Energetic particles in the comet Halley environment

An overview is presented of electrons, protons and heavier ions (E > 20 keV) recorded by the energetic particle detector EPONA in the Comet Halley environment, 12–15 March, 1986. Pick-up ions were detected at distances of up to at least 7.5 × 10⁶ km from the nucleus. Estimates of the energies that typical cometary ions may be expected to acquire from the solar wind pertaining at Encounter show that the pick-up process is insufficient to account for the energies of the particles detected. An additional mechanism must thus be postulated to account for the observed particle signatures. Preliminary correlations with magnetic and plasma wave data from other instruments suggest that the presence of MHD turbulence at several million kilometers upstream of the bowshock may have contributed to the acceleration of the first pick-up ions observed. The bowshock boundary (inbound) does not appear to have constituted a location where particle acceleration to high energies took place. Downstream of the shock boundary, hardening of the energy spectrum and the development of less anisotropic particle streaming was observed to occur when the spacecraft was in a turbulent environment 1 × 10⁶ km from the nucleus. The waxing influence of mass loading as a mechanism for reducing energetic particle fluxes as well as the depletion of energetic ions due to their escape along open field lines and to charge exchange collision with neutrals in a progressively more stagnant solar wind, may be inferred in a regime (seen on the magnetometer data to be largely non-turbulent) traversed by the spacecraft from 5 × 10⁵ km from the nucleus to within the magnetic pile-up region. A major burst of ions and electrons (not yet established to be of cometary origin) occurred when the spacecraft was close to the Contact Surface. A population of high energy electrons (from 180 keV to at least 300 keV) was detected for about one hour before Closest Approach and for several hours thereafter. Also an energetic beam of electrons was identified exiting from a location at about 1 × 10⁶ km from the nucleus (outbound). Finally, differences between inbound and outbound particle signatures are described.     

The first results from the Herschel-HIFI mission

This paper contains a summary of the results from the first years of observations with the HIFI instrument onboard ESA’s Herschel space observatory. The paper starts by outlining the goals and possibilities of far-infrared and submillimeter astronomy, the limitations of the Earth’s atmosphere, and the scientific scope of the Herschel-HIFI mission. The presentation of science results from the mission follows the life cycle of gas in galaxies as grouped into five themes: Structure of the interstellar medium, First steps in interstellar chemistry, Formation of stars and planets, Solar system results and Evolved stellar envelopes. The HIFI observations paint a picture where the interstellar medium in galaxies has a mixed, rather than a layered structure; the same conclusion may hold for protoplanetary disks. In addition, the HIFI data show that exchange of matter between comets and asteroids with planets and moons plays a large role. The paper concludes with an outlook to future instrumentation in the far-infrared and submillimeter wavelength ranges.     

Energetic particles in the night-time middle- and low-latitude ionosphere

Data are presented on the zones of energetic particle precipitation at middle and low latitudes observed during and after magnetic storm injection events. Satellite measurements of the equatorial zone ion flux (～ 10³ - 10⁴ cm^?2 s^?1 sr^?1 for E > 45 keV at 240 km) are consistent with the development of a temporary low altitude ion radiation belt at the magnetic equator. In the midlatitude ion zone the flux (～ 10³ - 10⁵ ions cm^?2 s^?1 sr^?1 for E > 45 keV at 220 km) is directly related to magnetic activity while the midlatitude electron zone flux has a delayed response (～ 4 days).     

Interpretation of the SOHO/UVCS observations of two CME-driven shocks

We report on the analysis of two fast CME-driven shocks observed with the UltraViolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO). The first event, detected on 2002 March 22 at 4.1 R_⊙ with the UVCS slit placed in correspondence with the flank of the expanding CME surface, represents the highest UV detection of a shock obtained so far with the UVCS instrument in the corona. The second one, detected on 2002 July 23 at 1.6 R_⊙ with the UVCS slit placed in correspondence with the front of the expanding CME surface, shows an anomalous deficiency of ion heating with respect to what observed in previous CME/shocks observed by UVCS, possibly reflecting the effect of different coronal plasma conditions over the solar cycle. From the two different sets of observations we derived an estimate for the shock compression ratio X, which turns out to be X = 2.4 ± 0.2 and X = 2.2 ± 0.1, respectively, for the first and second event. Comparison between the two events provides complementary perspectives on the dynamical evolution of CME-driven shocks.     

Development of plant protoplasts during the IML-1 mission.

During the 8 day IML-1 mission, regeneration of cell walls and cell divisions in rapeseed protoplasts were studied using the Biorack microscope onboard the Space Shuttle "Discovery". Samples from microgravity and 1g protoplast cultures were loaded on microscope slides. Visual microscopic observations were reported by the payload specialist Roberta Bondar, by down-link video transmission and by use of a microscope camera. Protoplasts grown under microgravity conditions do regenerate cell walls but to a lesser extent than under 1g. Cell divisions are delayed under microgravity. Few cell aggregates with maximum 4-6 cells per aggregate are formed under microgravity conditions, indicating that microgravity may have a profound influence on plant cell differentiation.     

The detection of energetic cometary and solar particles by the EPONA instrument on the Giotto mission

EPONA is an energetic particle detector system incorporating totally depleted silicon surface barrier layer detectors. Active and passive background shielding will be employed and, by applying various techniques, particles of different species, including electrons, protons, alpha particles and pick-up ions of cometary origin may be detected over a wide spectrum of energies extending from the tens of KeV into the MeV range.

The instrument can operate in two modes namely (a) in a cruise phase or storage mode and (b) in a real time mode. During the real time mode, observations at high spatial (octosectoring) and temporal (0.5s) resolution in the cometary environment permit studies to be made of accelerated particles at the bow shock and/or in the tail of the comet. In conjunction with magnetic field measurements on board Giotto, observations of energetic electrons and their anisotropies can determine whether the magnetic field lines in the cometary tail are open or closed. Further, the absorption of low energy solar particles in the cometary atmosphere can be measured and such data would provide an integral value of the pertaining gas and dust distribution. Solar particle background measurements during encounter may also be used to correct the measurements of other spacecraft borne instruments potentially vulnerable to such radiation.

Solar particle flux measurements, obtained during the cruise phase will, when combined with simultaneous observations made by other spacecraft at different heliographic longitudes, provide information concerning solar particle propagation in the corona and in interplanetary space.     

任务准备期内的军用飞机瞬时可用度

军用飞机是一种复杂的可修系统,其瞬时可用度计算是装备综合保障领域研究的难点。本文构建了基于作战任务和飞机技术状态驱动的随机维修网络(SMTN),SMTN中各项活动的维修时间服从不同分布,定义了SMTN的矩母函数并求解系统维修度函数的数字特征,将得到的期望和方差分别代入不同分布形式函数进行验证,从而选定符合实际情况的SMTN的维修度函数,并对任务准备期内的军用飞机可用度进行仿真。在计算过程中基于蒙特卡罗技术设计了一种新方法,在提高计算效率的同时,可以较好地反映维修保障过程的逻辑性、拓扑性和随机性,仿真结果可以真实反映装备在任务准备期内瞬时可用度的波动规律。该方法可以广泛应用到各种复杂的可修系统,为装备的使用决策提供依据,为保障系统的保障效能评估提供量化指标,对于综合保障领域"动态"指标的研究有着一定探索价值。     

The LET spectrum and its uncertainty during the CRRES mission.

We present Linear Energy Transfer (LET) spectra calculated for the 1990-1991 CRRES mission using the galactic cosmic ray (GCR) and solar energetic particle (SEP) models developed for the CRRES/SPACERAD program and presented by Chen, et al. 1992 at this conference. We discuss how the spectra vary with changes in the galactic cosmic ray and solar energetic particle models. Finally, we illustrate the application and significance of these results by using them to predict single event upset event rates in a sample integrated circuit memory device, a 256 x 4-bit bipolar static RAM (93L422).     

The high-LET radiation component measured during the EUROMIR-94 mission.

Stacks of CR-39 plastic nuclear track detectors were mounted inside the MIR-station during the EUROMIR-94-mission. We present LET-spectra determined separately for long range cosmic ray heavy ions and for short range target fragments produced in nuclear interactions of cosmic rays and measured charge distributions for relativistic and stopping particles.     

中性原子成像仪的定标测试

中性原子成像仪（NAIS-H）获取的高时空分辨率图像可为地球空间磁暴和亚暴过程的各类机制研究提供全景式的空间粒子分布数据,为磁层与电离层耦合、磁层能量耗散等MIT（磁层elax-elax电离层elax-elax热层耦合小卫星星座探测计划）科学研究任务提供重要的数据支撑.探测器的标定是研制过程的一个重要技术环节,是日后空间探测数据分析和反演基本依据.本文利用模拟信号源对中性原子成像仪原理样机的前端电子学系统进行了能谱定标,并利用电子加速器对标定的能谱进行了辐射测试验证.     

Dosimetry during the first IBIS facility flight.

The dosimetry of cosmic rays was performed during the first experimental flight of the IBIS facility. Different thermoluminescent detectors (TLD) have been used to measure the contribution of the low linear energy transfer component (LET < 10 keV/micrometer) and plastic nuclear track detectors (PNTD) for the high linear energy tranfer (LET) component. Several parameters of tracks have been measured to determine the LET spectra of primary and secondary charged particles. The total absorbed dose rate (TLD+PNTD) during the flight was 0.23 mGy/day and the dose equivalent rate using the ICRP 60 was 0.52 mSv/day. The corresponding mean quality factor was 2.4. These results are in agreement with those obtained aboard the MIR station with a tissue equivalent proportional counter.     

Cometary probe of the Venera-Halley mission

Venera-Halley mission is to be launched to Venus in Dec. 1984. It will fly by Venus in June 1985. Separation of the cometary probe and Venera descend module will take place at that time. The gravitational swing-by at Venus will provide the encounter with the Halley comet in March 1986. The remote sensing of the inner coma (TV-imagery, spectrometry in the region from 1200 A to 12 μm, polarimetry) and of the nucleus, direct measurements of dust fluxes, dust composition, plasma and magnetic field are planned in the framework of multinational cooperation.     

Food production and nutrition in Biosphere 2: results from the first mission September 1991 to September 1993.

The initial test of the Biosphere 2 agricultural system was to provide a nutritionally adequate diet for eight crew members during a two year closure experiment, 1991-1993. The overall results of that trial are presented in this paper. The 2000 m2 cropping area provided about 80 percent of overall nutritional needs during the two years. Adaptation of the crew to the diet which averaged 2200 calories, 73 g. of protein and 32 g. of fat per person over the course of the two years. The diet was primarily vegetarian, with only small amounts of milk, meat and eggs from the system's domestic animals. The crew experienced 10-20 percent weight loss, most of which occurred in the first six months of the closure reflecting adaptation to the diet and lower caloric intake during that period. Since Biosphere 2 is a tightly sealed system, non-toxic methods of pest and disease control were employed and inedible plant material, domestic animal wastes and human waste-water were processed and nutrients returned to the soil. Crop pests and diseases, especially broad mites and rootknot nematode, reduced yields, and forced the use of alternative crops. Outstanding crops included rice, sweet potato, beets, banana, and papaya. The African pygmy goats were the most productive of the domestic animals. Overall, the agriculture and food processing required some 45% of the crew time.     

Development studies of Aurelia (jellyfish) ephyrae which developed during the SLS-1 mission.

Aurelia polyps (scyphistomae) and ephyrae were exposed to microgravity for nine days aboard the space shuttle during the SLS-1 mission. During strobilation, polyps segment transversely and each segment develops into an ephyra. Polyps were induced to strobilate at 28 degrees C, using iodine or thyroxine, at L(Launch)-48h, L-24h, and L+8h. Ephyrae developed in the groups tested in space and on Earth. The number of ephyrae formed per polyp was slightly higher in the L+8h groups as compared with those induced at L-24h and L-48h. On Earth, iodine is used by jellyfish to synthesize jellyfish-thyroxine (Jf T4), needed for ephyra production. Since iodine-treated polyps strobilated and formed ephyrae in space, it appears that jellyfish can synthesize Jf-T4 in space. Indeed, two groups of polyps not given inducer formed ephyrae [correction of ephryae] in space, presumably due to enhanced Jf-T4 synthesis, utilization or accumulation. Some ephyrae that formed in space were also fixed in space on Mission Day (MD) 8; others were fixed post-flight. Examination of living ephyrae with the light microscope and fixed ones with the Scanning and Transmission Electron Microscopes revealed that those which developed in space were morphologically very similar to those which developed on Earth. Quantitation of arm numbers determined that there were no significant differences between space and Earth-developed ephyrae. Pulsing abnormalities, however, were found in greater numbers (18.3%) in space-developed ephyrae than in Earth-developed controls (2.9%). These abnormalities suggest abnormal development of the graviceptors, the neuromuscular system, or a defect in the integration between these systems in apparently microgravity-sensitive animals.     

Challenges of the rosetta sample return mission

Rosetta is a correrstone mission of the science programme of the European Space Agency (ESA) and it has been studied as a collaborative project with NASA. The major scientific objectives of Rosetta is to return cometary samples to Earth. About 20 kg of cometary material from up to 3m below the surface would be made available to the scientific community for analysis. Since relatively little is known a priory about the environment to be expected, the mission design must be based on a limited body of knowledge and rely on autonomy. The paper outlines the main mission characteristics and the experimental approach to demonstrate the mission feasibility.     

Issues of exploration: human health and wellbeing during a mission to Mars.

Today, the tools are in our hands to enable us to travel away from our home planet and become citizens of the solar system. Even now, we are seriously beginning to develop the robust infrastructure that will make the 21st century the Century of Space Travel. But this bold step must be taken with due concern for the health, safety and wellbeing of future space explorers. Our long experience with space biomedical research convinces us that, if we are to deal effectively with the medical and biomedical issues of exploration, then dramatic and bold steps are also necessary in this field. We can no longer treat the human body as if it were composed of muscles, bones, heart and brain acting independently. Instead, we must lead the effort to develop a fully integrated view of the body, with all parts connected and fully interacting in a realistic way. This paper will present the status of current (2000) plans by the National Space Biomedical Research Institute to initiate research in this area of integrative physiology and medicine. Specifically, three example projects are discussed as potential stepping stones towards the ultimate goal of producing a digital human. These projects relate to developing a functional model of the human musculoskeletal system and the heart.     

The relationship between plasma effects and cosmic radiation studied with TriTel-LMP measurements during the ESEO mission

The main point of the paper is to use the simultaneous measurements of the energetic particle flux by TriTel and those of electron density by a Langmuir probe to study the question of to what extent solar electromagnetic and corpuscular radiation (galactic cosmic rays, particle precipitation from the radiation belts) are responsible for the ionization of the atmosphere. The electron density measured by the Langmuir probe is the sum of the ionization produced by the solar electromagnetic radiation and that due to the corpuscular radiation. The ionization produced by the solar electromagnetic radiation may be computed. The flux of energetic particles in an energy range may be determined by taking the difference between the threshold energy of the TriTel telescopes and the energy corresponding to the local cut-off rigidity. As the ESEO satellite will have a quasi-polar and circular orbit, the cut-off rigidity will change from low to high latitudes, thus enabling the assignment of different energy bands for the telescopes. Thus, it will be possible to determine which energy bands of particle produce ionization at different latitudes.     

A lunar L2-Farside exploration and science mission concept with the Orion Multi-Purpose Crew Vehicle and a teleoperated lander/rover

A novel concept is presented in this paper for a human mission to the lunar L2 (Lagrange) point that would be a proving ground for future exploration missions to deep space while also overseeing scientifically important investigations. In an L2 halo orbit above the lunar farside, the astronauts aboard the Orion Crew Vehicle would travel 15% farther from Earth than did the Apollo astronauts and spend almost three times longer in deep space. Such a mission would serve as a first step beyond low Earth orbit and prove out operational spaceflight capabilities such as life support, communication, high speed re-entry, and radiation protection prior to more difficult human exploration missions. On this proposed mission, the crew would teleoperate landers/rovers on the unexplored lunar farside, which would obtain samples from the geologically interesting farside and deploy a low radio frequency telescope. Sampling the South Pole-Aitken basin, one of the oldest impact basins in the solar system, is a key science objective of the 2011 Planetary Science Decadal Survey. Observations at low radio frequencies to track the effects of the Universe’s first stars/galaxies on the intergalactic medium are a priority of the 2010 Astronomy and Astrophysics Decadal Survey. Such telerobotic oversight would also demonstrate capability for human and robotic cooperation on future, more complex deep space missions such as exploring Mars.     

A few metrological aspects of the Gaia mission

The ESA space astrometry mission Gaia is designed to measure the positions, parallaxes and proper motions of more than one billion stars of our Galaxy brighter than 20 magnitude. The expected astrometric accuracies are in the range 7–25 μas for the point-like sources down to 15 mag. To achieve this staggering performance, several issues of highly accurate metrology must be solved and implemented on the spacecraft. In this paper, I discuss first some constraining principles to perform global astrometry in space, and then a couple of examples of the metrological issues currently faced by the design or to be encountered during the operations. One concerns the optimisation of the sky coverage with a scanning instrument like Gaia, and the other deals with the instrument stability and how the stringent requirements are met in practice.     

Development of the EUV detector for the BepiColombo mission

An ultraviolet spectrometer, PHEBUS (Probing of Hermean Exosphere by Ultraviolet Spectroscopy) that is loaded onto the Mercury Planetary Orbiter in the BepiColombo mission is under development. The instrument, basically consisting of two spectrophotometers (EUV: 50–150 nm, FUV: 145–330 nm) and one scanning mirror, aims at measuring emission lines from molecules, atoms and ions present in the tenuous atmosphere of Mercury. The detectors employ microchannel plates as 2-D photon-counting devices. In order to enhance the quantum detection efficiencies, the surface of the top microchannel plates of EUV detector is covered with photocathode. This method enables us to identify weak atmospheric signatures such as neon (73.5 nm) and argon (104.8 nm), which could not be detected with conventional detector systems. This paper presents measurements of the performance characteristics of potassium bromide and esium iodide photocathodes, which have been evaluated for use in the EUV channel.