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Launch Costs

The following are launch costs for the Falcon Heavy rocket.

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Falcon Heavy launch costs, reported by SpaceX 1.

Costs have fallen substantially since the era of the space shuttle, which required $54,500 to deliver a kilogram to low earth orbit 2. Next generation designs, such as SpaceX's Starship 2, might further substantially reduce costs.

Energy consumption of the Falcon Heavy, a frequently used SpaceX rocket, are as follows.

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Launch energy of the Falcon Heavy, including the primary energy behind the RP-1 rocket fuel and liquid oxygen, but not to manufacture the rocket or other upstream costs. Total fuel needs are estimated from Spaceflight 101 3, energy intensity of kerosene (of which RP-1 is a variant) from MacKay 4, LOX from Shen and Wolsky 5, and primary energy conversions from Building Energy Codes Program 6.

Most rocket launches are to place satellites. From 2016 through 2018, launches went to the following destinations.

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Launches by destination from 2016-18. Source: Kyle 7.

Alternatives to Chemical Rockets

The rocket equation determines the fuel required to accelerate a rocket via on-board propulsion 8.

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The rocket equation. Δv is the desired change in velocity, ve = Ispg0 the exhaust velocity, m0 the initial mass (including propellant), mf the mass without propellant, and ln the natural log function. The rocket equation is idealized, and in reality the propellant required is slightly greater due to incomplete combustion, angled exhaust vector, atmospheric drag, etc. Image credit: ^Wikipedia

The following are approximate Δv requirements for common destinations.

Delta-V in Space
TripΔv (km/s)
Earth surface to Earth orbit8
Earth orbit to Earth-Moon Lagrange Point3.5
Earth orbit to low-Moon orbit4.1
Earth orbit to Lunar surface6
Earth orbit to near-Earth asteroids4+
Earth orbit to Mars surface8

Δv for common destinations. Source: Pettit 9.

Rockets are typically 85-90% propellant by mass at liftoff 9. Efforts to develop alternative launch systems typically do so through either increasing the propellant exhaust velocity or using alternatives to on-board propellant for propulsion.

The following exhaust velocities can be achieved from differing rocket fuels.

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Sources: Parkin and Lambot 10, Peschka 11, Pettit 9.

Methane and hydrogen present engineering challenges, though methane is of particular interest since it can be synthesized on the Moon or Mars for a return trip 12.

Thermal rockets--nuclear 13, microwave 10, laser 14, and solar 15--are active areas of research but are not in use today, though a solar thermal rocket is not suitable for launch from Earth. Microwave and laser thermal rockets are appealing options because they separate the energy source from the rocket. A microwave thermal rocket could achieve launch costs to low earth orbit as low as $125/kg 10. However, substantial research and development is still needed, and microwave and laser thermal rockets would require highly capital intensive ground facilities 10.

A spaceplane, such as the single-stage-to-orbit Skylon plane current under development 16, is air-breathing, thus reducing the thrust-to-weight ratio relative to rockets. However, it is not likely to be competitive in the launch market 17.

There are many proposals for launch megastructures that use electromagnetic or mechanical lift, such as the StarTram 18, launch loop 19, orbital ring 20, space elevator 21, and skyhook 22. Each of these concepts relies on speculative engineering and is probably not a near term option.

In the near term, there are no alternatives that are likely to displace chemical rockets, though nuclear, microwave, and laser thermal rockets are promising areas for research and development.

References

  1. Space Exploration Technologies. "Capabilities & Services". Accessed November 7, 2019. ↩

  2. Jones, H. "The Recent Large Reduction in Space Launch Cost". The 48th International Conference on Environmental Systems was held in Albuquerque, New Mexico, USA on 08 July 2018 through 12 July 2018. July 2018. ↩ ↩2

  3. Spaceflight 101. "Falcon Heavy". Accessed November 7, 2019. ↩

  4. MacKay, D. "Sustainable Energy - Without the Hot Air". UIT Cambridge, ISBN 978-0-9544529-3-3. Available free online from www.withouthotair.com. 2008. ↩

  5. Shen, S., Wolsky, A. "Energy and materials flows in the production of liquid and gaseous oxygen". August 1980. ↩

  6. Building Energy Codes Program. "Prototype Building Models High-rise Apartment". Building Technologies Office, Office of Energy Efficiency and Renewable Energy, U. S. Department of Energy. April 2011. ↩

  7. Kyle, E. "Space Launch Report". Accessed November 8, 2019. ↩

  8. Shortt, D. "Learn the rocket equation, part 1". The Planetary Society. April 2017. ↩

  9. Pettit, D. "The Tyranny of the Rocket Equation". National Aeronautics and Space Administration. May 2012. ↩ ↩2 ↩3

  10. Parkin, K., Lambot, T. "Microwave Thermal Propulsion". Sponsored by NASA Ames Research Center; Moffett Field, CA, United States, Defense Advanced Research Projects Agency; Arlington, VA, United States. August 2017. ↩ ↩2 ↩3 ↩4

  11. Peschka, W. Translated by Wilhelm, E., Wilhelm, U. "Liquid Hydrogen as a Rocket Propellant". Liquid Hydrogen, pp. 105-115. Springer-Verlag Wien New York. 1992. ↩

  12. Jeong, G., Bae, J., Jeong, S. Sohn, C. Yoon, Y. "Development Trend of Perspective Methane Rocket Engines for Space Development". Journal of the Korean Society for Aeronautical & Space Sciences 45(7), pp. 558-565. May 2017. ↩

  13. Mitchell, S., Johnson, L. "Nuclear Thermal Propulsion Update". Marshall Space Flight Center, National Aeronautics and Space Administration. April 2019. ↩

  14. Parkin Research. "Microwave Thermal Rockets and Laser Thermal Rockets". Accessed November 9, 2019. ↩

  15. Rabade, S., Liu, G., Barba, N., Garvie, L. "The Case for Solar Thermal Steam Propulsion System for Interplanetary Travel: Enabling Simplified ISRU Utilizing NEOs and Small Bodies". 67th International Astronautical Congress (IAC), Guadalajara, Mexico, 26-30 September 2016. September 2016. ↩

  16. Reaction Engines. "Home". Accessed November 9, 2019. ↩

  17. Dove-Jay, A. "Spaceplanes vs reusable rockets – which will win?". The Conversation. December 2015. ↩

  18. Powell, J., Maise, G. "StarTram: The Magnetic Launch Path to Very Low Cost, Very High Volume Launch to Space". 2008 14th Symposium on Electromagnetic Launch Technology, EML, Proceedings. June 2008. ↩

  19. Lofstrom, K. "The launch loop -- a low cost Earth-to-high orbit launch system". AIAA Paper 85-1368. 1985. ↩

  20. Meulenberg, A., Balaji, K. "The LEO Archipelago: A system of earth-rings for communications, mass-transport to space, solar power, and control of global warming". Acta Astronautica 68, pp. 1931-1946. 2011. ↩

  21. Edwards, B. "Design and Deployment of a Space Elevator". Acta Astronautica 47(10), pp. 735-744. 2000. ↩

  22. Bogar, T. et al. "Hypersonic Airplane Space Tether Orbital Launch System". NASA Institute for Advanced Concepts, University Space Research Association, Research Grant No. 07600-018, Phase 1 Final Report. January 2000. ↩