Mars Phobos and Deimos Survey (M-PADS) – A martian Moons orbiter and Phobos lander

We describe a Mars ‘Micro Mission’ for detailed study of the martian satellites Phobos and Deimos. The mission involves two ∼330 kg spacecraft equipped with solar electric propulsion to reach Mars orbit. The two spacecraft are stacked for launch: an orbiter for remote investigation of the moons and in situ studies of their environment in Mars orbit, and another carrying a lander for in situ measurements on the surface of Phobos (or alternatively Deimos). Phobos and Deimos remain only partially studied, and Deimos less well than Phobos. Mars has almost always been the primary mission objective, while the more dedicated Phobos project (1988–89) failed to realise its full potential. Many questions remain concerning the moons’ origins, evolution, physical nature and composition. Current missions, such as Mars Express, are extending our knowledge of Phobos in some areas but largely neglect Deimos. The objectives of M-PADS focus on: origins and evolution, interactions with Mars, volatiles and interiors, surface features, and differences. The consequent measurement requirements imply both landed and remote sensing payloads. M-PADS is expected to accommodate a 60 kg orbital payload and a 16 kg lander payload. M-PADS resulted from a BNSC-funded study carried out in 2003 to define candidate Mars Micro Mission concepts for ESA’s Aurora programme.     

A Revisit of the Phobos Events

The magnetic field disturbances detected by the Phobos-2 spacecraft in 1989 have been suggested to be caused by a ring of dust and/or gas emitted from the Martian moon, Phobos. The physical nature of these ``Phobos events' is examined using results from related investigations over the last twenty years. It is concluded that there is no clear evidence at present to support the association of magnetic field disturbances in the solar wind with Phobos. The situation will be further clarified taking advantage of the multi-spacecraft observations of the Yinghuo-1(YH-1), Mars Express and MAVEN missions beginning in 2012. It is expected that many novel features of solar wind interaction with Phobos (and possibly also Deimos) itself will also be revealed.      

Planned observation of Phobos/Deimos by Mars imaging camera (MIC) on NOZOMI

The large elongated orbit planned for NOZOMI around Mars, i.e. a periapsis of 150 km and an apoapsis of 15 R_M (R_M denotes the radius of Mars), will provide many occasions for encounters of NOZOMI with two Martian satellites, Phobos and Deimos, where NOZOMI is the former Planet-B meaning “Hope” in Japanese. We present a plan for imaging the two satellites by the Mars Imaging Camera (MIC) on board NOZOMI at such encounters during the mission lifetime of two years from October 1999. An Autonomous Tracking Mode is available for fly-by imaging of satellites. MIC scans the azimuth direction (orthogonal to the CCD line arrays) using the spacecraft spin at a rotation rate of 7.5 rpm, and has an image resolution of 80 arc second in both elevation and azimuth directions.The main science objectives of MIC, related to the two satellites, are (i) to study the size/spatial distributions of craters on both satellites, (ii) to examine the groove structure on Phobos, (iii) to image areas not yet seen areas of Deimos, and (iv) to derive its whole shape. We will, furthermore, search for the dust rings along the orbits of these two satellites in the forward scattering region of sunlight. The capability of MIC to execute these objectives are briefly summarized.     

基于火卫二视线测量的火星接近段自主导航算法

针对火星接近段导航通信时延大、存在通信盲区、自主导航可用观测信息有限等问题,提出了一种基于一组火卫二相对探测器视线矢量测量的天文自主导航算法,每个导航周期测量一组火卫二视线矢量可得到其中某一时刻探测器的完整轨道信息的估计值,该方法不依赖于轨道渐近线方向等先验信息。考虑到存在火卫二和火星在同一视场的情形,此时结合火星中心视线矢量方向以及火卫二的星历信息可估计出精度较高的探测器轨道半径,作为第一种方法的补充观测量,提高导航精度。最后给出仿真校验,验证了该方法的导航精度和可行性,表明该方案能够满足未来火星探测接近段自主导航需求。     

Mars ultraviolet imaging spectrometer experiment on the PLANET-B mission

An ultraviolet imaging spectrometer (UVS) has been developed for the PLANET-B spacecraft. The UVS instrument is composed of a grating spectrometer (UVS-G) and a D/H absorption cell photometer (UVS-P). The UVS-G is a flat-field type spectrometer measuring optical emissions in the FUV and MUV range between 115 nm and 310 nm with a spectral resolution of 2 – 3 nm. The UVS-P is a photometer detecting hydrogen (H) and deuterium (D) Lyman α emissions separately by an absorption cell technique. Scientific targets of the UVS experiment are the investigation of (1) hydrogen and oxygen coronas around Mars, (2) the D/H ratio in the upper atmosphere, (3) dayglow, (4) aurora and nightglow, (5) dust, clouds and ozone, and (6) the surface composition of Phobos and Deimos.     

Rapid impactor sample return (RISR) mission scenario

Due to the long lead time and great expense of traditional sample return mission plans to Mars or other astronomical bodies, there is a need for a new and innovative way to return materials, potentially at a lower cost. The Rapid Impactor Sample Return (RISR) mission is one such proposal. The general mission scenario involves a single pass of Mars, a Martian moon or an asteroid at high speeds (7 km/s), with the sample return vehicle skimming just 1 or 2 m above a high point (such as a top ridge on Olympus Mons on Mars) and releasing an impactor. The impactor strikes the ground, throwing up debris. The debris with roughly the same forward velocity will be captured by the sample return vehicle and returned to Earth. There is no delay or orbit in the vicinity of Mars or the asteroid: RISR is a one-pass mission. This paper discusses some of the details of the proposal. Calculations are presented that address the question of how much material can be recovered with this technique. There are concerns about the effect of Mars tenuous atmosphere. However, it will be noted that such issues do not occur for RISR style missions to Phobos, Deimos, or asteroids and Near Earth Objects (NEOs). Recent test results in the missile defense community (IFTs 6–8 in 2001, 2002) have scored direct hits at better than 1 m accuracy with closing velocities of 7.6 km/s, giving the belief that accuracy and sensing issues are developed to a point that the RISR mission scenario is feasible.     

Size distributions of circumplanetary dust

Dust rings have been observed around each of the giant planets and may also exist around Mars. The particles comprising these rings have short lifetimes due to a number of processes including exospheric and plasma drag, Poynting-Robertson drag, sputtering, collision with other circumplanetary particles, and the Lorentz force for charged grains. The supply of dust is maintained by collisions between macroscopic ring particles and bombardment of moons and ring particles by interplanetary impactors. All of the processes that act to remove or alter the circumplanetary dust grains are functions of particle size, so the initial size distribution of the grains released from an impact onto a moon or ring particle is modified. The size distribution of the impact ejecta can be described by a power-law of the form n(r)dr ∝r^−qdr where n(r)dr is the number of particles in the size range [r,r + dr] and q is the power-law index. For hypervelocity impact excavation, q ≈ 3.5. Drag acts more efficiently on smaller grains resulting in a reduction in q of 1. Other dynamical processes can lead to particle-size dependent collision rates with other circumplanetary objects. These processes can lead to local steepening of the size distribution (increase in q) and to truncation of the dust size distribution to a narrow range of sizes.     

Analytical expression for distant retrograde orbits around a small natural satellite

An analytical expression for distant retrograde orbits (DROs) is obtained in this study. Owing to the fact that a planar DRO is a closed orbit and can be expressed as an approximately elliptical orbit, respective geometries and periods of DROs are analytically calculated. A switching point, where various properties of planar DROs change abruptly with an increase in the orbital radius, is determined. The Mars–Deimos system is taken as a case study in this work. The proposed method can be applied to cases where the Hill’s approximation of the restricted three-body problem is valid. Numerical calculations are performed to validate the proposed method.     

Dust motion in Jupiter's tilted magnetic field

We outline an analytical method for studying the motion of charged dust particles that orbit an oblate planet having a tilted, offset, dipolar magnetic field. Our computed trajectories closely mimic previous numerical results; equilibrium dust potentials must be less then 10 volts or the Jovian ring would be thicker than observed. We identify several $\text{Lorentz resonances}$, where the periods of components of the Lorentz force, as seen by a reference particle moving in the equatorial plane, match the particle's orbital period; several seem to be near observed features of the Jovian ring system.     

火卫二地形地貌探测综述

火卫二(Deimos)是火星自然卫星之一,研究人员利用火星探测器对其地形地貌开展了大量研究.首先对火卫二的基本参数及起源假说进行了介绍,进而全面梳理了与火卫二相关的航天探测活动,重点对地形地貌探测活动进行了详细介绍,并对围绕火卫二地形地貌的研究成果进行了归纳分析,结果表明火卫二表面分布有撞击坑、风化层、明亮的反射物质及...     

Dynamics in the Phobos environment

The dynamical environment on and about the Martian moon Phobos is explored. This planetary moon provides a unique dynamical environment in the solar system, being subject to extreme tidal forces and having a characteristically non-spherical shape. Further, it is not in a fully circular orbit, meaning that it has librations that arise from its eccentricity, contributing to a periodic forcing environment. Thus, to plan and implement missions in the vicinity of and on Phobos will require these considerations be taken into account. In this paper the latest published models of the Phobos shape and dynamics are used to characterize its dynamical environment in close proximity orbit about the body, for motion across its surface and for controlled hovering motion in its vicinity. It is found that surface motion is subject to a number of “speed limits” that can cause a moving vehicle to leave the surface and to possibly escape the moon and enter orbit about Mars. In terms of orbital stability, the existence of libration orbit families are characterized down to the surface using an exact potential, and the known stable QSO orbits are shown to be associated with families of stable quasi-periodic orbits.     

Gravitational wave detection on the Moon and the moons of Mars

The Moon and the moons of Mars should be extremely quiet seismically and could therefore become sensitive gravitational wave detectors, if instrumented properly. Highly sensitive displacement sensors could be deployed on these planetary bodies to monitor the motion induced by gravitational waves. A superconducting displacement sensor with a 10-kg test mass cooled to 2 K will have an intrinsic instrument noise of 10⁻¹⁶ m Hz^−1/2. These sensors could be tuned to the lowest two quadrupole modes of the body or operated as a wideband detector below its fundamental mode. An interesting frequency range is 0.1–1 Hz, which will be missed by both the ground detectors on the Earth and LISA and would be the best window for searching for stochastic background gravitational waves. Phobos and Deimos have their lowest quadrupole modes at 0.2–0.3 Hz and could offer a sensitivity h_min ? 10⁻²² Hz^−1/2 within their resonance peaks, which is within two orders of magnitude from the goal of the Big Bang Observer (BBO). The lunar and Martian moon detectors would detect many interesting foreground sources in a new frequency window and could serve as a valuable precursor for BBO.     

火卫一周期准卫星轨道及入轨分析

围绕火卫一的准卫星轨道（QSOs）因其具有良好的稳定性,是火卫一探测任务最为实用的轨道。在平面圆型限制性三体问题模型下,利用庞加莱截面和KAM环迭代方法探究了准卫星轨道的周期轨道族,并给出不同能量准卫星周期轨道的初始条件。针对火卫一周期准卫星轨道入轨,提出一种转移轨道设计方法:对准卫星周期轨道调整速度后进行反向积分,直至离开火卫一邻近区域,从而得到由火星环绕轨道向火卫一周期准卫星轨道的转移轨道,并调整转移轨道参数对燃料与时间消耗进行优化。研究结果表明,当周期准卫星轨道能量处于特定区间时,存在特定速度脉冲区间,可利用火卫一引力实现较少燃料消耗的轨道转移;在该速度脉冲区间中,通过选取较小的速度脉冲,可缩短转移时间。      

Spectroscopic observation of Mars

Visible and near-infrared reflectance spectroscopy has proven a powerful tool for exploring the geology of Mars. Most of this data has been obtained from Earth, but the technique is ideally suited to orbital application, as proposed for the U.S. Mars Geoscience/Climatology Orbiter mission. Spectral reflectance in the near-UV and visible is highly diagnostic of ferric-iron mineralogy, and has shown that Fe³⁺ in the ubiquitous bright dust and soil is amorphous or poorly-crystalline. Other iron-oxide minerals, indicative of other modes or episodes of crustal alteration, may be found in spatially localized deposits. Clay minerals (hydroxylated silicates) have diagnostic vibrational absorptions throughout the near-infrared. While some form of bound water and/or OH has been known on Mars for many years, a new result presented here is the identification of structural OH in a dilute or poorly crystalline magnesian clay. Salts such as carbonates, sulfates, and nitrates have not yet been detected in martian soils but have diagnostic spectral features in the 3- to 4-μm region, best suited to Mars-orbital observation. Analysis of reflectance spectra of low-albedo regions is a primary source of evidence for a basaltic or ultramafic crust, with identification of abundant clinopyroxene and possible detection of other mafic minerals. The distinctive near-infrared spectral shape of dark regions indicates that the dark materials commonly consist of relatively unaltered rocks or rock fragments very thinly coated by (or mixed with) bright oxidized material similar to the global dust. Visible and near-infrared reflectance spectroscopy is also a sensitive technique for detecting and analyzing water ice, as has been demonstrated on Mars by observations of the north polar cap.     

Phobos-Grunt: Russian sample return mission

As an important milestone in the exploration of Mars and small bodies, a new generation space vehicle “Phobos-Grunt” is planned to be launched by the Russian Aviation and Space Agency. The project is optimized around a Phobos sample return mission and follow up missions targeted to study some main asteroid belt bodies, NEOs and short period comets. The principal constraint is use of the “Soyuz-Fregat” rather than the “Proton” launcher to accomplish these challenging goals. The vehicle design incorporates innovative SEP technology involving electrojet engines that allowed us to increase significantly the mission's energetic capabilities, as well as highly autonomous on-board systems. Basic criteria underlining the “Phobos-Grunt” mission scenario, scientific objectives and rationale including Mars observations during the vehicle's insertion into Mars orbit and Phobos approach maneuvers, are discussed and an opportunity for international cooperation is suggested.     

The geometry of the zodiacal dust bands

A program is in progress to use the best available IRAS data to determine the orbital parameters of the ensemble of particles which make up the zodiacal dust bands. Refinements on the early results of Gautier and Hauser include the use of a more complete set of data and improved treatment of ring profile effects due to dispersions in orbital parameters. Results to date include an analysis of the sensitivity of the observable parameters of the dust bands to changes in the orbital parameters of the particle ensemble.     

火星尘埃与探测

火星表面尘埃与太阳辐射、热辐射的相互作用直接影响火星大气的结构、热平衡和动力学过程,并会产生改变火星表面反照率和火星地貌的长期效应.火星尘埃环境还对登陆于火星表面的着陆器能源系统和光学载荷等系统构成影响.为此需开展火星大气尘埃的直接就位探测.在介绍了火星的尘埃特性与主要探测方法基础上,提出了采用微质量计技术开展火星表面尘埃就位探测的综合探测器方案.探测器包含3种传感器.尘埃累积传感器通过设置其敏感晶体表面朝上,可以探测火星表面尘埃的沉积质量与速率;荷电尘埃传感器通过加置不同极性的偏置电压,可以探测荷正电尘埃和荷负电尘埃的累积特性;磁尘传感器通过在敏感晶体后加设小型永久磁铁,可以探测磁性尘埃的累积特性.传感器感测质量范围为10^-11~10^-4g.火星尘埃综合探测器可应用于未来的火星着陆探测计划.     

小天体环的轨道动力学

随着天文观测的深入,发现不仅土星、木星等气态巨行星环绕有光环,某些小天体也环绕有光环。针对目前发现环的半人马型小天体女凯龙星（10199 Chariklo）,研究其引力场中粒子（视为质点）的轨道动力学,分析赤道椭率和小天体自转对环中粒子轨道运动的影响,通过庞加莱截面中的KAM环迭代,得到第一类周期轨道和1∶3共振周期轨道,并通过对比和分析得到小天体光环位置与小天体自转平运动共振的关系。研究结果表明:女凯龙星内环中的粒子最可能处在满足径向振荡幅值范围的第一类周期轨道及其附近的准周期轨道上,但不能排除处在1∶3共振周期轨道及其附近的准周期轨道上;外环中的粒子不可能处在1∶3共振周期轨道上,只可能处在第一类周期轨道及其附近的准周期轨道上。      

考虑太阳自转的天文多普勒差分导航方法

基于太阳震荡的时间延迟是一种新型天文导航量测量,可以提供探测器相对反射天体的距离信息,与星光角距量测量结合,可以提高导航性能。然而,星光角距量测模型与时间延迟量测模型均含有火卫一相对火星的位置矢量,火卫一的星历误差将影响导航精度。针对这一问题,提出了一种基于在线估计的天文测角/时间延迟量测组合导航方法,建立了包含火卫一位置及速度的状态模型,利用星光角距及时间延迟量测量同时对火卫一的位置和速度进行在线估计,仿真结果表明,提出的方法可以有效抑制火卫一星历误差对组合导航精度的影响,为探测器提供高精度的自主导航信息。