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Cassini's Saturn Mission Goes Out In A Blaze Of Glory (npr.org)

Posted by msmash on from the incredible-run dept.

An anonymous reader shares a report: Controllers at NASA's Jet Propulsion Laboratory sent a final command Friday morning to the Cassini spacecraft orbiting Saturn. Not long after, accounting for the vast distance the message traveled, the order was received, putting the craft into a suicidal swan dive, plummeting into the ringed planet's atmosphere. Flight Director Julie Webster called "loss of signal" at about 7:55 a.m. ET, followed by Project Manager Earl Maize announcing "end of mission" as the spacecraft began to break up in Saturn's atmosphere. "Congratulations to you all," Maize announced to applause. "It's been an incredible mission, incredible spacecraft, and you're all an incredible team." With Cassini running on empty and no gas station for about a billion miles, NASA decided to go out Thelma & Louise-style. But rather than careen into a canyon, the plucky probe took a final plunge into the object of its obsession. Just how obsessed? Its 13-year mission to explore the strange world of Saturn went on nearly a decade longer than planned. It completed 293 orbits of the planet, snapped 400,000 photos, collected 600 gigabytes of data, discovered at least seven new moons, descending into the famed rings and sent its Huygens lander to a successful 2005 touchdown on the surface of yet another moon, Titan. Also read: Cassini's Best Discoveries of Saturn and Its Moons.

74 comments

  1. RIP by gerrythegreat · · Score: 5, Insightful

    RIP Cassini you done good stuff for them science folk.

    1. Re:RIP by stealth_finger · · Score: 1

      Cassini is dead, long live Cassini

      --
      Wanna buy a shirt?
      https://www.redbubble.com/people/stealthfinger/shop?asc=u
    2. Re: RIP by gerf · · Score: 1

      I would like to know how much oxygen you breathe. And the cost benefit ratio of your existence to the universe.

    3. Re: RIP by Anonymous Coward · · Score: 0

      I'm guessing it's pretty low...

    4. Re: RIP by Anonymous Coward · · Score: 0

      I win the game of spot the science hater.

    5. Re: RIP by Anonymous Coward · · Score: 0

      Oh, go take a selfie, would ya?!

    6. Re: RIP by Waffle+Iron · · Score: 1

      Maybe not everything in this world always has to be about "Jobs". Maybe you could learn to live a little.

    7. Re: RIP by Anonymous Coward · · Score: 4, Informative

      Here you go: http://www.21stcentech.com/money-spent-nasa-not-waste/

      And this: https://www.sciencefriday.com/articles/meet-the-researchers-behind-the-cassini-mission/

      And from here: http://www.airspacemag.com/flight-today/team-cassini-180960062/

      "one of more than 5,000 people who have worked on the project over the years"

      Maybe next time do research on your own and get educated about the subject before you bitch about it.

    8. Re: RIP by Anonymous Coward · · Score: 1

      NASA has been a source for fundamental technology development for its entire existence. These technologies support industries that provide millions of jobs to Americans who work is every sector including medicine, information technology, communication and transportation.

      If you are trying to challenge the ideas of technology development and exploration, then kindly find yourself a nice tree to live in and a puddle of mud to drink, because that is were humans would be right now if regressive ideas like yours were controlling our fate.

    9. Re: RIP by TigerPlish · · Score: 0

      Ever been unemployed? Underemployed? It ain't easy.

        It's all about the jobs unless one is filthy rich and able to spend time and money doing worthwhile things that may or may not pay the rent and food.

      So yes, hurrah for all the science! things Cassini did, but also be cognizant of all the roofs it put over people's heads and how many mouths it fed, directly and indirectly.

      We need another impossible dream like apollo. Maybe direct similar energies and funds to cancer research.

      --
      The "Civilized World" jumped the shark ca. 1973.
    10. Re: RIP by Anonymous Coward · · Score: 1

      About $3.2 billion dollars worth over 30 years. So a little more than $100 million per year, on average. That's about the cost of one bombing mission to syria, which managed to destroy one airbase, per year.

    11. Re: RIP by Anonymous Coward · · Score: 1

      Yeah, I've been both. And you know what, I didn't spend my time looking for someone/something else to blame for my woes. I didn't become a bitter boy. That said, it's a total mind f*ck. But, I didn't lash out at to make myself feel better.

      Of course, I hold myself personally responsible for my actions and plan accordingly.

      You?

    12. Re: RIP by Anonymous Coward · · Score: 1

      You religious/luddite communists, and the things you think government should be doing, are hilarious.

      I realize that you had a stunning victory in the 2016 presidential election, comrade, and that's something we can't ignore. But do you really think America will roll over and play dead? We're totally going to bury you. By 2024 election everyone is going to realize that whatever commie runs on "jobs" is the guy that everyone needs to vote against. You're not going to kill technological/economic progress, you're not going to kill science, and you're not going to kill capitalism.

      Enjoy your Trump for now, but in the end, we'll win. Nobody is going to stay loyal to your promised poverty program, because once anyone tries poverty, they always want to go back to wealth. It's just a matter of time until people start voting their interests. Pretty much your only hope is to get rid of democracy. You might catch us with our pants down on that too, at first, but America will still end up burying you, because the right to bear arms shall not be infringed!

    13. Re:RIP by Anonymous Coward · · Score: 1

      Ooooh, a troll. I wanna play...

      Can you sat "Idiocracy"?

      I knew you could.

      And they say the movie industry doesn't reflect reality...

    14. Re: RIP by Anonymous Coward · · Score: 0

      Funny thing.
      I read a document called "Bootstrapping a global network infrastructure", that was written by a NASA staffer in the 90's (who later worked with me at Level(3) communications) and figured out how to apply it to my job.

      I have not been 'accidentally' unemployed for a significant amount of time since then.

    15. Re:RIP by Anonymous Coward · · Score: 0

      You do realize a large part of the cost for any mission that NASA does is salary paid, either direct to NASA employees or indirectly to contractors? O wait, you're just a troll, sorry to have fed you.

    16. Re: RIP by Anonymous Coward · · Score: 1

      ...Go.

      4chan.luser

    17. Re: RIP by MrKaos · · Score: 1

      Rather than pile on from that ivory tower, how about you tell me how many fucking US jobs this created. How many families were fed, how much production to the GDP was done, how any of this shit made any real sense at all other than to a few propeller heads. Go.

      I found a 2010 picture of the Cassini team and it looks like it created about 100 primary jobs related to the mission itself, I saw a later photo and there were a lot more people in the team. So at least 100 families were fed from STEM roles in the US. How is that bad, for the US or any other country for that matter.

      In terms of the GDP and propeller head it's much better that these skilled people were working for NASA and the product of their intellectual output can be utilized in the GDP, indirectly, instead of being unavailable through secret military or commercial contracts. Knowledge is the harvest from economies that generate surplus resources.

      It's true that it is easy to mod you out of existence however it's much better to dismantle the premise of your troll so that people see your rationale as the kind of regressive ignorance that prevents the whole human race from evolving. ANY spending on science and exploration is a win especially in the 21st century where knowledge is the new driver of economies.

      Perhaps that doesn't make a lot of sense to you, which is ok, because if you have to ask the question, you wouldn't understand the answer anyway.

      --
      My ism, it's full of beliefs.
  2. Cassini by tquasar · · Score: 2

    Some mission scientists were cheering and others crying when the final signal was lost, confirming the end of the craft and mission. It was launched in 1997! https://en.wikipedia.org/wiki/...

    1. Re:Cassini by magusxxx · · Score: 3, Funny

      And yet phones aren't expected to last past their year warranty. ;)

      --
      Care killed the cat, but satisfaction brought it back.
    2. Re:Cassini by Arnold+Reinhold · · Score: 4, Informative

      NASA-TV showed displays of the S-band and X-band carriers prior to loss of signal, sharp spikes above a noise background. The S-band signal faded out first, as the spacecraft began to lose pointing accuracy for its high gain antenna when the thrusters could no longer keep up with the atmospheric forces. The X-band signal persisted for a few more seconds (more antenna gain at the shorter wavelength, presumably) before it faded out, but then it reappeared briefly above the noise before going away forever. It was as if the spacecraft gave one last effort to stay in touch with home. A very sad moment.

    3. Re: Cassini by Anonymous Coward · · Score: 5, Informative

      You have it backwards. The upper display was x band. It faded first because the antenna has higer gain at the higher x band frequency, so the pointing is more critical. S band was on the bottom and faded a bit later because the dish has a wider beamwidth at 2 GHz than it does at 11 GHz.

    4. Re:Cassini by Tablizer · · Score: 1

      Can anyone by chance find a Youtube vid of those band screens during the dive?

      --
      Table-ized A.I.
    5. Re: Cassini by Arnold+Reinhold · · Score: 1

      Thanks for the correction.

    6. Re:Cassini by Anonymous Coward · · Score: 0

      Do not go gentle into that good night,
      Old age should burn and rave at close of day;
      Rage, rage against the dying of the light.

      Though wise men at their end know dark is right,
      Because their words had forked no lightning they
      Do not go gentle into that good night.

      Good men, the last wave by, crying how bright
      Their frail deeds might have danced in a green bay,
      Rage, rage against the dying of the light.

      Wild men who caught and sang the sun in flight,
      And learn, too late, they grieved it on its way,
      Do not go gentle into that good night.

      Grave men, near death, who see with blinding sight
      Blind eyes could blaze like meteors and be gay,
      Rage, rage against the dying of the light.

      And you, my father, there on the sad height,
      Curse, bless, me now with your fierce tears, I pray.
      Do not go gentle into that good night.
      Rage, rage against the dying of the light.

    7. Re:Cassini by fahrbot-bot · · Score: 1

      It was launched in 1997!

      And yet phones aren't expected to last past their year warranty. ;)

      Well... if the phone cost as mush as the spacecraft, it probably would. I'm guessing that cost was in the $1.4b "pre-launch dev" part. From Cassini–Huygens:

      The total cost of this scientific exploration mission was about US$3.26 billion, including $1.4 billion for pre-launch development, $704 million for mission operations, $54 million for tracking and $422 million for the launch vehicle.

      --
      It must have been something you assimilated. . . .
  3. Did it boldy go too? by RogueWarrior65 · · Score: 1

    I saw what you did there.

  4. Contamination by lazarus · · Score: 3, Interesting

    TFA states that plowing the craft into Saturn was necessary to prevent contamination of the moons, but the mission began with dropping a Huygens Lander on Titan.

    Seems like nobody has make the distinction between bacterial contamination and radioactive contamination. I suspect that the latter is actually the concern as the probe used an RTG for power and thus it was safest to de-orbit it into Saturn.

    RIP Cassini. Thanks for all the science.

    --
    I am not interested in articles about life extension advancements.
    1. Re: Contamination by Strider- · · Score: 4, Informative

      It was a worry over biological contamination. JPL (and NASA) have very specific protocols for planetary protection. Huygens went through some extreme decontamination prior to launch. Cassini, as an orbiting probe, not so much. Also, at launch we didn't know as much about the Saturn system and it's moons. The RTGs aren't really a concern, as they're not all that radioactive. Pu-238 is primarily an alpha emitter, and is mostly just toxic.

      --
      ...si hoc legere nimium eruditionis habes...
    2. Re:Contamination by Anonymous Coward · · Score: 0

      Huygens did not use an RTG. Just a short-lived battery

    3. Re:Contamination by MightyMartian · · Score: 0

      While it's possible there is life on Titan, it seems improbable; considering the extremely low temperatures. Titan has some of the conditions for life, but a lot of available free energy isn't one of them.

      --
      The world's burning. Moped Jesus spotted on I50. Details at 11.
    4. Re: Contamination by almitydave · · Score: 3, Informative

      It was a worry over biological contamination. JPL (and NASA) have very specific protocols for planetary protection. Huygens went through some extreme decontamination prior to launch. Cassini, as an orbiting probe, not so much. Also, at launch we didn't know as much about the Saturn system and it's moons.

      Specifically, we learned that Enceladus has a large subsurface ocean, at the bottom of which may lie hydrothermal vents. Since those on Earth are often teeming with life, we didn't want to risk contamination of Enceladus' oceans.

      --
      my, your, his/her/its, our, your, their
      I'm, you're, he's/she's/it's, we're, you're, they're
    5. Re:Contamination by UnknowingFool · · Score: 1

      Seems like nobody has make the distinction between bacterial contamination and radioactive contamination. I suspect that the latter is actually the concern as the probe used an RTG for power and thus it was safest to de-orbit it into Saturn.

      I'm pretty sure that because the Huygens lander was designed to land on the surface that NASA already made the distinction decades ago. Landing on the surface might introduce bacterial contamination and that's why most spacecraft are assembled in clean rooms.

      --
      Well, there's spam egg sausage and spam, that's not got much spam in it.
    6. Re:Contamination by SuiteSisterMary · · Score: 2

      The problem with statements like this is that every time we've pointed at somewhere on Earth and said 'That part is missing some essential Requirement for Life,' turns out we've been wrong.

      --
      Vintage computer games and RPG books available. Email me if you're interested.
    7. Re:Contamination by XXongo · · Score: 1

      While it's possible there is life on Titan, it seems improbable; considering the extremely low temperatures. Titan has some of the conditions for life, but a lot of available free energy isn't one of them.

      Titan almost certainly has a subsurface ocean, which could have hydrothermal energy, which on Earth life can use as an energy source. We don't know of exchange between the subsurface ocean and the surface, but there might be exchange of material. Therefore, even though it's unlikely, we don't want to contaminate the surface.

    8. Re:Contamination by Anonymous Coward · · Score: 0

      Titan has a sub-surface ocean, and is subject to gravitational forces from Saturn that apparently provide enough heat, along with ammonia acting as an anti-freeze, to keep the water liquid. So the sub-surface water is likely to be warmer than the 90 degrees Kelvin on the surface. Where there's a temperature delta, there is the potential for work, i.e., kinetic energy. So now it's a matter of defining how many zeros to the right of the decimal we can go and still have "a lot" of energy, particularly at the bacterial scale.

    9. Re:Contamination by Anonymous Coward · · Score: 0

      The RTG from the Apollo 13 LEM is still intact at the bottom of the Pacific ocean, which demonstrates how strong the casing is that it survived re-entry. Huygens didn't have one, but Cassini had three. There's a chance they all survived the spacecraft break-up to make to the delicate surface of Saturn, there to sink towards the hot, metallic hydrogen core until they disintegrate from the intense heat and pressure.

    10. Re: Contamination by Anonymous Coward · · Score: 0

      It was a worry over biological contamination. JPL (and NASA) have very specific protocols for planetary protection. Huygens went through some extreme decontamination prior to launch. Cassini, as an orbiting probe, not so much. Also, at launch we didn't know as much about the Saturn system and it's moons.

      Specifically, we learned that Enceladus has a large subsurface ocean, at the bottom of which may lie hydrothermal vents. Since those on Earth are often teeming with life, we didn't want to risk contamination of Enceladus' oceans.

      Really, they didn't want the Enceladusians to capture our technology.

    11. Re: Contamination by Anonymous Coward · · Score: 0

      It was a worry over biological contamination. JPL (and NASA) have very specific protocols for planetary protection. Huygens went through some extreme decontamination prior to launch. Cassini, as an orbiting probe, not so much. Also, at launch we didn't know as much about the Saturn system and it's moons.

      Specifically, we learned that Enceladus has a large subsurface ocean, at the bottom of which may lie hydrothermal vents. Since those on Earth are often teeming with life, we didn't want to risk contamination of Enceladus' oceans.

      Really, they didn't want the Enceladusians to capture our technology.

      Anything to delay the inevitable misunderstanding when they discover Mexican food.

    12. Re: Contamination by sysrammer · · Score: 1

      ...
      Specifically, we learned that Enceladus has a large subsurface ocean, at the bottom of which may lie hydrothermal vents. Since those on Earth are often teeming with life, we didn't want to risk contamination of Enceladus' oceans.

      Really, they didn't want the Enceladusians to capture our technology.

      Anything to delay the inevitable misunderstanding when they discover Mexican food.

      Talk about hydrothermal vents!

      --
      His ignorance covered the whole earth like a blanket, and there was hardly a hole in it anywhere. - Mark Twain
  5. A Planet, Seeded by Anonymous Coward · · Score: 0

    Cassini's crash into Saturn on September 15, 2017 marked the beginning of life on that world. A small colony of hardy bacteria survived the flight through space and the crash, and while most died out quickly, a few extremophiles survived and adapted. It wasn't until a hundred years passed that the Great Gooey Spot was first noticed at the Cassini crash site. Upon investigation by a manned craft, it was discovered to be a growing colony of of adapted bacteria which were beginning to spread across the surrounding area. Scientists were split on whether or not to wipe it out and preserve Saturn's natural state or let it grow and observe the evolution of life on a new world.

    1. Re: A Planet, Seeded by Anonymous Coward · · Score: 0

      Nice story, bruh. Except Saturn doesn't have a surface to crash on.

    2. Re: A Planet, Seeded by Anonymous Coward · · Score: 0

      Interesting! I knew it was a gas giant, but I didn't realize there was no solid mass at all.

      Upon further reading, I see that Jupiter could possibly have a solid surface, but it'd be 38,000 miles in, beneath a 25,000 mile deep sea of liquid metallic hydrogen at 55,000 degrees Fahrenheit.

  6. Farewell Cassini by Virtex · · Score: 1

    Farewell Cassini. You were an explorer, a pioneer, a scientist, a teacher, but most importantly, you were an inspiration to us all. You may be gone, but the legacy you left and the knowledge you taught us will outlive us all. Goodbye old friend, you will be missed.

    --
    For every post, there is an equal and opposite re-post.
    1. Re:Farewell Cassini by MightyMartian · · Score: 1, Insightful

      Indeed. Cassini is another great triumph of space exploration, and shows we can build some pretty damned hardy and long-lasting probes.

      --
      The world's burning. Moped Jesus spotted on I50. Details at 11.
    2. Re:Farewell Cassini by Hognoxious · · Score: 1

      Nothing on netcraft. Shenanigans!

      --
      Confucius say, "Find worm in apple - bad. Find half a worm - worse."
  7. Super advanced civilization by jfdavis668 · · Score: 0

    Saturn's super advanced civilization is now upset with us for crashing our spaceship into one of their shopping malls. They are preparing their battle fleet for a retaliatory strike.

    1. Re:Super advanced civilization by Anonymous Coward · · Score: 0

      Perhaps we can appease them by making sure they get the series finale of Single Female Lawyer.

  8. Life needs water (our kind of life, anyway) by XXongo · · Score: 5, Informative

    TFA states that plowing the craft into Saturn was necessary to prevent contamination of the moons, but the mission began with dropping a Huygens Lander on Titan. Seems like nobody has make the distinction between bacterial contamination and radioactive contamination. I suspect that the latter is actually the concern as the probe used an RTG for power and thus it was safest to de-orbit it into Saturn.

    It was a worry over biological contamination.

    Exactly. Huygens was battery powered: after the battery died, it dropped to a temperature of about 90K, barely above liquid nitrogen. No terrestrial life will contaminate anything at that temperature.

    Cassini, on the other hand, contained several RTGs. In the unlikely case that it did impace into Titan, the RTGs would keep a tiny fraction of the probe debris above the liquidus point of water, and hence in principle terrestrial contamination could survive and even multiply.

    The scenario is absurdly unlikely, of course, but it can't be absolutely ruled out, and since it can't be ruled out, it triggers the planetary protection protocol.

    1. Re:Life needs water (our kind of life, anyway) by arth1 · · Score: 0

      The scenario is absurdly unlikely, of course, but it can't be absolutely ruled out, and since it can't be ruled out, it triggers the planetary protection protocol.

      Yet it doesn't stop us from dropping dozens of probes and landers onto Mars and Venus...
      Nor did it stop the even more microscopic risk of contaminating life on Saturn itself - slingshoting Cassini at the sun or outer space would have been even "safer".

      I have a suspicion that the real goal was to go out in a spectacular "suicide", in order to create publicity. Nothing wrong with that, but be open about it.

    2. Re:Life needs water (our kind of life, anyway) by Tablizer · · Score: 3, Interesting

      dropped to a temperature of about 90K, barely above liquid nitrogen. No terrestrial life will contaminate anything at that temperature.

      Not necessarily. Spores could survive in a frozen state, and then later if a liquid water volcano or similar erupts, the spores could awake and seep toward the core. Unlikely and/or many years away, but not impossible.

      --
      Table-ized A.I.
    3. Re:Life needs water (our kind of life, anyway) by Anonymous Coward · · Score: 0

      slingshoting Cassini at the sun or outer space would have been even "safer".

      And impossible.

      a) The probe didn't have very much fuel left.
      b) Even with a full tank, it did not have an engine that could achieve escape velocity.
      c) The sun? Really? Do you have any idea how much delta-V you would need to try and hit the sun?

    4. Re:Life needs water (our kind of life, anyway) by Baloroth · · Score: 3, Funny

      Yet it doesn't stop us from dropping dozens of probes and landers onto Mars and Venus...

      All of which followed pretty strict decontamination procedures. Well, maybe not the Venus probes, but if Earth bacteria manages to survive on Venus, I say more power to them.

      --
      "None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
    5. Re:Life needs water (our kind of life, anyway) by XXongo · · Score: 4, Informative

      The scenario is absurdly unlikely, of course, but it can't be absolutely ruled out, and since it can't be ruled out, it triggers the planetary protection protocol.

      Yet it doesn't stop us from dropping dozens of probes and landers onto Mars and Venus...

      Mars probes are sterilized and follow a rigorous planetary protection protocol. This has a large and annoying effect on the Mars program: we're not allowed to land on the spots on Mars that have even a slight likelihood of having life or an environment where any possible form of Earth life could survive.

      Venus probes-- well, the surface of Venus is hostile to any possibly terrestrial forms of life, and while the upper atmosphere could possibly harbor extreme acidophiles, not anything that's likely to contaminate a probe. In any case, though, the missions to Venus went there before planetary protection protocols were put in place.

      Nor did it stop the even more microscopic risk of contaminating life on Saturn itself

      Cassini hit the Saturn atmosphere at a velocity of 34 km/sec-- 76,000 mph. No microscopic life is going to survive.

      Think of it as hitting with the energy of a 1/3 kiloton bomb.[ref]

      - slingshoting Cassini at the sun or outer space would have been even "safer".

      "Safer" but utterly impossible. The reason the mission was over was it was pretty much out of fuel.

      I have a suspicion that the real goal was to go out in a spectacular "suicide", in order to create publicity. Nothing wrong with that, but be open about it.

      Uh, no.

    6. Re:Life needs water (our kind of life, anyway) by Anonymous Coward · · Score: 0

      You don't "spiral into the sun" unless you have air resistance. Going into any other orbit was not an option, and either a solar intercept orbit or a solar escape trajectory would require more energy than Cassini used to get there in the first place. If you don't know anything about orbital mechanics, do us a favor and shut the hell up.

    7. Re:Life needs water (our kind of life, anyway) by arth1 · · Score: 1

      I think you missed the word "slingshot".
      The point is using the orbital movement and gravitational pull of Saturn and its larger moons to increase the speed with every passing until escape velocity has been achieved. You need very little fuel for such an operation, and we have used it many times in the past, including with Cassini itself, as it got gravity assist from Venus twice, then Earth, and then Jupiter. And it's how it has navigated through the Saturn system with extremely little fuel used.
      Departure from Saturn was one of the EOM options contemplated back in 2008, and it was not lack of fuel that stopped it. In fact, escaping to a heliocentric orbit was the easiest option, as it could be initiated from anywhere.

    8. Re:Life needs water (our kind of life, anyway) by Anonymous Coward · · Score: 0

      A few course corrections and we should be able to build up an orbital resonance with titan; a few passes later and get ejected from Saturn. A nice oberth burn on the lass Titan pass may or may not be able to get a Jupiter intercept. If so, hitting the sun is now easy.

    9. Re:Life needs water (our kind of life, anyway) by Strider- · · Score: 2

      Yet it doesn't stop us from dropping dozens of probes and landers onto Mars and Venus...

      As I mentioned above, there is an entire policy (and in fact a portion of the organization) dedicated to planetary protection. Surface landers, such as what are sent to Mars (and in the future Europa and/or Enceladus) are required to go through very strict decontamination regimens before they are launched. In addition to being assembled in clean rooms (as are all the probes), they are baked/irradiated/cleaned with caustic chemicals/etc... prior to launch to sterilize them as much as possible. They don't want to discover life on another planetary body, only to realize that it's life they brought with them.

      Venus is a slightly different beast, its surface conditions are so inhospitable (sulfuric acid rain, 400+C temperatures, etc...) that there is not much of a worry about possible contamination. The conditions would denature/destroy all known forms of life present here on Earth.

      The larger orbiters (Cassini, Galileo, and Juno) are a) a lot harder to sanitize to the same degree and b) are orbiters not intended to settle on a planetary body that could possibly harbor life. They're not cleaned to the same degree, so the general policy is to dispose of them safely so that there is no chance that they will impact a protected body. Due to the complexity of the Saturn system, the safest way was to drop it into Saturn itself.

      The other reason for this was that it is realistically a consequence of the final mission. For the past several months, Cassini has been plunging through the gap between Saturn and its rings. It did not have the fuel left to get out of that. This mission design gave the planetary scientists a wealth of new data on the rings, their mass, and composition.

      --
      ...si hoc legere nimium eruditionis habes...
    10. Re:Life needs water (our kind of life, anyway) by Anonymous Coward · · Score: 0

      Mars and Venus have little to no possibility of current life on them (at most Mars might have some subsurface soil bacterial on its way to extinction). I suppose life could exist on Saturn, but any organisms that could have been on Cassini would be frozen, then crushed, then barbecued in its atmosphere. Titan and Enceladus on the other hand could harbor thriving ecosystems, and at least in the case of Enceladus could (though unlikely) be contaminated by Earth bacteria. While it could be possible to gravity assistant Cassini out of the Saturn system why would you. It's 20 years old, its systems can't run forever, and you might as well try to extract a few last bits of science from it by crashing it into Saturn (as has been done with several probes) before it does become a piece of mildly radioactive space debris.

    11. Re:Life needs water (our kind of life, anyway) by Ranbot · · Score: 2

      I have a suspicion that the real goal was to go out in a spectacular "suicide", in order to create publicity. Nothing wrong with that, but be open about it.

      I don't think the goal was publicity, but I'm sure they don't mind the publicity either. If you read the article at the end it mentions there was science to be done that could only be obtained [hopefully] by a suicidal plunge through the atmosphere. Previously the probe could never get close enough to Saturn to record its exact magnetic tilt or directly analyze the atmosphere, both of which they are hoping to get readings of from Cassini's final descent. With the limited fuel remaining the suicide run was probably the most reliable means to safely "dispose" of the probe which obtaining new scientific data they couldn't before. If it gets a little public attention too, all the better, but I don't think that was the main goal.

      Furthermore, in my personal pessimistic opinion, I think saying this is a publicity stunt is giving the general public's interest in NASA/science way too much credit; and any positive PR made will fade long before there is any near-term benefit for NASA. The general public will forget about Cassini (if they paid attention at all) as soon as a Kardashian tweets something, or some athlete throws/kicks/carries a ball to score a point, or Putin says "boo!"...

    12. Re:Life needs water (our kind of life, anyway) by Anonymous Coward · · Score: 0

      If they had the fuel for that they'd have written the Jupiter intercept into the mission plan.

    13. Re:Life needs water (our kind of life, anyway) by Hognoxious · · Score: 1

      Slingshot it using what?

      --
      Confucius say, "Find worm in apple - bad. Find half a worm - worse."
  9. HAL by Anonymous Coward · · Score: 0

    I'm sorry Dave I'm afraid I can't do that.

  10. In the words of Neil Young... by Anonymous Coward · · Score: 0

    My my, hey hey
    Rock and roll is here to stay
    It's better to burn out
    Than to fade away
    My my, hey hey.

  11. Next time... by Anonymous Coward · · Score: 0

    ... build a probe that can refuel itself, please.

  12. You don't "spiral" into the sun. by XXongo · · Score: 2

    Yep. They could either have sent it out of the solar system (when it had enough juice left) or spiraling into the Sun. Didn't necessarily have to crash land on a planet.

    You don't "spiral" into the sun. You watch too much star trek. Orbits are not spirals.*

    Dropping into the sun would have required escaping Saturn's gravity well-- which Cassini didn't have the fuel to do-- and then cancelling out Saturn's orbital angular momentum around the sun, which requires 9.6 km/sec, well beyond anything remotely possible with Cassini even if it had full fuel tanks on its main braking engine.

    Going "out of the solar system" would require "merely" 4 km/sec after escaping Saturn's gravity well. Still not even remotely possible.

    --
    *(unless you have ion engines, which Cassini didn't)

    1. Re:You don't "spiral" into the sun. by Strider- · · Score: 2

      Dropping into the sun would have required escaping Saturn's gravity well-- which Cassini didn't have the fuel to do--

      Actually escaping Saturn's orbit and going into solar orbit was one of the possible end-of-mission scenarios. When they were looking at the options, it would only have required 5-35m/s of delta-v, well within Cassini's capabilities. However, having a planetary probe in heliocentric orbit doesn't get you much science, as its instruments aren't designed for that kind of thing. At most they would have had a semi-long term observation of the solar wind, which can be done with missions that are much easier to maintain and control.

      In the end, the wealth of data obtained by the final proximal orbits to Saturn were considered to be the best bang for the buck at the end of the probe's lifespan. The final retirement option chosen required about the same delta-v as an escape from Saturn, but achieved a whole lot more than just drifting around for ever.

      --
      ...si hoc legere nimium eruditionis habes...