Ionospheric Imaging from Geosynchronous Orbit

Robert. P. McCoy

Code 321SR, Space & Remote Sensing

Office of Naval Research

800 N. Quincy St.

Arlington, VA, 22217

Abstract

The Office of Naval Research is developing a multispectral ultraviolet imager to study ionospheric weather in real-time from geosynchronous orbit. The experiment, called the Ionospheric Mapping and Geocoronal Experiment (IMAGER), will image ultraviolet dayglow and nightglow emissions from the ionosphere and dayglow emissions from the thermosphere in four separate bands. The IMAGER telescope has a 1000 km x 1000 km field of view with a resolution of 10 km x 10 km. Typical nighttime integration time will be about 100 seconds per image. A two-axis gimbal will be used to point the telescope anywhere on the disk or limb of the Earth and a filter wheel select individual wavelengths. On the limb of the Earth, IMAGER will provide altitude profiles of electron density or neutral density.

The primary science goal of IMAGER is to provide real-time tracking of ionospheric irregularities and geomagnetic storms which cause scintillation on GPS, UHF, HF and other radio frequency propagation paths. At night, IMAGER will image nightglow from O+ + e- recombination in two separate bands. During the day, IMAGER will image dayglow from resonant scattering of O+ in the extreme ultraviolet, as well as emissions from atomic oxygen and molecular nitrogen. A nightside technique for determining 3-D imaging of electron density will be tested using alternating images from optically thin and thick recombination emissions. From geosynchronous orbit, IMAGER will be able to track the propagation of geomagnetic storms toward the equator.

The IMAGER experiment is one element in an overall ONR program aimed at improving the state of the art in space weather specification and forecast by adapting lessons learned from the meteorology community. The program is called “Space Weather – Learn from the Meteorologist”. The IMAGER concept is analogous to the current visible and IR GOES capability. Other elements of the ONR program involve the development of an assimilating model for the ionosphere. The IMAGER experiment will be launched into geosynchronous orbit in early 2006 as part of the DoD Space Test Program MLV-05 Mission. This Mission also contains the GIFTS/IOMI hyperspectral imaging spectrometer. Part of the IMAGER science plan is to coordinate observations with GIFTS/IOMI to look for synergistic science, connections and couplings between the lower atmosphere and ionosphere/thermosphere.