ESA GNC Conference Papers Repository
Assisted Reentry for All-Electric LEO Spacecraft
There have historically been only two strategies to choose from when designing a deorbiting capability for future LEO missions: controlled reentry requires a very large deorbit boost and thus a powerful propulsion system, while uncontrolled reentry is only allowed for small satellites that (almost) entirely burn up when reentering. Assisted Natural Reentry (or assisted reentry for short) intends to fill the continuum between these two extremes, thus offering more design flexibility to comply with the 1/10,000 rule in terms of ground risk. The main rationale is that if the orbital plane can be phased correctly with the Earth and the distribution of potential reentry locations can be confined to at most a couple of revolutions, the vast majority of reentries will occur above oceans, reducing the casualty risk by an order of magnitude with respect to uncontrolled reentry. We present the design and performances of an assisted reentry strategy tailored for an all-electrical LEO satellite, i.e. one with a very low thrust/mass ratio which only allows quasi-static perigee lowering and offers minimal control authority. We demonstrate with extensive simulation campaigns that despite high uncertainty in aerodynamic and atmospheric models and large density swings due to unpredicted changes in solar activity, the final dispersion can be kept within 2 orbits of the nominal reentry location, reducing casualty risk by a factor >5.