• World’s first balloon-based terahertz heterodyne spectrometer to measure atomic oxygen in the Earth’s upper atmosphere
• Atomic oxygen plays an important role in the corrosion and deceleration of low-flying satellites and as an indicator of climate change in the upper atmosphere
• Focus: Space, Earth observation, climate change
From August the 29th to September the 11th the DLR Institute of Optical Sensor Systems took part in the European HEMERA balloon flight campaign at the Esrange Space Center in northern Sweden. The aim was to measure atomic oxygen in the mesosphere and thermosphere of the Earth with the specially developed spectrometer OSAS-B (Oxygen Spectrometer for Atmospheric Science from a Balloon). OSAS-B is a heterodyne spectrometer and measures atomic oxygen at a frequency of 4. 7 THz (wavelength: 63 μm).
Atomic oxygen occurs at altitudes of 80 to over 500 km and is a major factor for the corrosion and deceleration of satellites in low Earth orbits. It also plays an important role in the photochemistry and energy balance of the upper atmosphere and is an indicator of climate change and its effects on the temperature and density of this atmospheric region.
The OSAS-B instrument is based on a superconducting hot-electron bolometer as a detector and a quantum cascade laser as a local oscillator, which are operated in a cryostat at 4. 3 K (-269°C) and 60 K (-213°C). It is the first of its kind in the world to be used on a stratospheric balloon. The maximum altitude reached on this first flight is 32. 8 km, for a total flight duration of 10 hours. The technology for OSAS-B originated from the development of the GREAT instrument on SOFIA. HEMERA is a European infrastructure project for the provision of flights with stratospheric balloons.
Spectrum of atomic oxygen measured with OSAS-B (3P1-3P2 fine structure transition, 0° elevation).