A preliminary study and review of methods of creating fuels in the outer solar system was conducted at the NASA Glenn Research Center in support of NASA’s exploration mission. Mining in the outer solar system is an important option for exploration because launching and bringing all the materials for exploration from Earth is expensive and may make the idea of long-term exploration untenable. The large reserves of atmospheric gases in the outer planets are an excellent resource for fuels and other life-sustaining or colony-building gases.
The highly energetic gases available in the outer planet atmospheres are excellent fuels for chemical and nuclear propulsion systems. Hydrogen and methane are excellent fuels for chemical rockets that can be used to ascend from and descend to the surfaces of moons. Hydrogen can also be the fuel of choice for nuclear fission and fusion rockets. Helium 3 (3He) is another future fusion reactor fuel that can be found in outer planet atmospheres (ref. 1). In addition, hydrogen, helium, and other ices found deep below the surface of Uranus and Neptune may be crucial to exploration beyond the solar system.
Atmospheric mining may be easier than mining on the surfaces of outer-planet moons, and the planets with abundant gases are in good locations for way stations for exploring beyond the edges of our solar system. On the other hand, the delta-V (change in velocity) required to repeatedly access the atmosphere of Jupiter or another outer planet and then return to orbit can be quite high. In addition, because the planets typically have powerful magnetic fields, vehicles will need to have good resistance to radiation to operate reliably.
One of the attractive materials that can be extracted from the solar system is 3He. It is deposited in lunar regolith (moon dust) and exists in the outer planet atmospheres. This material can be an excellent nuclear fusion fuel and can reduce the neutron radiation created during the fusion process, extending the life of future power reactors. However, the fraction of 3He in the lunar regolith is quite small: perhaps less than 5 to 100 parts per billion.
The predicted concentration of 3He in the helium portion of the atmosphere of Uranus is also quite small: approximately 1 part in 10,000. Despite the small levels, the argument has been made that it would be easier to extract 3He from gaseous helium in the outer planet atmosphere than from lunar regolith. Factories stationed in the atmosphere could mine the gas robotically and await orbital vehicles to gather the 3He and deliver it to other parts of the solar system.
If atmospheric mining of 3He could be made highly efficient, it could be much more attractive than lunar regolith mining, especially after a pipeline of deliveries was established. The figure illustrates one of three atmospheric mining options discussed in reference 1. Aerostats, or balloon-borne factories, are used to process and separate the atmosphere into the materials needed for propulsion.
Atmospheric mining of Uranus with aerostats.
Long description of figure.
Find out more about fuels and space propellants for reusable launch vehicles: http://sbir.grc.nasa.gov/launch/foctopsb.htm
Glenn contact:
Bryan A. Palaszewski, 216-977-7493, 216-433-5802 (fax), Bryan.A.Palaszewski@nasa.gov
Author:
Bryan A. Palaszewski
Headquarters program office:
Exploration Systems
Programs/Projects:
CEV, Vehicle Systems, RAC
Last updated: October 16, 2006
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