After 13 years of Cassini orbiting the planet, "Saturn continues to surprise us," Pitesky said.
Given their importance, data from the crossing are being sent to Earth twice, to make certain nothing is lost. It takes more than an hour for the signals to travel the approximately 1.6 billion kilometres between Saturn and Earth.
Twenty-one more crossings are planned - about one a week - before Cassini's fatal plunge in mid-September. The next one is Tuesday. Some of those passages will bring Cassini even closer to the planet as well as the innermost D ring. The gap between the rings and the top of Saturn's atmosphere is between 1,900 to 2,400 kilometres.
While risky, this 4 1/2-month grand finale is expected to yield a treasure trove of science. There's little to lose, even if the spacecraft is lost, given that its fuel tank is practically empty, according to NASA.
Cassini was launched in 1997 from Cape Canaveral, Florida, and reached Saturn in 2004.