The Canadian Enhanced Polar Outflow Probe (e-POP) mission in ILWS Andrew W. Yau a, * , H. Gordon James b , William Liu c a University of Calgary, Department of Physics and Astronomy, Institute for Space Research, 2500 University Dr NW, Calgary, Alta., Canada T2N1N4 b Communications Research Centre, 3701 Carling Ave, Ottawa, Ont., Canada K2H 8S2 c Canadian Space Agency, 6767 route de l ÕAe ´roport, Longueuil, Que., Canada J3Y 8Y9 Received 19 July 2004; received in revised form 13 January 2005; accepted 21 January 2005 Abstract The Enhanced Polar Outflow Probe (e-POP) small satellite mission will be CanadaÕs first mission contribution to the Interna- tional Living with a Star (ILWS) initiative. The e-POP project comprises three important and interconnected components: a small-satellite component to investigate atmospheric and plasma flows and related wave-particle interaction processes in the topside ionosphere, a coordinated ground-based and a theoretical assimilation component. Its scientific objectives are to quantify the micro- scale characteristics of plasma outflow and related micro- and meso-scale plasma processes in the polar ionosphere, explore the occurrence morphology of neutral escape in the upper atmosphere, and study the effects of auroral currents on plasma outflow and those of plasma microstructures on radio propagation. The escape of plasma from the polar ionosphere – its acceleration and subsequent transport towards the magnetosphere – is one of the most important processes in the Ionosphere–Thermo- sphere–Magnetosphere system. The e-POP science payload will carry a suite of 8 science instruments (experiments), including imag- ing plasma and neutral particle sensors, magnetometers, radio wave receivers, dual-frequency GPS receivers, CCD cameras, and a beacon transmitter. The imaging plasma sensors will measure particle distributions and the magnetometers will measure field- aligned currents on the time scale of 10-ms and spatial scale of 100 m. The neutral mass and velocity spectrometer will measure the density and velocity of major atmospheric species. The CCD cameras will perform auroral imaging on the time scale of 100-ms. The radio wave and GPS receivers will perform near real-time imaging studies of the ionosphere, in conjunction with ground-based radars, as will the beacon transmitter, in conjunction with ground receiving stations. The e-POP payload is scheduled for launch in 2007 as part of the Canadian CASSIOPE multi-purpose small satellite, and will be placed in a low-altitude, elliptical polar orbit (80° inclination, 325 km perigee, and 1500 km apogee). It will utilize the Ka band telemetry downlink on the companion communications technology demonstration payload onboard, to transmit the large volume (up to 15 gigabytes/day) of high-resolution science data to ground at a maximum telemetry rate exceeding 300 megabits/s. Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Outflow; Radio propogation; Small satellites; Magnetosphere–ionosphere interactions; Ionosphere–thermosphere 1. Introduction In this paper, we describe the scientific objectives and planned investigations of the Canadian Enhanced Polar Outflow Probe (e-POP) small satellite mission, in the context of the International Living with a Star (ILWS) program. The e-POP will be CanadaÕs first mission contribution to the ILWS initiative. It will be a part of the multi-pur- pose Canadian CASSIOPE small satellite mission, which will also carry a companion CASCADEe communications technology demonstration payload 0273-1177/$30 Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2005.01.058 * Corresponding author. Tel.: +1 403 220 8825; fax: +1 403 220 3616. E-mail addresses: yau@phys.ucalgary.ca (A.W. Yau), gordon. james@crc.ca (H.G. James), william.liu@space.gc.ca (W. Liu). www.elsevier.com/locate/asr Advances in Space Research 38 (2006) 1870–1877