Orbits Close to Asteroid 4769 Castalia
Orbits Close to Asteroid 4769 Castalia
复制标题
DOI：
10.1006/icar.1996.0072
复制
发表时间：
1996-05
期刊：
影响因子：
3.2
通讯作者：
D. Scheeres;S. Ostro;R. Hudson;R. A. Werner
中科院分区：
文献类型：
--
作者：
D. Scheeres;S. Ostro;R. Hudson;R. A. Werner
我们使用一个雷达衍生的物理模型4769卡斯特利亚（1989 PB），以调查近轨道动力学周围的小行星大小，均匀旋转的小行星。我们的分析方法提供了一个基础，系统研究粒子动力学接近任何均匀旋转的小行星。我们建立了一个雅可比积分存在的粒子轨道这颗小行星，检查随之而来的零速度表面，找到家庭的周期轨道，并确定其稳定性。所有在卡斯特利亚平均半径103以内的同步轨道和直接轨道都是不稳定的，容易受到卡斯特利亚的撞击或逃逸。逆行轨道大多是稳定的，允许粒子靠近小行星表面运行。我们推导出一个模型，使我们能够预测的逃逸条件的粒子在轨道上约卡斯特利亚和（临时）捕获条件的双曲闯入者。在卡斯特利亚1.5公里范围内的轨道将立即从系统中弹射出去。如果aV∞< 0.4 m/sec的双曲轨道的近心点半径在10.2 km以内，则卡斯特利亚有可能捕获它们。对于卡斯特利亚来说，这个捕获区域很小，但结果也适用于较大的小行星，它们的捕获区域也会更大。我们确定的喷出物的速度，无论是确保喷出物逃逸或重新影响的功能，在卡斯特利亚的表面上的位置上的界限。确保逃逸的速度范围为0.28至0.84米/秒，确保再次撞击的速度范围为0至0.18米/秒。这两个界限之间的速度导致逃逸，重新撞击，或潜在的有限时间稳定轨道。我们开发了一个简单的标准，可以确定一个粒子是否可以在过去从小行星上喷射出来，以及它是否会在未来撞击表面。
We use a radar-derived physical model of 4769 Castalia (1989 PB) to investigate close orbit dynamics around that kilometer-sized, uniformly rotating asteroid. Our methods of analysis provide a basis for systematic studies of particle dynamics close to any uniformly rotating asteroid. We establish that a Jacobi integral exists for particles orbiting this asteroid, examine the attendant zero-velocity surfaces, find families of periodic orbits, and determine their stability. All synchronous orbits and direct orbits within ∼3 mean radii of Castalia are unstable and are subject to impact or escape from Castalia. Retrograde orbits are mostly stable and allow particles to orbit close to the asteroid surface. We derive a model which allows us to predict the escape conditions of a particle in orbit about Castalia and the (temporary) capture conditions for a hyperbolic interloper. Orbits within 1.5 km of Castalia are subject to immediate ejection from the system. Hyperbolic orbits with aV∞< 0.4 m/sec can potentially be captured by Castalia if their periapsis radius is within ∼2 km. For Castalia this capture region is small, but the results also apply to larger asteroids whose capture regions would also be larger. We determine bounds on ejecta speeds which either ensure ejecta escape or re-impact as functions of location on Castalia's surface. The speeds that ensure escape range from 0.28 to 0.84 m/sec and the speeds that ensure re-impact range from 0 to 0.18 m/sec. Speeds between these two bounds lead either to escape, re-impact, or potentially finite-time stable orbits. We develop a simple criterion which can establish whether a particle could have been ejected from the asteroid in the past and if it will impact the surface in the future.