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Aerospace邊界層边界层，又称附面层是一个流体力学名词，表示流体中紧接着管壁或其他固定表面的部分。边界层是由黏滞力产生的效应，和雷诺数Re有关。 一般提到的边界层是指速度的边界层。在边界层外，流体的速度接近定值，不随位置而变化。在边界层内，在固定表面上流速为0，距固定表面越远，速度会趋近一定值。
In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary condition (zero velocity at the wall). The flow velocity then monotonically increases above the surface until it returns to the bulk flow velocity. The thin layer consisting of fluid whose velocity has not yet returned to the bulk flow velocity is called the velocity boundary layer. The air next to a human is heated, resulting in gravity-induced convective airflow, which results in both a velocity and thermal boundary layer. A breeze disrupts the boundary layer, and hair and clothing protect it, making the human feel cooler or warmer. On an aircraft wing, the velocity boundary layer is the part of the flow close to the wing, where viscous forces distort the surrounding non-viscous flow. In the Earth's atmosphere, the atmospheric boundary layer is the air layer (~ 1 km) near the ground.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 防热盾是航天技术中航天器在进入大气层时保护航天器不被热量破坏的保护层。一些高速飞机也需要防热盾。
In engineering, a heat shield is a component designed to protect an object or a human operator from being burnt or overheated by dissipating, reflecting, and/or absorbing heat. The term is most often used in reference to exhaust heat management and to systems for dissipating frictional heat. Heat shields are used most commonly in the automotive and aerospace industries.
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View content license ↗ 翼载（Wing loading）是飞机重量与机翼参考面积的比值。其中飞机的重量多选择正常起飞重量。而机翼的面积则选择包含部分机身的机翼参考面积。翼载是决定飞机机动性能、爬升性能和起降性能的关键参数。也是设计一架固定翼飞机时，最开始需要确定的参数之一。一般来说较小的翼载有利于提高机动性，而较大的翼载则有利于高速飞行和降低阻力。
In aerodynamics, wing loading is the total weight of an aircraft or flying animal divided by the area of its wing. The stalling speed, takeoff speed and landing speed of an aircraft are partly determined by its wing loading. The faster an aircraft flies, the more its lift is changed by a change in angle of attack, so a smaller wing is less adversely affected by vertical gusts. Consequently, faster aircraft generally have higher wing loadings than slower aircraft in order to avoid excessive response to vertical gusts. A higher wing loading also decreases maneuverability. The same constraints apply to winged biological organisms.
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View content license ↗ 动压（英语：dynamic pressure）是一个与流体力学有关的物理量，其定义为： q ≡ 1 2 ρ v 2 {\displaystyle q\equiv {\frac {1}{2}}\rho {{v}^{2}}} 其中的符号代表（使用国际单位制）：
In fluid dynamics, dynamic pressure (denoted by q or Q and sometimes called velocity pressure) is the quantity defined by: q = 1 2 ρ u 2 {\displaystyle q={\frac {1}{2}}\rho \,u^{2}} where (in SI units): q is the dynamic pressure in pascals (i.e., N/m2), ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m3), and u is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure.
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View content license ↗ 在流体力学中，雷诺数（英语：Reynolds number）是流体的惯性力 ρ v 2 L {\displaystyle {\frac {\rho v^{2}}{L}}} 与黏性力 μ v L 2 {\displaystyle {\frac {\mu v}{L^{2}}}} 的比值，它是一个无量纲量。 雷诺数较小时，黏滞力对流场的影响大于惯性力，流场中流速的扰动会因黏滞力而衰减，流体流动稳定，为层流；反之，若雷诺数较大时，惯性力对流场的影响大于黏滞力，流体流动较不稳定，流速的微小变化容易发展、增强，形成紊乱、不规则的紊流流场。
In fluid dynamics, the Reynolds number (Re) is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers, flows tend to be turbulent. The turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow (eddy currents). These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. The Reynolds number has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. It is used to predict the transition from laminar to turbulent flow and is used in the scaling of similar but different-sized flow situations, such as between an aircraft model in a wind tunnel and the full-size version.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 拉格朗日点（英语：Lagrange point，亦称平动点）是天体力学中两个大质量轨道物体的引力影响下，小质量物体的力学平衡点。在数学上，这涉及到限制性三体问题的解。 通常情况下，两个大质量物体对任意一点施加的力是不平衡的，这会改变该点上任何物体的轨道。在拉格朗日点，两个大物体的引力和离心力相互平衡。这可以使拉格朗日点成为卫星的绝佳位置，因为轨道校正时维持所需轨道的燃料需求保持在最低限度。 对于两个轨道体的任何组合都有五个拉格朗日点，L1至 L5，而所有这些都在两个大天体的轨道平面内。太阳-地球系统有五个拉格朗日点，而地月系统也有五个“不同的”拉格朗日点。L1、 L2、和L3在穿过两个大物体的中心的线上，而 L4和L5每个都位于由两个大物体的中心形成的正三角形的第三个顶点。 当两个物体的质量比足够大时，L4和L5点是稳定点，这意味着物体可以围绕它们运行，并且它们有将物体拉入其中的趋势。有几颗行星在它们相对于太阳的L4和L5点附近有特洛伊小行星，木星有超过一百万个这样的特洛伊天体。 一些拉格朗日点正被用于太空探索。日地系统中两个重要的拉格朗日点是在太阳和地球之间的L1，和在地球另一侧的同一条线上的L2；两者都在月球轨道之外。现时，一颗名为深空气候观测站（英语：Deep Space Climate Observatory，DSCOVR）的人造卫星位于L1通过拍摄影像并将其发回，以研究从太阳吹向地球的太阳风并监测地球气候。强大的红外层空间天文台，詹姆斯·韦伯太空望远镜位于L2。这使得卫星的大型遮阳板可以保护望远镜免受太阳、地球和月球的光和热的影响。L1和 L2拉格朗日点距离地球大约1,500,000 km（930,000 mi）。 欧洲航天局早期的盖亚望远镜，及其新发射的欧几里得都位于L2的利萨如轨道，而欧几里得遵循类似于JWST的晕轮轨道。每个太空天文台都受益于距离地球阴影足够远，可以利用太阳能电池板发电，不需要太多的电力或推进剂来维持空间站，不受地球磁层效应的影响，以及可以直接看到地球进行资料传输。
In celestial mechanics, the Lagrange points (), also called the Lagrangian points or libration points, are points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies. Mathematically, this involves the solution of the restricted three-body problem. Normally, the two massive bodies exert an unbalanced gravitational force at a point, altering the orbit of any other celestial body at that point. At the Lagrange points, the gravitational forces of the two large bodies and the centrifugal pseudo-force balance each other. This can make Lagrange points an excellent location for satellites, as orbit corrections, and hence fuel requirements, needed to maintain the desired orbit are kept at a minimum. For any combination of two orbital bodies, there are five Lagrange points, L1 to L5, all in the orbital plane of the two large bodies. There are five Lagrange points for the Sun–Earth system, and five different Lagrange points for the Earth–Moon system.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 太阳帆（也称为光帆，特别是它使用来自于太阳以外的光源时）是使用巨大的薄膜镜片，以太阳的辐射压做为太空船推进力的一种计划。辐射压非常小，但不同于火箭的是，太阳帆不需要燃料。推进力虽然很小，但是只要太阳继续照耀着，太阳帆就能继续运作。 太阳能集热器、温度控制面板和阳光下的树荫都可以视为特殊的太阳帆，太阳帆可以帮助在轨道上的太空船调整飞行姿态或是对轨道做少量的修正而无须耗费燃料，而用别的方法都必须消耗燃料才能操纵或控制飞行姿态。已经有一些小规模的，为特定目的建造的太阳帆被尝试过。一些无人太空船，像先锋10号，曾经成功的以这些技术延长了产品使用的期限。 太阳帆的科学性已经有良好的证明，但是处理大型太阳帆的技术仍未成熟，使得任务规划者不愿意贸然的投资下数以百万计的预算去开发太阳帆的操控结构。这种轻忽的心态使一些热心的民间机构试图私下发展，例如宇宙1号的计划。 太阳帆的观念是17世纪德国的天文学家约翰内斯·开普勒最早提出的 ，在1920年代后期，弗里德里希·灿德尔经过近十年的淬练才再度提出此一观念。
Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The two spacecraft to successfully use the technology for propulsion were IKAROS, launched in 2010, and LightSail-2, launched in 2019. A further demonstrator, Advanced Composite Solar Sail System (ACS3), was launched in 2024, and deployed successfully but is not being actively controlled due to a fault. A useful analogy to solar sailing may be a sailing boat; the light exerting a force on the large surface is akin to a sail being blown by the wind. High-energy laser beams could be used as an alternative light source to exert much greater force than would be possible using sunlight, a concept known as beam sailing. Solar sail craft offer the possibility of low-cost operations combined with high speeds (relative to chemical rockets) and long operating lifetimes.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 行星的逆行或视逆行运动是从特定有利位置观察到行星在与其系统内其它天体在相反方向上的视运动。顺行运动（英语：direct motion或prograde motion和prograde）在这种情况下有着相同的意义，但前者是天文学中传统的术语。然而direct现在已不太常见，而使用“prograde”的最早记录是在18世纪初。
Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the traditional term in astronomy. The earliest recorded use of prograde was in the early 18th century, although the term is now less common.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 微流星体是微小的流星体，是在太空中的微小固体，通常质量不到1公克。微陨石是穿越地球的大气层之后依然存在，并到达地球表面的这种物体。
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface. The term "micrometeoroid" was officially deprecated in 2017 by the International Astronomical Union, the primary international association of astronomers, as redundant to "meteoroid." It remains in use in astronautical engineering to refer to small, difficult to detect objects that can impact and damage spacecraft.
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View content license ↗ 电离辐射（英语：ionizing radiation）又称游离辐射，是指波长短、频率高、能量高的射线（粒子或波的双重形式）。辐射可分为电离辐射和非电离辐射，电离辐射可以从原子或分子里面电离过程（Ionization）中作用出至少一个电子。反之，非电离辐射则不行。电离能力，决定于射线（粒子或波）所带的能量，而不是射线的数量。如果射线没有带有足够电离能量的话，大量的射线并不能够导致电离。
Ionizing radiation, also spelled ionising radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light; their electromagnetic waves are on the high-energy portion of the electromagnetic spectrum. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation. Lower energy ultraviolet, visible light, infrared, microwaves, and radio waves are non-ionizing radiation. Nearly all types of laser light are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area cannot be sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts around 10 electronvolts (eV). Ionizing subatomic particles include alpha particles, beta particles, and neutrons. These particles are created by radioactive decay, and almost all are energetic enough to ionize.
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View content license ↗ 执行器（英语：Actuators）又称为促动器、致动器、操动件、执行机构、驱动器或驱动件，是一种将能源转换成机械动能的装置，并可借由执行器来控制驱使物体进行各种预定动作。这类机械能把能量转化为运动。根据能量来源分为：电动执行器、油压执行器及空压执行器等。按尺度来分可为普通执行器、微执行器和纳米执行器等。
An actuator is a component of a machine that produces force, torque, or displacement, when an electrical, pneumatic or hydraulic input is supplied to it in a system (called an actuating system). The effect is usually produced in a controlled way. An actuator translates a stimulus such as an input signal into the required form of mechanical energy. It is a type of transducer. In simple terms, it is a "mover". An actuator requires a control device (which provides control signal) and a source of energy. The control signal is relatively low in energy and may be voltage, electric current, pneumatic, or hydraulic fluid pressure, or even human power. In the electric, hydraulic, and pneumatic sense, it is a form of automation or automatic control. The displacement achieved is commonly linear or rotational, as exemplified by linear motors and rotary motors, respectively. Rotary motion is more natural for small machines making large displacements.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 在空气动力学中，升阻比（L/D）是指飞行器在同一迎角下升力与阻力的比值。飞行器的升阻比越大，其空气动力性能越好，对飞行越有利，也会有较佳爬升性能。升阻比的公式如下 L / D = L F D {\displaystyle L/D={L \over F_{D}}} 其中L为升力， F D {\displaystyle F_{D}} 为阻力。
In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under given flight conditions. The L/D ratio for any given body will vary according to these flight conditions. For an aerofoil wing or powered aircraft, the L/D is specified when in straight and level flight. For a glider it determines the glide ratio, of distance travelled against loss of height. The term is calculated for any particular airspeed by measuring the lift generated, then dividing by the drag at that speed. These vary with speed, so the results are typically plotted on a 2-dimensional graph. In almost all cases the graph forms a U-shape, due to the two main components of drag. The L/D may be calculated using computational fluid dynamics or computer simulation. It is measured empirically by testing in a wind tunnel or in free flight test.
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View content license ↗ 疲劳一词在材料科学领域， 意指物件因持续受到动态变化的应力而造成结构劣化。引起疲劳的动态变化应力通常远小于静态的极限拉伸应力或极限屈变应力。疲劳是渐进且局部的结构损坏过程，由于长时间日积月累而产生，所引起的破裂往往在毫无预警的情况下发生，可能直接导致事故（例如空难）的发生，因此相关的预防、检查、处理格外重要。
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure. Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal crystallising because of the brittle appearance of the fracture surface, but this has since been disproved. Most materials, such as composites, plastics and ceramics, seem to experience some sort of fatigue-related failure.
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View content license ↗ 立方卫星（英语：CubeSat）是一种用于太空研究的小型卫星，定义为10cm×10cm×10cm为每一标准单位，最大12单位，而每单位重量不超过1.33公斤（后来协议升级改为两公斤，并允许在一个轴向突起圆柱的额外空间），每一个立方卫星的体积和重量都是体积的倍数。截至2021年5月，人类已发射超过3000枚立方卫星，其中有2900多个成功部署至轨道，90多个因发射失败而被摧毁。 1999 年，加州理工州立大学和斯坦福大学制定了立方卫星的标准，以促进和发展设计，制造和测试用于近地轨道（LEO）的小型卫星所需的技术，这些技术具有多种科学性研究功能和探索新的空间技术。2013 年以前，立方卫星大多由学术界发射，而到了 2014 年，由于电子技术的进步，大多数新部署的立方卫星已经可以用于商业或业余项目。
A CubeSat is a class of small satellite with a form factor of 10 cm (3.9 in) cubes. CubeSats have a mass of no more than 2 kg (4.4 lb) per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats are deployed into orbit from the International Space Station, or launched as secondary payloads on a launch vehicle. As of January 2026, the Nanosatellite & CubeSat Database records 2,973 CubeSats launched, out of more than 3,200 nanosatellites launched since 1998. Jonathan McDowell's Jonathan's Space Report independently catalogues more than 3,200 CubeSats launched in total. In 1999, Jordi Puig-Suari, a professor at California Polytechnic State University, San Luis Obispo (Cal Poly) and Bob Twiggs, a professor at Stanford University Space Systems Development Laboratory, developed the CubeSat specifications to promote and develop the skills necessary for the design, manufacture, and testing of small satellites intended for low Earth orbit (LEO) that perform scientific research and explore new space technologies.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 人们对氧的同素异形体有着各种认知。其中最熟悉的是双氧（O2），大量存在于地球大气层，也被称为分子氧或三线态氧。另一个是高活性的臭氧（O3）。其他包括： 原子氧（O1，氧自由基） 单线态氧（O2），两种分子氧的亚稳态中的一种 氧4 （O4），另一种亚稳态形式 固氧存在于六种着色位中，一种是O8与另一种金属态形式
There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: Atomic oxygen (O•), a free radical. Singlet oxygen (O2*), one of two metastable states of molecular oxygen. Tetraoxygen (O4), another metastable form. Solid oxygen, existing in six variously colored phases, of which one is octaoxygen (O8, red oxygen) and another one metallic (ζ-oxygen).
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 地球静止轨道（或称地球赤道同步轨道，英语：geostationary orbit，简写：GEO）是指地球赤道面上方35,786km的圆形轨道，该轨道上航天器的运行方向和地球自转方向一致。在地球静止轨道上的航天器绕地球运行一周的时间和地球自转周期（一恒星日）相同，因此，在地面观测者看来，这样的航天器是在天空固定不动的。通信卫星和气象卫星一般运行在静止轨道，因此地面站天线只要对准卫星的定点位置就可以通讯，而不用转动天线。利用这个特点，把携带有可见光和近红外光传感器的海洋卫星发射到静止轨道上，这样就可以监测海洋环境的细微变化，比如GOCI卫星。 地球静止轨道是地球同步轨道的一个特例，二者之间有一些区别，地球同步轨道上的卫星每天在同样的时间通过地球上的同一个点，而地球静止轨道上的卫星一直固定在定点位置不动。 第一个提出把地球同步卫星用于通信的人是赫尔曼·波托奇尼克，他于1928年提出了这个设想（但并没有广为人知）。George O. Smith在系列科幻小说Venus Equilateral的第一个故事中提到了地球静止轨道，这是静止轨道第一次出现在大众文学作品中，但Smith并没有进行深入的探讨。1945年，英国著名科幻作家亚瑟·查理斯·克拉克在无线世界发表了一篇题为“Extra-Terrestrial Relays – Can Rocket Stations Give Worldwide Radio Coverage?”的文章，对地球静止轨道的原理进行了详细解释，这也使得地球静止轨道这个概念广泛传播。克拉克承认，他引入的地球静止轨道概念和Smith的The Complete Venus Equilateral有联系。克拉克第一个阐明了静止轨道对于广播和中继通讯卫星的作用。所以，有时候地球静止轨道也被称为克拉克轨道。相应的，海平面以上大约35,786km的地方有一片区域被称为克拉克带，它位于赤道平面内，可作为类静止轨道来使用。另外，克拉克轨道的周长大约是265,000km。
A geostationary orbit, also referred to as a GEO or GSO, is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day, and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C. Clarke in the 1940s as a way to revolutionise telecommunications, and the first satellite to be placed in this kind of orbit was launched in 1963. Communications satellites are often placed in a geostationary orbit so that Earth-based satellite antennas do not have to rotate to track them but can be pointed permanently at the position in the sky where the satellites are located.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 地球同步转移轨道（英语：geostationary transfer orbit，GTO）为霍曼转移轨道的运用之一，为椭圆形轨道，经加速后可达地球静止轨道（GEO）。近地点多在1000公里以下，远地点则为地球静止轨道高度35786公里。一般而言，地球同步转移轨道的近地点并无特别限制，但通常距地球表面数百公里，以降低ΔV（方向及速度改变量）的需求。 同步卫星的运作轨道为地球静止轨道，由地球同步转移轨道至地球静止轨道转换工作多由卫星自身动力进行，卫星在地球同步转移轨道的远地点附近变轨时，需要增加速度及改变速度的方向。在火箭性能方面，常以地球同步转移轨道酬载能力作为指标，该酬载能力较直接运送至地球静止轨道的数值为大。以三角洲四号重型运载火箭为例，其GTO运载能力为12,757公斤，而GEO运载能力仅为6,276公斤。
In space mission design, a geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a highly elliptical type of geocentric orbit, usually with a perigee as low as low Earth orbit (LEO) and an apogee as high as geostationary orbit (GEO). Satellites that are destined for geosynchronous orbit (GSO) or GEO are often put into a GTO as an intermediate step for reaching their final orbit. Manufacturers of launch vehicles often advertise the amount of payload the vehicle can put into GTO.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 死亡轨道（英语：Graveyard orbit），也称为垃圾轨道（junk orbit）或报废轨道（disposal orbit），是用于从通常运行轨道上脱离的空间轨道。一个重要的墓地轨道是在地球同步轨道上方的超同步轨道。卫星通常在其运行寿命结束时转入此类轨道，以降低与航天器碰撞和产生空间垃圾的可能性。
A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into such orbits at the end of their operational life to reduce the probability of colliding with operational spacecraft and generating space debris.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 日心轨道（也称为太阳系环线轨道）是围绕太阳系质量中心的轨道，这个质量中心通常位于太阳表面内或非常靠近太阳表面。太阳系中的所有行星、彗星和小行星以及太阳本身的运行都处于这样的轨道上，许多人造探测器和碎片也是如此。然而，太阳系中行星的卫星不在日心轨道上，因为它们围绕各自的行星运行（尽管月球围绕太阳有一个凸出的轨道）。 尽管太阳系的质心总是非常接近太阳，但随着时间的流转，它会在空间中移动，这取决于太阳系中其他大型天体的位置，例如木星和其它的气态巨行星，和它们当时所在的位置。类似的现象让我们可以通过迳向速度法探测系外行星。 在英文中，字首helio-源自于古希腊字"ἥλιος"（helios），意思就是"太阳"。在拟人化的希腊神话中还有赫利俄斯。 第一艘被送入日心轨道的太空探测器是1959年的月球1号。不正确的升空燃烧时间导致它错过了撞击月球的计划。
A heliocentric orbit (also called circumsolar orbit) is an orbit around the Sun. The inner planets are mainly influenced by the Sun's gravity, and orbit points close to the center of the Sun ('heliocentric' in a strict sense). The outer planets, and other more distant objects, tend to orbit points close to the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. Comets which traverse the inner Solar System shift between a nearly heliocentric focus, when they are close to the Sun, and a nearly barycentric one when they are more distant than Jupiter. All planets, comets, and asteroids in the Solar System, and the Sun itself are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits, as they orbit their respective planet (although the Moon has a convex orbit around the Sun).
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 在航天科学中，双椭圆转移是一种将航天器从一个轨道移动到另一个轨道的轨道机动，在某些情况下，消耗的ΔV（速度变化量，用以衡量一个航天器的机动能力）可能比霍曼转移更少。 双椭圆转移的轨迹由两个半椭圆组成。航天器在初始轨道的第一次加速会将航天器推进到第一个转移轨道，该轨道的远拱点（距离星球中心最远的点）为 r b {\displaystyle r_{b}} 。当航天器到达该点时，进行第二次加速，让轨道的近拱点抬升到目标轨道。航天器到达近拱点后，开始减速（大气减速或点火），降低远拱点，最终到达目标轨道。 虽然这种转移方法和霍曼转移相比，需要更多的发动机点火次数，并且通常需要更长的时间，但是当最终轨道与初始轨道的半长轴长度之比大于等于 11.94 时，如果所选择的中间轨道的远点适当，则双椭圆转移需要的总ΔV比霍曼转移要低。 双椭圆转移轨道的思路由阿里·斯滕菲尔德于1934年提出。
In astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer maneuver. The bi-elliptic transfer consists of two half-elliptic orbits. From the initial orbit, a first burn expends delta-v to boost the spacecraft into the first transfer orbit with an apoapsis at some point r b {\displaystyle r_{b}} away from the central body. At this point a second burn sends the spacecraft into the second elliptical orbit with periapsis at the radius of the final desired orbit, where a third burn is performed, injecting the spacecraft into the desired orbit.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 无工质型发动机（英语：propellantless drive），即无需火箭推进剂的发动机。有别于传统的需要喷射工质的发动机，无工质型发动机是不需要工作物质的。工质即工作物质，传统的工质型发动机（火箭和喷气式飞机）是依据动量守恒定律，靠燃料燃烧向后喷射工质来实现推进的。无工质发动机则相反。
Field propulsion refers to spacecraft propulsion concepts in which thrust arises from interactions with external fields or ambient media, rather than primarily from onboard chemical propellant. Early ideas grew from studies of radiation pressure and electrically driven motion; later contractor and agency surveys organized advanced concepts under thermal, field, and photon headings. Several related propulsion systems discussed alongside field propulsion in the broader historical literature surveyed here have since been demonstrated in practice, including electrodynamic tethers in orbit, and applications such as EHD thrust devices. In narrower modern literature, related propellant-less propulsion discussions often focus on environment-coupled systems, while the historical contractor and survey literature treated field propulsion more broadly and sometimes grouped related terrestrial electromagnetic propulsion and some beamed-energy concepts within the same analytical framework.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 冻结轨道是一种通过精确选择轨道参数使摄动效应最小化的航天器轨道。通过选取特定的初始轨道倾角、拱点位置与轨道离心率，使各摄动效应相互抵消，从而实现长期稳定的轨道运行，最大限度节省轨道保持所需的推进剂消耗。
In orbital mechanics, a frozen orbit is an orbit for an artificial satellite in which perturbations have been minimized by careful selection of the orbital parameters. Perturbations can result from natural drifting due to the central body's shape, or other factors. Typically, the altitude of a satellite in a frozen orbit remains constant at the same point in each revolution over a long period of time. Variations in the inclination, position of the apsis of the orbit, and eccentricity have been minimized by choosing initial values so that their perturbations cancel out. This results in a long-term stable orbit that minimizes the use of station-keeping propellant.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 最常见的远距逆行轨道（DRO）是指航天器绕卫星运行的轨道，由于卫星与行星-卫星系统的两个拉格朗日点（L1和L2）的相互作用，该轨道高度稳定。地月系统中的DRO是常见的一个例子，因此DRO一词有时也特指地月DRO。 更一般地说，一个质量可忽略不计的物体可以位于任何双体系统中较小天体周围的DRO中，例如行星-太阳或系外行星-恒星。 以绕月球运行的DRO中的航天器为例，该航天器的轨道方向与月球绕行星运行的方向相反。该轨道被描述为是“遥远的”，因为它经过拉格朗日点之外，而不是靠近月球。随着轨道越来越远，朔望周期（航天器两次经过行星和月球之间的时间间隔）变得越来越长，越来越接近月球绕行星运行的周期。恒星周期（从月球上观察飞船返回特定星座所需的时间）可能会比月球的轨道周期长得多。以木卫二为例，它的恒星周期约为木卫二轨道周期的八倍。 人们已经对DRO进行了数十年的研究。2022年4月，中国国家航天局的嫦娥五号轨道飞行器首次进入该轨道，随后美国宇航局的猎户座飞船在阿耳忒弥斯1号任务中于2022年11月进入该轨道。中国国家航天局的另外两艘航天器，DRO-A和DRO-B，于2024年尝试发射，但由于远征一号S上面级发生故障，被困在较低的轨道上。尽管之前出现了一些问题，但2024年7月15日，DRO-A和DRO-B最终进入预定的远距离逆行轨道。8月30日，两颗卫星与“DRO-L”卫星成功构建K频段微波星间测量通信链路，完成世界上首个地月空间三星星座建设。
In orbital mechanics, a distant retrograde orbit (DRO) is a highly stable retrograde orbit around the smaller of two bodies, passing outside the system's L1 and L2 Lagrange points. It is typically discussed in spacecraft orbits of natural satellites. The craft orbit is retrograde: moving in the direction opposite to the direction in which the moon orbits the planet. The orbit is distant: it passes above the Lagrange points, rather than being near the moon. Considering more distant orbits, the synodic period gets longer and approaches that of the moon going around the planet. The sidereal period can become much longer than the moon's orbital period. A hypothetical example with Europa has a sidereal period about eight times the orbital period of Europa. DROs have been researched for several decades. In April 2022, CNSA's Chang'e 5 orbiter became the first to enter the orbit, followed by NASA's Orion Spacecraft during the Artemis 1 mission which entered in November 2022.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 在物理学中，轨道是一个物体在引力作用下绕空间中一点运行的路径，比如行星绕一颗恒星的轨迹，或天然卫星绕一颗行星的轨迹。行星的轨道一般都是椭圆，而且其绕行的质量中心在椭圆的一个焦点上。 当前人们对轨道运动原理的认识基于爱因斯坦的广义相对论，认为引力是由时空弯曲造成的，而轨道则是时空场的几何测地线。为了简化计算，通常用基于开普勒定律的万有引力理论来作为相对论的近似。
In celestial mechanics, an orbit is the curved trajectory of an object under the influence of an attracting force. Alternatively, it is known as an orbital revolution, because it is a rotation around an axis external to the moving body. Examples for orbits include the trajectory of a planet around a star, a natural satellite around a planet, or an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets, and satellites follow elliptic orbits, with the center of mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion. Planets revolve around a star, a natural satellite around a planet, or an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 轨道保持是指使航天器与另一航天器或天体维持固定距离或飞行器与目标体保持同步运行的技术。对多数近地轨道卫星而言，必须持续抵消摄动效应的影响。对于环拉格朗日点的晕轮轨道航天器，轨道保持更具决定性意义。
In astrodynamics, orbital station-keeping is keeping a spacecraft at a fixed distance from another spacecraft or celestial body. It requires a series of orbital maneuvers (reboosts) made with thruster burns to keep the active craft in the same orbit as its target. For many low Earth orbit satellites, the effects of non-Keplerian forces, i.e. the deviations of the gravitational force of the Earth from that of a homogeneous sphere, gravitational forces from Sun/Moon, solar radiation pressure and air drag, must be counteracted. For spacecraft in a halo orbit around a Lagrange point, station-keeping is even more fundamental, as such an orbit is unstable; without an active control with thruster burns, the smallest deviation in position or velocity would result in the spacecraft leaving orbit completely.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 吻切轨道（英语：Osculating orbit）是太空中的天体在给定时间瞬间的开普勒轨道（即椭圆或其他二次曲线）。这是在天文学，特别是天文动力学，当中心的天体不受到摄动时，这就是当前的轨道向量状态（位置和速度）的轨道。
In astronomy and astrodynamics the osculating orbit of an object in space at a given moment in time is the orbit it would have around its central body if perturbations were absent. It is the orbit that coincides with the current position and velocity.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 外层空间中的航天器通过低能量转移轨道可以使用很少的燃料就改变轨道。这一轨道也被称为弱稳定性边界轨道，或弹道捕获轨道。这些特殊的轨道不仅在地月系可行，在其他卫星系统中也可行，例如在木星的卫星之间，有时被总称为星际转移网络。 采用低能量转移轨道的优点是可以用很小的速度增量穿越很长的距离，缺点是相比采用像霍曼转移轨道这种高能量的（即需要更多燃料的）转移轨道，需要更长的时间。
A low-energy transfer, or low-energy trajectory, is a route in space that allows spacecraft to change orbits using significantly less fuel than traditional transfers. These routes work in the Earth–Moon system and also in other systems, such as between the moons of Jupiter. The drawback of such trajectories is that they take longer to complete than higher-energy (more-fuel) transfers, such as Hohmann transfer orbits. Low-energy transfers are also known as weak stability boundary trajectories, and include ballistic capture trajectories. Low-energy transfers follow special pathways in space, sometimes referred to as the Interplanetary Transport Network. Following these pathways allows for long distances to be traversed for little change in velocity, or delta-v.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 最小轨道相交距离（Minimum orbit intersection distance，MOID）是天文学中用来评估天体之间潜在的近距离接近和碰撞风险的一种测量方法。它被定义为两个物体的吻切轨道最近点之间的距离，最受关切的是与地球发生碰撞的风险。地球MOID经常出现在数据库，例如JPL小天体数据库，中的是彗星和小行星。对其它的天体也有MOID值，例如木星MOID、金星MOID等等。 一个天体的地球MOID若小于0.05AU，就会归类为潜在威胁天体（potentially hazardous object，PHO），也就是说，对地球构成可能的风险。对于质量比地球大的天体，它值得注意的MOID值就会更大。例如，木星是最大的行星，木星MOID小于1AU就认为值得注意了。 因为行星经常会扰动小天体的轨道，低MOID并不意味着碰撞是不可避免的。在较小的天体被扰动到具有不同MOID值的不同轨道之前，两个天体必须同时到达它门轨道上的那个点。两个被引力锁定在轨道共振中的天体可能永远不会接近对方。随着时间向前推进，特别是较小的天接体被其它行星反复扰动之后的时间上，轨迹的数值积分会变得越来越发散。MOID的便利之处在于它可以直接从天体的轨道要素中获得，而且不需要对未来进行数值积分。 唯一一颗在杜林危险指数（自降级后）评定为4级的天体是阿登型小行星的(99942) 阿波菲斯。它的地球MOID为0.000316AU。这并不是目录中最小的地球MOID，许多具有低地球MOID的天体没有被归类为PHO，是因为这些天体的直径大约小于140米（或绝对星等，H < 22）。对于直径小于140米的小行星，因为非常昏暗，而且通常只有一个很短的观测弧，轨道确定得很差，地球MOID通常会更为实用。在撞击地球之前，唯一被探测到并计算出地球MOID的天体是小行星2008 TC3和2014 AA。2008 TC3在小行星中心的数据库中列出的MOID是0.00001，并且是在阿波罗型小行星中计算出最小的MOID。在更精确的喷射推进实验室的小天体数据库中，它的值甚至更小（0.0000078AU）。
Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of two bodies. Of greatest interest is the risk of a collision with Earth. Earth MOID is often listed on comet and asteroid databases such as the JPL Small-Body Database. MOID values are also defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on. An object is classified as a potentially hazardous object (PHO) – that is, posing a possible risk to Earth – if, among other conditions, its Earth MOID is less than 0.05 AU. For more massive bodies than Earth, there is a potentially notable close approach with a larger MOID; for instance, Jupiter MOIDs less than 1 AU are considered noteworthy since Jupiter is the most massive planet. A low MOID does not mean that a collision is inevitable as the planets frequently perturb the orbit of small bodies.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 交点进动（英语：Nodal precession）是卫星的轨道平面围绕天体的旋转轴的进动。这种进动是由于旋转体的非球面性质造成的，它会产生不均匀的引力场。以下讨论涉及人造卫星的近地轨道，它对地球的运动没有可测量的影响。像月球这样更大的天然卫星的交点进动则更为复杂。 在球体周围，轨道平面将保持固定在引力主体周围的空间中。然而，大多数物体都会旋转，这会导致赤道隆起。这种隆起会产生引力效应，导致轨道绕着主体的旋转轴进动。 进动的方向与公转的方向相反。对于围绕地球的典型顺行轨道（即在主体自转的方向上），升交点的经度减小，即交点向西进动。如果轨道是逆行，这会增加升交点的经度，即交点向东进动。这种交点进动使太阳同步轨道能够保持几乎恒定的相对于太阳的角度。
Nodal precession is the precession of the orbital plane (more specifically, the line of nodes) of a satellite around the rotational axis of an astronomical body such as Earth. This precession is due to the non-spherical nature of a rotating body, which creates a non-uniform gravitational field. The following discussion relates to low Earth orbit of artificial satellites, which have no measurable effect on the motion of Earth. The nodal precession of more massive, natural satellites like the Moon is more complex. Around a spherical body, an orbital plane would remain fixed in space around the gravitational primary body. However, most bodies rotate, which causes an equatorial bulge. This bulge creates a gravitational effect that causes orbits to precess around the rotational axis of the primary body. The direction of precession is opposite the direction of revolution. For a typical prograde orbit around Earth (that is, in the direction of primary body's rotation), the longitude of the ascending node decreases, that is the node precesses westward.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 极轨道，是一种高倾角轨道，其特点是沿此轨道运行的卫星在每次环绕天体（通常是地球，但也可能是其他天体）的圆周运动中都从两极上空经过。因此这类轨道的倾角是90度或接近90度。 极轨道经常为地球测绘卫星、遥感卫星、侦察卫星和一些气象卫星所采用。极轨道卫星的缺点是，不能对地球上某一点进行持续观测（这通常要靠地球静止轨道卫星来实现）。 当极轨道同时又是高椭圆轨道时，若其远地点位于极点上空，便可实现对极地地区的长时间观测（但这是从一个极远的距离进行观测）。典型的例子是苏联所发展的闪电轨道，许多军事卫星运行在这种轨道上。
A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of about 80–90 degrees to the body's equator. Launching satellites into polar orbit requires a larger launch vehicle to launch a given payload to a given altitude than for a near-equatorial orbit at the same altitude, because it cannot take advantage of the Earth's rotational velocity. Depending on the location of the launch site and the inclination of the polar orbit, the launch vehicle may lose up to 460 m/s of Delta-v, approximately 5% of the Delta-v required to attain Low Earth orbit.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
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