大气探测激光雷达组网观测一致性研究

通过激光遥感获取气溶胶、云垂直分布情况，对研究气溶胶、云微物理特性、辐射强迫效应以及污染物传输等具有重大意义。在实际应用中激光雷达受激光器能量、发散角以及透过率等影响，会导致各雷达面对同一目标物探测数据不一致。随着地基大气探测激光雷达逐步规模化、标准化，对雷达组网观测一致性开展研究具有重要意义。为保证组网激光雷达数据高质量和高可靠性，在雷达系统自标定基础上，利用太阳光度计、大气分子模型获取激光雷达系统常数，确保各激光雷达回波信号定量可比。通过激光雷达组网观测进行探测目标一致性比对试验，以验证激光雷达系统探测一致性精度。结果表明：标定后，532 nm距离修正信号在1~2 km区间相对偏差从64.89%降低到22.16%，在2~5 km区间相对偏差从49.26%降低到8.90%，在9.5~11.5 km相对偏差从46.83%降低到10.91%；532 nm退偏比在1~2 km区间相对偏差从69.68%降低到20.68%，在2~5 km区间相对偏差从71.24%降低到6.69%，在9.5~11.5 km相对偏差从140.24%降低到9.02%；532 nm后向散射系数在1~2 km区间相对偏差从37.45%降低到23.63%，在2~5 km区间相对偏差从29.15%降低到21.45%，在9.5~11.5 km相对偏差从76.02%降低到24.16%。组网激光雷达数据结果一致性较好，可在多站点进行高精度探测，在气候变化研究、碳排放监测和环境研究等领域发挥重要作用，为大规模大气变化规律研究提供高质量、有效数据。     

基于离子风电推进系统的平流层飞艇飞行轨迹分析

针对传统螺旋桨受大气密度等环境变化影响,推力和效率显著下降的特点,提出将新型离子风电推进系统应用于平流层飞艇,建立动力学模型和相应推力模型,通过Simulink模块开展轨迹跟踪与定点控制仿真,并对15 km到30 km高度上螺旋桨和离子风作为平流层飞艇主动力的飞行轨迹进行对比分析.结果 表明,40 kW功率下,在20 ...     

Optical effects of the operation of the onboard engine of the <Emphasis Type="Italic">Progress M-17M</Emphasis> spacecraft at thermospheric heights

This paper presents the results of optical observations in the active space experiment “Radar-Progress” on April 17, 2013, after switching on the approach-correction engine of the Progress M-17M cargo spacecraft at thermospheric heights (412 km), are presented in this paper. During engine operation, a region of enhanced emission intensity has been recorded. It was presumably related to the scatter of twilight solar emission at the engine exhausts in the cargo spacecraft orbit and, probably to the occurrence of an additional emission in the atomic oxygen line [OI] 630 nm. The maximum observed dimensions of the emission region were ~350 and ~250 km along the orbit and across it, respectively. The velocity of the expansion of the emission region at the first moments after the initiation of engine operation was ~7 and ~3.5 km/s along the orbit and across it, respectively. The maximum intensity of the disturbed region is estimated to be a value equivalent to ~40–60 R within the spectral band of 2 nm. No optical manifestation, which would exceed the natural variations in brightness of the night airglow and which would be related to possible large-scale modification of the ionosphere, was detected in the natural emission lines [O] 557.7 and 630.0 nm in a zone remote from the place of injection of engine exhausts.     

Time and energy characteristics of UV flashes in the atmosphere: Data of the <Emphasis Type="Italic">Universitetsky-Tatiana</Emphasis> satellite

Using a detector of near ultra-violet (UV) emission (wavelength range 300–400 nm) [1] onboard the Universitetsky-Tatiana satellite with an orbit height of 950 km and inclination of 81° we have detected and studied short UV flashes [2–5]. In this paper the observed UV flashes are classified according to the type of their time profiles, and the times of emission intensity rise and decay are investigated in every flash. Using the data on time profiles it turned out to be possible to estimate the flash energy in the atmosphere even in case of saturation of a signal measuring channel at the maximum of emission. The energy spectrum of observed flashes is estimated. Time and energy characteristics of the flashes are important for choosing a model of development of electric discharges in the upper atmosphere that are responsible for observed emission.     

Investigations of the Background Stratospheric Aerosol Using Multicolor Wide-Angle Measurements of the Twilight Glow Background

The first results of multiwave measurements of twilight background and the all-sky camera with a color (RGB) CCD matrix conducted in the spring and summer of 2016 in Central Russia (55.2° N, 37.5° E) have been discussed. The observations reveal the effect of aerosol scattering at heights of up to 35 km, which is substantially enhanced in the long-wave part of the spectrum (R band with an effective wavelength of 624 nm). An analysis of the behavior of the sky color during light period of twilight with allowance for the absorption by ozone in the Chappuis bands make it possible to restore the angular dependences of the intensity of the aerosol scattering of the light. This is used to determine the parameters of the lognormal distribution of aerosol particles over their sizes with a mean radius of 0.08 μm and a width of 1.5–1.6 for the stratospheric height interval.     

Spectral analysis of ionospheric disturbances in the phase delay and radio signal amplitude at limb paths according to the <Emphasis Type="Italic">COSMIC</Emphasis> data in periods of solar activity

Based on more than 4500 sessions of radio transillumination of Earth’s atmosphere along the satellite–atmosphere–satellite path obtained in the COSMIC experiment, the distribution along latitude and over local time of the spatial spectra of variations in the ionospheric phase delay and signal amplitude has been analyzed. The spatial spectra have been calculated for two height ranges, i.e., 60–80 and 80–100 km. In the phase signal spectrum within the height range 80–100 km, the second maximum in the vicinity of a frequency of 7–8 rad/km is clearly seen. Its diurnal and latitudinal behavior and its decrease towards high latitudes in both hemispheres can also be seen. In the height range of 60–80 km, this maximum is hardly observed. Although solar flares can lead to substantial local changes in the electron concentration, no substantial difference in the behavior of the spectral densities of the amplitude and phase delay at long limb paths was observed within these two height ranges on days of active and quiet sun. The latter fact makes it possible to develop a united algorithm of optimal ionospheric correction of the radio occultation data independent of solar activity.     

基于精确星光大气折射观测模型的轨道摄动研究

基于星光折射间接敏感地平自主导航方法,改进了现有的大气密度模型和固定高度(25km)的观测模型,建立了自适应连续高度(20km～50km)的星光折射观测模型,并在此观测模型的基础上深入分析研究了影响导航精度的各种轨道摄动力,包括地球形状各阶摄动力、不同高度的大气阻力摄动力、太阳光辐射压力等.提出一种精简的大气模式--静止变标高球面大气,解决了由于高层大气密度的求解复杂,使大气阻力摄动模型不精确的问题,由此取得了较好的导航定位精度.利用UKF和EKF两种不同非线性算法,对考虑各种摄动力后的导航定位精度进行全面的计算机仿真实验,并就仿真结果进行了误差分析,同时研究了各种有关参数对导航精度的影响.     

地磁扰动期间低轨目标轨道预报的误差修正

针对地磁扰动期间大气密度变化造成的低轨目标较大的轨道预报误差,提出一种根据POES卫星观测的极光能量注入数据改进短期轨道预报的方法。分析表明CHAMP卫星的沿迹大气密度及轨道衰减与极光能量注入具有较好的相关性。通过线性回归方法,建立轨道半长轴衰减及阻力调制系数的修正公式,并使用修正后的阻力调制系数取代两行元(TLE)中的该系数带入SGP4模型进行位置预报。该方案考虑了外推过程中地磁扰动引起的大气密度响应,能更准确地反映外推过程中大气阻力对轨道的影响。将其应用到2008年CHAMP卫星和国际空间站的轨道预报中,结果表明,半长轴和位置的预报误差可分别降低50%和30%左右。进一步对不同年份、不同轨道高度的目标进行了预报误差修正的分析,验证了该方法的普适性。     

一种适用于月球跳跃返回的改进解析预测校正制导律

解析落点预测-校正制导律具有计算量小的特点,适用于月球返回舱机载计算机的在线计算,针对其对远航程适应性差的问题,提出了一种改进的解析预测制导律。通过调整上升段的控制增益,减小返回舱飞离大气层时刻实际状态与标准状态的偏差,对飞出大气层的速度进行修正以补偿弹道段空气阻力引起的航程减小。二次再入段采用数值预测-校正制导,利用逐步校正的方法,解决了收敛问题,避免了复杂的基准弹道设计过程。数值仿真表明,所设计的制导律能够适用于远航程情况,在具有初始位置偏差、质量偏差、气动偏差、大气偏差的情况下,终端位置精度在5km以内,表明该制导律具有良好的鲁棒性,该制导律具有在线实施的潜力。
     

基于虚拟落点策略的月球返回飞船再入制导方法

针对长航程大偏差状况下阿波罗再入制导算法的精度退化问题提出改进,采用数值预测-校正方法规划和调制线性参数化的倾侧角剖面,给出了一种在全航程包络内适用的月球返回飞船再入制导方法。引入虚拟落点策略,在一次再入段利用算法预测能力预测二次再入段初始侧向偏差并进行前馈补偿,给出了简便有效的虚拟落点瞄准程序。大偏差任务想定下的蒙特卡洛仿真分析表明,该算法在3000km到10000km的再入航程范围内,能够确保偏差小于3km的落点精度。     

Russian system of countermeasures on board of the International Space Station (ISS): the first results

The system of countermeasures used by Russian cosmonauts in space flights on board of International Space Station (ISS) was based on the developed and tested in flights on board of Russian space stations. It included as primary components: physical methods aimed to maintain the distribution of fluids at levels close to those experienced on Earth; physical exercises and loading suits aimed to load the musculoskeletal and the cardiovascular systems; measures that prevent the loss of fluids, mainly, water-salt additives which aid to maintain orthostatic tolerance and endurance to gravitational overloads during the return to Earth; well-balanced diet and medications directed to correct possible negative reactions of the body to weightlessness. Fulfillment of countermeasure's protocols inflight was thoroughly controlled. Efficacy of countermeasures used were assessed both in- and postflight. The results of studies showed that degrees of alterations recorded in different physiological systems after ISS space flights in Russian cosmonauts were significantly higher than those recorded after flights on the Russian space stations. This phenomenon was caused by the failure of the ISS crews to execute fully the prescribed countermeasures' protocols which was as a rule excused by technical imperfectness of exercise facilities, treadmill TVIS particularly.     

基于星光大气折射的卫星自主轨道确定

本文研究了利用星敏感器进行卫星轨道确定的自主导航方案。这种自主导航方案完全利用高精度的CCD星敏感器，以及大气对星光折射的数学模型及误差补偿方法，精确敏感地平，从而实现航天器的精确定位。以某太阳同步轨道卫星为背景，针对本文给出的星光折射光的卫星导航方案，结合推广的卡尔曼滤波算法，使用模拟数据进行了仿真研究，定位精度为38m。仿真结果说明，星光折射角的测量误差和大气折射模型的不确定性是影响导航精度的主要因素。     

Radial propagation velocity of energetic particle injections according to measurements onboard the <Emphasis Type="Italic">Cluster</Emphasis> satellites

Injections of energetic electrons with a dispersion over energies were observed during the February 23, 2004 (at about 03:20 UT) substorm onboard the Cluster satellites in the vicinity of perigee near the midnight meridian. The delays in the particle observation caused by the energy dependence of the magnetic drift velocities made it possible to determine the position and time of the beginning of the drift, tracing the trajectories of the leading center of particles back in time in the magnetospheric model. The comparisons of the measurements of four satellites allowed us to determine the radial propagation of the injection front with a velocity of 100–150 km/s at a distance of 7–9 R _E. The comparison with a few previous measurements shows a substantial slowing down of injections as they approached the Earth, and this confirms the prospects of this method for more detailed study of propagation of plasma injection into the inner magnetosphere.     

Testing and evaluation of a method for locating potentially hazardous sites of eventual microdestruction and detecting marks of ISS RS hull leakage

In 2008, two experiments – BAR and EXPERT – were performed on the Russian segment (ISS RS) during ISS missions 16 and 17 using diagnostic equipment BAR. The experiments were aimed to enhance ISS safety by proposing means and methods of detecting leaks due to many factors including microdestruction of pressurized modules of the vehicle. The BAR experiment was designed to assess the ultraviolet background in 56 potentially dangerous locations identified by RS ISS designers and engineers. The method for locating sites carrying the risk of microdestruction of pressurized structure was verified. The study showed that the rate of microdestruction is highly affected by level of ultrasound vibrations caused by onboard equipment. The ultrasound measurements in 200 RS ISS sites were performed within the BAR experiment. The method consists of looking for surfaces with atmospheric condensate in the areas of increased levels of ultrasound vibrations. Twenty six sites were added to the nomenclature of potentially risky sites to be monitored on the regular basis. Some of these sites were contaminated by fungi and bacteria.     

Observations of the Auroral Kilometric Radiation onboard the Interball-1 satellite in 1995–1997

Results of two-year (August 1995–July 1997) continuous observations of the auroral kilometric radiation (AKR) in the AKR-X experiment on board the high-apogee Interball-1 satellite are presented. Observations were carried out in the minimum of solar activity in a frequency range of 100–1500 kHz. The most effective detections of AKR occurred near the maximum of its spectrum at a frequency of 252 kHz and also at a frequency of 500 kHz. The data obtained made it possible to study in more detail the character of AKR global directivity, its frequency dependence, and some other parameters of the emission. These data are interpreted qualitatively in the context of the emission mechanism caused by cyclotron maser instability.     

The fluid-dynamic disturbances induced on the ISS, based on the first acceleration measurements on board the space station

The different acceleration components on the ISS that are responsible for the generation of convective motions in a fluid cell either in the presence of density gradients or in quasi-isodense processes, are analyzed. The NASA measurements of the quasi-steady and periodic acceleration on the ISS are considered and their effects on fluid-dynamic experiments are computed and discussed under different assumptions. In particular, numerical simulations are carried out to identify the relative importance of linear and pendular accelerations, due to possible rotations of the P/L around its center of mass. The effects caused by variable accelerations created by an isolation mount that exhibits an attenuation factor not constant within the payload volume, caused by the reaction forces of the umbilicals, are computed and analyzed.     

Development of Satellite Methods for Radio Holographic Surveys of the Earth's Surface and Atmosphere

The methods of studying the Earth's surface and troposphere with the help of coherent radio waves radiated by satellites are considered. Some examples of measurements of the local relief of the Earth's surface by the method of radar interferometer are presented, as well as refraction profiles of the troposphere obtained by the radio holographic method. The described methods are promising for investigations of the local relief of the Earth's surface and its changes, for studying the characteristics of sea heaving, and for monitoring atmospheric processes.     

Aerobraking at Venus: A science and technology enabler

Venus remains one of the great unexplored planets in our solar system, with key questions remaining on the evolution of its atmosphere and climate, its volatile cycles, and the thermal and magmatic evolution of its surface. One potential approach toward answering these questions is to fly a reconnaissance mission that uses a multi-mode radar in a near-circular, low-altitude orbit of ∼400 km and 60–70° inclination. This type of mission profile results in a total mission delta-V of ∼4.4 km/s. Aerobraking could provide a significant portion, potentially up to half, of this energy transfer, thereby permitting more mass to be allocated to the spacecraft and science payload or facilitating the use of smaller, cheaper launch vehicles.Aerobraking at Venus also provides additional science benefits through the measurement of upper atmospheric density (recovered from accelerometer data) and temperature values, especially near the terminator where temperature changes are abrupt and constant pressure levels drop dramatically in altitude from day to night.Scientifically rich, Venus is also an ideal location for implementing aerobraking techniques. Its thick lower atmosphere and slow planet rotation result in relatively more predictable atmospheric densities than Mars. The upper atmosphere (aerobraking altitudes) of Venus has a density variation of 8% compared to Mars' 30% variability. In general, most aerobraking missions try to minimize the duration of the aerobraking phase to keep costs down. These short phases have limited margin to account for contingencies. It is the stable and predictive nature of Venus' atmosphere that provides safer aerobraking opportunities.The nature of aerobraking at Venus provides ideal opportunities to demonstrate aerobraking enhancements and techniques yet to be used at Mars, such as flying a temperature corridor (versus a heat-rate corridor) and using a thermal-response surface algorithm and autonomous aerobraking, shifting many daily ground activities to onboard the spacecraft. A defined aerobraking temperature corridor, based on spacecraft component maximum temperatures, can be employed on a spacecraft specifically designed for aerobraking, and will predict subsequent aerobraking orbits and prescribe apoapsis propulsive maneuvers to maintain the spacecraft within its specified temperature limits. A spacecraft specifically designed for aerobraking in the Venus environment can provide a cost-effective platform for achieving these expanded science and technology goals.This paper discusses the scientific merits of a low-altitude, near-circular orbit at Venus, highlights the differences in aerobraking at Venus versus Mars, and presents design data using a flight system specifically designed for an aerobraking mission at Venus. Using aerobraking to achieve a low altitude orbit at Venus may pave the way for various technology demonstrations, such as autonomous aerobraking techniques and/or new science measurements like a multi-mode, synthetic aperture radar capable of altimetry and radiometry with performance that is significantly more capable than Magellan.     

星载激光雷达高精高稳探测卫星系统保证技术

激光雷达探测精度高,具备全天时工作和垂直探测能力,在大气环境天基遥感领域应用广泛。基于CO_2柱线浓度激光遥感探测原理,分析了积分路径差分吸收星载激光雷达测量系统的激光波长、能量精度和稳定性及光轴指向精度等关键指标要求和功能模块配置,重点开展了星载激光雷达光机头部稳定安装、良好机热环境保障及星敏载荷一体化布局等整星层面系统设计保证,仿真结果初步表明设计方案可行。同时,提出了激光雷达波长、能量精度及稳定性实时监测、卫星对地光轴指向高精度测定和星地载荷光轴指向测量误差标定的地面试验验证要求,以确保系统设计的有效性,为激光雷达遥感卫星的研制提供了技术参考。     

Monitoring of the time and spatial distribution of neutron-flux spectral density outside the Russian segment of the <Emphasis Type="Italic">International Space Station</Emphasis> based on data from the BTN-Neutron space experiment

Results of measurements of neutron-flux spectral density in the vicinity of the International Space Station (ISS) based on BTN-Neutron space experimental data acquired in 2007–2014 have been presented in this paper. It has been shown that, during the flight of the ISS over different regions of the Earth’s surface, neutron flux in the energy range of 0.4 eV–15 MeV varies from 0.1 n/sm²/s in equatorial regions to 50 n/sm²/s in the South Atlantic anomaly region. The measurements were used to estimate the contribution of the neutron component to the overall exposure dose rate. The total contribution of fast neutrons is about 0.1–0.4 μ Zv/h above the equator area and more than 50 μ Zv/h above the South Atlantic anomaly region. A data analysis of BTN-Neutron data also showed that the time profile of neutron flux has long-periodic variations. It was found that, under the influence of Galactic cosmic rays (GCRs), modulation during 24th solar cycle neutron flux changed almost twofold (above high latitude regions). Maximum values of neutron flux were observed in January 2010 and minimum values were observed in January 2014.