The classical three-body system (e.g. Earth-Moon-satellite) generates five equilibrium solutions (the Lagrange points) where a satellite is stationary with respect to both celestial bodies. Natural periodic orbits can be found around these Lagrange points. By complementing the dynamics with a solar sail, the S4ILS project has found radically new families of orbits around the Lagrange points of the Earth-Moon system. These have been catalogued, using (where possible) the same terminology/denomination as used in the classical system. As such, “solar sail-versions” of, for example, Lyapunov orbits, halo orbits, vertical Lyapunov orbits, and so on, have been generated. But also some radically new orbit families have been produced, including “out-of-plane flower-shaped” orbits and “clover-shaped” orbits.
In terms of space situational awareness (SSA) applications, especially the clover-shaped orbits appear highly suitable. For example, a constellation of two mirrored clover-shaped orbits has been shown to provide almost uninterrupted coverage of the Arctic region to observe space weather events and, in particular, the auroral oval, which gives insight into the effect of space weather on the geosphere. In addition, all techniques developed for the Earth-Moon system have been translated to (binary) asteroid systems to create unique, previously unforeseen vantage points from where to monitor such asteroids over extended periods of time. Improving our knowledge on (binary) asteroid systems will increase our understanding of these primordial rocks, which will be vital for planetary defense purposes.
Besides the technical work on devising the above mentioned novel solar sail orbits and their applications for SSA, the dissemination of information to and communication activities with the research community and the general public have formed an integral part of the S4ILS project to maximize its impact. Examples of such knowledge transfer activities include colloquia, seminars, guest lectures, student supervision, participation in conferences, publications in peer-reviewed journals as well as the use of public websites such as the S4ILS page on the TU Delft website and dedicated pages on platforms such as ResearchGate and Facebook.
