Limits to rover miniaturisation and their implications for solar system exploration

Semiautonomous rover scaling is examined for exploration throughout the solar system. Communications to a relay orbiter is a major constraint, due to power requirements and decreasing antenna gain at small sizes. Also, analysis time scales adversely for power hungry Raman or surface abrasion, and also for low photon count gamma ray spectroscopy. 1 cm scale rovers with a MER like capability should be possible, and could operate on solar power to 40 AU. At 2 cm, rovers powered by current RTGs are feasible, and are useful in the outer solar system. Such rovers will return images, autonomously navigate from interest point to interest point, and autonomously deploy instruments. Analyses include elemental APX and gamma ray spectroscopy for elemental and Raman and IR spectroscopy for molecular and or mineralogical compositions. They can be built with current technology, the component size is similar to watch movements. Low temperatures are not an obstacle. Very high temperatures, e.g. 390 to 480 C for surface Venus, will require more work on high temperature electronics, but current work suggests that dense ICs for Venusian conditions should be feasible in the near future. Mm size rovers, designed primarily for imaging, are feasible at inner solar system solar flux levels. If deployed in large numbers, manufacturing developments would be needed to allow mechanised assembly of multiple MEMS systems. Miniature, degassing to space, RTGs could provide power in cold vacuum environments, as could advanced betavoltaic systems, though much work would be required to develop the latter.