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The effects of outgassing jets on the rotation of a comet nucleus and on the trajectory of an orbiting spacecraft.

机译：脱气射流对彗核旋转和轨道飞行器轨迹的影响。

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摘要

An outgassing jet model is presented in this thesis in support of spacecraft navigation for future missions to comets. The outgassing jet is modelled as an emission cone while the comet nucleus is modelled as a uniform density triaxial ellipsoid. The heliocentric orbit motion as well as in the strength of the outgassing jet are accounted for in the equations of motion. This model is used for predicting the rotational evolution of a comet nucleus as a result the outgassing jets' reactive torques as well as for simulation of an orbiting spacecraft's trajectory through jet passages and the estimation of the physical outgassing properties of jets from perturbations to the spacecraft's motion.;A model for the rotational evolution of a comet nucleus is presented and predicts possible levels of rotational excitation for a comet nucleus under torques produced by multiple discrete outgassing jets located on the surface. An analytical theory for the secular solution to the rotational motion of comets with an axis of symmetry is derived and used to predict rotational state changes over multiple perihelion passages. A method of characterizing the comet nucleus dynamics to predict the end state of the rotation is found from the averaged equations. Applications of these analytical results to predict the stochastic evolution of a comet nucleus rotation are outlined.;This thesis also identifies and analyzes stable Sun synchronous orbits in a Hill rotating frame which can be applied to any small body in the solar system. The stability of these orbits is due to the inclusion of solar radiation pressure effects. The stability of the orbits in terms of escaping the comet is analyzed though construction of zero-velocity curves and the use of spectral analysis. The effect of orbital perturbations from outgassing jets on the stability criterion are also considered in the stability analysis of a spacecraft in orbit about a comet. Once these orbits have been identified, the effects of a non-spherical body are explored. In addition, impulsive and finite burn control schemes to restrict a stable orbit's motion are determined, showing that it is feasible to implement a form of orbital hovering in the terminator plane of a comet.
机译：本文提出了一种脱气射流模型，以支持航天器导航以用于未来的彗星飞行任务。除气射流被建模为发射锥，而彗核被建模为均匀密度的三轴椭球。在运动方程中考虑了日心轨道运动以及除气射流的强度。该模型用于预测彗星核的旋转演化，从而得出脱气喷射器的反作用转矩，以及用于模拟通过喷射通道的在轨航天器的轨迹，并估算从扰动到航天器的喷射器的物理排气特性。提出了一个彗星核旋转演化的模型，该模型预测了位于表面上的多个离散除气射流产生的扭矩作用下，彗核的旋转激发的可能水平。得出了具有对称轴的彗星旋转运动的长期解决方案的解析理论，并用于预测多个近日点通行通道的旋转状态变化。从平均方程式中找到了一种表征彗星核动力学特征以预测旋转结束状态的方法。概述了这些分析结果在预测彗核旋转随机演化中的应用。本论文还确定并分析了Hill旋转框架中稳定的太阳同步轨道，该轨道可以应用于太阳系中的任何小物体。这些轨道的稳定性归因于太阳辐射压力的影响。通过构造零速度曲线和使用频谱分析，分析了绕逃脱轨道的稳定性。在围绕彗星运行的航天器的稳定性分析中，还考虑了脱气射流的轨道扰动对稳定性判据的影响。一旦确定了这些轨道，就可以探索非球形物体的影响。另外，确定了限制稳定轨道运动的脉冲和有限燃烧控制方案，这表明在彗星的终止平面上实施一种形式的轨道悬停是可行的。

著录项

  • 作者

    Byram, Sharyl M.;

  • 作者单位

    University of Michigan.;

  • 授予单位 University of Michigan.;
  • 学科 Engineering Aerospace.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 136 p.
  • 总页数 136
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 航空、航天技术的研究与探索;
  • 关键词

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