Cassini to perform death-plunge soon, NASA reminisces about the epic journey – Watch video

Image courtesy: NASA/JPL-Caltech

New Delhi: Ever since its launch 20 years ago in 1997, NASA's Cassini spacecraft has never failed to deliver what was expected of it.

Cassini's aim of investigating Saturn is truly a fruitful one, owing to all the amazingly informative insights into the evolution and structure of the ringed planet.

Through its adept photography abilities, the spacecraft has also sent back stunning images of Saturn, which have also helped divulge numerous secrets of the planet and its moons.

The 20-year-old spacecraft has been investigating the ringed planet for 13 years and it's finally time for NASA to say goodbye.

On September 15, 2017, Cassini will end its service and make a death-plunge into Saturn's atmosphere. Its mission-ending dive is a foregone conlclusion – an April 22 gravitational kick from Saturn's moon Titan placed the two-and-a-half ton vehicle on its path for impending destruction.

However, the spacecraft's last few days in Saturn's orbit will be lined with several mission milestones to prepare the vehicle for one last burst of trailblazing science.

"The Cassini mission has been packed full of scientific firsts, and our unique planetary revelations will continue to the very end of the mission as Cassini becomes Saturn’s first planetary probe, sampling Saturn's atmosphere up until the last second," said Linda Spilker, Cassini project scientist from NASA's Jet Propulsion Laboratory in Pasadena, California. "We'll be sending data in near real time as we rush headlong into the atmosphere – it's truly a first-of-its-kind event at Saturn."

Looking back at Cassini's epic journey and what it has achieved in all these years, the mission team at NASA/ESA have released a video showing a combination of animations and actual imagery returned over the course of the mission.

Check it out below:

According to NASA, the spacecraft is expected to lose radio contact with Earth within about one to two minutes after beginning its descent into Saturn's upper atmosphere. But on the way down, before contact is lost, eight of Cassini's 12 science instruments will be operating.

In particular, the spacecraft's ion and neutral mass spectrometer (INMS), which will be directly sampling the atmosphere's composition, potentially returning insights into the giant planet's formation and evolution.

On the day before the plunge, other Cassini instruments will make detailed, high-resolution observations of Saturn's auroras, temperature, and the vortices at the planet's poles. Cassini's imaging camera will be off during this final descent, having taken a last look at the Saturn system the previous day (September 14).

In its final week, Cassini will pass several milestones en route to its science-rich Saturn plunge. (Times below are predicted and may change slightly.)

September 9 – Cassini will make the last of 22 passes between Saturn itself and its rings -- closest approach is 1,044 miles (1,680 kilometers) above the clouds tops.

September 11 – Cassini will make a distant flyby of Saturn's largest moon, Titan. Even though the spacecraft will be at 73,974 miles (119,049 kilometers) away, the gravitational influence of the moon will slow down the spacecraft slightly as it speeds past. A few days later, instead of passing through the outermost fringes of Saturn's atmosphere, Cassini will dive in too deep to survive the friction and heating.

September 14 – Cassini's imaging cameras take their last look around the Saturn system, sending back pictures of moons Titan and Enceladus, the hexagon-shaped jet stream around the planet's north pole, and features in the rings.

September 14 (5:45 p.m. EDT / 2:45 p.m. PDT) – Cassini turns its antenna to point at Earth, begins a communications link that will continue until end of mission, and sends back its final images and other data collected along the way.

September 15 (4:37 a.m. EDT / 1:37 a.m. PDT) – The "final plunge" begins. The spacecraft starts a 5-minute roll to position INMS for optimal sampling of the atmosphere, transmitting data in near real time from now to end of mission.

September 15 (7:53 a.m. EDT / 4:53 a.m. PDT) – Cassini enters Saturn's atmosphere. Its thrusters fire at 10 percent of their capacity to maintain directional stability, enabling the spacecraft's high-gain antenna to remain pointed at Earth and allowing continued transmission of data.

September 15 (7:54 a.m. EDT / 4:54 a.m. PDT) – Cassini's thrusters are at 100 percent of capacity. Atmospheric forces overwhelm the thrusters' capacity to maintain control of the spacecraft's orientation, and the high-gain antenna loses its lock on Earth. At this moment, expected to occur about 940 miles (1,510 kilometers) above Saturn's cloud tops, communication from the spacecraft will cease, and Cassini's mission of exploration will have concluded. The spacecraft will break up like a meteor moments later.

(Video courtesy: NASA Jet Propulsion Laboratory)