This idea is a bit of a stretch
and it certainly remains to be seen if it is even practical at all. Yet setting up on a four mile high mountain
near the equator would at least get rid of a large part of the early staging
problem. One could level off an appropriate peak to
provide a full building base while placing a transparent Mylar bubble on top to
hold the air at a viable pressure. In
fact why do we not do just that? It is
completely feasible to place staged elevators in the mountain to allow people
to come to the top of the mountain.
Once established so that breathability
is assured, it is then easy to begin building down the mountain in levels along
the best slope by simply extending the enclosed air space downward. One could even put condos up there. In fact this would be a fabulous development that
would be increditably popular. Who would
not want to live above the clouds?
Returning to the idea of a
lighter that air tower, we are on far trickier ground. If it could be engineered, we escape the need
for massive mass stealing strength in the lower levels and provide a structure
that can be used to allow a load to rise slowly inside an internal track way
holding space frame.
The problem is that once you are
at the apex of this tower, you still have zero actual velocity. You would need an airship to take up the load
to get it free for launching, and if you have that why would you bother with
all this? An airship large enough to
lift the load to these increditable heights is too large structurally to
survive and the same must be true for tower components.
It does beg at least one other very
good question. Why not simply use an
oversized weather balloon to lift large craft up to operational elevation? One could even use hydrogen. Actual launch point is not important with
present day computer capability. We need
simply a high thrust rocket engine and sufficient fuel to pop into orbit. That way the pilot simply blows the
connection at the same moment he lights the engines and maneuvers into an
insertion path on an angle away from the balloon.
This is certainly our day for
enthusiastic speculations.
Could 100 Kilometer high towers usher in the next space age?
JULY 29, 2011
A private European organization has
a proposal for creating 100-300 kilometer high multipurpose towers. The towers
would be composed of moveable lighter-than-air rings stacked upon each other.
Modules would be added from the bottom up and filled with a light gas. Shuttles
within the shaft could take people and payloads to the top, slowly but
inexpensively. In an interview with Sander Olson, Patrick Vankeirsbilk
describes how the first towers could become operational within a decade, and
could be used both for tourism and for getting payloads inexpensively into
space.
Patrick Vankeirsbilck
Question: How did the concept of the Spaceshaft originate?
The concept only emerged within the past five years or so. I was
approached by a business partner who worked on offshore oil platforms. He was
working on buoyant structures in the ocean, which he transposed into buoyant
structures in the atmosphere. He called this concept SpaceShaft, and we believe
that this concept could provide an inexpensive way to lift structures into
space, using current technology.
Question: And this shaft is a single structure?
Yes, but to reach Space there would be a need of multiple shafts
arranged inside one another and so combined into a telescopic system. The specs
of each shaft would depend upon their intended operational purpose, functional
requirements, the materials that will be used, etc. …. For example; shafts
intended to operate within dense atmospheric regions have requirements that are
different to those that will extend into thin density regions, and these have
also different material requirements that the shafts that are intended to reach
into space. Preliminary calculations which I have done indicate that with
current materials we could reach heights of 100 kilometers. Ultimately we
believe that structures as high as 300 kilometers are achievable.
Question: Would the shaft be made from Kevlar?
We are looking at kevlar or any other aramid-based fiber. We are
examining composite materials made from Mylar. The SpaceShaft won't require any
fundamentally new materials, such as carbon nanotubes. Composites currently
used in aircraft can withstand extreme compression, so we are looking for
partners who can provide the necessary computing resources and expertise to do
the necessary testing. The computer modeling should give us the confidence to
know that the materials can withstand the stresses.
Question: How would the SpaceShaft be constructed?
The basic concept involves using "lighter-than-air building
blocks", which are partially inflated with Helium. The building blocks are
basically converted science balloons that instead of having a payload gondola
they have a skeleton with the equivalent mass. The skeleton is used to provide
the geometry and mechanical functionality we ultimately need (as for the
assembly process or to resist the compressive conditions the structure
undergoes at altitudes where there is no longer buoyancy but pure weight).
Prior to the fabrication and deployment processes we calculate the needed
volume of the vessel as to keep the structure floating at a target altitude in
which buoyancy is cancelled by the weight. The typical altitudes will range
between 30 to 50 km.
Once the diameter of the sectional ring has been decided, we start
building up, from the surface of our planet, letting each building section
levitate enough (and under permanent control,) as to insert new building blocks
right underneath. Once tightly secured to each other; both sets are made to
repeat the described procedure. And so, with each new inserted module, even
more buoyancy is achieved, pushing up the entire structure above and piercing
through the weight barrier. The resulting artifact is not a tower, (because is
not standing on a surface, or has foundations,) but it could be compared to a
floating scaffolding structure. The beauty of this system is that we do not
have to do any construction work at high altitudes; it will all be done at
ground level-upwards, completely removing the imperative need of transporting
building components using flying vehicles or rockets.
Once a stack of these sectional rings have an altitude that equals that
of our original calculation for altitude, we know that the vessel at the top no
longer has the desired buoyancy. But because there is an accumulation of
buoyancy from underneath, the vessel will be jacked-up to a higher level and so
this effect is repeated for a known number of times, up to a chosen targeted
altitude, such that of the Karman line which is the official borderline that
delimits the aerodynamic atmosphere from space.
Question: Wouldn't helium be too costly to float this structure?
Using Helium exclusively is clearly not feasible; besides its cost, we
would need to consume up to 35% of the world's annual Helium extraction just to
deploy a one time SpaceShaft. Hydrogen gas is not an option, due to
flammability issues. And there is even another problem; some gas will leak out,
although we don't expect this to be a major problem if neglected. To resolve
these issues we are developing a mechanism by which the need of Helium can be
reduced by up to 50% of the total need and keeps the gas from escaping out to
the atmosphere due to desorption through permeation, (a process in which the
small molecular size of the He. atom finds a way out of the pressure vessel
through the porosity of the containing membrane).
Question: How well will the system handle the failure of an individual module?
The system will be designed to tolerate the failure of individual and
multiple modules.
…
Moreover, the SpaceShaft has the added benefit of being mainly buoyant
at low altitudes, (this is due to the inherent buoyancy of the HyperCubes,) and
so making it more unlikely to collapse. Which is a behavior opposite to that of
a compression structure, (that would first bend followed by collapse,) when a
significant number of modular failures are achieved. Furthermore, we also
envision the implementation of secondary systems to perform the necessary
maintenance on damaged modules, so that the entire system should be quite safe
to operate.
Question: How would you send people up the shaft?
Although there are windowed elevators on the outside of a SpaceShaft,
(that could provide for some form of entertainment, certainly the view alone
would be breathtaking,) these are mainly meant for localized maintenance and
would only climb through atmospheric altitudes located between sea-level and
mid height elevations. Actual transport to the edge of space will happen by the
service of a shuttle travelling within the conduit of the central shaft. For
sure both sets of elevators, external and internal, would allow tourists to
stop at the amenities on platforms built on the mooring hubs.
Question: What diameter would the SpaceShaft need to be?
The larger the diameter of the shaft, the stiffer it will be, and the
less effort that will be needed to keep it stable against side winds. To get a
better sense of the dimensions we are talking about, at sea level; the diameter
of the shaft will be about one kilometer, while at the top about 100 m, pretty
much like a gigantic tapered mast. It is important to underline that the system
is tapered because is telescopic in nature, (that the external tubular shafts
allow for the innermost ones to move vertically,) and that guy lines are also
used to force it to a vertical orientation.
Question: Couldn't you use the elevator as a pulley, to bring cargo to
the top with minimum energy?
Yes, but this configuration is so inefficient that it is a completely
undesirable mechanism. Whereas our system is designed to be a much more
efficient elevator system, in which a pair of active mechanisms are
simultaneously employed. The main mechanism, being that of the deployment
process itself, whereby payload is placed inside containing spaces of selected
HyperCubes that make up the sectional rings and are elevated together with the
whole structure while this is being jacked-up. Such a method follows a "first-in
to first-out" logic sequence (FI-FO). Although this is a relatively slow
uni-directional mechanism, it has extremely powerful lifting capacity, is
inexpensive, clean and is reusable. This method would allow for a CONSTANT FLOW
of sectional rings, (with their contained cargo,) to be dispatched at the top.
By doing so, we should be able to transport, in a continuous flow, thousands of
tons of cargo, (or rockets,) just by using this method. The other system
consists of a fast, bi-directionally travelling, hybridly powered shuttle.
However, with a significantly lesser carrying capacity, but still comparable to
current rocket systems and would also allow for passengers transport.
Question: How difficult will it be to fabricate these rings?
We have been in discussion with companies and some Universities here in
Belgium
Question: Assuming sufficient funding, how long would it take to
construct the first SpaceShaft?
Once the infrastructures to fabricate the building blocks and that for
the deployment of the rings are in place, I estimate that we could construct a
100 kilometer shaft within a year. Every hour or so, a ring could be placed
underneath the stack. We could have the necessary infrastructure within five
years. Material costs for a 100 km shaft would be about 40 million Euros, so
the entire 100 km structure would cost perhaps 40 million Euros to build. That
doesn't include, however, the costs of building the factory to fabricate the
building blocks. Such a factory could easily cost 60 million Euros or more. So
a very rough estimate is that we could create a 100 km SpaceShaft for 100
million Euros.
Question: What is your assessment of the space elevator?
We have studied the concept of the space elevator, and we hope that the
idea eventually comes to fruition. But there are a number of daunting and
unresolved technical challenges to creating such a space elevator. First, for
the tether, one has to fabricate huge quantities of carbon nanotube filaments.
Then, as to provide the counterbalance to stretch the tether, one has to have a
substantial counterweight at the top end-point of the system at a far away
distance nearing 140000 km. Then avoiding collisions with satellites would be
problematic. By contrast, the SpaceShaft paradigm is doable, now, with current
technology and compatible with "NASA's Proposal for a Balloon Assisted Launch
System”[[1]].
Question: What would the primary benefit of a 100 km SpaceShaft be?
The primary benefit would be to have a permanent and inexpensive means
of getting payloads, (and space vehicles,) up-to and from the edge of space. At
100 km, getting into orbit is much easier than from the ground. Space vehicles,
such as SpaceShipTwo or Pegasus XL, could then takeoff from the fly deck on a
tangential direction, (relative to orbital paths,) and so benefitting from the
gained free-ride velocity attained during the ascent. So the cost of getting
payloads into orbit using a SpaceShaft would perhaps be about 1% of the cost of
using conventional rockets.
Tourism is another market; since each SpaceShaft could easily
accommodate hundreds of tons of cargo on their fly-decks, and a craft operating
above the atmosphere wouldn't need landing gear, wings, or aerodynamic
surfaces. Space vehicles such as those previously mentioned could then takeoff
and travel from one SpaceShaft to the other in just a couple of hours. And so
we could provide intercontinental transportation without polluting the
atmosphere.
And we are even looking into the possibility of using high altitude
structures to change the planet's climate.
Question: How would the risk of collisions with planes and satellites
be addressed?
Obviously this structure would need to have warning lights, but also
have a surrounding no-fly zone, to keep away unauthorized visitors.
Furthermore, an Air Traffic Control service will be necessary.
Because your question involves two different flying environments, it
also deserves two answers; one regarding a dense region of the atmosphere and
one for a region that is of very thin density.
At dense atmospheric regions!
Since most parts of the system are buoyant, the structure could survive
a collision with a large object and falling debris are of concern at ground
level. If severed the top structure would go down slowly and special procedures
will be followed as to re-unite the sections. If there are multiple severed
sections; these would eventually become floating objects, laying on a resting
horizontal position, at altitudes anywhere between 25 and 50 km, from where
they could then be salvaged.
At thinly dense atmospheric regions!
Two severed section: Lower section remains standing. Upper section,
(found at heights outside the dense region of the atmosphere,) should quickly
fall down, loosing momentum and speed; this would eventually become a floating
object, finally laying on a resting horizontal position, (this final condition
would happen at altitudes anywhere between 25 and 50 km,) from where the
section could then be salvaged.
Question: Could a 100 kilometer SpaceShaft be fully operational within
a decade?
Assuming sufficient funding; we could even have a pair, or more, of
operational SpaceShafts within ten years. Even just having a pair of these
could allow us to have combined operations between both SpaceShafts; like
having a ferry transportation service occurring at LEO from one fly-deck to the
next.
It is important to recognize that since the beginning of written
history we have evidence of how skilled humans are in building increasingly
sophisticated and taller structures. Mostly these improvements have had major
steps forward thanks to the discovery on how to use the existing materials at
hand and with the very particular properties needed and the development of the
necessary newer techniques for their employment, and as a result achieving
incredibly new heights. So it is pretty much a matter of accepting the
engineering challenge in learning how to use the materials and developing the
construction skills.
The SpaceShaft concept isn't as ambitious as the space elevator but it
is much more feasible. For 130 million Euros we could design and construct a
100 kilometer tall SpaceShaft within a decade. Once we have SpaceShafts up and
running, the frontier of space will finally be open to humanity.
[1] www page; “Proposal for a Balloon
Assisted Launch System” at
http://space-academy.grc.nasa.gov/y2008/group-project/proposal-for-a-balloon-assisted-launch-system/
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