Cassini's Last Days

[Clueless Morgan]

Thought y'all would appreciate this:
https://www.nytimes.com/2017/09/08/scien...ience&_r=0

It links to an article and a really cool 4-minute video which talks about the Cassini mission and the many many images that came back of Saturn's moons.

On September 15th, Cassini will dive into Saturn and burn up in its atmosphere so that it doesn't remain in orbit around Saturn and inadvertently crash onto Titan or Enceladus or any other moon which might have life and thereby contaminate it with Earth microbes which might have survived.

Good by, Cassini, you were worth every penny.



Here's to hoping we continue our exploration of the solar system and beyond.

[GUBU]

The bastard! It promised me back the €50 I lent it when it got back from its mission.

[vorlon13]

I'm pretty sad about it. Losing an old, dear friend.

[Anomalocaris]

This effort to avoid contaminating the moons of gas giants is pretty ridiculous.   If in the staggeringly unlikely event the earth microbes on the probes survive the trip there, through countless orbits through radiation belts before the probe finally impacts with a moon, the impact, and the conditions on the moon, and then establish a durable colony, I would say we were just given the very first long shot at ensuring some earthly life will survive the extinction of life on earth.

In 3-4 billion years, even before the sun becomes a red giant and eventually engulf the earth, what we deliver by accident to the gas giants may be the last remaining vestige of life from earth.

[vorlon13]

A more specific concern about that was the RTGs on Cassini. After an impact onto an icy surface, the RTG 'debris' will continue to radiate heat for thousands of years. In fact, since the RTGs were engineered to withstand a worst case launch failure scenario at Cape Kennedy, it is possible there would be somewhat intact, or 'less dispersed' RTG debris in a possibly aqueous environment. Additionally, the radiation dosage Cassini received at Saturn was far less than Galileo, for instance, received at Jupiter. Also, Cassini itself has numerous heaters throughout, and there are areas in it that have not been outside of a rather tolerable temperature environment since it's construction and launch.

So, the possibility of culturing live bio samples from Cassini even today is not a zero, and an impact onto an icy surface would not necessarily kill them, and the on board RTGs would continue to maintain a possibly benign environment for them for potentially thousands of years after such an impact.

And we (the US) has signed a treaty controlling disposition of such space flown hardware . . . .

[Clueless Morgan]

This effort to avoid contaminating the moons of gas giants is pretty ridiculous.   If in the staggeringly unlikely event the earth microbes on the probes survive the trip there, through countless orbits through radiation belts before the probe finally impacts with a moon, the impact, and the conditions on the moon, and then establish a durable colony, I would say we were just given the very first long shot at ensuring some earthly life will survive the extinction of life on earth.

In 3-4 billion years, even before the sun becomes a red giant and eventually engulf the earth, what we deliver by accident to the gas giants may be the last remaining vestige of life from earth.

Interesting thought...

[Anomalocaris]

A more specific concern about that was the RTGs on Cassini.  After an impact onto an icy surface, the RTG 'debris' will continue to radiate heat for thousands of years.  In fact, since the RTGs were engineered to withstand a worst case launch failure scenario at Cape Kennedy, it is possible there would be somewhat intact, or 'less dispersed' RTG debris in a possibly aqueous environment.  Additionally, the radiation dosage Cassini received at Saturn was far less than Galileo, for instance, received at Jupiter.  Also, Cassini itself has numerous heaters throughout, and there are areas in it that have not been outside of a rather tolerable temperature environment since it's construction and launch.

So, the possibility of culturing live bio samples from Cassini even today is not a zero, and an impact onto an icy surface would not necessarily kill them, and the on board RTGs would continue to maintain a possibly benign environment for them for potentially thousands of years after such an impact.

And we (the US) has signed a treaty controlling disposition of such space flown hardware . . . .

A construction designed to not be too shattered by an impact with the ground at terminal velocity in earth's atmosphere does not stand an RTG in good stead in the case of an impact at orbital speeds with a large solid body. There is an 2 order of magnitude difference in impact velocity and 4 order of magnitude difference in pact energy. If the RTG shatters any warmth the smitherines provide will be attended by lethal radiation. Even if the RTG were to survive more or less intact and melt a patch of ice and keep it liquid for thousands of years with its waste heat, that is still a very short period for microbes to evolve. Any microbe adopted to the pool heated by the RTG is unlikely to survive once RTG's heat output peters out.

Last but not least, we need a lifeboat for some life on earth! Damn it!

[vorlon13]

And let's consider the surface of Enceladus; thousands of years of essentially a 'snowlike' material accumulating in a weak gravitational field. IOWs if you were trying to find as benign a naturally occurring surface to plop Cassini into as there could be, there it is.

And don't scoff at how sturdy the fuel element containment is. They're extremely robust.

[ignoramus]

This effort to avoid contaminating the moons of gas giants is pretty ridiculous.   If in the staggeringly unlikely event the earth microbes on the probes survive the trip there, through countless orbits through radiation belts before the probe finally impacts with a moon, the impact, and the conditions on the moon, and then establish a durable colony, I would say we were just given the very first long shot at ensuring some earthly life will survive the extinction of life on earth.

In 3-4 billion years, even before the sun becomes a red giant and eventually engulf the earth, what we deliver by accident to the gas giants may be the last remaining vestige of life from earth.

Interesting thought...

How do you guys think we got here in the first place!
We are someone else's germs! We just grew legs and learnt to fling shit around, that's all.

[Fireball]

We come from Tardigrades