DISCOVERER: Final results and outcomes

The DISCOVERER project commenced in 2017 with the aim to advance the development of key technologies to enable the commercially viable, sustained operation of satellites in very low Earth orbits (VLEO). Funded by the European Commission through Horizon 2020, the project ends this month. This paper presents an overview of the key achievements and current status of the project. The project set out to advance the development of, and demonstrate, several technologies with the long-term aim of enabling the commercial use of VLEO. These technologies include: 1. aerodynamic materials which encourage specular scattering of the incoming flow to minimise drag and increase the performance of aerodynamic surfaces in the highly rarefied flows experienced in VLEO 2. aerodynamic attitude control methods to compensate for the dynamic flow environment, especially lower in the VLEO altitude range 3. atmosphere breathing electric propulsion (ABEP), combining an optimised atmospheric intake with advanced RF Helicon-based plasma thruster, for drag compensation DISCOVERER’s test satellite, the Satellite for Orbital Aerodynamics Research or SOAR, was deployed from the International Space Station in June 2021 and re-entered the atmosphere in March 2022. The primary aim was to measure the induced drag and lift on different aerodynamic materials candidates in VLEO by exposing panels, coated in various novel and control materials, to the flow at different orientations whilst observing the induced attitude and orbit perturbations produced. Early analysis of the results from the mission shows promising results for the novel materials developed as part of the project. Parallel studies on the long-term survivability of these materials to the space environment have been on-going through exposure tests on the exterior of the International Space Station through the MISSE programme. The project has also been developing a ground-based facility, the Rarefied Orbital Aerodynamics Research facility, to characterise the gas surface interaction properties of materials to atomic oxygen at orbital velocities. Characterisation of the facility itself is on-going. In support of ABEP technology, the experimental development and characterisation of an RF Helicon-based plasma thruster has been on-going, along with detailed computational modelling of aerodynamic intakes. Whilst the thruster has already been operated, current work focusses on the characterisation of its performance. Finally, work to place these technological developments into context has also been progressed. On overview of the overall achievements in this area is provided, including business modelling of the VLEO market ecosystem, which identifies the enormous market potential for VLEO missions. Peer Reviewed Article signat per 30 autors: Peter C.E. Roberts, Nicholas H. Crisp, Steve Edmondson, Antonio Arcos, Georg H. Herdrich, Jonathan Skalden, Silvia Rodriguez-Donaire, Daniel Garcia-Almiñana, Alejandro Macario-Rojas, Katharine L. Smith, Ciara Mcgrath, Sarah J. Haigh, Vitor T.A. Oiko, Brandon E.A. Holmes, Luciana A. Sinpetru, Virginia Hanessian, Simon Christensen, Thomas Kauffman Jensen, Jens Nielsen, Morten Bisgaard, Francesco Romano, Stefanos Fasoulas, Constantin Traub, Konstantinos Papvramidis, Miquel Sureda, Dhiren Kataria, Badia Belkouchi, Alexis Conte, Simon Seminari, Rachel Villain