Humankind’s exploration and use of outer space are first and foremost limited by the obligation of non-appropriation. This prohibition, with an aim to prevent conflicts arising from competing territorial claims, does not extend to the exploitation of abiotic resources in space. Recent state practice has shown a clear trend of regarding such exploitation as a freedom of exploration and use of outer space. The future international legal regime should prohibit property claims over natural resources in place on celestial bodies, avoid the controversial issue of ownership, co-ordinate the resource activities of different entities by a stage-specific and priority-right-based mechanism, and harden the obligations of capacity-building and co-operation. The ideas of parallel system and monetary benefit sharing should not be discarded although resistance from major space-faring countries is foreseeable.

In recent years, there has been a surge of private investment in space resources and the enactment of domestic legislation aimed at protecting property rights over the resources to be extracted. This article argues that the unilateral exploitation of space resources is not prohibited by the principle of non-appropriation and is consistent with the freedom of use for common benefit and interests, with the caveat that it does not exclude others from exploitation or exacerbate inequality among States. It also argues that a laissez-faire approach would be detrimental to the orderly, sustainable and safe exploitation and use of space resources and calls for the establishment of an international regulatory regime consisting of rules concerning international coordination, benefits sharing and environmental protection.

The inadequacy of existing international law in the prevention of an arms race in outer space leaves uncertainties to international peace and security. The resurgence of aggressive space programmes in the new millennium has intensified concerns over the possible degradation of outer space into an area of conflicts, prompting various initiatives aimed to fill this loophole. The year 2014 witnessed the release of the revised draft PPWT proposed by China and Russia at the CD, the fifth public edition of the ICoC promoted by the EU, and the adoption of the Resolution on “No first placement of weapons in outer space” in the General Assembly. This paper attempts to make a comparison between the three initiatives in terms of their postulated primary-level obligations, namely to what extent space weapons are prohibited on the chain of “research, development, testing, placement and use”, and the verification of compliance with these obligations.

Hafnium dioxide (HfO2) thin films were synthesized on silicon and quartz substrates by thermal oxidation of metallic hafnium films in oxygen. The crystalline structure and optical properties of the HfO2 films were systematically investigated using x-ray diffraction, ultraviolet (UV)-Raman, and UV-visible spectrophotometer techniques. All the films thermally oxidized at 450 to 800 °C were mostly monoclinic. Interestingly, cubic phase coexisted with monoclinic phase in the films thermally oxidized at 500 to 600 °C. The corresponding optical band gap (Eg) varied from 5.92 to 6.08 eV for the films with a different phase ratio (cubic to monoclinic one) ranging between 0 and 1:3. These results imply that the mixed phase could have a certain effect on the increase of the Eg of HfO2 films.