Measuring the economic benefits of a national planetary protection policy to regulate future private space activities between Earth and Mars: Results of a contingent valuation survey in Greece

The emergence of private space actors may soon enable the growth of the novel market segments of space research and exploration, space resources utilization, and human access to space. The interdisciplinary field of Planetary Protection has to keep up with these advances. Planetary Protection is defined as a set of guidelines that aim to prevent the forward contamination of celestial bodies with biological material from Earth and the backward contamination of the terrestrial biosphere with extraterrestrial biological material. As space entrepreneurs acquire and develop the resources and competencies for commercial access to space, significant questions are expected to be raised in the future with respect to potential forward and backward contamination issues, particularly with respect to activities between Earth and Mars. Although such private activities do not seem to pose a serious Planetary Protection threat at the moment, certain preparatory steps need to be taken in order to prudently inform the relevant policy-making procedures. This work describes the application of the Contingent Valuation Method, a useful tool of the environmental economics discipline, with the aim of demonstrating a novel approach to estimate the economic valuation of the external benefits of preventing forward and backward contamination between Earth and Mars. Particularly, via a survey specifically developed for this purpose, a set of questions are used to elicit the perceived economic value that respondents place on the prevention of forward and backward contamination; the survey is administered to a national probability sample in Greece, and the generated data is processed through statistical analysis. The Contingent Valuation Method is a popular and well-established stated preference valuation technique; these techniques are often the more suitable choice for ex-ante valuations of future changes, and are currently the only known approach to capture all the aspects of the economic value of non-market goods. Through an initial proof-of-concept in Greece, the goal of this work is to provide useful insights on the expected external benefits of a national Planetary Protection policy to regulate future private space activities between Earth and Mars, and to encourage a larger-scale application of this tool in other countries around the world.     

Performance improvement of real-time PPP ambiguity resolution using a regional integer clock

Obtaining reliable GNSS uncalibrated phase delay (UPD) or integer clock products is the key to achieving ambiguity-fixed solutions for real-time (RT) precise point positioning (PPP) users. However, due to the influence of RT orbit errors, the quality of UPD/integer clock products estimated with a globally distributed GNSS network is difficult to ensure, thereby affecting the ambiguity resolution (AR) performance of RT-PPP. In this contribution, by fully utilising the consistency of orbital errors in regional GNSS network coverage areas, a method is proposed for estimating regional integer clock products to compensate for RT orbit errors. Based on Centre National d’Études Spatiales (CNES) RT precise products, the regional GPS/BDS integer clock was estimated with a CORS network in the west of China. Results showed that the difference between the estimated regional and CNES global integer clock/bias products was generally less than 5 cm for GPS, whereas clock differences of greater than 10 cm were observed for BDS due to the large RT orbit error. Compared with PPP using global integer clock/bias products, the AR performance of PPP using the regional integer clock was obviously improved for four rover stations. For single GPS, the horizontal and vertical accuracies of ambiguity-fixed PPP solutions were improved by 56.2% and 45.3% on average, respectively, whereas improvements of 67.5% and 50.5% in the horizontal and vertical directions, respectively, were observed for the combined GPS/BDS situation. Based on a regional integer clock, the RMS error of a kinematic ambiguity-fixed PPP solution in the horizontal direction could reach 0.5 cm. In terms of initialisation time, the average time to first fix (TTFF) in combined GPS/BDS PPP was shortened from 18.2 min to 12.7 min. In view of the high AR performance realised with the use of regional integer clocks, this method can be applied to scenarios that require high positioning accuracy, such as deformation monitoring.     

Initial accuracy and reliability of current BDS-3 precise positioning,velocity estimation,and time transfer (PVT)

The primary system of Chinese global BeiDou satellite system (BDS-3) was completed to provide global services on December 27, 2018; this was a key milestone in the development process for BDS in terms of its provision of global services. Therefore, this study analyzed the current performance of BDS-3, including its precise positioning, velocity estimation, and time transfer (PVT). The datasets were derived from international GNSS monitoring and assessment system (iGMAS) tracking networks and the two international time laboratories in collaboration with the International Bureau of Weights and Measures (BIPM). With respect to the positioning, the focus is on the real-time kinematic (RTK) positioning and precise point positioning (PPP) modes with static and kinematic scenarios. The results show that the mean available satellite number is 4.8 for current BDS-3 system at short baseline XIA1–XIA3. The RTK accuracy for three components is generally within cm level; the 3D mean accuracy is 8.9 mm for BDS-3 solutions. For the PPP scenarios, the convergence time is about 4 h for TP01 and BRCH stations in two scenarios. After the convergence, the horizontal positioning accuracy is better than cm level and the vertical accuracy nearly reaches the 1 dm level. With respect to kinematic scenarios, the accuracy stays at the cm level for horizontal components and dm level for the vertical component at two stations. In terms of velocity estimation, the horizontal accuracy stays at a sub-mm level, and the vertical accuracy is better than 2 mm/s in the BDS-3 scenario, even in the Arctic. In terms of time and frequency transfer, the noise level of BDS-3 time links can reach 0.096 ns for long-distances link NT01–TP02 and 0.016 ns for short-distance links TP01–TP02. Frequency stability reaches 5E–14 accuracy when the averaging time is within 10,000 s for NT01–TP02 and 1E–15 for TP01–TP02.     

北京空间机电研究所50年成就与展望

文章介绍了北京空间机电研究所50年来在回收与着陆技术、航天光学遥感技术和复合材料成型技术领域所取得的成就,并对三大技术领域的后续发展进行了展望.     

Proposed strategies for optical observations in a future European Space Surveillance network

Two ESA-funded feasibility studies that aimed to develop observation strategies, to propose suitable sensor architectures, and to assess the expected performance of an independent European Space Surveillance System were carried out during the last years. The French company ONERA led two study teams comprising a number of European companies.     

Analytical and semi-analytical inverse kinematics of SSRMS-type manipulators with single joint locked failure

Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators.     

空间光学系统技术发展探讨

文章总览国际典型大科学工程和计划，对空间光学系统技术在过去20年的发展做出了简要的归纳和总结。同时通过跟踪一些领域前沿和技术生长点，指出了一些可能对未来空间光学系统带来重大改变的方向。     

Investigations of the evolution of optical characteristics and dynamics of proper rotation of uncontrolled geostationary artificial satellites

On the base of the photometrical data an analysis of the periods and light curves of the uncontrolled artificial satellites was performed.     

Proposal for a United Nations Basic Space Technology Initiative

The United Nations Programme on Space Applications, implemented by the United Nations Office for Outer Space Affairs, promotes the benefits of space-based solutions for sustainable economic and social development. The Programme assists Member States of the United Nations to establish indigenous capacities for the use of space technology and its applications. In the past the Programme has primarily been focusing on the use of space applications and on basic space science activities. However, in recent years there has been a strong interest in a growing number of space-using countries to build space technology capacities, for example, the ability to develop and operate small satellites. In reaction to this development, the United Nations in cooperation with the International Academy of Astronautics has been organizing annual workshops on small satellites in the service of developing countries. Space technology related issues have also been addressed as part of various other activities of the Programme on Space Applications. Building on these experiences, the Office for Outer Space Affairs is now considering the launch of a new initiative, preliminarily titled the United Nations Basic Space Technology Initiative (UNBSTI), to promote basic space technology development. The initiative would be implemented in the framework of the Programme on Space Applications and its aim would be to help building sustainable capacities for basic space technology education and development, thereby advancing the operational use of space technology and its applications.     

Turbulence,complexity, and solar flares

The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and an output (electrical current build up and resistive dissipation) in the corona. Although initially localised, this redistribution affects neighbouring regions and an avalanche occurs resulting in large scale eruptions of plasma, particles, and magnetic field. As flares are powered from the stressed field rooted in the photosphere, a study of the photospheric magnetic complexity can be used to both predict activity and understand the physics of the magnetic field. The magnetic energy spectrum and multifractal spectrum are highlighted as two possible approaches to this.