It's been just under 20 years since NASA's Cassini spacecraft left Earth for its mission to Saturn - but in just a few days, it will undertake its Grand Finale, intentionally plummeting into Saturn's atmosphere to be pressurized into oblivion.
Each fly-by provided a gravitational "kick" that boosted Cassini's speed to more than 42,500mph and helped the probe on its way.
When it launched, Cassini-Huygens was the biggest, most complex interplanetary spacecraft ever flown. "The haze has cleared remarkably as the summer solstice has approached", Cassini Project Scientist Linda Spilker said in a news conference September 13. The spectrometer will attempt to investigate what material is from the rings and what material is part of the atmosphere. Navigators will also be analyzing this information in the hopes of confirming that Cassini is precisely on track and ready to plunge into Saturn at the designated time, location, and altitude.
The Cassini spacecraft was launched from Cape Canaveral in October 1997 and then spent seven years in transit to Saturn. Eastern Time for the spacecraft, but given the time it takes for the signal to reach Earth, we will receive those last bits of data just before 8 a.m. - long after Cassini is "gone". "It will radiate across the solar system for almost an hour and a half after Cassini itself has gone", Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory, said in a statement.
Saturn is something of a solar system unto itself (minus the requisite sun).
NASA has confirmed that the Cassini spacecraft successfully completed its final flyby of the moon Titan and is now on course for its fatal encounter with Saturn on Friday.
What kind of mission will actually follow up on the curiosities Cassini has piqued?
One of NASA's most successful missions the study of Saturn is coming to an end on Friday.
The UVIS has already fostered "scores of dazzling discoveries" - including a salty, subterranean ocean on one of Saturn's moons which scientists think may have conditions favorable for primitive life.
Cassini is being driven into Saturn's atmosphere to ensure that the probe doesn't contaminate the moons Titan and Enceladus - both of which may be capable of supporting life - with microbes from Earth. For the scientists who began working on the project in the 1980s, it is the end of decades of work culminating in scientific progress and never-before-seen images of Saturn's rings, moons and surface.
Cassini was the NASA-developed Saturn orbiter, and Huygens was the European-built probe that sat on-board, which would eventually descend on to the surface of Saturn's biggest moon, Titan.
Scientists plan to collect data from the spacecraft's instruments until the very end of the mission.
On the eve of its final descent, other instruments will make detailed observations of Saturn's aurora borealis, temperatures and polar storms.
The last hours of Cassini's mission could provide valuable data to answer some of researchers' most persistent questions: How was Saturn formed, does it have a solid core, and how long is a Saturnian day? Four years became thirteen, as Cassini continuously exceeded expectations and NASA kept discovering new tasks for the probe.
No trace of Cassini is expected to escape Saturn's gravity field. After nearly 20 years in space, 13 of which at Saturn, Cassini will not even leave a mark in the planet's clouds - it will simply go silent and fade away.