Do some meteorites come from interstellar space?

We review observational evidence that suggests that a small percentage (<2%) of incoming meteors are in hyperbolic orbits, and that the percentage increases with decreasing mass. Considering random stellar motions in the solar neighbourhood, interstellar meteors would be expected to arrive at earth with geocentric velocities ranging from about 21 to 78 km/s. Classical meteorite theory precludes meteorite survival above about 28 km/s geocentric velocity, and ablate most of the mass even for velocities in the low twenties. Hence while interstellar meteorites are possible, there would be strong biases against them. The case has been argued that the Pultusk (1868) meteorite has a well determined hyperbolic orbit. However, this is based on visual observations, and leads to other conclusions regarding the trajectory which seem unreasonable, and we discount this claim. Micrometeorite (or more precisely ablation product) survival is also a strong function of entry velocity, with very little residual mass survival for velocities above 40 km/s. It is unlikely that interstellar material would be represented in the interplanetary dust particle (IDP) collections, and even cometary origin IDPs are strongly discriminated against. Radiation pressure from sun like stars is effective in ejecting meteoroids of radius 0.4 μm and smaller. Conversely, particles of this size can be slowed upon entry, and could survive. It is unclear whether these small particles are part of existing IDP collections, but they should be strongly favoured.