91-year-old namesake

The spacecraft is the only NASA probe in history to be named after a living person－in this case, 91-year-old solar physicist Eugene Parker, who first described the solar wind in 1958.

Parker said last week that he was "impressed" by the Parker Solar Probe, calling it "a very complex machine".

"I really have to turn from biting my nails in getting it launched, to thinking about all the interesting things which I don't know yet and which will be made clear, I assume, over the next five or six or seven years," Parker said on NASA TV.