Cassini made its last closest approach to Titan on September 11 at 12:04 p.m. PDT, at an altitude of 73,974 miles (119,049 kilometers) above the moon’s surface, causing the spacecraft to slingshot into its final approach to Saturn – but not before it would send final images from Titan to Earth, eagerly awaited by scientists, including McEwen. And so Cassini and its traveling companion, the Huygens lander, actually provided the first hard look at Saturn, its rings and moons. According to NASA, no spacecraft has ever ventured so close to the planet before. In particular, the spacecraft’s ion and neutral mass spectrometer, which will be directly sampling the atmosphere’s composition, will potentially offer insights into the giant planet’s formation and evolution, according to NASA.
Advertisement
Its mission complete, the probe is low on fuel – and will perish as it is pulled towards the ringed planet.
Cassini’s final chapter began with its last Titan flyby, on Monday (Sept. 11), which gave the probe the nudge it needed to head toward Saturn.
This will likely happen around 6:30 a.m. Now, we reflect on Cassini’s many triumphs, and stand vigil to witness the spacecraft’s last moments, pushing the boundaries of what engineering can do one final time.
It will be possible, but hard, to observe Cassini’s death from Earth, due to the spacecraft’s small size and the position of Saturn in the sky.
From orbit, Cassini has provided researchers with such a wealth of data that its mission was extended twice, first for the northern hemisphere’s spring equinox in 2010 and then for the summer solstice in 2017. It arrived six years later, having navigated the risky asteroid-belt that lies between us and Saturn, but with only basic instrumentation on board it wasn’t able to gather much scientific data.
A high-point of the mission came in January 2005 when Huygens dropped through the dense hydrocarbon atmosphere of Saturn’s largest moon Titan, and touched down on a pebble-strewn surface with the consistency of wet sand.
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. The final dive on Friday is a dramatic conclusion to this unique, long and scientifically valuable goodbye.
Because Saturn is so far from Earth, Cassini will have been gone for about 83 minutes by the time its final signal reaches NASA’s Deep Space Network station in Australia on September 15.
During its parachute descent the probe captured images of features that looked like shore lines and river systems on Earth.
If you’d like to follow along with Cassini’s Grand Finale, there are a few things you can do. A year on Saturn equals almost 30 Earth years.
Cassini was launched in 1997 and arrived at Saturn seven years later.
Cassini discovered six moons – some barely a mile or two across – as well as swarms of moonlets that are still part of Saturn’s rings. Cassini has collected 450,000 images using a visible light camera. We learned there are 3-D structures in the rings. The huge outer “E” ring forms from the icy plumes that spray from the unexpectedly active Enceladus.
Future engineers will borrow that trick to explore Jupiter’s moon Europa with the Clipper mission, which is planned to launch in the 2020s.
Jim Green, director of NASA’s planetary science division, told reporters that NASA is studying proposals that were submitted to the New Frontiers competition for a new planetary science mission.
Advertisement
Even though Huygens had already landed on Enceladus, Nasa did not want to risk contaminating the pristine environments with Earth bugs.
