I gotta say, Cassini has been a hell of a flagship mission for NASA. I'm gonna be sad to see it go, but the wealth of data returned is staggering. The understanding already gained and the new mysteries to solve are really exciting. And who can forget the first discovery of lakes and rivers on the surface of another world? And the first pictures of the surface of a world shrouded in clouds since Venera managed to beam a couple images back from Venus in the 1970s?

Some of the images are absolutely breathtaking. I consider Saturn, though named for a male deity, to be the queen of the solar system. Wide shots of the whole planet, flattened a little from its fast spin, rings in full glory and a whole host of attendant moons. The mysterious hexagonal polar vortex wreathed in swirling storms. Tethys hanging like a bauble with the rings and ring shadows in the background.

Here are a few: http://www.nbcnews.com/slideshow/greatest-hits-cassini-s-incredible-tour-saturn-n749311

Cassini will fall into Saturn's atmosphere and burn up on September 15. Before that happens, mission planners have Cassini doing a series of very close dives in between the planet and its rings. Expect another trove of fantastic images.

JPL has put out an animated short about Cassini's end. It's available up to 1440p - I suggest watching it in full screen.

https://www.youtube.com/watch?v=xrGAQCq9BMU

No doubt Cassini has been a resounding success! The data and images gathered are pure gold, and we've learned so much about Saturn and it's moons. Hopefully we will send another mission to Saturn's moons Enceladus and Titan that can detect life forms in the near future.

It should be a hell of an ending for that big old Cassini spacecraft, incredible to see it still operational after all this time.

I first became more aware of the mission via what passed for late night TV in the UK of the early 1990's, the Open University did a doc called 'Design For An Alien World', in 1992/3, where a group of nerdy young men, seemingly from central casting, at a UK university, were designing a lander for Titan, to be a major part of the ESA contribution to this US built and US launched orbiter. Problem was, what was Titan like? The Voyagers could not see through the clouds and were fly by's. Was the surface a vast ocean of hydrocarbons, or a frozen version, or something in between, maybe a thin crust that could support the small lander or maybe not. What if it lands in a hydrocarbon lake, if they exist, some data from Voyagers suggested hydrocarbons.

Then the instrument package, with severe weight and mass limits, plus all of the above problems, you might land OK but would any science return be possible with so many unknowns?
We know what happened in the end of course, Huygens made it, returned data and those eerie images, an add on to a far bigger, much wider ranging mission, still a relief after losing Beagle 2.
There's a full scale mock up of Huygens in the Science Museum in London, small as it is, fascinating to think the real one made the farthest landfall of any man made object to date, something that will remain for at least decades to come.

But Cassini's mission has if anything, put other Moons of Saturn nearer the top of the table for potential life forms, over Titan, though Saturn's biggest Moon is still there.
Enceladus is screaming for at least an orbiter better yet closely followed, if possible, by a lander, small scale spacecraft though.

Cassini is the last of it's kind, in size with associated cost - though the science return from such a long term and robust mission is the payback, advances in technology have driven down size, Cassini after all was conceived over 30 years ago, was launched nearly 20 years ago, when an i-phone would have seemed unlikely to be around a decade hence, when they started building Cassini mobile phones were more like bricks.

A good call by NASA/JPL to end the mission by combing a suitably spectacular end, good science right up to the last and making sure that Cassini could not one day compromise the search for life on those moons.
It will be interesting to see how the old bird does in the ring gap dives to come, useful data in any case, then of course the ultimate close up of the planet itself.

That's part of what's so amazing about this - Cassini really is very old tech by modern standards. The control computer is broadly comparable to an Intel 80286 (286) or so - a 16-bit processor with more advanced instructions than the 286, but capable of addressing less memory - a little over 2MB of RAM at a maximum with an add-on, or 128KB without! I crushed a microSD card smaller than a dime with 32,000 times the capacity between my fingers last week after it started failing and I couldn't overwrite my data. (And yes, I was pretty tripped out by doing so.)

We're certain to see missions to Enceladus, and of course there is a huge focus on Europa. I'm not sure where Titan will fit in given that detection of life "as we know it," if it exists on Titan, is likely not feasible with current technology and understanding. And it's quite clear that between Mars, Europa, and now Enceladus, the focus at NASA is on the search for life as we know it. That said, a Titan-specific mission would be a huge boon to planetary sciences and the understanding of how solar systems form. It is the only other world besides ours with a thick atmosphere and liquids on the surface. That alone makes it well worth the expense and effort, even though it is otherwise so very different.

To be honest, I really wish somebody would send at least a little orbiter to Uranus. It's so tantalizingly mysterious. But, it's not really on anybody's extended timeline or wish list at all, it seems. It is a strange planet though, and given its unusual orientation I'm sure we'd find quite a few mysteries to explore if we only looked.

treetreeseven wrote:

That's part of what's so amazing about this - Cassini really is very old tech by modern standards.

you only need the processing oompf for gaming and "windows waiting for user input faster".

Experiments on Cassini-Huygens were one of the first big ones to use AntiFuse FPGA based hardware. Quite the step forward to
provide more functionality on the hardware side. ( Same for Rosetta, slightly later in time. the MIRO preprocessor doing 2x8Bit @200MS into a
cyclic accumulator would not have been possible without.)

The end is nearby. Below is a graph showing the 22 orbits of Cassini’s Grand Finale. Then on September 15, Cassini will make one final slingshot dive right into Saturn.

The closest approach to Saturn during these passes will be between about 1,010 and 1,060 miles (1,630 and 1,710 kilometers) above Saturn's cloud tops.

Cassini-Huygens by the numbers:

treetreeseven wrote:

JPL has put out an animated short about Cassini's end. It's available up to 1440p - I suggest watching it in full screen.

https://www.youtube.com/watch?v=xrGAQCq9BMU

An excellent video, well worth watching.


Tugg

So rather than crash her into the rings they crash her onto the planet, hoping that all will burn up and no fragments hit the surface, how do we know the effect of earth microbes or whatever material the ship picked up in transit?
I am not an environment geek, but I think the rings would be a better resting place, how about trying to park her in the rings and let her die there, she may continue to transmit for years to come...

par13del wrote:

So rather than crash her into the rings they crash her onto the planet, hoping that all will burn up and no fragments hit the surface, how do we know the effect of earth microbes or whatever material the ship picked up in transit?

Atmospheric heating on entry will kill anything on the surface of the probe and quite quickly the pressure and heat inside Saturn will crush the spacecraft and melt the remains.

par13del wrote:

I am not an environment geek, but I think the rings would be a better resting place, how about trying to park her in the rings and let her die there, she may continue to transmit for years to come...

She doesn't have the fuel to "park" in a stationary orbit. Plus once she is in the rings she'll be subject to constant impacts which will degrade any remaining usable life.

par13del wrote:

So rather than crash her into the rings they crash her onto the planet, hoping that all will burn up and no fragments hit the surface, how do we know the effect of earth microbes or whatever material the ship picked up in transit?
I am not an environment geek, but I think the rings would be a better resting place, how about trying to park her in the rings and let her die there, she may continue to transmit for years to come...

First, even if parked in orbit with the rings, there is no guarantee that sometime int he future it might not become dislodged and impact something that it can affect (remote possibility yes but they are wanting remove all possibility).
Second, Saturn has no "surface" to impact, anything solid is at the core (of which next to nothing is known) which is some 37,000 miles (60,000 km) below the visible cloud surface we see from earth. And the temp there is estimated 12,000 kelvin and at 13 million Earth atmospheres, not much life is likely to exist there

Any fragments that survive atmospheric incineration will not survive much beyond.

Tugg

par13del wrote:

I think the rings would be a better resting place, how about trying to park her in the rings and let her die there, she may continue to transmit for years to come...

Not got the fuel for that, or the control.
Also,can't run the risk of collision and therefore contamination: in particular, the contamination of where there may be the possibility of life as we understand it, Titan.
Burn up and complete disintegration by ploughing into the gas giant Saturn IS the 'environmental thing' to do.

It has to go. Come the day the sun swells up, moons like Titan and Enceladus will be almost tropical compared to today's bitterly cold wasteland. There may already be the precursors of life there (in fact that's been more or less confirmed by analysing the hydrocarbons there) and we as a species should not be harming or contaminating that with whatever Cassini is carrying.

It's a bet on the deep future, basically. Futurists have speculated that Titan could develop ammonia-breathers as indigenous life. Humans should have vacated the neighbourhood by then.

They're probably more worried about Enceladus since it could support water-based biochemistry right now, let alone in the future.

It's almost time to say goodbye. Cassini was without a doubt a grand mission, some of the best photos are truly stunning, and I hate when people overuse that word in reference to images. But it's hard to see a good shot with two or three moons hanging above the rings like baubles and not be moved on some level.

treetreeseven wrote:

They're probably more worried about Enceladus since it could support water-based biochemistry right now, let alone in the future.

It's almost time to say goodbye. Cassini was without a doubt a grand mission, some of the best photos are truly stunning, and I hate when people overuse that word in reference to images. But it's hard to see a good shot with two or three moons hanging above the rings like baubles and not be moved on some level.

For me the most intriguing imagery were those taken of the rings and some of the perturbation patterns therein:
https://www.google.com/search?q=cassini ... s&tbm=isch

Less than 8 hrs to go:
https://saturn.jpl.nasa.gov/mission/sat ... ssini-now/


Tugg

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

77west wrote:

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

Good Bye!
we first met at the cradle, me bringing some "toys".

Cassini's impact on Earth isn't over yet. Our voyages into space are such an inspiration - it's gratifying when years of careful planning and teamwork widen our horizons. Though I'm sad our presence in Saturn's orbit has come to an end, for now. Hard to let such a historical vehicle go.



https://www.universetoday.com/wp-conten ... 01/691.jpg

The wavemaker moon, Daphnis, is featured in this view, taken as NASA’s Cassini spacecraft made one of its ring-grazing passes over the outer edges of Saturn’s rings on Jan. 16, 2017. This is the closest view of the small moon obtained yet. Daphnis is 5 miles or 8 kilometers across.
Credit: NASA/JPL-Caltech/Space Science Institute
Source: https://www.universetoday.com/133129/un ... th-spiral/

77west wrote:

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

It didn't burn as there is no oxygen at Saturn. Cassini simply disintegrated.

KarelXWB wrote:

77west wrote:

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

It didn't burn as there is no oxygen at Saturn. Cassini simply disintegrated.

To my understanding it was frictional based disintegration and the friction created significant heat, in the thousands of degrees range. So while most think of "burn" in the earth sense, which it did not do due to the lack of oxygen, it did "burn" in the frictional heating till vaporization and disintegration sense.

Semantics and scientific definitions aside, Cassini will be missed, she did an amazing job for so many years.

Tugg

KarelXWB wrote:

77west wrote:

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

It didn't burn as there is no oxygen at Saturn. Cassini simply disintegrated.

While I don't really think it did burn, fire does not require oxygen, it just requires an oxydizer. But I don't think anything in Saturn's atmosphere would be suitable oxidizer.

Best regards
Thomas

tommy1808 wrote:

While I don't really think it did burn, fire does not require oxygen, it just requires an oxydizer. But I don't think anything in Saturn's atmosphere would be suitable oxidizer.

Not really: 75% Hydrogen, 25% Helium, all under remarkable pressure.
https://en.wikipedia.org/wiki/Aluminium_hydride
No idea if the environment fits to "go there".

Though I don't think Cassini survived beyond a couple of millibars.

A classic and pioneering mission, nice article here about some of those involved over all those years, interesting how close Cassini came to being axed, the international aspect to it helping to prevent this, as well as enabling that amazing landing on Titan. One part of the mission still there, by far the most distant landfall of a human object. Hopefully Cassini's work at Encaledus might see a mission there in the not too distant future to match Huygens.

http://www.bbc.co.uk/news/resources/idt ... ens_saturn

For those arguing over whether Cassini burnt or not.
Although colloquially known as 'burn up', the intense heat generated by the friction with Saturn's atmosphere, vaporised Cassini.

ChrisKen wrote:

For those arguing over whether Cassini burnt or not.
Although colloquially known as 'burn up', the intense heat generated by the friction with Saturn's atmosphere, vaporised Cassini.

Now here's a fun question: How long will it take a surviving piece to reach the solid core? 37,000miles beneath the cloud tops! (Of course I don't think anything it was built with can survive 21,000F temps!)

Tugg

ChrisKen wrote:

For those arguing over whether Cassini burnt or not.
Although colloquially known as 'burn up', the intense heat generated by the friction with Saturn's atmosphere, vaporised Cassini.

Burn or not burn? On https://saturn.jpl.nasa.gov/mission/gra ... /overview/ NASA writes: "Cassini will burn up and disintegrate like a meteor". NASA may be wrong on this one, but then there is so much else about Cassini which they got right.

It hit the Saturn upper atmosphere at a speed of 68,000 mph or 110,000 km/h. That is four times faster than an Earth satellite. So yes, it vaporized.

KarelXWB wrote:

77west wrote:

And she is gone. About 15 minutes ago Cassini burned up in Saturn's atmosphere. What a craft... time to rest now after 20 years of work.

It didn't burn as there is no oxygen at Saturn. Cassini simply disintegrated.

As per the comment above, it burned up, according to NASA. Obviously not "burn" in the sense of burning in an Oxygen environment. It heated up and was effectively vaporised.

A BBC documentary on the mission last night featured many of those who had operated and designed Cassini, one lady, an Engineer at JPL with program for decades, during the final plunge used the term 'burning up'.
And she seemed OK with that.