For many years, the motto in space travel was: rockets are disposable products. However, this view has changed in recent years. The industry is moving towards sustainability and reusability, if only for economic reasons. However, this requires one thing above all: protecting the rocket from the enormous heat during re-entry into the atmosphere.

Heat shields are as old as space travel itself, but they have hardly kept up with the developments in the industry and still pose a major challenge for any re-entering spacecraft. For decades, there were only so-called ‘ablative heat shields’ and heat protection tiles made of high-temperature ceramics were developed, among others, for the Space Shuttles. However, neither of these systems is really economical or sustainable.
The concept of transpiration cooling was therefore developed years ago: A fluid is forced through a surface and mixes with the hot boundary layer, thus cooling it and protecting the spcecraft. The idea is therefore relatively simple and the maintenance effort is minimal. The concept of transpiration cooling could lead to cost, time and possibly weight savings. Nonetheless, the underlying physics and system are complex and need to be investigated under real flight conditions before being deployed on bigger spacecraft.
Despite the complexity, TRACER aims to investigate such a transpiration cooling system and to be the first to test and validate transpiration cooling on a sounding rocket in a flight experiment.