S4ILS · Solar Sailing for Space Situational Awareness In the Lunar System

Solar Sailing for Space Situational Awareness In the Lunar System

The 21st of May 2010 saw the dawn of a new era in space propulsion when the Japanese Space Agency launched its IKAROS spacecraft. Twenty days into the mission, IKAROS unfurled a 14x14 m2 solar sail that would take the probe on a six-month voyage to Venus. A solar sail rides on sunlight the way that sailboats ride on the wind. Therefore, propelled solely by the solar photons reflecting off the 7.5 micrometer thin, highly reflective membrane, IKAROS was the first to demonstrate a notion that had been around for nearly a century: that spacecraft can be propelled through space by sunlight. Solar Sailing for Space Situational Awareness In the Lunar System (S4ILS) has exploited the potential of this new, elegant and truly exciting field of space propulsion. While it is often proposed as a propulsive means for missions around the Sun or in the Sun-Earth system, S4ILS has demonstrated its potential much closer to home, in the Earth-Moon system, opening up radically new possibilities in spaceflight. As an enabler of diverse products and services that are crucial to modern day society (navigation, communication, Earth observation), spaceflight is extremely vulnerable to threats from space objects and space weather events. Combining the potential of solar sailing and the need to keep ground and space assets safe from natural and man-made threats from space, the overall objective of the S4ILS project has been to deliver, for the first time, radically new solar sail periodic orbits in the Earth-Moon system and utilize these for the benefit of space situational awareness. Concrete results include a catalogue of new families of solar sail periodic orbits at the Lagrange points of the Earth-Moon system (e.g., Lyapunov orbits, halo orbits, vertical Lyapunov orbits, and so on) as well as radically new orbit families around Earth (e.g., “flower-shaped” and “clover-shaped” orbits). A constellation of two solar sail clover-shaped orbits can provide unprecedented capabilities for space weather observations as they enable a continuous view of the entire (Ant)Arctic region. As such, the constellation provides uninterrupted observations of the entire auroral oval and the direct response of the magnetosphere to changes in the solar wind. The view will also allow the detection and imaging of rarely observed phenomena such as transpolar arcs and cusp spots to further the understanding of the cause for and relation between these phenomena. By transferring the techniques developed for the Earth-Moon system to other dynamical systems, further new insights in the solar sail dynamics in proximity of, for example, asteroids and binary asteroids has been obtained. This has resulted in new vantage points from where to monitor these primordial rocks to better understand them for planetary defense purposes. For example, families of solar sail periodic orbits high above a binary asteroid pair have been designed to allow unique, previously unknown and geostationary-equivalent vantage points from where to monitor the asteroid(s) over extended periods of time.

Data: CORDIS, © European Union