IN-SITU EXPLORATION OF EARTH’S ATMOSPHERE USING NOVEL SPACECRAFT DESIGN

Abstract

Altitudes between 40 and 140 km are not accessible for conventional aircraft and spacecraft for long-term duration. In particular the region around 100 km, the upper mesosphere and lower thermosphere (UMLT), is of great interest to scientists and engineers since it forms the transition from earth to space. Important physical phenomena take place at this region that have a strong influence on the atmospheric layers below. The scientific need to explore this region is very high. So far, the UMLT region has been accessible mainly to remote sensing observations, which are subject to vertical and horizontal smoothing of the measured information, and require an underlying model and possibly not existing a priori information about the subject of interest. Therefore, in-situ measurements in the UMLT region on a global scale would be of inestimable value. However any conventional spacecraft will quickly suffer from free molecular friction at UMLT altitudes, leading to rapid orbital decay. We intend to highlight the scientific need for in-situ measurements in the UMLT region and discuss several mission case studies. The impact of the special conditions at that altitude on the spacecraft design require a careful consideration.