In the upcoming years, there are many missions planned for operating in dense atomic oxygen and high drag environments, for instance EnVision, an ESA mission to Venus, or various Earth orbiters that will operate in VLEO, mainly focused on Earth observation and telecommunications. What these missions have in common is passing through upper layers of planetary atmosphere with relatively high density, including atomic oxygen. This results in interactions between the gases and materials surfaces which will create particularly harsh environment for spacecraft materials, including atomic oxygen erosion and drag.

In case of the Envision mission, the harshest environment will be experienced during the aerobraking phase, once the spacecraft is lowering its altitude passing through the atmosphere of Venus, where the residual atmosphere (in particular highly reactive atomic oxygen) will act on surfaces of materials in combination with high temperatures originating from the solar irradiation and aerothermal fluxes. In case of the Earth orbiters, roughening of materials surfaces can lead to excessive use of the propellant and reduction in the spacecraft lifetime.

This poster will present highlights of recent atomic oxygen testing activities in the ESA ESTEC laboratories and the LEOX facility, including latest results from the high temperature Envision testing as well as examples from other ESA missions. A variety of materials have been tested at different temperatures, including solar array materials, cables, and thermal and optical coatings. The main focus has been on analysing and predicting surface modifications due to atomic oxygen erosion, including recession, roughening, and other changes in the functional properties of the materials (thermal, optical). The outlook and challenges for future testing activities will also be presented, in view of the increasing interest in the subject of ground based atomic oxygen testing for dense atomic oxygen and high drag environments.