The IMAP-Ultra Energetic Neutral Atom (ENA) Imager
M. Gkioulidou, G. B. Clark, D. G. Mitchell, A. R. Dupont, K. L. Anderson, S. Begley, M. Bzowski, E. R. Christian, C. E. Cook, A. B. Crew, M. J. Cully, R. Demajistre, T. J. Diaz, R. J. Drexler, N. T. Dutton, C. J. Gingrich, J. R. Hayes, C. M. Huber, J. Hutcheson, S. E. Jaskulek, P. Kollmann, M. T. LeBlanc, J. Lees, D. J. McComas, K. S. Nelson, C. W. Parker, D. B. Reisenfeld, E. A. Rollend, C. E. Schlemm, N. A. Schwadron, R. Verrill, J. Yen, Jieyun Yin
Abstract
NASA’s Interstellar Mapping and Acceleration Probe (IMAP), a spinner spacecraft in orbit around L1, is taking in situ observations of thermal, pickup, and energetic particles, while simultaneously remotely sensing the effects that these particles have in the outer heliosphere, by measuring Energetic Neutral Atoms (ENA) emissions produced by neutralized energetic ions when they charge exchange with interstellar neutral particles in that region. The IMAP-Ultra instrument (Ultra), one of the three ENA imagers on IMAP, measures the emission of the highest energy ENAs produced in the heliosheath and beyond. Ultra consists of two sensors with one sensor angled at 90° (Ultra 90 ) and the other at 45° (Ultra 45 ) from the spacecraft’s spin axis. Ultra was designed and optimized to measure hydrogen (H) ENAs from 5 – 40 keV, but the sensors have been demonstrated to measure H from ∼3 – 300 keV. Additionally, Ultra’s large ∼96° × 120° field of view (FoV) is capable of achieving angular resolutions ≤ 6° FWHM for ≥ 10 keV for H ENAs. Ultra provides high spatial resolution, full heliosphere maps, detecting changes in the spatial distribution of ENAs, on time scales sufficient to track both solar cycle as well as other major variations.