Elfen

Currently there are no measurements of heavy ions by upstream solar wind monitors, typically placed at the Lagrange 1 or 5 positions, nor in the inner magnetosphere. The influence of these ions, therefore, is unmeasured, unmonitored, and unquantified. The solar wind primarily consists of electrons and protons, although a small percentage will be an ion of an element that is largely or entirely stripped of its outer electrons. Due to the mass density of these ions, collectively, they may have a large impact on the Earth’s magnetosphere. The additional dynamic pressure they impose may result in a significant Earthward shift of the magnetopause boundary with implications for the understanding of space weather. The dayside solar wind charge exchange interaction that results in X-ray emissions to be imaged by upcoming missions such as SMILE is underpinned by the dynamic solar wind composition. In addition, competing processes of ion outflow and in flow in the inner magnetosphere is badly constrained. Furthermore, heavy ions can be used to trace particle entry into the nightside magnetosphere so that competing theories to the formation of the low-latitude plasma sheet can be distinguished.

Elfen is a novel mission that will constrain the influence of heavy ions on the dayside of the magnetosphere, as well as the mechanism that feed the formation and evolution of the nightside low-latitude plasma sheet. The current mission solution is to fly a 16U CubeSat in a low-latitude circular orbit at 12 Earth radii (RE) with a science payload of two instruments. The first instrument is a plasma spectrometer (the Triple Fast Imaging Plasma Spectrometer, T-FIPS) that will measure the heavy ion composition for ions such as C6+ and O7+, the second a magnetometer (MAGIC) to measure the contemporaneous in situ magnetic field providing knowledge of magnetic regimes and boundaries. T-FIPS, led by University of Michigan, has evolved from the FIPS instrument flown on the MESSENGER spacecraft. MAGIC, built by Imperial College London, has flight heritage on CubeSats such as CINEMA and the ESA’s RadCube mission.

At SPL, we have undertaken Concurrent Design Facility studies to significantly mature the mission profile and engineering subsystems. Our team has involved early career engineers, several second-year engineering undergraduates, and post graduate students, with oversee from senior engineers and academics. We have worked closely with The Meridian Space Command, who is co-located at SPL, with further consultancy from SystemLevel Ltd. We have recently completed a 12-month UKSA Bilateral-funded project and we work towards building a structural thermal model of the spacecraft. The spacecraft structure has been provided by EnduroSat, Bulgaria, who are also supporting the platform design. The MAGIC magnetometer has involved development of a CubeSat compatible boom, developed by Oxford Space Systems, and supplied to Imperial College London for testing as a key part of the bilateral project. T-FIPS continues development and testing in Michigan with financial support in the US. Two members of the team recently visited University of Michigan to gain a deeper understanding of T-FIPS and to discuss science projects related to Elfen’s goals with solar wind and Solar System experts.

One challenge is to achieve our desired orbit at a distance of a least 12 RE from the Earth. Elfen needs to orbit at this distance to be able to sample either the pristine solar wind or shocked magnetosheath plasma on the dayside of the Earth, and then it will sample the plasma sheet on the nightside. The incoming solar wind and interplanetary magnetic field causes dynamic changes and reconfigurations of the Earth’s magnetosphere, but the substructures under consideration are large, hence this orbit offers an excellent science duty cycle for the mission. Elfen has provoked conversations and early designs for an Electric Transfer Vehicle (ETV) with Th Meridian Space Command and Pulsar Fusion, a UK company that provides propulsion for space applications. The ETV as designed in its current configuration could take rideshare payloads from Low Earth Orbit to lunar orbit insertion.

Pulsar recently invited a delegation from SPL to attend the Space-Comm Expo held at ExCeL, London in March 2025. SPL engineers displayed at 3D model of the Elfen spacecraft and ETV, plus demonstrated an Augmented Reality/Virtual Reality simulation with a headset which proved popular with attendees. The event provoked useful discussions for the Elfen team and a fantastic opportunity for the junior members to speak to attendees and celebrate their work during the exhibition. The Elfen team also has promoted the mission at a variety of scientific meeting and conferences.