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  • Asteroids can provide an abundant supply of other resources

    2019-07-15

    Asteroids can provide an abundant supply of other resources, such as carbon, nitrogen, or calcium compounds, but will only be useful once the space economy is sufficiently developed to provide economically interesting uses for them. Others, such as titanium or aluminium, also exist in asteroids, but their relative abundances and the melanocortin 1 receptor requirements of their extraction make them less appealing in their typical uses (structural alloys), than ferrous metals [3].
    Defining Asteroid-COTS As explained before, this paper applies the methodology exposed by Zuniga et al. for the LCOTS proposal [1] to study a potential ACOTS program. This methodology defines first the objectives and phases of the program, and then evaluates the capabilities that could be developed by the industry under a COTS-like program. The same process will be followed here.
    Proposed ACOTS After evaluating the possible capabilities, the potential ACOTS program can be outlined. From the evaluation in Table 2, it is clear that the production of PGMs and semiconductors should be left out of the program, given the low market expectations or the low interest for Moon and Mars missions. Other capabilities, such as instrumentation or communications, could be left out due to the high maturity of the industry and the high market expectations, which could allow the industry to develop everything on their own. This would mean that a potential ACOTS program would have to wait for the industry to have demonstrated remote sensing instrumentation on their own, but two companies expect to do exactly that in 2017 [17], [18]. The final outline of the ACOTS program would be:
    Asteroid first or Moon first? In terms of maturity, it is obvious that the LCOTS program from Zuniga et al. [1] is more attainable for the industry than the proposed ACOTS. The competitors of the Google Lunar XPrize program and NASA\'s CATALYST are in a much better position to start work on the first phase of the LCOTS program than any of the companies considered in this paper for ACOTS. We also have a better knowledge of the resource distribution on the Moon, thanks to a number of prospecting missions in the early 2000s. In this regard, it could be more reasonable to implement an LCOTS program first, and develop capabilities on the Moon before moving onto asteroids.
    Conclusions
    Funding
    Introduction One major challenge in the chemistry and physics of actinide and lanthanide (f-ion) complexes is the understanding of the role that f-electrons play in the magnetism in general and in the exchange coupling in particular. This is in marked contrast to transition-metal magnetochemistry where a straightforward spin-only Hamiltonian approach clarifies the magnetic behavior and quantifies the exchange coupling between d-electrons [1], [2]. Other than -systems, exchange coupling in few actinide and lanthanide complexes have been analyzed quantitatively since a spin-only Hamiltonian is not applicable to systems with unquenched orbital angular momenta [3], [4]. This difficulty complicates efforts to explain the magnetic behavior of lanthanides and actinides complexes. Calculations of exchange parameters for lanthanides are more difficult than those for transition metal compounds due to the complicated electronic structure of ions. As a consequence little is still known about specific mechanism of exchange interactions in actual lanthanide or actinide compounds. It is generally recognized that strong magnetic anisotropy is an almost universal property of f-block element compounds [5], [6], [7], [8]. In some cases the exchange interactions are so anisotropic that they can not be rationalize even qualitatively in term of conventional isotropic Heisenberg Hamiltonian. This is closely related to the unquenched orbital moment of f electrons and the strong spin-orbit coupling [9]. This is not, however, a general rule and in some cases the coupling seems to be isotropic and can be described by a Heisenberg-type Hamiltonian. That is the case for example of the complexes Cs3Yb2Cl9 and Cs3Yb2Br9 described by Güdel et. al. in 1990. using neutron spectroscopy [10]. In 2005 Palii et al. tried to reveal the physical origin of this feature using a model of the kinetic exchange between two octahedral coordinated Yb3+ as a theoretical consideration [11], [12], [4]. They shown that the anisotropy of the coupling is directly related with the nature of the orbitals involved in the kinetic exchange mechanism. Some years before in 1996, V.S. Mironov attempted to describe the possible mechanism of the coupling in complexes using similar models and rationalized the mechanism using the direct hopping between 4f orbitals and excitations from 4f to 5d orbitals [7].