The OSIRIS instrument on the Odin spacecraft

TLDR

OSIRIS on the Odin spacecraft is designed to retrieve altitude profiles of terrestrial atmospheric minor species by observing limb‑radiance profiles. It uses a grating optical spectrograph that records 280–800 nm scattered sunlight spectra at ~1 nm resolution while the Odin spacecraft performs repetitive vertical limb scans to sweep a 1 km field of view from ~10 to 100 km, monitoring absorption features for altitude profiles, detecting airglow, and employing a three‑channel infrared imager to capture limb radiance at 1.27 µm and 1.53 µm, with tomographic inversion of the resulting images producing two‑dimensional emission distributions. PACS Nos.: 07.05.Pj, 07.60.Dq, 07.60.Rd, 07.87, 94.10.Dy, 94.10.Fa, 94.10.Gb, 94.10.Rk.

Abstract

The optical spectrograph and infrared imager system (OSIRIS) on board the Odin spacecraft is designed to retrieve altitude profiles of terrestrial atmospheric minor species by observing limb-radiance profiles. The grating optical spectrograph (OS) obtains spectra of scattered sunlight over the range 280–800 nm with a spectral resolution of approximately 1 nm. The Odin spacecraft performs a repetitive vertical limb scan to sweep the OS 1 km vertical field of view over selected altitude ranges from approximately 10 to 100 km. The terrestrial absorption features that are superimposed on the scattered solar spectrum are monitored to derive the minor species altitude profiles. The spectrograph also detects the airglow, which can be used to study the mesosphere and lower thermosphere. The other part of OSIRIS is a three-channel infrared imager (IRI) that uses linear array detectors to image the vertical limb radiance over an altitude range of approximately 100 km. The IRI observes both scattered sunlight and the airglow emissions from the oxygen infrared atmospheric band at 1.27 µm and the OH (3-1) Meinel band at 1.53 µm. A tomographic inversion technique is used with a series of these vertical images to derive the two-dimensional distribution of the emissions within the orbit plane. PACS Nos. : 07.05.Pj, 07.60.Dq, 07.60.Rd, 07.87, 94.10.Dy, 94.10.Fa, 94.10.Gb, 94.10.Rk