This article could start with a nice "found oxygen on the moon", maybe written in all capitals to underline the importance of the discovery. But we would make a mistake, because the presence of theoxygen it had long been known on Earth's natural satellite. Not in the weak lunar atmosphere, not produced by plant beings: to find it you have to search … in lunar soil.
Is it possible to use this oxygen to make a hostile atmosphere like that of the Moon habitable? ESA is developing a method to be able to extract this resource, but not without difficulty.
The Regulations
The lunar soil is characterized by many layers, the outermost of which is a layer of rock called "Mother Rock". This Mother Rock it is covered with dusty material, technically defined as granulomateria heterogeneous. The name makes the idea of a "loam" in short.
Whoever is reading this article will surely have had the opportunity to see one of the most important images in human history: the footprint left by the astronaut Neil Armstrong during the first Moon Landing (July 20, 1969).
Here, that is the dusty material of heterogeneous granulomatter: the regulate. We told you about it some time ago in conjunction with the opening of the lunar soil samples of the Apollo missions. It is therefore the most external part of the lunar soil, the one in contact with the atmosphere and which, surprisingly, it also contains oxygen.
Two fists of dust
The following image has a certain charm, because it shows two portions of regolith in two different states: in the left part of the image you can observe the regolith as it appears in nature, while on the right there is the same rule but treated through a process of oxygen extraction from the inside. After extracting all the oxygen present, what remains is a set of metal alloys.
So in reality, the advantages deriving from this operation are two: having obtained a certain quantity of oxygen and a certain quantity of metals. This concept is very important because, in a hostile and almost "sterile" environment like the lunar one, having a available on site both oxygen and metal means being able to think of using them to develop technologies directly on the Moon, such as metal structures and systems for the propellant production for rockets.
Was it luck?
The samples taken from the surface of the Moon confirm that the lunar regolith is composed for the About 40% oxygen by weight, which makes it the most abundant element present inside. There is no need to underline how oxygen is an extremely precious resource, but it is instead a duty to specify an aspect linked to its extraction. The oxygen present in the regulator is chemically bound to the material in the form of oxides, therefore it is not available for immediate use.
A highly engineered extraction process is needed. The study that describes it the various stages is part of a project managed through the ESA Networking and Partnering Initiative, taking advantage of an advanced network of academic researchers, aimed precisely at space applications.
Here is the recipe
The treatment to which the lunar regolith sample was subjected was carried out using a method called electrolysis of the molten salt (molten salt electrolysis). There are alternative methods of extracting oxygen, but the study has come to show that these processes obtain significantly lower yields, while some have been directly excluded as they require the melting of the regulated at temperatures above 1600 ° C.
The process involves placing the regulated powder in a container coated with calcium chloride spindle (CaCl2), which acts as electrolyte, or rather from a substance that in the molten state manifests the transformation of the molecules that compose it into ions (charged particles). Everything is heated to 950 ° C. At this temperature the regolith remains solid.
By passing through a stream of electric current, oxygen is extracted from the regulate by "migration", that is separates from the rest of the metal components of the regolite and distances itself. The process seems simple, but in total they have been necessary 50 hours to extract 96% of total oxygen, with an extraction percentage that stops at 75%, if the process is interrupted after the first 15 hours. This practice is based on the FCC process, which has been expanded by a British company called Metalysis , which deals with the commercial production of metals and alloys.
Mark Symes, project supervisor at the University of Glasgow, explains: "We are working with Metalysis and ESA to translate this industrial process into the lunar context, and the results so far are very promising"James Carpenter, ESA Lunar Strategy Manager comments:"This process would give lunar colonists access to oxygen for fuel and life support, as well as a wide range of metal alloys for on-site production: but the exact amount of raw material available would depend on where they land".
The machinery is not small
A prototype of the tool with which it can be extracted has been installed in the Materials and Electrical Components Laboratory of the European Space Research and Technology Center, for friends ESTEC, based in Noordwijk in the Netherlands.
Having such a device in an academic structure is a great opportunity: it lends itself to the study and development of the phases of extraction and production of oxygen, as well as being able to measure the amount of oxygen by means of a mass spectrometer to obtain a precise reading of the draw.
Alexandre Meurisse, ESA researcher, adds: "Now that we have everything in operation, we can try to improve some aspects, for example by reducing the operating temperature, and maybe design a new version of this system (portable, NDR) that could one day fly to the Moon to be used directly there".
The plant works silently, for now the oxygen produced in the process is discharged into a discharge pipe and released into the atmosphere, but one day it will be stored and made available for use on Earth. The ultimate goal would be to design a "pilot plant" capable of functioning properly sustainable on the moon, with the first working demonstration for the mid 2020.
The two largest space agencies are preparing the way for a return to the moon, as we have repeatedly told you here on the pages of Everyeye. This means that a general "preparation" of the aerospace sector is underway to meet the demands of a possible scientific and commercial activity outside the Earth's atmosphere.
It is of a similar opinion too Tommaso Ghidini, head of ESA's Structures, Mechanisms and Materials Division, who comments as follows: "ESA and NASA are returning to the moon via manned missions, this time with the intent to stay on. Consequently, we are shifting our engineering approach towards a systematic use of lunar resources. We are working with our management colleagues for human and robotic exploration, European industry and academia to provide high-level scientific approaches and key enabling technologies such as this, necessary to ensure a sustained human presence on the Moon and perhaps, someday, Mars".
Image credits: European Space Agency (ESA) – University of Glasgow
