Telescope of extreme ultraviolet (TEX) onboard SELENE: science from the Moon

I Yoshikawa,G Murakami,M Nakamura,T Toyota,M Kikuchi,W Miyake,A Yamazaki,S Kameda,F Ezawa,M Taguchi,K Yoshioka

doi:10.1186/bf03352805

Abstract

Abstract The Upper Atmosphere and Plasma Imager (UPI) is to be launched in 2007 and sent to the Moon. From the lunar orbit, two telescopes are to be directed towards the Earth. The Moon has no atmosphere, which results in there being no active emission near the spacecraft; consequently, we will have a high-quality image of the near-Earth environment. As the Moon orbits the Earth once a month, the Earth will also be observed from many different directions. This is called a “science from the Moon”. The two telescopes are mounted on a two-axis gimbal system, the Telescope of Extreme ultraviolet (TEX) and Telescope of Visible light (TVIS). TEX detects the O II (83.4 nm) and He II (30.4 nm) emissions scattered by ionized oxygen and helium, respectively. The targets of extreme-ultraviolet (EUV) imaging are the polar ionosphere, the polar wind, and the plasmasphere and inner magnetosphere. The maximum spatial and time resolutions are 0.09 Re and 1 min, respectively.

Highlights

Standard theories on the polar wind indicate that only light ions such as H+ and He+ can overcome the terrestrial gravitational potential to escape from the polar ionosphere due to a pressure gradient along open field line and that the O+ outflow is limited due to both its large mass and its loss by charge exchange with neutral H in the atmosphere (e.g., Axford, 1968; Banks and Holzer, 1968)
In this paper we present the design of the Upper Atmosphere and Plasma Imager (UPI)-Telescope of Extreme ultraviolet (TEX) imager and its calibrated performance
Science Target The UPI-TEX instrument provides global images of plasmas in the vicinity of the Earth by detecting helium ions (He intensity from source (II)) (30.4 nm) emission scattered by He+ ions and O II (83.4 nm) emission by O+ ions

Summary

Introduction

Standard theories on the polar wind indicate that only light ions such as H+ and He+ can overcome the terrestrial gravitational potential to escape from the polar ionosphere due to a pressure gradient along open field line and that the O+ outflow is limited due to both its large mass and its loss by charge exchange with neutral H in the atmosphere (e.g., Axford, 1968; Banks and Holzer, 1968). 2. Science Target The UPI-TEX instrument provides global images of plasmas in the vicinity of the Earth by detecting He II (30.4 nm) emission scattered by He+ ions and O II (83.4 nm) emission by O+ ions. In recent studies, such as that of Matsui, it has been possible to determine the rate of ion leakage from the plasmasphere provided that the amount of plasma supplied directly from the ionosphere is not dominant.

Results

Conclusion