ESA Balloon Campaign to Measure Atomic Oxygen in the Upper Earth Atmosphere Using the DLR OSAS-B Spectrometer

Atomic oxygen is the predominant species in the upper Earth atmosphere between 80 and 600 km. Accurate measurements are important for modeling the mesosphere and lower thermosphere, particularly with regard to predicting the “drag” effect on satellites and space debris in low Earth orbits - that is, their deceleration in the residual atmosphere. Four staff members from the DLR Institute of Space Research (Enrico Dietz, Lukas Jehna, Alexey Semenov, and Martin Wienold) participated with the OSAS-B (Oxygen Spectrometer for Atmospheric Science on a Balloon) in the ESA’s “Keystone TVBallet” stratospheric balloon campaign from August 17 to 30. This is a measurement campaign in preparation for the “Keystone” satellite mission, part of ESA’s Earth Explorer Program. OSAS-B is a heterodyne spectrometer designed to measure the emission of atomic oxygen at 2.1 and 4.7 THz. These two transitions are the only ones in the atmosphere that are thermally excited, meaning they provide direct information about local temperature and concentration. The measurements were conducted in parallel with those taken by the Canadian OSIRIS instrument from the University of Saskatchewan. OSIRIS is a UV/VIS spectrometer that, in parallel with OSAS-B, measures the green 577 nm emission from atomic oxygen, which can be observed shortly after sunset and is also responsible for the aurora. The goal of the campaign is to develop a better understanding of atomic oxygen in the mesosphere and lower thermosphere through the joint analysis of various measurement methods, thereby preparing for future satellite missions.