Solar System Studies with LEM

Soft X-ray emission lines provide a unique probe of the physics of planets and comets in our solar system. At 1 eV resolution, individual charge exchange lines from both comets and the upper planetary atmosphere of Mars can be isolated. These identify, in exquisite detail, charge exchange lines and their broadening which identify varying particle populations, velocities and therefore the underlying physical processes. At this resolution, Jupiter is a fundamental atomic physics and plasma physics laboratory. Lines from the local hot bubble reveal both the large-scale structure of the heliosphere and that of the ISM, providing prototypes for other systems. Lines below 400 eV allow us to test our models of fundamental physics. The LEM probe will provide impeccable spectral resolution from 0.2 -2.0 keV to explore this science.