There is another mechanism for the recent astronomical production of strange matter. As mentioned above, non-strange quark matter is unstable at zero external pressure. However, it is only unstable by a few 10's of MeV. Pressures at the cores of neutron stars may be sufficient to overcome this instability. As soon as this quark core exists, it will become favorable to lower the energy by changing some of the light quarks to strange quarks. At the same time, the quark matter core of the star can grow by absorbing neutrons, since there is then no coulomb barrier to overcome. The entire neutron star will soon become strange quark matter.
Strangelets could then be created from collisions between these strange `neutron' stars. Numerical simulations of head-on collisions of neutrons stars suggest that as much as 13% of the total mass of the system might be ejected. These potentially relativistic strangelets would eventually be impingent upon the Earth's atmosphere. Even if such collisions are rare, binary systems may eject some mass during mass transfer, or in the decay of the binary system. I will examine attempts to detect such astronomical sources of strangelets in the next sections.