Space elevator economics
Encyclopedia
Space elevator
economics compares the cost of sending a payload into Earth orbit via a space elevator with the cost of doing so with alternatives, like rocket
s.
launch to about US$
40,000/kg for a Pegasus
launch (2004). Some systems under development, such as new members of the Long March
CZ-2E, offer rates as low as $5,000/kg, but in between 1988-1998 had failure rate
s close to 30%. Various systems that have been proposed have offered even lower rates, but have failed to get sufficient funding (Roton; Sea Dragon
), remain under development, or more commonly, have financially underperformed (as in the case of the Space Shuttle
). (Rockets such as the Shtil-3a
, which offers costs as low as $400/kg, rarely launch but it has a comparatively small payload, and is partially subsidized by the Russian navy as part of launch exercises.)
Geosynchronous rocket launch technologies deliver half to a third as much payload to geosynchronous orbit than to LEO
. The additional fuel required to achieve higher orbit severely reduces the payload size. Hence, the cost is proportionately greater. Bulk costs to geosynchronous orbit are currently about $20,000/kg for a Zenit
-3SL launch.
Rocket costs have changed relatively little since the 1960s, but the market has been very flat. It is, however, quite reasonable to assume that rockets will be cheaper in the future, particularly if the market for them increases. At the same time, it is quite reasonable to assume the market will increase, particularly if rockets become cheaper.
Disposable rocket costs are significantly affected by production volumes of the solid parts of the rocket, and by launch site costs. Intuitively, since propellant
is by far the largest part of a rocket, propellant costs would be expected to be significant, but it turns out that with hydrocarbon
fuel these costs can be under $50 per kg of payload. Thus, the more launches a system performs the cheaper it becomes. Economies of scale mean that large production runs of rockets greatly reduce costs, as with any manufactured item, and reuseable rockets may also help to do so. Improving material and practical construction techniques for building rockets could also contribute to this. Greater use of cheap labour (globalisation) and automation is practically guaranteed to reduce manpower costs. Other costs, such as launch pad costs, can be reduced with very frequent launches.
received funding from NIAC
from 2001 to 2003 to write a paper, describing a space elevator design. In it he stated that: "The first space elevator would reduce lift costs immediately to $100 per pound" ($220/kg). However, as with the initial claims for the space shuttle
, this is only the marginal cost
, consisting of the electricity
required to lift the elevator payload, but not operating overhead and maintenance; whereas the fixed cost
s would be US$6 to 12 billion, for construction; and one-way designs (such as Edwards') will add to the cost of the elevators.
The gravitational potential energy of any object in geosynchronous orbit (GEO), relative to the surface of the earth, is about 50 MJ (15 kWh) of energy per kilogram
(see geosynchronous orbit
for details). Using wholesale electricity prices for 2008 to 2009, and the current 0.5% efficiency of power beaming, a space elevator would require USD
220/kg just in electrical costs. Dr. Edwards expects technical advances to increase the efficiency to 2%. It may additionally be possible to recover some of the energy transferred to each lifted kilogram by using descending elevators to generate electricity as they brake (suggested in some proposals), or generated by masses braking as they travel outward from geosynchronous orbit (a suggestion by Freeman Dyson
in the 1980s).
For the space elevator, the efficiency of power transfer is just one limiting issue. The cost of the power provided to the laser is also an issue. While a land-based anchor point in most places can use power at the grid rate, this is not an option for a mobile ocean-going platform. A specially built and operated power plant is likely to be more expensive up-front than existing capacity in a pre-existing plant. Up-only climber designs must replace each climber in its entirety after each trip. Some designs of return climbers must carry up enough fuel to return it to earth
, a potentially costly venture.
is often quoted as part of the launch price. A comparison can therefore be made between the marginal cost
s of fully or partially expendable rocket launches and space elevator marginal costs. It is unclear at present how many people would be required to build, maintain and run a 100,000 km space elevator and consequently how much that would increase the elevator's cost. Extrapolating from the current cost of carbon nanotube
s to the cost of elevator cable is challenging.
Space elevators have high capital cost but presumably low operating expenses, so they make the most economic sense in a situation where they would be used to handle many payloads. The current, inelastic launch market may not be large enough to make a compelling case for a space elevator, but a dramatic drop in the price of launching material to orbit would likely result in new types of space activities becoming economically feasible. In this regard they share similarities with other transportation infrastructure projects such as highway
s or railroads. In addition, launch costs for probes and craft outside Earth's orbit would be reduced, as the components could be shipped up the elevator and launched outward from the counterweight
satellite. This would cost less in both funding and payload, since most probes do not land anywhere. Also, almost all the probes that do land somewhere have no need to carry fuel for launch away from their destination. Most probes are on a one-way journey.
, ariane, etc.), documenting this. Russian space tourism
does partially fund ISS development obligations, however.
It has been suggested that governments are not usually willing to pay the capital costs of a new replacement launch system. Any proposed new system must provide, or appear to provide, a way to reduce overall projected launch costs. This was the nominal impetus behind the Space Shuttle
program.
Alternatively, according to a paper presented at the 55th International Astronautical Congress in Vancouver
in October 2004, the space elevator
can be considered a prestige megaproject
and the current estimated cost of building it (US$6.2 billion) is rather favourable when compared to the costs of constructing bridges, pipelines, tunnels, tall towers, high speed rail links, maglevs and the like. It compares well to the costs of other aerospace systems as well as launch vehicles.
For comparison, in potentially the same time frame as the elevator, the Skylon, 12,000 kg cargo capacity spaceplane (not a conventional rocket) is estimated to have an R&D and production cost of about $15 billion. The vehicle has about the same $3,000/kg price tag. Skylon would be suitable to launch cargo and particularly people to low/medium Earth orbit. Early space elevator designs move only cargo, although to a much wider range of destinations. Later, tourism would seem possible as safety parameters are established.
Space elevator
A space elevator, also known as a geostationary orbital tether or a beanstalk, is a proposed non-rocket spacelaunch structure...
economics compares the cost of sending a payload into Earth orbit via a space elevator with the cost of doing so with alternatives, like rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
s.
Costs of current systems (rockets)
The costs of using a well-tested system to launch payloads are high. Prices range from about $4,300/kg for a ProtonProton rocket
Proton is an expendable launch system used for both commercial and Russian government space launches. The first Proton rocket was launched in 1965 and the launch system is still in use as of 2011, which makes it one of the most successful heavy boosters in the history of spaceflight...
launch to about US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
40,000/kg for a Pegasus
Pegasus rocket
The Pegasus rocket is a winged space launch vehicle capable of carrying small, unmanned payloads into low Earth orbit. It is air-launched, as part of an expendable launch system developed by Orbital Sciences Corporation . Three main stages burning solid propellant provide the thrust...
launch (2004). Some systems under development, such as new members of the Long March
Long March rocket
A Long March rocket or Chang Zheng rocket as in Chinese pinyin is any rocket in a family of expendable launch systems operated by the People's Republic of China. Development and design falls under the auspices of the China Academy of Launch Vehicle Technology...
CZ-2E, offer rates as low as $5,000/kg, but in between 1988-1998 had failure rate
Failure rate
Failure rate is the frequency with which an engineered system or component fails, expressed for example in failures per hour. It is often denoted by the Greek letter λ and is important in reliability engineering....
s close to 30%. Various systems that have been proposed have offered even lower rates, but have failed to get sufficient funding (Roton; Sea Dragon
Sea Dragon (Rocket)
The Sea Dragon was a 1962 design study for a fully reusable two-stage sea-launched rocket. The project was led by Robert Truax while working at Aerojet, one of a number of designs he created that were to be launched by floating the rocket in the ocean...
), remain under development, or more commonly, have financially underperformed (as in the case of the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
). (Rockets such as the Shtil-3a
Shtil'
Space launch vehicle Shtil Space launch vehicle Shtil Space launch vehicle Shtil (Russian: (Штиль - calm (weather)), is a converted SLBM used for launching artificial satellites into orbit. It is based on the R-29RM designed by State Rocket Center Makeyev and related to the Volna Launch Vehicle....
, which offers costs as low as $400/kg, rarely launch but it has a comparatively small payload, and is partially subsidized by the Russian navy as part of launch exercises.)
Geosynchronous rocket launch technologies deliver half to a third as much payload to geosynchronous orbit than to LEO
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
. The additional fuel required to achieve higher orbit severely reduces the payload size. Hence, the cost is proportionately greater. Bulk costs to geosynchronous orbit are currently about $20,000/kg for a Zenit
Zenit rocket
Zenit is a family of space launch vehicles designed by the Yuzhnoye Design Bureau of Ukraine. Zenit was built in the 1980s for two purposes: as a liquid rocket booster for the Energia rocket and, equipped with a second stage, as a stand-alone rocket...
-3SL launch.
Rocket costs have changed relatively little since the 1960s, but the market has been very flat. It is, however, quite reasonable to assume that rockets will be cheaper in the future, particularly if the market for them increases. At the same time, it is quite reasonable to assume the market will increase, particularly if rockets become cheaper.
Disposable rocket costs are significantly affected by production volumes of the solid parts of the rocket, and by launch site costs. Intuitively, since propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...
is by far the largest part of a rocket, propellant costs would be expected to be significant, but it turns out that with hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
fuel these costs can be under $50 per kg of payload. Thus, the more launches a system performs the cheaper it becomes. Economies of scale mean that large production runs of rockets greatly reduce costs, as with any manufactured item, and reuseable rockets may also help to do so. Improving material and practical construction techniques for building rockets could also contribute to this. Greater use of cheap labour (globalisation) and automation is practically guaranteed to reduce manpower costs. Other costs, such as launch pad costs, can be reduced with very frequent launches.
Cost estimates for a space elevator
For a space elevator, the cost varies according to the design. Bradley C. EdwardsBradley C. Edwards
In space engineering, Bradley C. Edwards is a researcher who is notable for having worked on Space elevators. He received funding from NIAC from 2001 to 2003 to write a paper proposing a way in which one could be built...
received funding from NIAC
NASA Institute for Advanced Concepts
right|200pxNASA Institute for Advanced Concepts was a NASA-funded program that was operated by the Universities Space Research Association for NASA from 1998 until its closure on 31 August 2007. NIAC sought proposals for revolutionary aeronautics and space concepts that could dramatically impact...
from 2001 to 2003 to write a paper, describing a space elevator design. In it he stated that: "The first space elevator would reduce lift costs immediately to $100 per pound" ($220/kg). However, as with the initial claims for the space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, this is only the marginal cost
Marginal cost
In economics and finance, marginal cost is the change in total cost that arises when the quantity produced changes by one unit. That is, it is the cost of producing one more unit of a good...
, consisting of the electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
required to lift the elevator payload, but not operating overhead and maintenance; whereas the fixed cost
Fixed cost
In economics, fixed costs are business expenses that are not dependent on the level of goods or services produced by the business. They tend to be time-related, such as salaries or rents being paid per month, and are often referred to as overhead costs...
s would be US$6 to 12 billion, for construction; and one-way designs (such as Edwards') will add to the cost of the elevators.
The gravitational potential energy of any object in geosynchronous orbit (GEO), relative to the surface of the earth, is about 50 MJ (15 kWh) of energy per kilogram
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
(see geosynchronous orbit
Geosynchronous orbit
A geosynchronous orbit is an orbit around the Earth with an orbital period that matches the Earth's sidereal rotation period...
for details). Using wholesale electricity prices for 2008 to 2009, and the current 0.5% efficiency of power beaming, a space elevator would require USD
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
220/kg just in electrical costs. Dr. Edwards expects technical advances to increase the efficiency to 2%. It may additionally be possible to recover some of the energy transferred to each lifted kilogram by using descending elevators to generate electricity as they brake (suggested in some proposals), or generated by masses braking as they travel outward from geosynchronous orbit (a suggestion by Freeman Dyson
Freeman Dyson
Freeman John Dyson FRS is a British-born American theoretical physicist and mathematician, famous for his work in quantum field theory, solid-state physics, astronomy and nuclear engineering. Dyson is a member of the Board of Sponsors of the Bulletin of the Atomic Scientists...
in the 1980s).
For the space elevator, the efficiency of power transfer is just one limiting issue. The cost of the power provided to the laser is also an issue. While a land-based anchor point in most places can use power at the grid rate, this is not an option for a mobile ocean-going platform. A specially built and operated power plant is likely to be more expensive up-front than existing capacity in a pre-existing plant. Up-only climber designs must replace each climber in its entirety after each trip. Some designs of return climbers must carry up enough fuel to return it to earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, a potentially costly venture.
Contrasting rockets with the space elevator
Government funded rockets have not historically repaid their capital costs. Some of the sunk costSunk cost
In economics and business decision-making, sunk costs are retrospective costs that have already been incurred and cannot be recovered. Sunk costs are sometimes contrasted with prospective costs, which are future costs that may be incurred or changed if an action is taken...
is often quoted as part of the launch price. A comparison can therefore be made between the marginal cost
Marginal cost
In economics and finance, marginal cost is the change in total cost that arises when the quantity produced changes by one unit. That is, it is the cost of producing one more unit of a good...
s of fully or partially expendable rocket launches and space elevator marginal costs. It is unclear at present how many people would be required to build, maintain and run a 100,000 km space elevator and consequently how much that would increase the elevator's cost. Extrapolating from the current cost of carbon nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...
s to the cost of elevator cable is challenging.
Space elevators have high capital cost but presumably low operating expenses, so they make the most economic sense in a situation where they would be used to handle many payloads. The current, inelastic launch market may not be large enough to make a compelling case for a space elevator, but a dramatic drop in the price of launching material to orbit would likely result in new types of space activities becoming economically feasible. In this regard they share similarities with other transportation infrastructure projects such as highway
Highway
A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...
s or railroads. In addition, launch costs for probes and craft outside Earth's orbit would be reduced, as the components could be shipped up the elevator and launched outward from the counterweight
Counterweight
A counterweight is an equivalent counterbalancing weight that balances a load.-Uses:A counterweight is often used in traction lifts , cranes and funfair rides...
satellite. This would cost less in both funding and payload, since most probes do not land anywhere. Also, almost all the probes that do land somewhere have no need to carry fuel for launch away from their destination. Most probes are on a one-way journey.
Funding of capital costs
Note that governments generally have not historically even tried to repay the capital costs of new launch systems from the launch costs. Several cases have been presented (space shuttleSpace Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, ariane, etc.), documenting this. Russian space tourism
Space tourism
Space Tourism is space travel for recreational, leisure or business purposes. A number of startup companies have sprung up in recent years, hoping to create a space tourism industry...
does partially fund ISS development obligations, however.
It has been suggested that governments are not usually willing to pay the capital costs of a new replacement launch system. Any proposed new system must provide, or appear to provide, a way to reduce overall projected launch costs. This was the nominal impetus behind the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
program.
Alternatively, according to a paper presented at the 55th International Astronautical Congress in Vancouver
Vancouver
Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...
in October 2004, the space elevator
Space elevator
A space elevator, also known as a geostationary orbital tether or a beanstalk, is a proposed non-rocket spacelaunch structure...
can be considered a prestige megaproject
Megaproject
A megaproject is an extremely large-scale investment project. Megaprojects are typically defined as costing more than US$1 billion and attracting a lot of public attention because of substantial impacts on communities, environment, and budgets. Megaprojects can also be defined as "initiatives that...
and the current estimated cost of building it (US$6.2 billion) is rather favourable when compared to the costs of constructing bridges, pipelines, tunnels, tall towers, high speed rail links, maglevs and the like. It compares well to the costs of other aerospace systems as well as launch vehicles.
Total cost of a privately funded Edwards' Space Elevator
A space elevator built according to the Edwards proposal is estimated to cost $20 billion ($40B with a 100% contingency). This includes all operating and maintenance costs for one cable. If this is to be financed privately, a 15% return would be required ($6 billion annually). Subsequent elevators would cost $9.3B and would justify a much lower contingency ($14.3B total). The space elevator would lift 2 million kg per year per elevator and the cost per kilogram becomes $3,000 for one elevator, $1,900 for two elevators, $1,600 for three elevators, until construction costs are recovered, after which this drops significantly.For comparison, in potentially the same time frame as the elevator, the Skylon, 12,000 kg cargo capacity spaceplane (not a conventional rocket) is estimated to have an R&D and production cost of about $15 billion. The vehicle has about the same $3,000/kg price tag. Skylon would be suitable to launch cargo and particularly people to low/medium Earth orbit. Early space elevator designs move only cargo, although to a much wider range of destinations. Later, tourism would seem possible as safety parameters are established.
See also
- MegaprojectMegaprojectA megaproject is an extremely large-scale investment project. Megaprojects are typically defined as costing more than US$1 billion and attracting a lot of public attention because of substantial impacts on communities, environment, and budgets. Megaprojects can also be defined as "initiatives that...
- Commercialization of spaceCommercialization of spaceCommercialization of space is the use of equipment sent into or through outer space to provide goods or services of commercial value, either by a corporation or state. Examples of the commercial use of space include satellite navigation systems, satellite television and satellite radio...
- Space elevator constructionSpace elevator constructionThe construction of a space elevator is considered to be a large project. Like other historical large projects it entails technical risk: some advances in engineering, manufacture and physical technology are required...
- Space elevator safetySpace elevator safetyThere are risks associated with never-before-done technologies like the construction and operation of a space elevator. A space elevator would present a navigational hazard, both to aircraft and spacecraft. Aircraft could be dealt with by means of simple air-traffic control restrictions...
- Lunar space elevatorLunar space elevatorA lunar space elevator is a proposed cable running from the surface of the Moon into space.It is similar in concept to the better known Earth space elevator idea...
- Space elevators in fictionSpace elevators in fictionThis is a list of occurrences of space elevators in fiction. Some depictions were made before the space elevator concept became fully established.-Novels and Fairy tales:* 2061: Odyssey Three, novel by Arthur C. Clarke...
- Elevator:2010Elevator:2010Elevator:2010 is a competition with monetary prizes similar to the Ansari X Prize, but with the purpose of developing space elevator and space elevator-related technologies...
- Orbital ringOrbital ringAn Orbital Ring is a concept for a space elevator that consists of a ring in low earth orbit that rotates at above orbital speed, that has fixed tethers hanging down to the ground.The structure is intended to be used for space launch....
- Space tetherSpace tetherSpace tethers are cables, usually long and very strong, which can be used for propulsion, stabilization, or maintaining the formation of space systems by determining the trajectory of spacecraft and payloads...
- Tether propulsion
- Non-rocket spacelaunchNon-rocket spacelaunchNon-rocket space launch is a launch into space where some or all needed speed and altitude is provided by non-rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have been proposed...