Space elevator economics

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 rockets.

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 Proton launch^[1] to about US$40,000/kg for a Pegasus launch (2004).^[2][3] Some systems under development, such as the SpaceX Falcon Heavy, offer rates as low as $1,600/kg.^[4] 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). The Shtil-3a rocket offers costs approximately $400/kg, but launches are infrequent and have a comparatively small payload, and its costs are partially subsidized by the Russian navy as part of launch exercises.^[1])

Rocket costs have changed relatively little since the 1960s, but the market has been very flat.^[3]

Cost estimates for a space elevator

For a space elevator, the cost varies according to the design. Bradley C. Edwards received funding from NIAC from 2001 to 2003 to write a paper,^[5] 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).^[6][7]

The gravitational potential energy of any object in geosynchronous orbit (GEO), relative to Earth's surface, 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 US$220/kg just in electrical costs. Dr. Edwards expects technical advances to increase the efficiency to 2%.^[8][9]

However, due to the fact that space elevators would have a limited throughput as only a few payloads could climb the tether at any one time, the launch price may be subject to market forces.

Funding of capital costs

According to a paper presented at the 55th International Astronautical Congress^[10] in Vancouver in October 2004, the space elevator can be considered a prestige megaproject whose current estimated cost (US$6.2 billion) is favourable compared to other megaprojects e.g. bridges, pipelines, tunnels, tall towers, high-speed rail links and maglevs. Costs are also favourable compared to that of other aerospace systems and launch vehicles.^[11]

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).^[12]

For comparison, in potentially the same time frame as the elevator, the Skylon, a 12,000 kg cargo capacity single-stage-to-orbit spaceplane (not a conventional rocket) is estimated to have an R&D and production cost of about $15 billion.^[12] 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.^[13]

See also

References