I read an article on CNN today about the New Horizons Probe that is nearing Jupiter on its way to Pluto. What caught my eye was the following line:

“NASA’s New Horizons, the fastest spacecraft ever built by humans, is due to reach Jupiter, our solar system’s largest planet and fifth from the sun, after a 13-month journey from Earth, flying almost half a billion miles.”

Is it necessary to qualify that the spacecraft was built by humans? Have we been testing non-human spacecraft? Or are they refering to feline spacecraft?