NASA Tests Lunar Rovers And Oxygen Production Technology

Lunar Analog Field Demonstrations of In-Situ Resource Utilization & Human Robotic Systems hosted by PISCES, the Pacific International Space Center for Exploration Systems, a joint U.S. - Japan venture based in Hilo, Hawai'i, concluded this week. The tests focused on lunar production of oxygen for life support.


Life support for a four (4) to six (6) person outpost would require about two (2) metric tons of oxygen per year according to NASA. The tests featured several experiments:

There were three (3) rovers:

• Cratos
• Bucketdrum
• CMU's SCARAB (Selectively Compliant Articulated Robot Arm Rover)

And four (4) independent experiments

• Lockheed's PILOT (Precursor ISRU Lunar Oxygen Testbed)
  
• Lockheed's ROxygen
• RESOLVE (Regolith and Environment Science and Oxygen and Lunar Volatile Extraction)
• Michelin Lunar Wheel

Scarab was the testbed for both the RESOLVE drilling science package and the Michelin Lunar Wheel, developed by Clemson University for Michelin. RESOLVE featured a core sample drill developed by NORCAT (Northern Centre for Advanced Technology), a Canadian Space Agency contractor. The Bucketdrum rover was used to feed simulated regolith into the PILOT plant and Cratos delivered material into the ROxygen plant.

However, these were just the big name projects at the test. The were numerous smaller projects going on - testing of other gear from Canada and Germany took place during the near two-week project.

The main objective for the two week program was to get the experiements working in the field. This allows operation in non-ideal conditions similar to those that we would face on the Moon and allows us to account for them before we land. Hilo was chosen because volcanic soil closely mimics the regolith found on the lunar surface.



ASTRODAY.NET has the largest collection of pictures from the event and even a movie. Make sure you check them out.

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Solar Power on the Moon

A new type of solar cell that doesn't use silicon in their construction has been developed. According to New Scientist, the new design is dye based and sprayed onto a substrate of titanium dioxide. Titanium dioxide (TiO2) is found on the lunar surface. It is concentrated in the maria. Aside from free samples of TiO2 in the maria, it is locked up in ilmenite - TiO3. This is significant because ilmenite is a major source of lunar oxygen. Hydrogen reduction of ilmenite is one of the simplest processes for in-situ production of oxygen for fuel and life support.

FeTiO3+H2 ---->Fe+TiO2+H2O

The reduction produces free iron, titanium dioxide and water. The water can be cracked into its constituents through electrolysis.

The dye is used to coat TiO2 grains, which sit in an electrolyte in the solar cells. The whole mixture is sandwiched between two electrodes; a transparent glass sheet doped with tin oxide to make it conducting and an opaque rear panel. This allows a current to flow when the cell is placed in sunlight

But the efficiency of dye-sensitised solar cells designed for outdoor conditions is currently about 6%. That's light years from the 42.8% efficiency reached by some silicon solar cells and well below the 15% standard for many silicon designs.

Michael Grätzel of the Swiss Federal Institute of Technology in Lausanne, Switzerland – who co-invented dye sensitised solar cells in 1991 – had thought it may be possible to double the efficiency of his low-cost cells simply by designing one that collects light from both sides simultaneously.

Now Grätzel's team, working with Seigo Ito of the University of Hyogo, Japan, has done just that. Their new dye-sensitised solar cell is almost as efficient at converting light into energy when it strikes the rear side as when it strikes the front.

To achieve the trick, Grätzel's team first replaced the opaque back panel with a second sheet of glass, making the entire device transparent.

The new panel is also coated with tin oxide and acts as the second electrode, donating electrons back to the electrolyte to complete the circuit. But because it is transparent, it lets light into the system from the rear.

Robert Hertzberg, chairman and co-founder of G24 Innovations, a company based in Cardiff in the UK that manufactures dye-sensitised solar products. "This technology allows you to capture power in low light, even rainy conditions," he says. "Silicon cells only allow you to capture power during a short window [when light is intense]." That means the cells give a better performance over the whole day even if they are less efficient under ideal conditions.

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DIY Lunar Concrete

An update to this article has been posted here.

Normal concrete is cement + aggregates + water = concrete.  On the moon, this present a problem.  For all intents and purposes, water is non-existent.  Portland cement is carbon intensive like water, carbon is almost non-existent (5-280 ppm in the regolith).

Dr Houssam Toutanji, a civil engineer at the University of Alabama-Huntsville has developed a new process for making concrete on the Moon.  Dr. Toutanji proposes plain regolith be used as the aggregate and sulfur baked out of the regolith be used as the binding agent.    The sulfur needs to be in a liquid or semi-liquid state, so it needs to heated to between 130 and 140 °C.  To strip the sulphur out of the regolith will require a solar oven capable of heating the regolith to very high temperatures to extract the sulfur, which is only present in regolith around levels of 400-1300 ppm.

This new lunar concrete cures in hours, versus 7 to 28 days for normal concrete.  NASA's Marshall Spaceflight Center tested the new process  using a lunar simulant.  Mixing 35 grams of pure sulfur to every 100 grams of simulant into 5 cm, the blocks were cured and then subjected to thermal stresses before their compressive strength was meaured.  Plain lunar concrete withstood 17 MPa.  Silica, which is also present on the Moon, can be added for strength and that boosted the number 20 MPa.

As Milton Friedman said, there is no free lunch.  In order to get enough sulfur for the process, tons and tons of regolith will have to be processed.  Now if a full blown bootstrapping operation is going on, this is no problem, just one more step.  But if not, that is alot of expense to go through for just concrete.  It's another reason to make sure when we get up to the Moon we bootstrap to keep costs down.

Another NASA researcher, Peter Chen, came up with using epoxy as a binding agent.  However, epoxy cannot be made on the Moon and must be shipped up from Earth.  With current launch prices hovering around $10,000 per pound, it seems a long shot.

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