Cassini has crashed into Saturn | Hacker News Reader

Cassini has crashed into Saturn

washingtonpost.com

69 points_128 comments

Final Images ( choose Grand Finale )

https://saturn.jpl.nasa.gov/galleries/images/

I wonder if it got destroyed or just lost the signal due to the atmosphere.

Amazing times to live.

Incredible. It's easy to forget that it's not so long ago that our not-too-distant ancestors looked up at the sky and noticed that these stars wandered in the sky a little bit differently from the others. What they would have thought if they'd have known that we would be sending probes to these places and sending images home.

we've probably seeded it now with bacteria from earth.

That's why they crashed it into Saturn, to avoid possibly infecting the moons which might have life

What about huygens ? was it entirely free of "polluants" ?

I think the fear was more about contaminating Enceladus where liquid water is known to exist than Titan where it does not.

Cassini is plutonium powered, which is the main problem.

So they weren't concerned about organic but radioactive spoiling ? I guess organic and simple material would degrade in Saturn condition anyway ..

That's actually an interesting question - are there layers of Saturn's atmosphere where Earth-borne bacteria could survive? Someplace where the temperature and pressure are capable of supporting life, and where there might be some nutrients for them to feed on?

Well if there are any tardigrades on board they'd probably be able to survive:

> Individual species of tardigrades can survive extreme conditions that would be rapidly fatal to nearly all other known life forms, including complete global mass extinction events due to astrophysical events, such as supernovae, gamma-ray bursts, large asteroid impacts, or passing-by stars. Some tardigrades can withstand temperatures down to 1 K (−458 °F; −272 °C) (close to absolute zero) while others can withstand 420 K (300 °F; 150 °C) for several minutes, pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. They can go without food or water for more than 30 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce.

From Wikipedia: https://en.wikipedia.org/wiki/Tardigrade

They'd survive for a while but in the end they'd have to live off something, what would they live off on Saturn?

A more likely candidate would be Saturn's largest moon, Titan, which contains ammonia, a number of complex chemicals, and possibly water.

I remember reading that the Mars rover went through "planetary protection" which is basically a decontamination process. I wonder if a similar thing happened here and how thorough this process is.

Could bacteria survive for 20 years in space?

After 20 years hungry tardigrada should have eaten them all.

Not to "relevant XKCD" the situation, but yes. TLDR is that bacteria die at a rate of about 30% every 6 years, so after 30 years there's still 16% of the original bacteria left.

https://what-if.xkcd.com/117/

That is pretty incredible I have to say. Amazing how tough bacteria are even in the extremes of deep space.

Not sure if a fireball trailing through another planet's atmosphere leaves much behind.

One of the theories of the origin of life on Earth is that it was seeded here by Martian rocks that originated from that planet when struck by other rocks. So, it's not totally implausible, although less so here since Saturn's atmosphere doesn't really stop.

That's not a theory, that's someone injecting creation myth into science.

It violates Occam's Razor badly.

It is less plausible than life just starting on earth.

There is no good reason for adding the complexity of starting elsewhere, surviving being blasted off planetary surface, surviving long enough to reach earth, somehow reaching earth, surviving reentry, surviving alien conditions on earth, and somehow thriving... while the original source died off and/or cannot be found, if talking about Mars.

It is miraculous thinking, and has no place alongside more reasonable ideas.

Better Saturn than Enceladus. That was the point of the exercise.

I assume it would just be with tardigrades, but can they even survive / thrive on Saturn?

The probe burned with very high temperature, not sure any organic chemical can survive.

Let the new experiement begin.

Earlier discussion:

https://news.ycombinator.com/item?id=15256418

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