HENON

The mission

Heliospheric Pioneer for Solar and Interplanetary Threats Defence (HENON) is an upcoming 12U XL CubeSat mission aimed at performing a demo of Space Weather measurements in Distant Retrograde Orbit (DRO) for 3-6 hour advanced warning of solar storms (sunward side). The mission will be a demo of deep space CubeSat technologies, also performing a transfer from Sun-Earth L1/L2 to DRO using electric propulsion.

Platform: 12U XL CubeSat.
Payloads: Energetic particle flux telescope (proto/electron/heavy ion), magnetometer on boom, Faraday Cup Analyzer.
Programme: General Support Technology Programme (GSTP).
Consortia: Argotec (prime), INAF, Uni. Calabria, Uni. Florence, SpaceDys, IMT, Mars Space, Imperial College, ASRO/Uni. Turku.

Mission description

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) is a stand-alone deep space CubeSat demonstrator mission targeting space weather observations from a Distant Retrograde Orbit (DRO) in the Sun-Earth system in order to enhance forecasting capabilities and science. Advances in Space Weather forecasting require longer advance warning times for solar storms coming from Coronal Mass Ejections (CMEs) and their resulting Solar Proton Events (SPEs). Today, advanced warning is provided by spacecraft located at Lagrange L1 point between the Sun and Earth, and in the 2030s by Vigil at L5. By exploiting measurements on the sunward side of the DRO (at ~0.1 AU from Earth), which has never been explored before, the HENON 12U XL CubeSat will enable a significant improvement in the advance warning time and hence forecasting of major solar events compared to spacecraft at Sun-Earth L1. It will also provide complementary observations to those acquired at L5. In the future, following a successful HENON mission, a fleet of 4-5 CubeSats equally spaced in the DRO could provide continuous measurements on the sunward side. 

The HENON spacecraft will be equipped with a payload suite consisting of state-of-the-art, miniaturised space weather instrumentation tailored for measuring the physical quantities relevant for monitoring, warnings and modelling, in order to detect heliospheric disturbances several hours in advance of arrival at Earth when located in the upstream portion of the orbit. In addition, measurements in the leading and trailing parts of the DRO can be used to enhance space weather modelling. The selected payload enables the following observations which are considered to be relevant for near real-time space weather monitoring for operational applications: 

• solar energetic particles; 
• heliospheric plasma; 
• interplanetary magnetic field. 

The IOD objective for the mission shall lead to the maturation of the critical technologies to high Technology Readiness Levels (TRL) such that they may be used in future operational missions with a lower risk. The objectives of the HENON mission are to: 

• demonstrate near real-time in-situ monitoring of the space environment in deep space for Space Weather forecasting tools and services; 
• demonstrate the provision of timely near real-time alerts with significantly increased warning times compared to L1 when upstream of the Earth; 
• operate a spacecraft in the unexplored DRO orbits for the first time; 
• demonstrate the reliable use of CubeSat technologies in deep space. 

After launch injection onto a near Earth escape trajectory (e.g. Sun-Earth Lagrange point 1 or 2) using a piggyback launch opportunity, the spacecraft reaches the DRO using its own onboard miniaturised electric propulsion system, and communicates with ESTRACK ground stations using an X-band transponder for TT&C. The low thrust transfer to the DRO takes around 14 months, followed by 12 months of space weather observations in the DRO. 

Mission status

Launch: Sun-Earth L2 transfer in Dec. 2026.
Status: PDR completed Nov. 2023, Phase C ongoing, CDR in June 2025.