<p>The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission is a CubeSat Space Weather mission, designed to operate in a Sun-Earth Distant Retrograde Orbit (DRO) at more than 10 million km from the Earth. HENON will embark payloads tailored for Space Weather (SWE) observations, i.e., a high-resolution energetic particle radiation monitor, a Faraday cup, and a magnetometer enabling it to provide quasi-real-time monitoring of the interplanetary conditions in deep space. HENON has many important goals, such as demonstrating CubeSat capabilities in deep space, including long-duration electric propulsion with periodic telemetry and command, and robust attitude control for deep-space operations. It will pave the way for a future fleet of spacecraft on DROs, providing continuous near real-time measurements for SWE forecasting. This paper focuses on the mission analysis performed for phase A/B, with the main goal of defining a baseline transfer trajectory to a heliocentric DRO in co-orbital motion with the Earth. The proposed transfer leverages a rideshare opportunity on a mission escaping Earth’s gravity field, most likely one headed toward the Sun–Earth L₂ region, and relies exclusively on on-board electric propulsion to reach deep space, making it a pioneering demonstration of this approach and the technology. Under appropriate assumptions on the electric propulsion system performances, s/c mass and propellant budget, it will be shown that the HENON target DRO can be reached in about 1 year, taking into account also periodic interruptions of thrusting to allow for Telemetry, Tracking and Command.</p>