pressure vessels are capable of holding between 30,000 psi to 200,000 psi. A Space Tube with 43,500 psi or 3,000 bars at its base could deliver normal sea level pressure up to geostationary height. So it suggests it can be done, a extremely long pressurised tubes that can be extend a long way into space, with today’s technology.

Although in theory, a pressurised tube could make it all the way up to geostationary orbit, it will be a big project costing a lot of money. So before doing that, there is a more modest target that would be a lot easier and cheaper, and that is low orbital height of 120 miles high (190 kilometres). A pressurised tube of 300 bars could probably deliver between 1-2 bars of air pressure at that height. While 30,000 psi or 2068 bars would deliver 7 times that amount of air pressure.

So a pressurised tube can deliver to this orbital height, the upper stage of rockets, that do not have to be fired up there by really large throw-a-way rockets. At that height, it can accelerate horizontally with no air resistance and without needing to push upwards enormous fuel tanks a hundred miles.

The objection to this, is that surely an extremely high tube would fall over and normally that would be true. But a pressurised tube can use a variety of different ways to to keep it vertical, while at the same time provide upwards lift to counter compression forces. The pressurised air in the tube can be vented outside to give both sideways and upwards push, to the whole structure.

The thrust of compressed air can be increased with electric propulsion like Arcjets, Resistojets or even a Ion drive. These can be powered from electric cables from a ground based power station. Electric fans or propellers can also use the compressed air to give greater push where the atmosphere is too thin for propellers to operate. Even lighter-than-air gases like methane or hydrogen can be pumped up the tube and the gases can be burnt in combustion chambers along with compressed air, to blast out with the thrust of a jet-engine.

Venting air out of the tube will create a strong upwards air current and this can be utilized, with fixed curved blades shaped like a fan. As the air comes up the tube the fixed blades will turn the air sideways creating upwards lift or use autorotation rotors. Downward facing aerofoils can also use the upwards air currents in the tube to give sideways push to help keep the tube upright.

Also, lightweight reaction wheels can be used. These are used by satellites like space telescopes to turn the satellite in whatever direction that is needed, by changing the speed of their spin. Although they are light weight they can be very powerful if the revolutions are high. Which they can be, if using electricity from electrical cables from the ground.

Reaction wheels are used not only on satellites but people can use them to balance things like poles. So they would be perfect to balance a tube in the thin air of the upper atmosphere above the weather where there are no strong winds. Though in the troposphere where there will be less an issue about weight, reaction wheels can be made heavier to have the power to counter any swaying movement by the tube.

Though probably downward facing aerofoils would probably be more effective in the pressurized air of the lower tubing. While reaction wheels will be more effective further up as the air pressure in the tube decreases.

DETAILS

Probably the best way to engineer a tube like this is to build it similar in shape to the Eiffel Tower, with a wide base and a cone like shape going up to top of the troposphere and then a straight tube after that. But a wide cone, could dramatically add cost to the whole project so a straight tube would be easier to build and can be kept upright in the troposphere with jet thrusters, heavy weight reaction wheels or downward facing aerofoils.

Jet thrusters will have more power than any strong wind like gales, cyclones or the jet-stream blowing against the tube. The gases can be burnt in combustion chambers along with compressed air, to blast out with the thrust of a jet-engine. There can be 4 or 5 of them around the tube with perhaps gimbaled nozzles and only used when the wind becomes too strong for reaction wheels or aerofoils. There will have to be more on the tube that is really needed, in case, some of them don’t work properly when switched on.

Obviously it wouldn’t be a good idea to have these thrusters on all the time and they can be used only where there are strong winds. They can be controlled by movement and pressure sensors, gyroscopes, computers, anemometers and wind vanes. Nowadays, technology like this is used to keep small multi-copters stable, as well as rockets as they leave the launch pad.

An alternative to jet thrusters are fans, compressed air from the tube can be boosted by a fan or propeller when vented out of the tube. The problem with this, is that there will be a big difference in pressure between the pressurized air in the tube and the air outside the tube, especially if it is in the thin air of the upper atmosphere. So the air will come out of the vent holes extremely fast and so it would need a extremely high speed propeller to be propel this air even more quickly.

The way around this is to vent the air downwards into a diffuser, a cone shaped tube, which will decelerate and expand the air. Then a fan or propeller just inside the wider mouth of the cone, can accelerate the air once again, giving more lift.

Above the troposphere the tube will be above the weather so hopefully gas jets won’t have to be used. The thrust of compressed air can also be increased with electric propulsion like Arcjets, Resistojets or even a Ion drive. On spacecraft these are powered by solar panels which are limited in power. Whereas a Space Tube wouldn’t have any such restrictions as electric jets can be powered from electric cables from the ground. The advantage of electric jets is that they would be far less bulky than a large diffuser and fan and there is no need to pump gas up the tube if using gas jets. All that is needed is an electric cable to power them.

Some people might object that venting air out of the tube will greatly reduce its air pressure, and it will to some degree. But if the amount of air escaping is controlled and calculated, then the compressors on the ground can compensate for the lost air and keep the pressure high by having more compressors, pump extra air into the tube.

Although pressurised tubes made from carbon fibre will be able to resist downwards compression forces to some degree, a tube of a hundred miles or more, will become extremely heavy. So any upwards lift that can be gained with any type of thrusters or fixed vanes will be make it possible for the mast to be longer. All these things will be needed to keep the tube upright and resist downward compression forces.

So the supply of compressed air is important but will be drained off to power thrusters of various types, but this is not as bad as it seems. The water supply in any town is being drained off all the time by all the houses and businesses in the town. Yet the water industry can still keep the water pressure consistent through the use of water towers.

The same will be true in a Space Tube, providing the compressors can keep the pressure in the tube consistent on the ground, then air will always flow upwards to to replace any air vented out of the tube. So there needs to be pressure sensors in the tube, so if the pressure has decreased, then computers will automatically switch on more compressors.

But if that is not enough and too much air is vented out of the tube, then the air pressure on the ground can be increased. This means the lower tubes need to be stronger so high pressures can be used. Which is not a bad thing as the lower tubes need to be strong to resist downward compression forces anyway. So the air pressure can be extremely high in the lower tubing but made a lot less higher up, by venting air and so being able to have lighter tubing in the upper atmosphere.

Venting air out of the tube will also have another advantage, as it will create a upward current of air that can be used to help lift the tube. Curved vanes shaped like fan blades but fixed to the walls, will deflect the up coming air sideways and create lift. This will also create a vortex effect in the tube and this can be utilized by another fixed fan above it, angled in the opposite direction, which can use the upwards spinning air to create even more lift. There can be any number of these fixed vanes going up inside the tube.

The fixed vanes will slow down the air but it will be only a temporary effect as the air will speed up because of the air pressure underneath it, and the air being vented from the tube above it. The design of these fixed vanes may have to change to deal with different air pressures. Near the base the high air pressure will be greater than surface water, so the design of the vanes would probably look more like ship’s propellers and will be as powerful, in the high air pressure. But further up the tube the air pressure and speed of the upward air will decrease and so the design of the fixed vanes will have to change to be the most efficient in these conditions.

Instead of fix vanes autorotation rotors can be used instead. This is how helicopters can glide if they lose power, the rotors are angled downward so the rotors can turn and give the helicopter lift. Autogyros do the same thing. This would probably give more lift than fix vanes. Though the advantage of fix vanes is there is no moving parts, so nothing can go wrong with them.

The upward flow of air can also give sideways push through downward facing aerofoils. Some people would question if aerofoils would work in an enclosed tube but we have to remember that aerofoil designs are tested in wind tunnels. Which are enclosed tubes of either a square or round shape, where they measure the lift of these aerofoils in these tunnels.

There are two ways of doing this. The first is to put the downward facing aerofoil in ball-bearing or ball-roller rings around the inner surface of the tube. So the aerofoil can be turned in whatever direction to counter any swaying movement or the force of the wind. They would have to be symmetric aerofoils like the tail fins of an aircraft, so it can turn like a tail fin to give sideways lift, in either direction or go into a vertical neutral position when the tube is stable. Although this would be an efficient design it would be hard to get to, if anything goes wrong with it. As it will be within a pressurised tube that humans can’t access.

The alternative to this, would be to have two downward facing aerofoils, at a 90 degrees angle to each other. So both aerofoils can work together to counter any sideways movement by the tube from any direction. There can be a reasonable gap between them to lessen the turbulence created by the lower aerofoil on the upper one. This design wouldn’t be so efficient, but less that can go wrong with it. The turning shaft that creates the angle of attack for the aerofoils, can go right through the walls of the tube to servo motors and computers on the outside of it. This then means the set-up is partly repairable if anything goes wrong with it. Again it will be guided by movement and pressure sensors, anemometers and wind vanes.

Gas jets would give both a upwards as well as a sideways push but they would have to be switched on all the time to do this. Though if needed, perhaps if the gas that is burnt is hydrogen which means mostly water will come out of its exhaust, and that might be more acceptable. Perhaps they can be use only when a spacecraft or some other cargo is being lifted up the tube to give it more stability and the ability of the tube to carry up a heavier cargo.

In the lower tubing fixed vanes and downward face aerofoils will be very effective in the pressurized fast moving air. But further up the tube, the speed and air pressure will gradually drop away and reaction wheels will then become more effective in keeping the tube vertical.

There is a case for making the base of the tube wider than the top which will help keep up the pressure in the tube, the higher it goes. But this will make constructing the tube complicated and more expensive, while straight tubing will be a lot easier and any gains by reducing the diameter of the tube can be compensated for, by increasing the air pressure at the bottom.

Then there is the problem of transporting spacecraft up in the tube and there are many options. One possibility is to have another tube within the main tube and spacecraft can be transported within it, at normal air pressure. Or perhaps even push a spacecraft up with compressed air. In the 19^th and 20^th centuries there was pneumatic tube transport, where mail was transported through tubes by air pressure. Air pressure trains were proposed then, but were never successfully built.

The only problem with this, is that it is another extremely long tube will greatly add to the weight to the whole structure. Though surprisingly it will also add a upwards force. Because if the bottom of the tube is off the ground, then it will float upwards.

The pressure in the tube will be more than surface water and so a hollow tube can float in it. If there is a gap between the bottom of the inner tube and the ground and the outer tube is pressurised to something like 300 bars. Then there will be a upwards pressure of 300 bars underneath the tube while the other end of the tube is open and in space, so there won’t be any counter pressure on top pushing down, although there will still be the weight of an extremely long tube.

The fixed curved vanes and downward facing aerofoils can go around the inner tube in the gap between the inner and outer tube, fixed to the walls. Another advantage it could have is that because spacecraft will be going up inside the tube then rotors can be used on the outside of the tube, to keep the tube upright in the troposphere rather than use jet thrusters.

Taking a spacecraft up on the outside of the tube would be difficult as it will have to go pass thrusters and reaction wheels. The way around this is to put the reaction wheels out of the way, inside the tube. Though this will mean the reaction wheels operating in compressed air with air friction slowing them down. But that shouldn’t be too much a problem as it will only use up a little more electricity. Or the reaction wheels can be boxed in with panels around them.

The bigger problem is that if any break down, then it would be very difficult to get to, to repair them. But this is also the problem with reaction wheels on satellites and there is not a lot that can go wrong with them. Though some have gone wrong on satellites, but manufacturers now have the knowledge of why they went wrong.

Even gas thrusters can put inside the tube with only the nozzle outside, though thrusters can also be pointed downwards on the side of the tube and so won’t stick out too far. And any side push can be obtained with thrust vectoring. So the nozzle can be manipulated to move in different directions. This is possible with VTOL aircraft and gimbaled nozzles on rockets. Though the nozzles on these jets need to be always angled away from the tube to prevent any damage.

Then there is the problem of that taking up a spacecraft on the outside will unbalance the tube and there needs a counter weight, like another spacecraft, on the other side. The spacecraft can use the crawlers invented for the Space Elevator to climb up the outside of the tube, but using bars or rails instead of cables. It can also be powered from a small electric rail like a train using a pantograph to transfer power from electric line or track to the vehicle.

The problem of needing two spacecraft going up together to balance the tube, can be solved by the spacecraft being pushed up in some form of climbing vehicle, which has its own thrusters and reaction wheels on it, to balance it. There will be a limit in how heavy a payload a tube can take up into space but that can be greatly increased by rocket power. The vehicle can have on it, first of all, rockets designed to work best in the thick atmosphere of the troposphere, or use a jet engine.

So the rocket will be on the vehicle and the nozzles angled so it doesn’t damage the tube or anything it is pulling up. As at the same time it is pulling up a train of fuel tanks and using the fuel in the tank at the bottom first. Then as each tank’s fuel is used up, it can be released and allowed to drop down the climbing rail. Along with the rockets or jet-engines that are no longer needed. As it goes into the upper atmosphere, it will now it will now use a rocket optimised for the stratosphere and higher and so take it up to the top of the tube.

The descent of fuel tanks and rocket or jet motors, can be slowed down and stop near the ground by magnetic brakes, that are used by drop towers in funfairs. As the rocket is supported by the tube it doesn’t have to try to obtain escape velocity, while punching through the thick air of the troposphere, carrying tons of fuel. It can go up a lot more slowly.

The vehicle will also be using the power of electric motors from electricity from the ground delivered by and electric rail and a pantograph, so it won’t be only be dependant only on the rocket alone for upwards push. Then when the vehicle has delivered the spacecraft it can also drop to the ground and its fall will again be stopped by magnetic brakes near the ground. As the tube is stronger near the ground more weight can be pushed up, but then as the fuel tanks drop down, the weight will decrease but at the same time, the tube becomes more lightly built. So a pressurised tube could deliver genuine reusable rockets and fuel tanks.

Although by having a tube near low orbital height a rocket should be launched horizontal. But it would be complicated to do this. So it would be better to still launch a rocket vertical with again nozzles angled away from the tube and when the rocket is clear of the tube, to then use side thrusters or reaction wheels to turn the rocket nearly horizontally in space. Then switch to full power to obtain orbital speed.

Although a runway might be possible if a large amount of compressed air can be delivered to the top of the Space Tube. Then this compressed air can be vented downwards through a number of vents underneath the runway to support it. Electric jets or fans using the compressed air, along with long braces from the tube, will also be help to support it. Though it will also need a small crane or hoist on the runway to turn the spacecraft horizontally.

A large platform on top of the tube can be used for many other things like different types of telescopes or house scientists who want to study space.

Another big advantage of going up on the outside of the tube is that the climbing rails can take up a viewing platform as well. Nowadays there are observation towers with a moving observation platform right around the tower. So to have a observation platform that can go right up into space would be a great tourist attraction.

There will have to be a big gap between the viewing platform and the outside of the tube so it can pass thrusters, gas pipes, electric cables and sensors. A moving platform would also be a great help for maintenance to allow workmen to access the thrusters, cables, pipes, computers etc. If anything go wrong. It can also take up scientists, as well.

There are a few complications having one tube and perhaps some of them can be solved by having three or four tubes. The big advantage of this is that all the tubes can be tied together with struts and braces like a lattice mast, giving it structural stability. Then rockets and other cargoes can be transported up between the tubes and large reaction wheels can be put on the outside of the mast attached to either the struts or tubes.

Perhaps in the troposphere large rotors can replace large reaction wheels. These would be more powerful in dealing with strong winds and perhaps could replace gas jets. They could be attached to each tube and be able to turn 90 degrees or 120 degrees, (depending if it is a 3 or 4 tube mast). It would also help to have reversible rotors that can move air backwards or forward depending on the direction of the wind. It would also help to stagger the height of the rotors so the turbulent air from one rotor won’t interfere with another one.

It would even be a bit help with maintenance as one tube can be shut down and worked on, while it is being supported by the other three tubes that are still active.

The only drawback with this is that one large tube will have far more compressed air in it, for the same weight than 3 or 4 smaller tubes. So therefore have more power to overcoming compression forces by venting more air downwards. This means a compressed tube lattice mast, may not be able to go as high as just one large single tube unless the the compressed air inside the smaller tubes is a lot higher.

So just one large tube is the best solution because of the power-to-weight ratio, even if it creates a few complications like sending up space cargo on the outside of the tube. The power-to-weight ratio will also increase by making the diameter of the tube larger. This is because the area of a circle will increase a lot more in relationship to its circumference.

BUILDING A SPACE TUBE

The obvious material to construct it all would be carbon fibre as it is used in pressure vessels and is between four and five times lighter than steel, while holding in the same amount of pressure. Though graphene and other new materials could be even better, once they are mass produced. The trouble with carbon fibre is that although it has high tensile strength it is not so strong in compression. This suggests that there might be a case for using metals which are as strong in compression as in tension. So perhaps aluminium reinforced with carbon fibre in a geometric truss design might be a possibility.

Steel and other hard metals can also be used in joints and around the holes where the thrusters are fixed to the tubes and perhaps even used for the lower tubes. There will be greater internal pressure near the ground than at the top, so the tubes can be made heavier at the bottom and lighter as it rises higher. Then there is the problem of building it. There is no way it can be built like a normal building, it would be impractible to have steeple jacks constructing it, in the tratosphere, in space suits. So a better way is build the top first then jacked it up and then put tubing put under it and jacked it up again, and so on.

That creates another problem because the lightly constructed top tubes will have to go through strong winds of the troposphere. So the best way to deal with this, is to build the more robust tubes of the troposphere first.

The less joints for the whole tube, the better, because joints add weight and air can leak from them. Carbon fibre tubes can be joined together with a inner ferrule tube but it is important that the tube can sway and move without breaking. The problem with carbon fibre is that it is a very stiff material so some of the joints need to be able to move. So there has to be some play in some of the joints and the gaps filled with rubber O-rings.

So to build it with long tubes it best to build it in a tall building that is wide enough to lift upright tall tubing and start off with the tubes near the top of the troposphere. So this tube will be jacked up to the top of the building and another tube put underneath, and so on, but sooner or later the tube will encounter strong winds and need jet thrusters to keep it upright. Things like fixed vanes, downward facing aerofoils cannot be put in at this stage of the constrution. While reaction wheels can only be used on the outside of the tube. So this means temperary rotors can also be used as well to keep the tube upright.

The problem with jet thrusters is they have been designed to work in compressed air. There are a few way to tackle this problem. The first is to have small jet engines instead of jet thursters. Though at a later date the jet-engines will have to be removed and thrusters take their place. Or use rotors or propellers to keep the tube upright. The final way, is to pressurise the tube as it is being constructed. Which will mean putting a temperory cap on the top troposphere tube.

The only way to do this would be to pressurize the whole building. But no human can work in air that is pressurized too much, so the construction will have to be done with robots, like used in car factories. The tubes will have to be brought into the building through a long air-lock and the tubes fixed together with quick-action couplings.

On top of the building there will be a pipe the same diameter as the couplings. The tube is pushed up these pipes to a platform above. Now, the diameter of the tubes and the couplings are going to be different which means when the couplings come out of the top of the tube, the gap is filled with two halves of a metal plate with two half circles cut out of them, that are pushed together with hydraulic pressure to fill in the gap. It can be opened again when the next coupling comes up.

Once the tube is above the platform the side thrusters can be put on. The thrusters will be an issue because compressed air will be rushing out of the holes they go into and the pressure will badly hurt any human that got in the way. So when the vent holes appear above the platform, the thrusters will again have to be fixed into place with a robot using hydraulic power, either screwing them in or again using quick-action couplings.

Once the more robust tubes are constructed the lighter tubing above the troposphere can be construct inside the troposphere tube. This then will mean that upper atmosphere tubing will have to be of a smaller diameter to fit inside the troposphere tube. One objection to this and that is the upper atmosphere tubing could block off the vent holes feeding the thrusters of the troposphere tube. But upper tubing will have its own vent holes in them and there has to be a gap to put in coupling joints.

This will mean there has to platform at the top of the troposphere tube. But that can be a viewing platform taken up on climbing rails. Working in the thin air of the upper atmosphere is not a job for humans so again it will need robots to do this. The lid on the top troposphere tube will have to be taken off and the top tube pushed through which would have its own lid on it. Robots again will put on the side thrusters when their holes appear above the platform as well as electrical cables, motion sensors and computers.

It it was decided to put a platform or runway on top of the tube then it will be best to be build it now. As the tube becomes longer it will become heavier and will probably need all the downward thrust of all the thrusters to help lift it up so more tubes can be put underneath it. It will certainly need this lift when the final part has to be lifted up out of the troposphere tube and fixed to the top of it.

Then there will be the problem of putting fixed vanes, downward facing aerofoils and perhaps heavy duty reaction wheels in the troposphere tubing. The lighter reaction wheel will have already been put into the tube above the troposphere along with fixed vanes and aerofoils. All these things can be taken into the tube through the airlock, then taken up the inside of the tube with the same climbing platform used to lift the final section of tube. So there will have to be climbing rails inside the troposphere tube.

It will be the same if it was decided to have a inner tube to take up spacecraft. The inner tube can be built with the upper outer tubing in the upper atmosphere tubing. Then the inner tube in the troposphere tube can be put in afterwards along with fixed vanes and aerofoils as well as a air-lock near the bottom. Then all the pressurized air in the inner tube can be released.

The same principles can apply if building a lattice mast out of pressurized tubing. The tubes can be joined on top of each other in the part of the building that has compressed air in it. Then the struts, braces, rotors, reaction wheels and thrusters can be put together when the four tube come out of four holes on the top of the compressed air section.

There is a case for putting a light outer tube over the pressurized tube to cover things like electrical cables, gas pipes, computers and sensors. This can be put on later using the maintenance platform. The problem is that in a tube of a hundred miles, even a light outer covering can end up weighing many tons overall. Though all things fixed to the outside of the tube will need some sort of covering so it might be an option.

FUTURE POSSIBILITIES

The tube or mast can be used like a satellite and broadcast TV and radio, as well as being used like a weather satellite or observatory. Once a tube going up to low earth orbit has been built and in operation, then the experience of doing this will make it possible to know if going further is feasible.

One of the big problems for a Space Tube is the number of satellites and space junk in orbit. The Space Tube will be going at the speed the Earth rotates at about a 120 miles in height. Satellites and space junk will be moving at speeds up to 17,000 mph, so a Space Tube would be a sitting duck. Whereas anything below low Earth orbit will end up falling back to Earth and burning up. This suggest a Space Tube would be safer being below low Earth orbit.

Although there is big benefit to get to geostationary orbit but that is 35,786 kilometres or 22,236 miles high. This will mean being able put satellites in orbit with just thrusters. It also means the Space tube could transport cargo back to Earth without needing heat sheilds. Which will make space mining possible.

Perhaps the tube can avoid any satellites and space junk by swaying. After all a tube over a hundred miles high or more, can sway a long way side by side. So the thrusters can move the whole tube a many meters to get out of the way of anything in orbit that might crash into it. This might be possible if everything in orbit is tracked.

Though the mast will still be in danger of very small space junk like small pieces of metal that can puncture the walls of the tubes. Though workmen on the maintenance platform can probably fix any hole in the tube there is a danger of space debris doing more damage than that.

So the tube will probably need a Whipple Shield that protects many satellites today, but also adds to their weight. So the tube will end up with a lighter outer tube. Though the effectiveness of the Whipple Shield might be increased with air pressure between the shield tube and the main tube.

It may be possible for the Space Tube to get to higher by simply making it larger. An 8 meter diameter tube would have a circumference of 25 meter and a area of 50 square meters, so the area would be twice the circumference. Whereas 16 meter diameter tube would have a circumference of 50 meters but have a area of 202 square meters. So the area would be 4 times the circumference.

This means that as the tube diameter increases the volume of air in the tube will increase more than the weight of the tube. So the increasing the diameter of the tube will make the power-to-weight ratio higher. This suggests the way to make the Space Tube more effective is to just build them larger. Although lighter building materials like graphene and a increase in air pressure within the tube, will also help.

A larger tube might allow a pneumatic tube to be put inside it and it can be used like a giant air gun. So a spacecraft can be accelerated up the tube using air pressure underneath it, without needing rocket propulsion.

Perhaps the Space Tube might make the Space Elevator possible. They could work together where the Space Tube reaches a height where a cable from a Space Elevator to the Space Tube will be of a length that won’t break. One advantage of this is that a cable is less likely to be hit by space junk than a large tube, at orbital height.

CLAIMS

1) High air pressure can be extended all the way into space in a extremely long tube pressurized by compressors from the ground.

2) The air pressure in the tube can be used to give both upwards and sideways force to keep the tube upright and overcome downward compression forces from the weight of the tube.

3) Upwards and sideways force in the tube is created by venting the air out of it, or using the upwards current of air, created by the venting, to give aerodynamic push by fixed vanes or aerofoils.

4) Gas jets, electric thrusters, fans, propellers, fixed vanes, autorotation rotors, aerofoils and reaction wheels guided by computers, gyroscopes and sensors can also be used to keep the tube upright and help overcome downward compression forces.

5) Rockets, spacecraft, cargoes, observation platforms all can be transport up to the top of the tube into space.

6) The Space Tube can be used to broadcast TV and radio as well as weather data and even telescopes of various kinds can be put on top of it, on a large platform.

7) A Space Tube and Space Elevator can work together so a cable from a Space Elevator can be lowered to the Space Tube and so shorten the length of cable from the Space Elevator.

8) A Space Tube can have a pneumatic tube inside it to push up spacecraft with air pressure.