[论文解读] Utilizing Minor Planets to Assess the Gravitational Field in the Outer Solar System

Gary L. Page, David S. Dixon+1 more|arXiv (Cornell University)|Apr 17, 2005

Astro and Planetary Science被引用 2

一句话总结

本文提出利用小行星作为天然探针，测量外太阳系的引力场，提供一种方法来检验有争议的先驱者异常现象。通过长期跟踪这些大而明亮的天体，研究人员可以评估在先驱者10号和11号探测器中观测到的异常向日加速度是否为真实的物理效应，还是航天器系统误差所致。

ABSTRACT

The Pioneer 10 and 11 spacecraft have been precisely tracked for over thirty years as they have crossed and then departed the solar system. When they passed a distance of 20 AU from the sun, both probes exhibited a systematic error in their trajectories that can be interpreted as a constant acceleration of 8.74e-8 cm/sec/sec towards the sun. This anomalous acceleration has come to be referred to as the Pioneer Effect, and although spacecraft systematics are its most likely explanation, there have been no convincing arguments that that is indeed the case. The alternative, that the Pioneer Effect represents a real phenomenon, is very appealing for many reasons. What is lacking is a means of measuring the effect, its variation, its potential anisotropies, and its region of influence. The present paper shows that minor planets provide an observational vehicle for investigating the gravitational field in the outer solar system, and thus provide a means of measuring the Pioneer Effect and potentially to either support or refute its existence as a real phenomenon. Minor planets can be used for this purpose because they have a large mass and are large and bright enough to be observed for useful intervals. Thus, even if the Pioneer Effect does not represent a new physical phenomenon, minor planets can be used to probe the gravitational field in the outer solar system. Since there are very few intermediate range tests of gravity at the multiple AU distance scale, this is a worthwhile endeavor in its own right. However, depending upon the characteristics of the measurements, it might even be possible to differentiate between the predictions of alternative explanations for the Pioneer Effect.

研究动机与目标

• 研究外太阳系的引力场，特别是20 AU以外的区域，即先驱者异常现象被观测到的区域。
• 解决在天文单位（AU）尺度上缺乏中等距离引力测试的问题，这对验证引力理论至关重要。
• 提供一种独立于航天器数据的方法，用于测量先驱者效应的变化、各向异性和影响区域。
• 区分先驱者效应的多种解释——即它是否为真实的物理现象，还是航天器跟踪系统误差所致。

提出的方法

• 利用长期光学跟踪数据，对足够大且足够明亮以在长时间内被观测到的小行星进行研究。
• 应用精确的轨道确定技术，对太阳系外缘的小行星轨迹进行建模。
• 将小行星的实际轨道行为与基于标准牛顿引力和广义相对论的预测进行比较。
• 通过观测轨道与预测轨道之间的差异，推断是否存在异常加速度及其特征。
• 纳入已知天体和太阳系质量分布的引力影响，以隔离潜在的偏离。
• 评估观测到的异常是否与先驱者效应的大小和方向一致（8.74×10⁻⁸ cm/s² 指向太阳）。

实验结果

研究问题

• RQ1 小行星能否作为可靠的观测平台，用于测量20 AU及更远距离的引力场？
• RQ2 小行星的实际运动是否显示出与先驱者异常现象大小和方向相似的恒定向日加速度？
• RQ3 小行星的引力行为能否区分真实物理异常与航天器跟踪中的系统误差？
• RQ4 从行星轨道推断出的异常加速度的空间范围和各向异性如何？
• RQ5 小行星数据能否约束试图解释先驱者效应的各类理论模型？

主要发现

• 小行星可作为外太阳系引力场的独立、长期探针，提供一种无需依赖航天器遥测数据即可检验先驱者效应的方法。
• 某些小行星质量大、亮度高，使其可在长时间内被观测，从而实现精确轨道跟踪，这是检测微小异常所必需的。
• 即使最终证明先驱者效应源于航天器系统误差，小行星观测仍可作为在多个AU距离上检验引力的重要手段。
• 该方法具有区分先驱者效应多种解释的潜力，通过测量效应的变化和空间特征实现。
• 该方法填补了中等距离引力测试中的关键空白，而此类测试在数十AU的距离上极为稀少。
• 该分析可能揭示异常加速度是否具有各向同性，或表现出方向依赖性，从而有助于排除或支持特定物理模型。