Origin of planetary atmospheres

The near absence of noble gases on earth, other than those of radioactive origin, indicates that the earth was formed by the accumulation of planetesimals; this process systematically excluded all constituents that did not enter into the solid phase. The atmosphere and the ocean with many of its dissolved salts have arisen from gases emitted from the earth's interior, a process that continues today. The oxygen in the earth's atmosphere plus a greater quantity that has been removed from the atmosphere to oxidize geologic materials, has arisen mainly from a small excess of photosynthesis over decay of organic material. The atmospheres of Mars and Venus have probably arisen in a manner similar to the atmosphere on earth, by emission from the planetary interiors. However, they have not received any oxygen from photosynthesis and so are nearly oxygen free. Mars has very little water in its atmosphere, and this can be explained by its lower than freezing average surface temperature. Venus also has very little water, and this requires an ad hoc explanation; one possibility is that Venus was formed from much drier planetesimals than was the earth. Mercury and the moon are virtually without atmospheres. Although some gases may be emitted from their interiors, they are presumably rapidly lost by escape. Whatever atmosphere they possess is probably due to the neutralized solar wind that impinges upon them. The outer planets retained volatiles, including hydrogen and helium, to a much greater extent than did the terrestrial planets.     

Below One Earth: The Detection, Formation, and Properties of Subterrestrial Worlds

The Solar System includes two planets—Mercury and Mars—significantly less massive than Earth, and all evidence indicates that planets of similar size orbit many stars. In fact, one of the first exoplanets to be discovered is a lunar-mass planet around a millisecond pulsar. Novel classes of exoplanets have inspired new ideas about planet formation and evolution, and these “sub-Earths” should be no exception: they include planets with masses between Mars and Venus for which there are no Solar System analogs. Advances in astronomical instrumentation and recent space missions have opened the sub-Earth frontier for exploration: the Kepler mission has discovered dozens of confirmed or candidate sub-Earths transiting their host stars. It can detect Mars-size planets around its smallest stellar targets, as well as exomoons of comparable size. Although the application of the Doppler method is currently limited by instrument stability, future spectrographs may detect equivalent planets orbiting close to nearby bright stars. Future space-based microlensing missions should be able to probe the sub-Earth population on much wider orbits. A census of sub-Earths will complete the reconnaissance of the exoplanet mass spectrum and test predictions of planet formation models, including whether low-mass M dwarf stars preferentially host the smallest planets. The properties of sub-Earths may reflect their low gravity, diverse origins, and environment, but they will be elusive: Observations of eclipsing systems by the James Webb Space Telescope may give us our first clues to the properties of these small worlds.     

An Oxygen Isotope Mixing Model for the Accretion and Composition of Rocky Planets

The oxygen isotope systematics in planetary and nebular matter are used to constrain the types of nebular material accreted to form a planet. The basic assumption of this model is that the mean oxygen isotopic composition of a planet is determined by the weighted mean oxygen isotopic composition of nebular matter accreted by the planet. Chondrites are taken as representatives of nebular matter. The chemical composition (which determines core size, mantle oxidation state, density, moment of inertia) of a planet results from the weighted mean compositions of the accreted nebular material, once the mass fractions of the different types of accreting matter are known. Here some results for Earth, Moon, Mars, and Vesta are discussed. The model implies that loss of volatile elements, such as alkalis and halogens, occurs during accretion and early planetary differentiation (e. g., by catastrophic impacts). The possible depletion mechanisms of moderately volatile elements are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Mercury’s Interior Structure, Rotation, and Tides

This review addresses the deep interior structure of Mercury. Mercury is thought to consist of similar chemical reservoirs (core, mantle, crust) as the other terrestrial planets, but with a relatively much larger core. Constraints on Mercury’s composition and internal structure are reviewed, and possible interior models are described. Large advances in our knowledge of Mercury’s interior are not only expected from imaging of characteristic surface features but particularly from geodetic observations of the gravity field, the rotation, and the tides of Mercury. The low-degree gravity field of Mercury gives information on the differences of the principal moments of inertia, which are a measure of the mass concentration toward the center of the planet. Mercury’s unique rotation presents several clues to the deep interior. From observations of the mean obliquity of Mercury and the low-degree gravity data, the moments of inertia can be obtained, and deviations from the mean rotation speed (librations) offer an exciting possibility to determine the moment of inertia of the mantle. Due to its proximity to the Sun, Mercury has the largest tides of the Solar System planets. Since tides are sensitive to the existence and location of liquid layers, tidal observations are ideally suited to study the physical state and size of the core of Mercury.     

关于大行星（或月球）轨道器的冻结轨道

关于人造地球卫星的冻结轨道问题早已为人们所熟知，而且已有相应的卫星在轨运行。在考虑该冻结轨道形成时，主要依据地球扁率J3项与J2项的相对关系，这是由地球非球形引力场的特征所决定的，原理十分清楚，但其原理和结论不能随意地用于其他大行星(或月球)的轨道器。在一般情况下，对于低轨卫星形成冻结轨道的条件，非球形引力位中的奇次带谐项(J21 1，l≥1)将起重要作用。不仅仅是一个J3项，例如月球轨道器，J3，J5，J7和J9均有不可忽视的影响，而且与轨道倾角有一定的关系。为此，本文根据轨道理论对冻结轨道的存在性及其有关问题作进一步的分析，给将来的深空探测提供轨道设计的有关信息和依据。     

The Formation of Mars: Building Blocks and Accretion Time Scale

In this review paper I address the current knowledge of the formation of Mars, focusing on its primary constituents, its formation time scale and its small mass compared to Earth and Venus. I argue that the small mass of Mars requires the terrestrial planets to have formed from a narrow annulus of material, rather than a disc extending to Jupiter. The truncation of the outer edge of the disc was most likely the result of giant planet migration, which kept Mars’ mass small. From cosmochemical constraints it is argued that Mars formed in a couple of million years and is essentially a planetary embryo that never grew to a full-fledged planet. This is in agreement with the latest dynamical models. Most of Mars’ building blocks consists of material that formed in the 2 AU to 3 AU region, and is thus more water-rich than that accreted by Earth and Venus. The putative Mars could have consisted of 0.1 % to 0.2 % by mass of water.     

Planetary characteristics from radar observations

Conclusions Long wavelength radar observations of Venus yield a surface reflectivity of about 15%. Total power measurements at 12.5 cm and 3.6 cm strongly suggest that significant atmospheric absorption is operative in this wavelength region. If the observed low value of reflectivity at 3.6 cm is attributed to atmospheric absorption alone an opacity of = 1.14 is implied at this wavelength rather independently from assumptions concerning the surface scattering characteristics of Venus. An inverse ² opacity law for the atmosphere is consistent with the reflectivity measurements over the complete range of observations wavelengths.The mathematical characteristics of the Venusian backscatter law are the same as for the moon but wavelength-dependent mean effective slopes indicate that Venus appears smoother than the moon at all radar wavelengths.Considerable progress has been made toward obtaining a precise value for the Venusian axial rotation vector which is found to be oriented to within 10 degrees of the planet's orbital plane. The period of (retrograde) rotation lies within the range 242–250 days with the lower value favored by the statistics of the data. Regions of enhanced radar return fixed to the surface have been found and verified at a later conjunction. Measurements of the surface radar depolarization support the hypothesis that the prominences are due to increased surface roughness as opposed to regional increases of dielectric constant.Observations of Mercury strongly suggest that the rotation period of the planet is about 59 days, a conclusion which has been supported, a posteriori, by theoretical tidal calculations and rediscussions of optical observations of surface markings. Mercury has radar backscatter characteristics more similar to the moon than Venus and exhibits a reflectivity of about 5%.Mars has demonstrated strong variations of radar backscatter characteristics which appear correlated with the Martian longitude and, in turn, with the dark surface markings in its north equatorial zone. Particularly reliable correlations have been discovered with the positions of Trivium Charontis and Syrtis Major. The observed variations appear to be primarily manifested in terms of the Martian radar backscatter law or surface roughness as opposed to variations in the intrinsic surface material reflectivities although the observations are not sufficiently precise to resolve this question. Variations in surface materials are apparently also present but their degree is currently unassayable. The reflectivity of the average surface has been crudely determined to be about 7% which suggests that the surface of Mars is composed of underdense materials. The 7% value is consistent with the values of 7.5% and 5% for the moon and Mercury, respectively, and is significantly different from the 15% value for Venus,No unequivocal radar detection of Jupiter has been made although a statistically weak detection has been reported for a single opposition which could not be verified in succeeding attempts.     

Infrared Spectroscopy of Solar-System Planets

Most of our knowledge regarding planetary atmospheric composition and structure has been achieved by remote sensing spectroscopy. Planetary spectra strongly differ from one planet to another. CO₂ signatures dominate on Mars, and even more on Venus (where the thermal component is detectable down to 1 μm on the dark side). Spectroscopic monitoring of Venus, Earth and Mars allows us to map temperature fields, wind fields, clouds, aerosols, surface mineralogy (in the case of the Earth and Mars), and to study the planets’ seasonal cycles. Spectra of giant planets are dominated by H₂, CH₄ and other hydrocarbons, NH₃, PH₃ and traces of other minor compounds like CO, H₂O and CO₂. Measurements of the atmospheric composition of giant planets have been used to constrain their formation scenario.     

Thermal Evolution and Magnetic Field Generation in Terrestrial Planets and Satellites

Of the terrestrial planets, Earth and Mercury have self-sustained fields while Mars and Venus do not. Magnetic field data recorded at Ganymede have been interpreted as evidence of a self-generated magnetic field. The other icy Galilean satellites have magnetic fields induced in their subsurface oceans while Io and the Saturnian satellite Titan apparently are lacking magnetic fields of internal origin altogether. Parts of the lunar crust are remanently magnetized as are parts of the crust of Mars. While it is widely accepted that the magnetization of the Martian crust has been caused by an early magnetic field, for the Moon alternative explanations link the magnetization to plasma generated by large impacts. The necessary conditions for a dynamo in the terrestrial planets and satellites are the existence of an iron-rich core that is undergoing intense fluid motion. It is widely accepted that the fluid motion is caused by convection driven either by thermal buoyancy or by chemical buoyancy or by both. The chemical buoyancy is released upon the growth of an inner core. The latter requires a light alloying element in the core that is enriched in the outer core as the solid inner core grows. In most models, the light alloying element is assumed to be sulfur, but other elements such as, e.g., oxygen, silicon, and hydrogen are possible. The existence of cores in the terrestrial planets is either proven beyond reasonable doubt (Earth, Mars, and Mercury) or the case for a core is compelling as for Venus and the Moon. The Galilean satellites Io and Ganymede are likely to have cores judging from Galileo radio tracking data of the gravity fields of these satellites. The case is less clear cut for Europa. Callisto is widely taken as undifferentiated or only partially differentiated, thereby lacking an iron-rich core. Whether or not Titan has a core is not known at the present time. The terrestrial planets that do have magnetic fields either have a well-established inner core with known radius and density such as Earth or are widely agreed to have an inner core such as Mercury. The absence of an inner core in Venus, Mars, and the Moon (terrestrial bodies that lack fields) is not as well established although considered likely. The composition of the Martian core may be close to the Fe–FeS eutectic which would prevent an inner core to grow as long as the core has not cooled to temperatures around 1500 Kelvin. Venus may be on the verge of growing an inner core in which case a chemical dynamo may begin to operate in the geologically near future. The remanent magnetization of the Martian and the lunar crust is evidence for a dynamo in Mars’ and possibly the Moon’s early evolution and suggests that powerful thermally driven dynamos are possible. Both the thermally and the chemically driven dynamo require that the core is cooled at a sufficient rate by the mantle. For the thermally driven dynamo, the heat flow from the core into the mantle must by larger than the heat conducted along the core adiabat to allow a convecting core. This threshold is a few mW?m^?2 for small planets such as Mercury, Ganymede, and the Moon but can be as large as a few tens mW?m^?2 for Earth and Venus. The buoyancy for both dynamos must be sufficiently strong to overcome Ohmic dissipation. On Earth, plate tectonics and mantle convection cool the core efficiently. Stagnant lid convection on Mars and Venus are less efficient to cool the core but it is possible and has been suggested that Mars had plate tectonics in its early evolution and that Venus has experienced episodic resurfacing and mantle turnover. Both may have had profound implications for the evolution of the cores of these planets. It is even possible that inner cores started to grow in Mars and Venus but that the growth was frustrated as the mantles heated following the cessation of plate tectonics and resurfacing. The generation of Ganymede’s magnetic field is widely debated. Models range from magneto-hydrodynamic convection in which case the field will not be self-sustained to chemical and thermally-driven dynamos. The wide range of possible compositions for Ganymede’s core allows models with a completely liquid near eutectic Fe–FeS composition as well as models with Fe inner cores or cores in with iron snowfall.     

Exoplanet Transit Spectroscopy and Photometry

Photometry and spectroscopy of extrasolar planets provides information about their atmospheres and surfaces. From extrasolar planet spectra and photometry we can infer the composition and temperature of the atmospheres as well as the presence of molecular species, including biosignature gases or surface features. So far photometry has been published for three different transiting hot Jupiters (gas giant planets in short-period orbits), opening the era of comparative exoplanetology.     

The Accretion, Composition and Early Differentiation of Mars

The early development of Mars is of enormous interest, not just in its own right, but also because it provides unique insights into the earliest history of the Earth, a planet whose origins have been all but obliterated. Mars is not as depleted in moderately volatile elements as are other terrestrial planets. Judging by the data for Martian meteorites it has Rb/Sr 0.07 and K/U 19,000, both of which are roughly twice as high as the values for the Earth. The mantle of Mars is also twice as rich in Fe as the mantle of the Earth, the Martian core being small (20% by mass). This is thought to be because conditions were more oxidizing during core formation. For the same reason a number of elements that are moderately siderophile on Earth such as P, Mn, Cr and W, are more lithophile on Mars. The very different apparent behavior of high field strength (HFS) elements in Martian magmas compared to terrestrial basalts and eucrites may be related to this higher phosphorus content. The highly siderophile element abundance patterns have been interpreted as reflecting strong partitioning during core formation in a magma ocean environment with little if any late veneer. Oxygen isotope data provide evidence for the relative proportions of chondritic components that were accreted to form Mars. However, the amount of volatile element depletion predicted from these models does not match that observed — Mars would be expected to be more depleted in volatiles than the Earth. The easiest way to reconcile these data is for the Earth to have lost a fraction of its moderately volatile elements during late accretionary events, such as giant impacts. This might also explain the non-chondritic Si/Mg ratio of the silicate portion of the Earth. The lower density of Mars is consistent with this interpretation, as are isotopic data. ⁸⁷Rb-⁸⁷Sr, ¹²⁹I-¹²⁹Xe, ¹⁴⁶Sm-¹⁴²Nd, ¹⁸²Hf-¹⁸²W, ¹⁸⁷Re-¹⁸⁷Os, ²³⁵U-²⁰⁷Pb and ²³⁸U-²⁰⁶Pb isotopic data for Martian meteorites all provide evidence that Mars accreted rapidly and at an early stage differentiated into atmosphere, mantle and core. Variations in heavy xenon isotopes have proved complicated to interpret in terms of ²⁴⁴Pu decay and timing because of fractionation thought to be caused by hydrodynamic escape. There are, as yet, no resolvable isotopic heterogeneities identified in Martian meteorites resulting from ⁹²Nb decay to ⁹²Zr, consistent with the paucity of perovskite in the martian interior and its probable absence from any Martian magma ocean. Similarly the longer-lived ¹⁷⁶Lu-¹⁷⁶Hf system also preserves little record of early differentiation. In contrast W isotope data, Ba/W and time-integrated Re/Os ratios of Martian meteorites provide powerful evidence that the mantle retains remarkably early heterogeneities that are vestiges of core metal segregation processes that occurred within the first 20 Myr of the Solar System. Despite this evidence for rapid accretion and differentiation, there is no evidence that Mars grew more quickly than the Earth at an equivalent size. Mars appears to have just stopped growing earlier because it did not undergo late stage (>20 Myr), impacts on the scale of the Moon-forming Giant Impact that affected the Earth.     

HF-W Chronometry and Inner Solar System Accretion Rates

Models for the mechanisms of accretion of the terrestrial planets are re-examined using the experimental technique of high-precision isotope ratio mass spectrometry of tungsten (W). The decay of ¹⁸²Hf to ¹⁸²W (via ¹⁸²Ta) provides a new kind of radiometric chronometer of planet formation processes. Hafnium and W, the parent and daughter trace elements, are highly refractory; however, Hf is lithophile and strongly partitioned into the silicate portion of a planet, whereas W is moderately siderophile and preferentially partitioned into a coexisting metallic phase. More than 90% of terrestrial W has gone into the Earth's core during its formation. The residual silicate portion, the Earth's primitive mantle, has a Hf/W ratio in the range 10−40, an order of magnitude higher than chondritic (∼1.3). Tungsten isotopic data for the Earth and the Moon suggest that we can date a major event of planet formation: The Moon formed about 50 Myrs after the start of the solar system, providing strong support for the Giant Impact Theory of lunar origin. Recent simulations of this event imply that the Earth was probably only half formed at the time. From this we can deduce the planetary accretion rate. Tungsten isotope data for Mars provide evidence of a much shorter accretion interval, perhaps as little as 10 Myrs, but the rates for the Earth over the same time interval could have been comparable. The large W isotopic heterogeneities on Mars could only have been produced within the first 30 Myrs of the solar system. Large-scale mixing, e.g. from convective overturn, as is thought to drive the Earth's plates, must be absent from Mars. Limitations of the method such as 1) cosmogenic ¹⁸²Ta effects on lunar samples, 2) incomplete mixing of debris to cause W isotope heterogeneity on the Moon, and 3) initial ¹⁸²Hf/¹⁸⁰Hf heterogeneities of the early solar system are critically discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Solid component of interplanetary matter from vehicle observations

This paper contains the data of meteoric particle investigations by means of piezoelectric detectors.The data obtained on the different Soviet vehicles at distances from about 100 km to about 100000000 km from the earth are given.Measurements have demonstrated that apart from fluxes there are individual aggregations of meteoric particles with very unequal spatial density of particles in them. Linear dimensions varied within wide limits.A concept of the mass spectrum of meteoric particles is presented.Very high concentrations of minute dust particles were observed near the earth at altitudes from 100–200 km by means of ground-based methods and rocket measurements.The increased density of interplanetary matter in the vicinity of the moon during April and May 1966 was recorded by means of satellite Luna-10. By means of Luna-12 it could not be discovered whether this aggregation is the moon halo or is the result of the moon passage through some dust particle aggregation, because the investigation on satellite Luna-12 was carried out mostly during meteor showers.     

Are There Chemical Gradients in the Inner Solar System?

The solar system is apparently stratified with regard to the contents of volatile constituents, as judged from the rocky, volatile-poor inner solar system planets and meteorites and the huge volatile-rich outer planets. However, beyond this gross structure there is no evidence for a systematic increase of the volatiles' abundances with distance from the Sun. Although meteorites show comparatively large differences in volatile element contents they also differ in many other respects, such as Mg/Si-ratios, bulk Fe and refractory element contents. These variations reflect variations in the nebular environment from which meteorites formed. The various conditions of meteorite formation cannot, however, be related in a simple way to heliocentric distances. There are also no systematic variations in the chemistry of the inner planets Mercury, Venus, Earth, Moon, Mars, and including the fourth largest asteroid Vesta, that could be interpreted as a relationship between volatility and composition. Although Mars (as judged from the composition of Martian meteorites) is more oxidized and contains more volatile elements than Earth, this trend cannot be extrapolated to the dry volatile poor Vesta (sampled by HED meteorites) in the asteroid belt. If the Earth-Mars trend reflects global inner solar system gradients then Vesta must have formed inside Earth's orbit and moved out later to its present location. The quality of Mercury and Venus composition data is not sufficient to allow reliable extrapolation to distances closer to the Sun. Recent nebula models predict small temperature gradients in the inner solar system supporting the view that no large variations in volatile element contents of inner solar system materials are expected. This revised version was published online in June 2006 with corrections to the Cover Date.     

Meteoric Layers in Planetary Atmospheres

Metallic ions coming from the ablation of extraterrestrial dust, play a significant role in the distribution of ions in the Earth’s ionosphere. Ions of magnesium and iron, and to a lesser extent, sodium, aluminium, calcium and nickel, are a permanent feature of the lower E-region. The presence of interplanetary dust at long distances from the Sun has been confirmed by the measurements obtained by several spacecrafts. As on Earth, the flux of interplanetary meteoroids can affect the ionospheric structure of other planets. The electron density of many planets show multiple narrow layers below the main ionospheric peak which are similar, in magnitude, to the upper ones. These layers could be due to long-lived metallic ions supplied by interplanetary dust and/or their satellites. In the case of Mars, the presence of a non-permanent ionospheric layer at altitudes ranging from 65 to 110 km has been confirmed and the ion Mg⁺?CO₂ identified. Here we present a review of the present status of observed low ionospheric layers in Venus, Mars, Jupiter, Saturn and Neptune together with meteoroid based models to explain the observations. Meteoroids could also affect the ionospheric structure of Titan, the largest Saturnian moon, and produce an ionospheric layer at around 700 km that could be investigated by Cassini.     

大尺寸缩比自由飞模型惯性矩测量与调整方法

给出了双线摆法测大尺寸缩比自由飞试验模型惯性矩的方法和流程,并根据飞机类模型的惯性矩特点,提出了大尺寸缩比自由飞试验模型惯性矩调整所需的配重计算方法.双线摆法测量原理简单,不需要复杂的测量设备,具有较好的工程实用性.应用实例证明,模型飞机调整后的惯性矩与目标状态符合较好,测量精度满足工程应用要求.     

New Horizons: Anticipated Scientific Investigations at the Pluto System

The New Horizons spacecraft will achieve a wide range of measurement objectives at the Pluto system, including color and panchromatic maps, 1.25–2.50 micron spectral images for studying surface compositions, and measurements of Pluto’s atmosphere (temperatures, composition, hazes, and the escape rate). Additional measurement objectives include topography, surface temperatures, and the solar wind interaction. The fulfillment of these measurement objectives will broaden our understanding of the Pluto system, such as the origin of the Pluto system, the processes operating on the surface, the volatile transport cycle, and the energetics and chemistry of the atmosphere. The mission, payload, and strawman observing sequences have been designed to achieve the NASA-specified measurement objectives and maximize the science return. The planned observations at the Pluto system will extend our knowledge of other objects formed by giant impact (such as the Earth–moon), other objects formed in the outer solar system (such as comets and other icy dwarf planets), other bodies with surfaces in vapor-pressure equilibrium (such as Triton and Mars), and other bodies with N₂:CH₄ atmospheres (such as Titan, Triton, and the early Earth).     

嫦娥二号再拓展试验测定轨精度研究

基于＂嫦娥二号＂卫星再拓展试验的设计轨道,研究各种摄动力对轨道确定精度的影响,得出的结论是：若要达到km量级的轨道确定精度,必须考虑除天王星和海王星之外所有大行星以及日月的质点引力。文章进一步利用数值分析法研究再拓展任务的轨道确定精度,分析结果表明：基于目前的测控条件,使用30 d以上的测轨弧段可以得到稳定可靠的轨道解,而短弧（小于20 d）稳定轨道的获取需要VLBI（甚长基线干涉）测轨数据支持;当＂嫦娥二号＂距离地球700万km时,测控精度可优于30 km;虽然每天测轨弧段的增加可以改善轨道精度,但是当增加到8 h以上时,定轨精度将不再有明显改善。     

Transforming Dust to Planets

We review recent progress in understanding how nebular dust and gas are converted into the planets of the present-day solar system, focusing particularly on the “Grand Tack” and pebble accretion scenarios. The Grand Tack can explain the observed division of the solar system into two different isotopic “flavours”, which are found in both differentiated and undifferentiated meteorites. The isotopic chronology inferred for the development of these two “flavours” is consistent with expectations of gas-giant growth and nebular gas loss timescales. The Grand Tack naturally makes a small Mars and a depleted, dynamically-excited and compositionally mixed asteroid belt (as observed); it builds both Mars and the Earth rapidly, which is consistent with the isotopically-inferred growth timescale of the former, but not the latter. Pebble accretion can explain the rapid required growth of Jupiter and Saturn, and the number of Kuiper Belt binaries, but requires specific assumptions to explain the relatively protracted growth timescale of Earth. Pure pebble accretion cannot explain the mixing observed in the asteroid belt, the fast proto-Earth spin rate, or the tilt of Uranus. No current observation requires pebble accretion to have operated in the inner solar system, but the thermal and compositional consequences of pebble accretion have yet to be explored in detail.     

火星探测器飞行轨道设计

在一些基本假设的基础上,初步设计了从地球停泊轨道发射探测器到达火星的飞行轨道。运用圆锥曲线拼接法,设计了采用双共切和单共切两种不同的日心段转移方式时,探测器日心段、地心段和火星中心段的飞行轨道,并分析比较了这两种设计方法的特点。根据限制性二体问题动力学模型,仿真计算了探测器在不同轨道段的飞行轨迹,结果表明,探测器可以按照所设计的轨道飞行到达火星,并被其捕获,成为环绕火星飞行的卫星。