COMPASS-2 and VULKAN satellite system for the short-term earthquake warning

The beginning of the 21th century was marked by important transition - from discussions on the physical reality of the ionospheric precursors of earthquakes to the practical realization of the dedicated space projects for registration of these precursors from space. Up to now there are 3 space vehicles launched: COMPASS-1, Russia (December 2001), Quakesat, USA (June 2003), and DEMETER, France (June 2004). It was demonstrated that for the real-time monitoring of the short-term precursors in the ionosphere, it is not enough one satellite. That's why the Vulkan project was proposed - the constellation of small satellites on two altitude levels ~ 500 km, and ~ 1000 km. To check some ideas and technological developments the pre-system pilot project COMPASS-2 will be launched in the first half of 2005. the paper presents the physical background of the created satellite constellation, payload selection as a result of analysis of the previous satellite missions connected with the precursors registration, satellite orbit configuration, and the problems of the data assimilation, processing and interpretation.