The scale of the solar system is slowly changing, likely increasing as a result of solar mass loss, with additional change possible if there is a secular variation of the gravitational constant, G. The measurement of the change of scale could provide insight into the past and the future of the solar system, and in addition a better understanding of planetary motion and fundamental physics. Estimates for the expansion of the scale of the solar system are of order 1.5 cm year-1 AU-1, which over several years is an observable quantity with present-day laser ranging systems. This estimate suggests that laser measurements between planets could provide an accurate estimate of the solar system expansion rate. We examine distance measurements between three bodies in the inner solar system -- Earth's Moon, Mars and Venus -- and outline a mission concept for making the measurements. The concept involves placing spacecraft that carry laser ranging transponders in orbit around each body and measuring the distances between the three spacecraft over a period of several years. The analysis of these range measurements would allow the co-estimation of the spacecraft orbit, planetary ephemerides, other geophysical parameters related to the constitution and dynamics of the central bodies, and key geodetic parameters related to the solar system expansion, the Sun, and theoretical physics.

中文翻译：

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三部曲，一种用于测量太阳系扩张的行星大地测量任务概念

太阳系的尺度正在缓慢变化，可能由于太阳质量损失而增加，如果引力常数 G 存在长期变化，则可能会发生额外变化。 尺度变化的测量可以提供对过去的了解以及太阳系的未来，此外还可以更好地了解行星运动和基础物理学。估计太阳系规模扩大的数量级为 1.5 cm year-1 AU-1，这在几年内是当今激光测距系统可观测到的数量。这一估计表明行星之间的激光测量可以提供对太阳系膨胀率的准确估计。我们检查了太阳系内部三个天体之间的距离测量——地球的月球，火星和金星——并概述了进行测量的任务概念。该概念涉及将携带激光测距转发器的航天器放置在围绕每个天体的轨道上，并在几年内测量三个航天器之间的距离。对这些距离测量的分析将允许对航天器轨道、行星星历、与中心天体的构造和动力学相关的其他地球物理参数以及与太阳系膨胀、太阳和理论相关的关键大地测量参数进行共同估计。物理。