Cryogenic gas cell for infrared space instrumentation

The Doppler Wind and Temperature Sounder (DWTS) is being developed for flight on NASA’s Dynamical Neutral Atmosphere-Ionosphere Coupling (DYNAMIC) satellite. DWTS will view the Earth limb orthogonal to the spacecraft ram and uses gas-filter correlation radiometry to detect the Doppler shift of atmospheric emission. The observations yield horizontal winds and kinetic temperature with high precision, excellent spatial resolution, and altitude coverage from 40–250 km. DWTS detects Doppler shifting of NO and 13CO2 atmospheric emission lines by passing the incident light through an onboard cell containing both gases that is cooled to near cryogenic temperatures. This work describes the DWTS instrument, and the results of a recent program completed to space qualify the gas cell. This effort integrated a flight-like gas cell into a prototype DWTS optical bench assembly (OBA) and subjected it to extended periods in thermal vacuum, repeated thermal cycling, and vibrational testing, all consistent with anticipated launch and flight conditions. Detailed observations of the DWTS gas cell indicate that it survived testing without compromise and justify a technology readiness level (TRL) of six.