SPACE MINING: AN ALTERNATIVE SOURCE FOR RARE EARTH ELEMENTS AND BEYOND?

Humankind has always been curios about and afraid of outer space at the same time. For example, asteroids have been only considered as one of the possible cause of the Earth‚Äôs doom day. Remember the hit movie Armageddon (1998) where Bruce Wills starred as the leader of an amateur astronaut team to destroy one of those giant asteroids heading to Earth? If not, it is probably time that you should at least see the trailer. Leaving this common ‚Äďand still existing- fear of an asteroid hitting the Earth scenario aside, a totally different approach to those ‚Äúaimlessly‚ÄĚ floating rocks has been arisen in the last couple of decades: Can they be a new source for what we need in the Earth?

The answer¬†to that seems to be yes, at least theoretically and somewhat partially. It is theoretically positive, because we know that those rocks and the Earth accreted from the same starting material. Perhaps unfortunately, most of the heavy metals on the Earth‚Äôs crust had been pulled into the core while everything was still ‚Äúhot‚ÄĚ due to relatively stronger gravity force leaving much less of them available for mining now. These eventually-rare heavy metal deposits that we currently have actually came from the rains of asteroids hit to the Earth‚Äôs crust. On the other hand, the answer is partially yes, because asteroids are attractive for their high grades of particular heavy metals (higher than the richest deposits in the Earth) that are essential for daily-life to industrial purposes such as platinum group of metals (PGMs), iron, nickel, cobalt etc. Hence, the target metals recoverable from the asteroids seem to be relatively limited to these heavy and rare metals. Nevertheless, the ‚Äúmetal menu‚ÄĚ is already quite promising and has the potential of getting more diverse within time as we identify more and more asteroids out there.

Harvestor concept by Deep Space Industry

According to two overly-dedicated and young companies based in USA, namely, Deep Space Industries and Planetary Resources, the space mining idea can be practically realized before 2025 [1]. Indeed, in 2012, a plan was announced by Planetary Resources which was instantly and financially supported by some of the important billionaires such as Larry Page (Google’s co-founder) and James Cameron (director of the movie Avatar -the blue one- and explorer). You can see their enthusiasm in their introduction video to explain why they are volunteer for space mining.

Briefly can be summarized, both of these companies have offered a very similar approach in their space mining activities for the next decade. The first job to be done is to explore and specify the target asteroids available for mining. For that, they will start by launching fleets of small spacecraft to analyze and catalogue around 9000 near-earth-asteroids (NEAs) as there are billions of various types of asteroids throughout the belt that can extend as far as to Jupiter (see the image of asteroid belts). Once defined by means of composition and feasibility, target asteroids will be determined for mining operations. The next step is focusing on the strategy of mining which is the first of several related challenges. For example, the size of the asteroid and the orbit in which it is floating are serious issues which can be treated by two strategies: either (a) transporting the whole mining equipment to the asteroid surface thereby constructing sort of a space plant or (b) bringing asteroid (by actually moving it) into a stable orbit around the Earth or even the Moon and performing the mining and transportation actions simultaneously [2]. Option (a) is planned for relatively big asteroids with orbits that regularly bring them towards the Earth and option (b) is the plan for those with relatively small nearby asteroids. In either strategy the aim is to ease the transportation of miners, equipment and excavated or in-situ processed products between the Earth and the host asteroid. This will impose an immense technological challenge forcing the scientists to develop new technologies. There are several valuable web pages around the internet for exploring more about the asteroid classifications, technical and mining challenges and mining projects offered so far [3] [4] [5] (references thereby).

asteroid-belt

As introduced in the beginning, surprisingly the aimed revenues have been focused on rare and precious minerals of PGMs (ruthenium, rhodium, palladium, osmium, iridium, and platinum) along with gold, tungsten, manganese, molybdenum, iron, nickel and cobalt [6]. It is also important to note that other components of asteroids are also being considered for in-situ utilization during extraction and transportation. For example, water and/or ice layers on the surface of asteroids are extremely valuable for not only supplying the hydration need of the space miners but also for supplying the two most important contents of a rocket fuel as propellants: hydrogen and oxygen. To put everything together please have a look to this interesting short video below.

Within this aspect, space mining seems to be partially self-supporting business with lots of offerings not only by means of the revenue obtainable from the precious metals but also for maintaining the source for them. According to Deep Space Industries, if just 10% of the mass of the asteroid that passed close by the Earth in February 2013 consisted of iron, nickel and other metals, then it would have been worth $130 billion (£85 billion) [7]. Yet there is this question which is still valid: Is it worth it? Well, surprisingly there are lots of discussions going on in the internet and there are actual debates on such business for economics and even legality aspects. As an introduction to these issues, two YouTube videos are available one-click away.

Apart from all these information, questions and debates, although it has not been widely considered, I would like to put a new question: Could asteroids also be a new source of rare earth metals? It seems logical to estimate that as more and more asteroids are scanned for their chemical compositions, the ‚Äúmetal menu‚ÄĚ offered by them could unavoidably extend to include rare earth metals as well. Expectedly, the need for rare earth metals may be partially or perhaps completely supplied from these space treasures leading to a whole new story in rare earth metal history. Fortunately with the pace in technological developments especially in robot industry, we are not going to wait for a really long time to see it and I, speaking for myself, would like to be alive to see at least the first trial.

Lastly, I imagine that a successful space mining program could be the first steps of space colonization of humankind. It is not hard to see that was what James Cameron imaging in his mind while filming the Avatar movie and financially supporting the Planetary Resources. Or this could be another conspiracy theory in the internet but the suspicion is there. Despite it could be a bold idea against Mendeleev, is not it exciting to think that we may even discover new element/s that could offer so many things beyond our imagination just like in Transformers movie series? Maybe the Periodic Table is more than an unfinished Tetris block as we know it. Or this could simply be a wild imagination and oversimplification of science.

Overall, regardless of the outcome of these space mining projects, the inspiration of such an idea is already satisfying to my opinion.

References

 

[1] “http://www.bbc.com/news/science-environment-21144769,” [Online].
[2] “http://en.wikipedia.org/wiki/Asteroid_mining,” [Online].
[3] “http://www.astronomysource.com/tag/rare-earth-metals-from-asteroids/,” [Online].
[4] “http://en.wikipedia.org/wiki/Asteroid_mining,” [Online].
[5] “http://ens-newswire.com/2013/01/23/asteroid-miners-in-a-race-for-rare-metals/,” [Online].
[6] “http://www.planetaryresources.com/asteroids/composition/,” [Online].
[7] “http://www.rsc.org/chemistryworld/2013/05/mining-ocean-seafloor-asteroids-space-minerals,” [Online].

 

 

Rare Earths for Medical Applications

Lanthanides are used in many medicinal applications, such as in anti- tumor agents and kidney dialysis medicine. One of the most known application of these elements is the use of Gadolinium in Magnetic Resonance Imaging (MRI). (1)

The first medical applications in this field became reality shortly after the development of magnetic resonance imaging and the introduction of this technique in medical diagnosis. MRI is an NMR technique that visualizes, with a very high resolution, the morphology of the body. The intensity of each voxel in a three-dimensional image reflects the intensity of the 1H NMR signal of the water in the corresponding part of body. The intensities of these signals and, consequently, the contrast of the images are dependent on magnetic relaxation of the nuclei. Relaxation can be enhanced by paramagnetic compounds, and the lanthanide ion Gd(III) with its seven unpaired electrons is the paramagnetic champion of the periodic table. This ion is ideal for improving the contrast in MRI scans. Gd(III) chelates such as Gd(DTPA) and Gd(DOTA) have been developed that have a very low toxicity, even at the relatively high doses in which they are applied. These contrast agents are as safe as an aspirin, and they have contributed to the success of MRI in clinical diagnostics. Nowadays, about 30% of MRI scans are performed after administration of a Gd(III)-based contrast agent.The luminescent properties of the lanthanides also have been utilized in medical diagnosis. A variety of luminescent bioassays and sensors have been developed that take advantage of the unique luminescent properties of these elements, such as a relatively long-lived emission. (2)

 

MRI-scan-room

Fig 1. Magnetic resonance imaging (MRI)

Europium compounds, for example are often used in molecular genetics to mark specific strands of DNA. Europium oxide was also used in cathode ray television sets as the red glowing dye in the trichromatic setup. (3)

The¬†treatment for high blood phosphate uses compounds called phosphate binders; in the gut these prevent phosphate uptake from the diet. ‘The ideal phosphate binder should have low solubility and little or no systemic adsorption. It should be non-toxic and available in a palatable oral dosage form. Aluminium and calcium based phosphate binders can cause problems due to metal ion absorption, he said. Fosrenol¬†(lantnanum carbonate chewable tablets) avoids the adverse effects associated with earlier drugs because it cannot cross the gut lining and so is not transmitted to the rest of the body. (4)

A new focus nowadays has been put on the anti-cancer treatment use of lanthanides, because of their therapeutic radioisotopes. The dominant pharmacological applications of lanthanides are as agents in radioimmunotherapy and photodynamic therapy. (5)

(1) http://nuclearweaponarchive.org/Usa/Med/Lbfm.htm

(2) http://pubs.acs.org

(3) Shriver and Atkins Inorganic Chemistry

(4) http://www.rsc.org

(5) Kostova, I. Current Medicinal Chemistry РAnti-Cancer Agents, Lanthanides as Anticancer Agents, Volume 5, Number 6, November 2005, pp. 591-602(12)

The losses in permanent magnets.

Dear reader,

One of the aspects that limit the use of permanent magnets based on rare earths is the working temperatures stability. The magnetic characteristics of the permanent magnets should not change drastically during the working time of the equipment. Therefore, the study of the changes over the time and with temperature of the physical properties of permanent magnets is a technical problem of great interest. These losses can be classified as:

            reversible loss of magnetization, due to the temperature dependence of saturation magnetization and anisotropy coefficient. These losses are removed by returning to the initial temperature. Reversible losses always should be taken into consideration, by making some calculations in order to use these magnets at temperatures higher than ambient temperature.

¬†¬†¬†¬†¬†¬† ¬† ¬†¬† irreversible losses, are determined by the temperature dependence of the coercive field. At high temperatures the coercive field decreases and the magnetization of various magnetic domains can be reversed, leading to irreversible losses of the magnetic induction. These losses exist also after the return to the initial temperature, and can be eliminated by a new magnetization. The irreversible losses depend on the value of coercive field, on the variation with temperature, and on the working point of the magnet (B/¬ĶoH). The irreversible variations can be prevented by a thermal stabilization treatment.

             irremediable losses, are due to the material losses, to the deterioration of the  magnetic surfaces, to the oxidation, and due to the structural change. These losses cannot be removed by remagnetization.

The reversible and irreversible losses, are due to the  effects induced by the increase of the internal energy of the magnet at high temperatures. This thermal energy can lead to the activation of the magnetic domain wall motion and to the process of reversal magnetization, as a result of weakening of the magneto-crystalline energy. The returning to the initial temperature does not return the magnetic domain walls in the same positions, thereby is appearing an irreversible variation in the magnet flux.

The increase of temperature involves an increase in thermal energy, which can lead to a relative remoteness between the spin magnetic moments and the initial direction of magnetization, resulting in the decrease of the individual magnetization of each magnetic domain in part, and hence of the variation of the magnetic flux of the magnet.

In certain temperature limits, returning to the initial temperature leads to a returning at the initial value of the flux, these are reversible loss with the temperature.

Reversible and irreversible magnetic losses that may occur in the operation of the magnet, in various conditions are strongly dependent on factors such as: the intrinsic coercivity, the linearity of the demagnetization curve, the Curie temperature of the alloy, the operating point, the demagnetization factor, temperature.