Spontaneous rotation of a nanosatellite FITSAT-1

TL;DR

This paper explains the spontaneous rotation of a tiny satellite caused by thermal interactions with air molecules, revealing a mechanism applicable to small objects orbiting planets with atmospheres.

Contribution

It introduces a novel thermal interaction mechanism causing satellite rotation, supported by dimension analysis, relevant for small objects in planetary atmospheres.

Findings

Thermal interaction induces satellite rotation.

Torque is significant for small satellites.

Applicable to objects orbiting radiating planets.

Abstract

Spontaneous rotation of an ultra-small satellite was observed and its driving torque was explained by the thermal interaction between the air molecules and the surfaces of the satellite heated by the radiation from the earth. This mechanism has the similarity with a usual radiometer, except the point that the velocity of the satellite is sufficiently faster than that of the thermal velocity of the air molecules, and that the mean free path of the air molecules is sufficiently longer than the characteristic length of the satellite. Using dimension analysis, the torque was found to be significant to a small size of satellite. This rotation mechanism can be applied to any small objects, which are revolting around a planet radiating a black body radiation and has the atmospheric gas.