The Occultation Wave Limb Sounder (OWLS) on INSPIRESat-3
Abstract
Solar occultations served as an early work-horse for characterizing the temperature and density of Earth's thermosphere because of the technique's capability of making self-calibrated measurements of thermospheric density from roughly 90 to 400 km. However, solar occultations have been abandoned in recent decades, and few, if any, satellite-borne solar occultation instruments designed specifically for characterizing the thermosphere have ever flown. Meanwhile, few other methods have been proven capable of profiling the 120-300 km region of the thermosphere, leading some authors to label this region the "Thermospheric Gap" due to its lack of measurements. The Occultation Wave Limb Sounder (OWLS) instrument scheduled to fly on the INSPIRESat-3 small-sat aims to fill the Thermospheric Gap by making solar occultation measurements from 90 to 400 km, spanning from the mesopause to the exobase. OWLS is capable of measuring major neutral species (O2, N2 and O) density and temperature at 20 km vertical resolution below 150 km, and 5 km resolution above 150 km. In addition to simply filling the Thermospheric Gap, a primary focus of the OWLS mission is to understand how gravity waves propagate and dissipate in the thermosphere, addressing a Key Science Goal of the 2013 NAS Solar and Space Physics Decadal Survey. OWLS will achieve its science goals with two ultraviolet channels. One channel is a full-disk integrated far ultraviolet spectrograph for measuring density, temperature and abundance from 90-250 km at high absolute accuracy and 20 km vertical resolution, using methods proven in the early 1970s. The second channel is an extreme ultraviolet (EUV) imager with bands at 20 and 30 nm for measuring density, temperature and abundance from 150-400 km at <5 km vertical resolution, using technology proven on the Solar Dynamics Observatory and methods proven recently for EUV photometers at both Earth and Mars. This talk will describe the OWLS science objectives, instrumentation, measurement principles, and anticipated observations.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E3372T