NASA’s Cassini spacecraft set off for Saturn roughly two decades ago and has spent the last 13 years exploring the ringed planet and some of its many moons. On Friday, it is slated to put an end to both its mission and itself.

NASA’s Cassini spacecraft set off for Saturn roughly two decades ago and has spent the last 13 years exploring the ringed planet and some of its many moons.
The agency notes, in that time, "[Cassini] expended almost every bit of the rocket propellant it carried," and, on Friday, is slated to put an end to both its mission and itself. 
“The spacecraft will make its final approach to the giant planet Saturn. But this encounter will be like no other," according to NASA. "This time, Cassini will dive into the planet's atmosphere, sending science data for as long as its small thrusters can keep the spacecraft's antenna pointed at Earth. Soon after, Cassini will burn up and disintegrate like a meteor.” 
The decision to retire the spacecraft in such a dramatic fashion is said to be in the interest of future exploration.
“[The] two moons of Saturn, Enceladus and Titan, have captured news headlines over the past decade as Cassini data revealed their potential to contain habitable – or at least ‘prebiotic’ – environments,” NASA notes.
“In order to avoid the unlikely possibility of Cassini someday colliding with one of these moons, NASA has chosen to safely dispose of the spacecraft in the atmosphere of Saturn," the agency continues. "This will ensure that Cassini cannot contaminate any future studies of habitability and potential life on those moons.” 
While the spacecraft will be gone, its collection of data about the ringed planet will leave scientists with a wealth of information to examine. 
NASA, the European Space Agency, and the Italian Space Agency are all involved in the Cassini mission.