NASA is getting ready to launch a probe that will ultimately make it out to Pluto. This new mission, called New Horizons, will take some seven years to reach its destination to the ninth planet in our solar system (last year a tenth planet was discovered well past Pluto's orbit). What many people do not realize is that, for years and numerous missions (six Apollo missions and 19 others, including more recent missions to Mars and the 1997 Cassini mission to Saturn), NASA has had up to 80 pounds of plutonium and other radioactive elements on probes that serve as power sources and to help keep the spacecraft warm. The New Horizons probe will have 24 pounds inside special casing at launch time. Of course, the main risk is that there could be an explosion at launch time (tomorrow) that will dissipate plutonium, one of the mroe deadly materials known to humans, into the atmosphere, where it could spread over some number of square miles of land.
NASA and the Department of Energy estimate the odds of this happening at 1 in 350 chances. The White House had to approve the mission because of this potential threat. The estimated threat to humans living within 60 miles of the launch site, which is Cape Canaveral in Florida, is minimal, with a worst-case scenario of some individuals ingesting an amount of radiation that is at 80% of what we take in naturally from background radiation in one year's worth of time. At each launch are teams of experts trained to handle nuclear accidents in the environment and for public safety issues. Good luck to NASA for this latest mission which, in addition to studying Pluto, will study the Kuiper Belt outside of Pluto's orbit. This is a region with numerous icy bodies that become comets when they enter the solar system.