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In situ resource utilization

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ISRU Reverse Water Gas Shift Testbed (NASA KSC).

In space exploration, in-situ resource utilization (ISRU) describes the proposed use of resources found or manufactured on other astronomical objects (the Moon, Mars, Asteroids, etc.) to further the goals of a space mission.

According to NASA, "In-situ resource utilization will enable the affordable establishment of extraterrestrial exploration and operations by minimizing the materials carried from Earth."[1]

ISRU can provide materials for life support, propellants, construction materials, and energy to a science payload or a crew deployed on a planet, moon, or asteroid.

It is now very common for spacecraft to harness the solar radiation found in-situ, and it is likely missions to planetary surfaces will also use solar power. Beyond that, ISRU has not yet received any practical application, but it is seen by exploration proponents as a way to drastically reduce the amount of payload that must be launched from Earth in order to explore a given planetary body.

Uses

Solar cell production

It has long been suggested that solar cells could be produced from the materials present on the lunar surface. In its original form, known as the solar power satellite, the proposal was intended as an alternate power source for Earth. Solar cells would be shipped to Earth Orbit and assembled, the power being transmitted to Earth via microwave beams.[2] Despite much work on the cost of such a venture, the uncertainty lay in the cost and complexity of fabrication procedures on the lunar surface. A more modest reincarnation of this dream is for it to create solar cells to power future lunar bases. One particular proposal is to simplify the process by using Fluorine brought from Earth as potassium fluoride to separate the raw materials from the lunar rocks.[3]

Rocket propellant

Rocket propellant from water ice has also been proposed for the moon, mainly from ice that has been found at the poles. Most schemes would try to electrolyse the water and form hydrogen and oxygen. The likely difficulties include working at extremely low temperatures and simply digging the material. Proposals also exist to heat the water in a nuclear or solar thermal rocket,[4] which seems to give very much more mass delivered to LEO as it avoids the large amount of equipment needed to electrolyse water.[5]

Aluminium as well as other metals have been proposed for use as rocket propellant made using lunar resources,[6] and proposals include reacting the aluminium with water.[7]

Oxygen to breathe and water to drink

Water ice could replenish a space ship's water tanks. Water is needed for hygiene and obviously to drink, but may also be used for radiation protection in deep space (living quarters inside a double-walled cylindrical water tank). Splitting water allows the creation of rocket propellant, but also liberates oxygen that could be used to replenish the atmosphere in a closed-loop recycling system.

Metals for construction or return to Earth

Asteroid mining could also involve extraction of metals for construction material in space, which may be more cost-effective than bringing such material up out of Earth's deep gravity well, or that of any other large body like the Moon or Mars. Metallic asteroids contain huge amounts of siderophilic metals, including precious metals.

Locations

Mars

ISRU research for Mars is focused primarily on providing rocket propellant for a return trip to Earth — either for a manned or a sample return mission — or for use as fuel on Mars. Many of the proposed techniques utilize the well-characterised atmosphere of Mars as feedstock. Since this can be easily simulated on Earth, these proposals are relatively simple to implement, though it is by no means certain that NASA or the ESA will favour this approach over a more conventional direct mission.[8]

A typical proposal for ISRU is the use of a Sabatier reaction, CO2 + 4H2 → CH4 + 2H2O, in order to produce methane on the Martian surface, to be used as a propellant. Oxygen is liberated from the water by electrolysis, and the hydrogen recycled back into the Sabatier reaction. The usefulness of this reaction is that only the hydrogen (which is light) need be brought from Earth.[9]

A similar reaction proposed for Mars is the reverse water gas shift reaction, CO2 + H2 → CO + H2O. This reaction takes place rapidly in the presence of an iron-chrome catalyst at 400 Celsius,[10] and has been implemented in an Earth-based testbed by NASA.[11] Again, oxygen is recycled from the water by electrolysis, and only a small amount of hydrogen is needed from Earth. The net result of this reaction is the production of oxygen, to be used as the oxidizer component of rocket fuel.

Another reaction proposed for production of oxygen is electrolysis of the atmosphere, 2CO2 (+ energy) → 2CO + O2.

The Moon

Footprint in lunar regolith.

On the moon, the lunar highland material anorthite is similar to the earth mineral bauxite, which is an aluminium ore. Smelters can produce pure aluminum, calcium metal, oxygen and silica glass from anorthite. Raw anorthite is also good for making fiberglass and other glass and ceramic products.[12]

Over twenty different methods have been proposed for oxygen extraction on the moon.[6] Oxygen is often found in iron rich lunar minerals and glasses as iron oxide. The oxygen can be extracted by heating the material to temperatures above 900 °C and exposing it to hydrogen gas. The basic equation is: FeO + H2 → Fe + H2O. This process has recently been made much more practical by the discovery of significant amounts of hydrogen-containing regolith near the moon's poles by the Clementine spacecraft.[13]

Lunar materials may also be valuable for other uses. It has also been proposed to use lunar regolith as a general construction material,[14] through processing techniques such as sintering, hot-pressing, liquification, and the cast basalt method. Cast basalt is used on Earth for construction of, for example, pipes where a high resistance to abrasion is required. Cast basalt has a very high hardness of 8 Mohs (diamond is 10 Mohs) but is also susceptible to mechanical impact and thermal shock[15] which could be a problem on the moon.

Glass and glass fibre are straightforward to process on the moon and Mars, and it has been argued that the glass is optically superior to that made on the Earth because it can be made anhydrous.[12] Successful tests have been performed on earth using two lunar regolith simulants MLS-1 and MLS-2.[16] Basalt fibre has also been made from lunar regolith simulators.

In August 2005, NASA contracted for the production of 16 metric tons of simulated lunar soil, or "Lunar Regolith Simulant Material."[17] This material, called JSC-1a, is now commercially available for research on how lunar soil could be utilized in-situ.[18]

Martian Moons, Ceres, asteroids

Other proposals[19] are based on Phobos and Deimos. These moons are in reasonably high orbits above Mars, have very low escape velocities, and unlike Mars have return delta-v's from their surfaces to LEO which are less than the return from the Moon.

Ceres is further out than Mars, with a higher delta-v, but launch windows and travel times are better, and the surface gravity is just 0.028 g, with a very low escape velocity of 510 m/s. Researchers have speculated that the interior configuration of Ceres includes a water-ice-rich mantle over a rocky core.[20]

Near Earth Asteroids and bodies in the asteroid belt could also be sources of raw materials for ISRU.

ISRU classification

In October 2004, NASA’s Advanced Planning and Integration Office commissioned an ISRU capability roadmap team. The team's report, along with those of 14 other capability roadmap teams, were published May 22, 2005.[21] The report identifies seven ISRU capabilities: (i) resource extraction, (ii) material handling and transport, (iii) resource processing, (iv) surface manufacturing with in-situ resources, (v) surface construction, (vi) surface ISRU product and consumable storage and distribution, and (vii) ISRU unique development and certification capabilities.

See also

References

  1. ^ "In-Situ Resource Utilization". NASA Ames Research Center. Retrieved 2007-01-14.
  2. ^ "Lunar Solar Power System for Energy Prosperity Within the 21st Century". World Energy Council. Retrieved 2007-03-26.
  3. ^ Landis, Geoffrey. "Refining Lunar Materials for Solar Array Production on the Moon" (PDF). NASA. Retrieved 2007-03-26.
  4. ^ http://www.neofuel.com/space98/
  5. ^ http://www.neofuel.com/moonice1000/
  6. ^ a b Hepp, Aloysius F.; Linne, Diane L.; Groth, Mary F.; Landis, Geoffrey A.; Colvin, James E. (1994). "Production and use of metals and oxygen for lunar propulsion". AIAA Journal of Propulsion and Power. 10 (16, ): 834–840. doi:10.2514/3.51397. Retrieved 2009-12-09.{{cite journal}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)
  7. ^ http://www.theregister.co.uk/2009/08/24/nasa_alice_test/
  8. ^ "Mars Sample Return". www.esa.int. Retrieved 2008-02-05.
  9. ^ "Sizing of a Combined Sabatier Reaction and Water Electrolysis Plant for Use in In-Situ Resource Utilization on Mars". www.clas.ufl.edu. Retrieved 2008-02-05.
  10. ^ "The Reverse Water Gas Shift". Retrieved 2007-01-14.
  11. ^ "Mars In Situ Resource Utilization (ISRU) Testbed". NASA. Retrieved 2007-01-14.
  12. ^ a b "Mining and Manufacturing on the Moon". NASA. Archived from the original on 2006-12-06. Retrieved 2007-01-14.
  13. ^ "The Clementine Bistatic Radar Experiment". Science Magazine. Retrieved 2007-02-12.
  14. ^ "Indigenous lunar construction materials". AIAA PAPER 91-3481. Retrieved 2007-01-14.
  15. ^ "Cast Basalt" (PDF). Ultratech. Retrieved 2007-01-14.
  16. ^ http://science.nasa.gov/newhome/headlines/space98pdf/fiber.pdf
  17. ^ "NASA Science & Mission Systems Office". Retrieved 2007-01-14.
  18. ^ "bringing commercialization to maturity". PLANET LLC. Archived from the original on 2007-01-10. Retrieved 2007-01-14.
  19. ^ Anthony Zuppero and Geoffrey A. Landis, "Mass budget for mining the moons of Mars," Resources of Near-Earth Space, University of Arizona, 1991 (abstract here or here)
  20. ^ Thomas, P.C (2005). "Differentiation of the asteroid Ceres as revealed by its shape". Nature. 437 (7056): 224–226. Bibcode:2005Natur.437..224T. doi:10.1038/nature03938. PMID 16148926. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  21. ^ "NASA Capability Roadmaps Executive Summary" (PDF). NASA. |page = p.264 ff

Further reading

  • Resource Utilization Concepts for MoonMars; ByIris Fleischer, Olivia Haider, Morten W. Hansen, Robert Peckyno, Daniel Rosenberg and Robert E. Guinness; 30 September 2003; IAC Bremen, 2003 (29 Sept – 03 Oct 2003) and MoonMars Workshop (26-28 Sept 2003, Bremen). Accessed on 18 January 2010
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