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Serious / In two weeks, the Cassini Spaceprobe will burn up over Saturn
« on: September 01, 2017, 05:52:37 PM »
YouTube
Unless you've been absent since April, this has been going around newsfeeds and the internet at large that the Cassini spaceprobe (as part of the Cassini-Huygens probes) is soon to end it's mission in a blaze of glory by hitting Saturn's upper atmosphere at ~110,000km/h (or ~120,000km relative to Saturn's centre). It was launched in 1997 and completed it's original mission objectives by 2008, and has since been on two extended missions since that lasted until about now. Cassini's Grand Finale mission began in April 26th this year, when its orbit around Saturn took it between the gas giant and the rings, making it smaller and more elliptical. That is, until it takes its 22nd and final orbit, its periapsis will take it into the atmosphere, causing it to tumble and burn up.
A brief overview of the Cassini-Huygens mission:
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(Source: Science Overview)
Before Cassini, we had only brief glimpses of the discoveries awaiting us at Saturn. Pioneer 11 and Voyagers 1 and 2 conducted flybys decades ago, taking pictures, measurements and observations as they zoomed past. These missions shed new light on Saturn’s complicated ring system, discovered new moons and made the first measurements of Saturn’s magnetosphere. But these quick encounters didn’t allow time for more extensive scientific research.
Cassini changed all that. It began the first in-depth, up-close study of Saturn and its system of rings and moons in 2004. It became the first spacecraft to orbit Saturn, beginning a mission that yielded troves of new insights over more than a decade. The Saturnian system proved to be rich ground for exploration and discoveries, and Cassini's science findings changed the course of future planetary exploration.
"We're looking at a string of remarkable discoveries -- about Saturn's magnificent rings, its amazing moons, its dynamic magnetosphere and Titan's surface and atmosphere," said Linda Spilker, Cassini's project scientist. "Some of the mission highlights so far include discovering that Titan has Earth-like processes and that the small moon Enceladus has a hot-spot at its southern pole, plus jets on the surface that spew out ice crystals, and liquid water beneath its surface."
Studying Saturn’s Many Moons
Some of the most surprising scientific findings have come from encounters with Saturn’s fascinating, dynamic moons. Cassini's observations of Saturn's largest moon, Titan, have given scientists a glimpse of what Earth might have been like before life evolved. They now believe Titan possesses many parallels to Earth, including lakes, rivers, channels, dunes, rain, clouds, mountains and possibly volcanoes.
The data from the Cassini spacecraft and the European Space Agency's Huygens probe, which plunged through Titan's dense, smoggy atmosphere to land on its surface in 2005, have generated hundreds of scientific articles and been the subject of special issues of the world’s most important scientific journals.
Enceladus, too, proved to be a rich source of discovery. The spray of icy particles from the surface jets forms a towering plume three times taller than the width of Enceladus itself. Cassini confirmed that the plume feeds particles into Saturn's most expansive ring, the E ring. The spacecraft has come as close as 15 miles (25 kilometers) from the moon's icy surface during its investigation, revealing the presence of a global subsurface ocean that might have conditions suitable for life.
Extending the Mission
The Cassini mission has seen two mission extensions, allowing for more flybys, investigations and measurements, over a longer span of time. When its initial four-year tour of the Saturn system was complete in 2008, the Cassini-Huygens saga had brought a new dimension of understanding to the complex and diverse Saturn system.
The two-year Cassini Equinox Mission brought continued excitement. During that first extended mission, the spacecraft made 60 additional orbits of Saturn, 26 flybys of Titan, seven of Enceladus, and one each of Dione, Rhea and Helene. The Equinox mission allowed for observations of Saturn's rings as the sun lit them edge-on, revealing a host of never-before-seen insights into the rings' structure.
Since 2010, the spacecraft has conducted a second, seven-year-long, extended mission called the Cassini Solstice Mission. This final mission will conclude with a phase known as The Grand Finale -- 22 deep dives between Saturn's cloud tops and innermost ring before it plunges into the giant planet's atmosphere.
First and last (most recent) viable images taken by Cassini
Taken: Feb. 20, 2004 1:11 AM
Received: Feb. 22, 2004 12:42 AM
The camera was pointing toward DIONE, and the image was taken using the CL1 and CL2 filters.
(Saturn centred)
Taken: Feb. 20, 2004 2:59 AM
Received: Feb. 22, 2004 1:06 AM
The camera was pointing toward SATURN, and the image was taken using the CL1 and MT2 filters.
Taken: Aug. 31, 2017 2:50 PM
Received: Sep. 1, 2017 4:41 AM
The camera was pointing toward SATURN, and the image was taken using the MT2 and CL2 filters.
As of now, it's <700,000 km/<400,000 mi from Saturn, travelling at ~28,700 kmph/~17,800 mph relative to Saturn, and will cross the rings of Saturn for the final time in 14 hours and 20 minutes.
Since the original video release in April I've been using stills of the video above for my desktop, and was awaiting some form of NASA livestream to "watch" it - sure there'd be nothing more than a diagram of it's trajectory until it blipped off the proverbial radar and stopped transmitting data, but it was something at least. However, plans got in the way and now it's unlikely I'll be keeping up to date until a few weeks later. So I thought hey, why not make a thread on the thing.
There's not really a point of discussion here, so I'll leave you with this from the FAQ;
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FAQ
Was it always planned that Cassini would end its mission by plunging into Saturn, or did this decision come about recently?
The preferred end-of-mission plan for Cassini has always been to safely dispose of the spacecraft in the upper atmosphere of Saturn. The exact “when” and “how” of the mission’s conclusion has evolved over the years as the scientifically productive mission has been granted three extensions by NASA. The current “Grand Finale” scenario – to send the spacecraft on a series of orbits between the planet and its rings -- has been part of the mission plan since 2010 and was developed in detail over the past four years.
Could microbes really have survived onboard Cassini for this long in space? Is this truly a concern that influenced the decision to deorbit into Saturn?
Based upon exposure experiments on the Space Station, it is known that some microbes and microbial spores from Earth are able to survive many years in the space environment– even with no air or water, and minimal protection from radiation. Therefore, NASA has chosen to dispose of the spacecraft in Saturn’s atmosphere in order to avoid the possibility that viable microbes from Cassini could potentially contaminate Saturn’s moons at some time in the future.
Why is it safe to dispose of a spacecraft by burning it up in Saturn’s atmosphere? Are we polluting Saturn? What about the possibility of life there?
Disposing of Cassini in Saturn’s atmosphere is safe. The spacecraft will enter Saturn’s atmosphere at high speed and will burn up like a meteor. Any spacecraft material that survives atmospheric entry, potentially including its radioisotope fuel, will sink deep into the planet where it will melt and become completely diluted as it mixes with the hot, high-pressure atmosphere of the giant planet. Saturn’s atmosphere does not have conditions that would be favorable to life as we know it, according to evaluations by the Committee on Space Research of the International Council for Science.
With the "Grand Finale" being planned to prevent the risk of microbial contamination from Earth to potential moons orbiting Saturn, do you think we should have more regulations on space-waste like this? Even missions like the rovers on Mars with what knowledge we have today have that risk we may have to consider in future, whereas missions like Rosetta on the 67P Comet don't matter if you slam a probe into it.
