Application of ion irradiation experiments to planetary surfaces in the Outer Solar System

Experimental results on the interaction between fast bombarding ions and solid targets simulating satellite surfaces in the Outer Solar System are reviewed. Applications to Jovian, Saturnian, Uranian, Neptunian, and Plutonian systems suggest the important role played by cosmic and magnetospheric ions in eroding material, in redistributing it on the surfaces of some objects, and in producing either thin or thick mantles of dark organics.     

The Late Heavy Bombardment in the Inner Solar System: Is there any Connection to Kuiper Belt Objects?

Data from lunar samples (Apollo, Luna, and lunar meteorites) indicate that the Moon was subjected to an intense period of bombardment around 3.85 billion year ago (Ga). Here a short review of this topic is given. Different interpretations exist, which either take this as the tail end of an intense but declining accretion period, or which consider a spike in the accretion rate at that time. The latter is the so-called Late Heavy Bombardment. Considering the enormous amount of matter that is required to accrete in the inner solar system at that time, and problems with deriving this mass from the asteroid belt, it is suggested that the Kuiper Belt objects could be a source for this bombardment spike, possibly linked to the late migration of Neptune outwards in the solar system.     

Ocean Worlds in the Outer Regions of the Solar System (Review)

There is an astonishing variety of celestial bodies in the outer regions of the Solar System: Europa, with its bizarre surface features, Enceladus, small but geologically active, Titan, the only moon with a significant atmosphere, Pluto, with its nitrogen glaciers, and many others. Over the past 25 years, measurements from spacecraft have shown that many of these celestial bodies are ocean worlds with large volumes of liquid water trapped under icy surfaces. This new group of celestial bodies, ocean worlds, is important for research for several reasons, but the most convincing and at the same time the simplest reason is that they can be potential habitats. Life, as we know it, requires liquid water in addition to energy, nutrients, and a sustainable environment. All these requirements can be met for some of these celestial bodies. The moons of the giant planets on which the presence of the subsurface ocean is established (Europa, Ganymede, Titan, and Enceladus) and their astrobiological potential are discussed.     

Biological Activity in the Early Solar System in Its Outer Regions (University College Cardiff Press, 1985)

Chemoautotrophic microorganisms were able to replicate and evolve in the interiors of some10¹¹ cometary bodies that occupied the outer regions of the solar system some 4 billion years ago. The requirement of a liquid condition within comets was maintained for an initial epoch through the energy released in radioactive decays. When such energy sources eventually became exhausted inward freezing led to the production of multi-cracked, fragile cometary structures. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Hill stability of inclined small mass binary systems in three-body systems with special application to triple star systems, extrasolar planetary systems and Binary Kuiper Belt systems

The dynamical stability of a bound triple system composed of a small binary or minor planetary system moving on a orbit inclined to a central third body is discussed in terms of Hill stability for the full three-body problem. The situation arises in the determination of stability of triple star systems against disruption and component exchange and the determination of stability of extrasolar planetary systems and minor planetary systems against disruption, component exchange or capture. The Hill stability criterion is applied to triple star systems and extrasolar planetary systems, the Sun-Earth-Moon system and Kuiper Belt binary systems to determine the critical distances for stable orbits. It is found that increasing the inclination of the third body decreases the Hill regions of stability. Increasing the eccentricity of the binary also produces similar effects.These type of changes make exchange or disruption of the component masses more likely. Increasing the eccentricity of the binary orbit relative to the third body substantially decreases stability regions as the eccentricity reaches higher values. The Kuiper Belt binaries were found to be stable if they move on circular orbits. Taking into account the eccentricity, it is less clear that all the systems are stable.     

XUV Photometer System (XPS): Solar Variations during the SORCE Mission

The solar soft X-ray (XUV) radiation is important for upper atmosphere studies as it is one of the primary energy inputs and is highly variable. The XUV Photometer System (XPS) aboard the Solar Radiation and Climate Experiment (SORCE) has been measuring the solar XUV irradiance since March 2003 with a time cadence of 10 s and with about 70% duty cycle. The XPS measurements are between 0.1 and 34 nm and additionally the bright hydrogen emission at 121.6 nm. The XUV radiation varies by a factor of ∼2 with a period of ∼27 days that is due to the modulation of the active regions on the rotating Sun. The SORCE mission has observed over 20 solar rotations during the declining phase of solar cycle 23. The solar XUV irradiance also varies by more than a factor of 10 during the large X-class flares observed during the May–June 2003, October–November 2003, and July 2004 solar storm periods. There were 7 large X-class flares during the May–June 2003 storm period, 11 X-class flares during the October–November 2003 storm period, and 6 X-class flares during the July 2004 storm period. The X28 flare on 4 November 2003 is the largest flare since GOES began its solar X-ray measurements in 1976. The XUV variations during the X-class flares are as large as the expected solar cycle variations.     

Network science, NetLander: a european mission to study the planet Mars

The planet Mars has many Earth like characteristics, but its evolution is different. An important future step in Mars’ geophysics is to deploy a network of stations at the surface of Mars inorder to study a wide range of properties of this planet, going from its deep interior structure to its atmosphere. Each ground station (small landers) will contain the same scientific instruments/experiments. The collected data will improve our knowledge of the Martian interior, surface and atmosphere, as well as its evolution. An important part of these objectives can only be achieved by a network of surface stations, as a network gives unique possibilities for performing studies of global scale phenomena and studies requiring simultaneous measurements from several sites.     

Structure and evolution of a quasi-collisional gas torus (case of the Triton hydrogen torus)

Quite generally, the atmosphere of a planet has an escaping component that forms a gas cloud in its circumplanetary space. This gas cloud is frequently detectable and its observation provides important information about both the source and the circumplanetary environment. As a result, there is a strong motivation to investigate the nature of such gas clouds. Up to now, attention has been directed almost exclusively to the case of collisionless clouds, i.e., the collision time is much longer than the lifetime of the cloud constituents. In this study, we consider the relatively unexplored case of a quasi-collisional cloud, i.e., the self-collision time is much longer than the orbital period and much shorter than the lifetime of the cloud constituents. A slightly modified version of the traditional DSMC approach is applied to the case of the hydrogen torus of Triton, which is an example of a spatially axisymmetric quasi-collisional cloud that is generated from a source orbiting a central planet. A large number of calculations were performed for different models, primarily with different source velocity distributions. The results for two models that bracket the full span of these calculations are presented in detail and compared. The spatial structure and temporal evolution is discussed for these systems. The effect of lifetime processes and radiation pressure is also discussed.     

The Solar Radiation and Climate Experiment (SORCE) Mission for the NASA Earth Observing System (EOS)

The NASA Earth Observing System (EOS) is an advanced study of Earth's long-term global changes of solid Earth, its atmosphere, and oceans and includes a coordinated collection of satellites, data systems, and modeling. The EOS program was conceived in the 1980s as part of NASA's Earth System Enterprise (ESE). The Solar Radiation and Climate Experiment (SORCE) is one of about 20 missions planned for the EOS program, and the SORCE measurement objectives include the total solar irradiance (TSI) and solar spectral irradiance (SSI) that are two of the 24 key measurement parameters defined for the EOS program. The SORCE satellite was launched in January 2003, and its observations are improving the understanding and generating new inquiry regarding how and why solar variability occurs and how it affects Earth's energy balance, atmosphere, and long-term climate changes.     

Solar activity in the sixteenth and seventeenth centuries (a revision)

Maximum relative sunspot numbers for the 16th and 17th century were computed by means of the dependence of the maximum relative sunspot numbers on the solar cycle rise time and on the cycle asymmetry. In these dependencies four separate modes of relations, two for odd and two for even cycles, were identified. These modes are coupled two and two in even-odd cycle pairs. The rise times and the asymmetries of solar cycles in the 16th and 17th centuries were taken from cycle extreme estimates by Schove (1979), from auroral and telescopic sunspot observations during this period, but with some necessary corrections. Annual relative sunspot numbers and decade averages were estimated from the cycle maxima and the epochs of extremes. In addition, the efficiency of auroral records in latitudes lower than 55 deg was computed for the time interval 1500–1868. For this purpose the dependence of occurrence numbers of aurorae on the cycle and decade means of the relative sunspot numbers was derived.     

90年代太阳模型和太阳震荡研究进展(I):太阳模型研究进展(英)

太阳模型的研究是了解太阳整体结构和性质的极为重要的手段。90年代以来太阳模型研究取得了进展。随着MHD及OPAL物态方程的引入,理论上的太阳振荡频率与观测值的差别已大为减小,而考虑湍流频谱分布的局域对流理论和三维流体动力学模拟结果可对太阳内部对流能量传输过程有更深刻的理解．以前所发现的理论模型与反演结果得到的初始氦丰度的差别已能由扩散过程加以解释,而太阳表面锂丰度亏损问题也可以由扩散过程或早期演化星风来加以解决,太阳中微子问题则似应由粒子物理而不是天体物理来解决。     

太阳活动起源研究（Ⅰ）：太阳活动周的经验和半经验模型

概括了从观测上发现的太阳活动主要特征，对Babcock的太阳活动周经验模型和Leighton的半经验模型分别作了阐述，简要讨论了与Babcock和Leighton模型有关的后续研究情况。     

太阳活动起源研究(I):太阳活动周的经验和半经验模型

概括了从观测上发现的太阳活动主要特征，对Ｂａｂｃｏｃｋ的太阳活动周经验模型和Ｌｅｉｇｈｔｏｎ的半经验模型分别作了阐述，简要讨论了与Ｂａｂｃｏｃｋ和Ｌｅｉｇｈｔｏｎ模型有关的后续研究情况。     

90年代太阳模型和太阳震荡研究进展(II):太阳振荡研究进展(英)

太阳振荡研究现已成为研究太阳内部性质的新手段,也成为检验太阳模型构造时输入物理参量的最重要工具。90年代以来理论与观测日震频率的差别已随输入物理参量及太阳振荡理论的改进而大为减小,可是现有的差别仍远大于观测误差。由日震反演可对太阳内部对流区、表面氦丰度及自转随纬度和径向的分布都有更多了解。太阳振荡的湍动随机激发及激发源的位置都已得到研究,不过现在问题还未完全解决。今后一方面要探测更多的振动方式,另一方面也需要解决不同观测者得到的结果存在系统差的问题,而最外层的非绝热现象及理论与观测存在差别仍是最关键的难题。     

Design,Fabrication and Assembly of the Solar Upper Transition Region Imager(SUTRI)

The Solar Upper Transition Region Imager(SUTRI) focuses on the solar transition region to achieve dynamic imaging observation of the upper transition region. In this paper, we report the optical system design, mechanical design, ultrasmooth mirror manufacture and measurement, EUV multilayer film coating, prelaunch installation and calibration for the SUTRI payload at IPOE, Tongji University. Finally, the SUTRI carried by the SATech-01satellite was successfully set to launch. All functions of thi...