Project Icarus: A Review of Local Interstellar Medium Properties of
  Relevance for Space Missions to the Nearest Stars
  I review those properties of the interstellar medium within 15 light-years of
the Sun which will be relevant for the planning of future rapid ($v /ge 0.1c$)
interstellar space missions to the nearest stars. As the detailed properties of
the local interstellar medium (LISM) may only become apparent after
interstellar probes have been able to make in situ measurements, the first such
probes will have to be designed conservatively with respect to what can be
learned about the LISM from the immediate environment of the Solar System. It
follows that studies of interstellar vehicles should assume the lowest
plausible density when considering braking devices which rely on transferring
momentum from the vehicle to the surrounding medium, but the highest plausible
densities when considering possible damage caused by impact of the vehicle with
interstellar material. Some suggestions for working values of these parameters
are provided. This paper is a submission of the Project Icarus Study Group.
