The European Space Agency (ESA) is making significant progress on Henon, its upcoming technological mission that aims to set a milestone in space exploration. This will be the first CubeSat to independently travel into deep space, communicate directly with Earth, and perform autonomous maneuvers to reach its final orbit around the Sun.
With a size comparable to carry-on luggage, the small satellite will test technologies that could enhance early warnings of solar storms by as much as six hours in advance. Henon, which stands for Heliospheric Pioneer for Solar and Interplanetary Threats Defence, is designed as a demonstrator for cutting-edge technologies in the small satellite segment.
The mission will take Henon as far as 24 million kilometers from Earth, significantly surpassing the conventional boundary of 2 million kilometers that defines deep space. Although other ESA missions, such as Juventas and Milani, part of the Hera program, will travel beyond this limit, Henon will stand out for doing so without relying on a mother ship.
While Juventas and Milani will transmit their data through Hera, Henon will communicate directly with ESA”s Estrack network using a miniaturized deep space transponder currently in development. “Henon will enable us to establish a direct communication link with our network,” explained Roger Walker, head of the ESA”s CubeSat technology program.
Henon”s pioneering nature also extends to its propulsion system. It will incorporate a next-generation electric propulsion system, featuring a miniaturized ion engine powered by the satellite”s own solar panels and propelled by charged xenon atoms. This innovation will allow significant maneuvers to position the spacecraft in its final orbit, a first for a CubeSat. Walker noted that “once proven, this technology will pave the way for future low-cost missions to the Moon, asteroids, and even Mars.”
The mission”s primary contractor, Argotec, recently completed the detailed design phase of the satellite, successfully passing the Critical Design Review (CDR), a crucial technical milestone for the project. Davide Monferrini, director of the Henon program at Argotec, emphasized the importance of this achievement, stating that “this milestone is the result of extraordinary teamwork and validates a truly innovative configuration integrating three payloads and multiple miniaturized subsystems, including our Curie Power Suite, the advanced power conditioning and distribution unit that acts as Henon”s “electric heart”.”
Having surpassed this review, the team is preparing for the next phase: functional validation using a FlatSat, a prototype test bench where the satellite”s electronic components will be connected and tested on a table. Simultaneously, a structural model will be constructed and subjected to vibration, vacuum, radiation, and extreme temperature tests to ensure its durability in the deep space environment.
The launch of Henon is scheduled for late 2026 as a secondary payload aboard a larger mission. From its initial insertion point at Lagrange 2 of the Sun-Earth system, located 1.5 million kilometers from our planet, the CubeSat will use its electric propulsion to move into a distant retrograde orbit around the Sun.
This trajectory, conceptualized in 1969 by French astronomer Michel Henon, inspired the mission”s name and represents another historic “first”: Henon will be the first spacecraft to fly in this type of orbit, which is more elliptical than Earth”s and varies in distance from 12 to 24 million kilometers from our planet. From our perspective, its movement will appear to describe an ellipse around Earth, though it will actually be orbiting the Sun.
The Henon mission is being developed under ESA”s General Support Technology Programme (GSTP), which promotes in-orbit validation of new technologies. The dual objective here is to demonstrate the technical feasibility of an autonomous deep-space CubeSat and, at the same time, generate direct benefits for space monitoring.
Thanks to its advantageous position on the solar side of the distant retrograde orbit, Henon will test miniaturized instruments capable of detecting solar emissions that herald magnetic storms. “We will be able to confirm the arrival of a solar storm between three and six hours before it reaches Earth, compared to current warnings that are limited to 15 to 60 minutes,” Walker explained.
Juha-Pekka Luntama, head of the ESA”s Space Weather Office, highlighted the operational potential of the project: “Demonstrating this capability with Henon will move us closer to a future constellation of small satellites in retrograde orbit, capable of providing continuous monitoring of solar storms. This will give operators of critical infrastructure, such as terrestrial power grids, ten times more time to implement mitigation measures and prevent damage.”
Henon represents a synthesis of multiple advancements in miniaturization, autonomy, and energy efficiency. Its ability to communicate directly with Earth, navigate independently, and operate in such extreme conditions marks a qualitative leap in the use of CubeSats, which have traditionally been limited to low Earth orbits. If the mission meets its objectives, the ESA will have demonstrated not only the maturity of a new type of platform for deep space exploration, but also a more flexible and cost-effective model for future scientific and observational missions. With its small size and disproportionate ambition, Henon embodies a new era in European space engineering: that of small satellites with significant capabilities, ready to venture further than ever imagined.
