This is still possible, by the way. Humanity hasn't lost the ability to create simple computers. :) We just see less of them because the complex ones are more useful for day-to-day life.

Shortly before Cassini was launched there were some people on my college campus protesting the mission on grounds of risk of radioactive debris spreading if the launch failed. Motivated by my distaste for fearmongering, I did some reading and found that nearly all the scholarly research and engineering studies suggested the risk was infinitesimal, and in a worst case scenario the spread of dangerous concentrations of radiation would be highly localized.

Aside: Bill Nye (himself a trained engineer) also uses his position as Executive Director of The Planetary Society to advocate for the use of nuclear power generators in deep space missions.