Space telescopes, interstellar probes and directed panspermia

Giant telescopes in interplanetary space can measure the distances, velocities, and atmospheric composition of extrasolar planets. Such telescopes can very dramatically reduce the cost of unpeopled interstellar missions much as ground based astronomy has reduced the cost of interplanetary exploration. A long (not less than 100,000 km) linear accelerator located in interplanetary space can accurately propel pods containing trillions of living spores into interstellar space. Together the telescopes and the accelerator should make it possible to hit all interesting planets within a 100 light year radius of the sun. If, as is often argued, there are numerous long-lived technical civilizations in the Milky Way galaxy, then life on earth may well have originated elsewhere.