Using a Solar Sail for a Plasma Storm Early Warning System

It has been already established that geomagnetic storms can provoke a lot of trouble near the Earth, such as the loss of spacecraft or the degradation of GPS signal and even on the ground with the collapse of electricity distribution systems. High energy protons could even be lethal to astronauts performing extravehicular activity. Accurate predictions of such events can be made by monitoring the upcoming solar wind. Such detection can be provided by magnetometers and particle detectors on spacecraft located between the Sun and the Earth. The L1 Lagrangian point of the Sun-Earth system, which is lying at a distance of 1.5 million of kilometers upstream from the Earth, offers a very appreciable opportunity to detect storm triggering conditions about one hour before the corresponding solar wind reaches the Earth. Nevertheless, it would be very useful to extend the horizon of this space weather prediction by placing the detection system farther away from the Earth. This can be done through the utilization of a solar sail facing the Sun: the light radiation pressure would act oppositely to the gravitational attraction of the Sun, enabling to achieve an orbit period identical to the Earth's one but closer to the Sun. It is possible, for instance, to double the warning delay by using a solar sail with an area to mass ratio of 45 (for instance 6400 square meters for less than two hundred kilograms), placed at a distance of 3 million kilometers from the Earth and always facing the Sun. The requested performances to maintain such an orbit are obtainable by using state of the art technologies. In the paper, after reminding the basics of solar sailing and space environment monitoring, the principles of the proposed system are depicted and a mission scenario together with a description of the instrumental payload are proposed. Finally, preliminary mass and link budgets are presented.