Abstract The Small Expendable-Tether Deployment System (SEDS) provides a low-cost facility for deploying tethered payloads in space. Among various objectives, SEDS' first flight will assess the capability of tethered platforms to carry out measurements in the upper atmosphere. The performance of onboard instruments is seriously affected by the payload's attitude dynamics. In this paper, SEDS' attitude dynamics and stability are analytically and numerically analysed for the nominal mission. It is shown that although a passive damper can be used to reduce the amplitudes of the attitude angles, appropriate control techniques are required for scientific instrumented platforms.