After 20 years of flying through space, 13 of which were spent orbiting around Saturn and its moons, Cassini, a space probe launched by NASA, the European Space Agency, and the Italian Space Agency in 1997, is finally going to meet its demise by flying into, and disintegrating in, the ringed beauty's atmosphere. Like TARS from Interstellar, Cassini will continue to send back data to scientists until the very last moments before its destabilization and eventual vaporization, helping to enrich our lives as its own comes to an end. Tomorrow.
NASA says that the willful annihilation of Cassini in Saturn's atmosphere is necessary because the probe is nearly out of fuel, and that if left adrift, it could crash into one of Saturn's moons, leading to contamination. The concern is that there could be stowaway microbes inside Cassini, which found their way aboard the probe here on Earth. And because the inside of Cassini is warm — it has a radioisotope thermoelectric generator (RTG) like the one Mark Watney uses to keep warm in The Martian — it's possible that these microbes are still alive. A lifeless plunge into Enceladus, Titan, or another Saturnian moon could then taint future science done on those tantalizing worlds. We don't want to introduce foreign organisms to an environment that may already contain alien life.
Discovering that Enceladus may be a viable home for alien organisms -- the moon has liquid water, a source of internal heat, and key chemical ingredients in its oceans -- was one of the crowning discoveries of the Cassini mission, which delivered a treasure trove of scientific data, as well as a seemingly endless catalog of jaw-dropping photographs. According to NASA, Cassini has delivered roughly 453,000 images of Saturn and its moons (a handful of which you can find in the image gallery below), discovered two oceans on Titan and Enceladus, and discovered six moons. Cassini has also been the direct source for about 4,000 scientific papers.
The probe also gave us our first look at the rocky surface of Titan, when the Huygens lander that was piggybacking on the space probe successfully jettisoned itself and landed on the Saturnian moon. Not only was Huygens able to reveal a plethora of surface and atmospheric details from Titan, it also stood, and still stands, as the most distant landing of any spacecraft in history.
From the beginning, Cassini has given us one incredible image or discovery after another, starting with the images of Earth, Venus and Jupiter that it first captured while it was using the three planets for gravitational boosts on its 1.2 billion-mile journey to Saturn. The final few months of the probe's mission, dubbed the "Grand Finale" by NASA, have been no different, as it was sent on an orbital trajectory between Saturn and its rings. It flew in and out of this region 22 times in as many weeks, giving us new measurements of the rings' mass and also determining that the space between the rings and Saturn is indeed empty. (This part of the mission was saved for last because it was possible this wasn't the case, and Cassini would've been destroyed by rocks or ice.)
After its two Grand Finale orbits, Cassini will be pushed onto its final trajectory toward Saturn's atmosphere, a process that's visualized in the clip above. During the final two orbits, Cassini will take one last series of images of Saturn, some of its moons, and a moonlet (a small moon) that could soon depart from Saturn's rings, before collecting its final bits of data before destruction. But this has all been a part of plan that's been worked out for some time now, and Earl Maize, the Cassini project manager, summed up the thinking well when he said that "Cassini's own discoveries were its demise."
During its final descent into Saturn's atmosphere, which NASA engineers have dubbed the "goodbye kiss," Cassini will position itself to immediately relay all the data it's collecting back to Earth, as opposed to storing it for eventual transfer as it usually would. The data will also be brand new, as Cassini will be using its Neutral Mass Spectrometer, or INMS, to "sniff" out the chemical composition of Saturn's atmosphere, and also collect other data with its dozen on-board scientific instruments.
As for future missions, unfortunately, this is likely the last time we'll see a space probe headed for Saturn for at least a generation. There is plenty to get excited about regarding exploration beyond low earth orbit, the Moon, and Mars however, as NASA should be launching its Europa Clipper mission sometime in the early 2020s. While the Europa Clipper probe is headed for Europa (duh), a moon orbiting Jupiter that has similar energetic water plumes bursting from its surface. Yes, there may be alien life there too.
Cassini is set for destruction on September 15th. You can watch NASA coverage of the event from 7 to 8:30 a.m. EDT here.
What do you think about this Cassini Grand Finale? Does this seem like a fitting end to the space probe's 20-year journey? Let us know your thoughts in the comments below!
Images: NASA Jet Propulsion Laboratory
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