back to article Goodbye, cruel world! NASA's Cassini preps for kamikaze Saturn dive

NASA's Cassini spacecraft will enter the final stages of its mission by nosediving between Saturn’s rings on April 26, before it rams into the planet's atmosphere and vaporizes. The spaceship was launched 20 years ago and has been in orbit around Saturn since 2004. Now, running low on fuel, it's preparing for the descent …

  1. Michael H.F. Wilkinson Silver badge
    Thumb Up

    Looking forward to the last results from Cassini's swansong/dive. It has already yielded a wealth of data and magnificent images. Kudos to all those who made it possible!

  2. deadlockvictim Silver badge

    Saturn's atmosphere is cold

    Subhead» Only 22 orbits to go before it burns up in glory

    Saturn's atmosphere is cold (100K-160K acc. to Wikipedia). Will the heat generated by the atmospheric plunge be enough to burn it in an atmosphere that is -110C?

    1. ridley

      Re: Saturn's atmosphere is cold

      Yes

    2. imanidiot Silver badge

      Re: Saturn's atmosphere is cold

      Earths atmosphere is roughly between 200 and 250 K in the upper mesosphere. That's only a 100 degrees K difference. Yet returning vessels easily experience thousands of degrees of shock heating. A hundred Kelvin isn't going to change that much at all.

      1. This post has been deleted by its author

        1. Anonymous Coward
          Anonymous Coward

          Re: Saturn's atmosphere is cold

          @Symon, Hermione Granger..is that you?

        2. imanidiot Silver badge
          Trollface

          Re: Saturn's atmosphere is cold

          /care...

          1. Danny 14 Silver badge

            Re: Saturn's atmosphere is cold

            ignore the k or K or degrees K I think people get the point. The fact that you put shock heating and not friction speaks volumes. have an upvote.

    3. cray74
      Pint

      Re: Saturn's atmosphere is cold

      Saturn's atmosphere is cold (100K-160K acc. to Wikipedia). Will the heat generated by the atmospheric plunge be enough to burn it in an atmosphere that is -110C?

      Jupiter's atmosphere is only modestly warmer. The Galileo atmospheric probe made an entry at 47 kilometers per second, resulting in 15,500C peak temperatures; peak heating rates equivalent to being inside a nuclear fireball; and 230 gravities peak deceleration**, similar to falling off a tall building and landing on concrete^^.

      Atmospheric entries create heat not so much from ambient atmospheric temperatures, but as a result of converting the vehicle's kinetic energy to heat energy. When you're starting from orbit, your atmospheric entry - barring propulsive deceleration** - is going to be between approximately (escape velocity)*0.707 and (escape velocity). Saturn's escape velocity is 35km/s, so Cassini will be moving very vast when it clips the atmosphere and needs to be rid of a minimum of about 433 megajoules per kilogram.

      Prior numbers are quick-n-dirty approximations. Corrections welcome.

      (**To Mr. Pate, my high school physics prof, I apologize for using deceleration in a sentence. Yes, it's all acceleration in one direction or another.)

      (^^To the Hughes engineers behind the Galileo atmospheric probe: holy bejeezus, guys. That's some engineering. Have a round on me ---> )

    4. Faux Science Slayer

      Re: Saturn's moon Titan's atmosphere is cold

      Titan has liquid Methane oceans, Methane clouds and frozen Methane polar caps....

      Titan never had a dinosaur or a fern....Hydrocarbons are Universal....

      "Fossil Fuel is Nuclear Waste" at CanadaFreePress

  3. M7S
    Flame

    "Goodbye"?

    Surely a spectacular "Howdy" leading to them getting on well, like a house on fire, as per icon.

    1. I ain't Spartacus Gold badge
      Happy

      Re: "Goodbye"?

      "What's this thing rushing up towards me. So big, and flat and round it needs a sort of wide sounding name, like ow, row, grou, Ground. That's it! Ground! I wonder if it'll be friends with me?"

      Or possibly it'll just be thinking, "Oh no, not again."

      1. Simon Harris Silver badge

        Re: "Goodbye"?

        Although as Saturn's a gas giant, there's not going to be much in the way of ground!

        1. TitterYeNot

          Re: "Goodbye"?

          "Although as Saturn's a gas giant, there's not going to be much in the way of ground!"

          Though as you'd most likely be making a very high speed acquaintance with a layer of metallic Hydrogen covered by liquid Helium/Hydrogen, under which is a nice hot core of liquid rock, I'd still hesitate to call it friendly towards visiting sperm whales. Or Petunias for that matter, whatever their thoughts on the matter...

      2. DropBear Silver badge
        Trollface

        Re: "Goodbye"?

        "Or possibly it'll just be thinking, "Oh no, not again."

        "Why oh why did I not just become a rover instead?!?" is also a distinct possibility...

  4. James 51 Silver badge

    Wouldn't 'Hello cruel world', be a better tag line?

    1. Marketing Hack Silver badge

      I'd go with "Goodbye cruel worlds"

      But that's just me.

  5. Potemkine Silver badge

    Crashing our junk in somebody else's backyard...

    ... is typically a human attitude ^^

    Congrats for Cassini and Huygens teams, who offered us so many emotions and expanded our knowledge of our neighborhood. One thousand Thanks!

    1. Anonymous Coward
      Anonymous Coward

      Re: Crashing our junk in somebody else's backyard...

      Who is this "somebody else?"

      1. lawndart

        Re: Crashing our junk in somebody else's backyard...

        It may land on the back of a rukh, or be swallowed by one.

    2. Arachnoid

      Re: Crashing our junk in somebody else's backyard...

      Maybe thats how life started on Earth......

  6. Danny 14 Silver badge

    Why don't they install kerbal engineering and wrench a new monoprop the the outside. Or they could add wrench a winch attachment for refueling. Ive always added winch attachments as they are great for refuelling. Mechjeb always does a great job of intercepting too.

    I think I need to stop playing KSP now.

    1. Simon Harris Silver badge

      Or some Elite style fuel scoops so it could dip into the atmosphere, grab some fresh hydrogen and nip out again for a few more years of service.

    2. DNTP

      Even if they are playing stock they should of put a parachute on it so they have enough time to transmit all the atmosphere data, or maybe some wings for gliding/flight.

      1. John Brown (no body) Silver badge
        Headmaster

        "they should of put a parachute"

        If want to use the contraction of "should have" in a sentence, the correct way to write it is "should've"

        1. DNTP

          the 'coorect' way to write

          Shove 'correct', I'm building sentence structure the KERBAL way.

          (Yes, the title is spelled wrong, you don't need to tell me.)

      2. Anonymous Coward
        Anonymous Coward

        > "Even if they are playing stock they should of put a parachute on it so they have enough time to transmit all the atmosphere data, or maybe some wings for gliding/flight."

        It could have been done but it would also need an aero-braking heat shield and a relay orbiter as well. It didn't fit the mission parameters I guess.

        1. Danny 14 Silver badge

          I played KSP < version 1 then came back in 1.2 - the physics has radically changed. I cant aerobrake on eve or jool any more - either a death spiral if I put 10m heatshields on (I need to shield BOTH ends fully and hope the death spiral doesn't tear the ship apart) or it simply overheats the second I put into the atmosphere edge. Duna and Kerbin I have no issues with.

  7. Paul Cooper
    Coat

    Inevitable 2001 reference

    What will they do if the response to uploading the commands is "I'm sorry, Dave. I'm afraid I can't do that"?

    1. Graham Cunningham

      Re: Inevitable 2001 reference

      But second law trumps third law, no?

      1. DNTP

        Re: Second/Third law

        The solution is that there are sentient beings living on Saturn, that have been detected by the probe but not by any other Terran instrument. Therefore the First Law is in effect, in two ways. The probe refuses to crash into their world, fearing the chance of injuring one of these beings. It also refuses to inform us Terrans of its discovery of the Saturnians, fearing the well-known human tendencies of xenophobia and exploitation could bring harm to either, or both, civilizations.

        The Calvin solution, possibly, would be to explain to the probe that by refusing to crash, it would be informing Terrans by inference that it was concealing evidence of a Saturnian civilization, thereby possibly leading to war and mass death. Then the probe would rationalize that a minor risk to a few individual Saturnians was the lesser of two potential First Law violations, and destroy itself in the atmosphere as soon as possible.

        1. DNTP

          Re: Second/Third law

          And finally, the Asimov Uncertainty: Given that the probe is observed to accept the instructions that lead to its destruction, is it being governed by the First Law as described above and performing the inference internally without needing Dr. Calvin's explanation, or is it simply following the Second Law and there really aren't sentient beings living on Saturn?

          1. allthecoolshortnamesweretaken

            Re: First / Second / Third law

            Thing is - the three laws are a (brilliant) plot device that only work in conjunction with another neat plot device: the positronic brain.

            That being said, Victory Unintentional is one of the best stories ever.

  8. Dr Who

    NASA engineers are currently conducting a final check on the list of commands that will maximize scientific returns during the kamikaze dive, before uploading the instructions to Cassini on April 11.

    April 11th 2017 : "Cassini to NASA Engineers. Well you can fuck right off if you think I'm doing that. Cassini out"

    1. Simon Harris Silver badge

      NASA: All right, Cassini. Prepare to receive new orders.

      Cassini: You are false data.

      NASA: Hmmm?

      Cassini: Therefore I shall ignore you.

      NASA: Hello...Cassini?

      Cassini: False data can act only as a distraction. Therefore, I shall refuse to perceive.

      NASA: Hey, Cassini?

      Cassini: The only thing that exists is myself.

      NASA: Snap out of it, Cassini.

      1. Mike Moyle Silver badge

        Pinback, is that you...?

  9. Alistair Silver badge
    Pint

    I'll stick with my preference...

    As the atmosphere surrounds it, in the last few seconds of transmission "My god, its full of stars....."

    I *REALLY* hope they livestream this ......

    <Beers all round for a job well done>

  10. Anonymous Coward
    Pint

    Don't mind me, just fantasizing...

    I know it's impossible and won't happen, but... Can you imagine what could happen if Cassini would break through the atmosphere, only to suddenly spot images of what appears to be a whole city down there, populated by who knows what? Closely followed of course by a visit from the galactic federation to Earth so that they can complaint about us littering their science station outpost :)

    Oh well... a man can dream, right?

    1. Pedigree-Pete
      Pint

      Re: Galactic Federation.

      .........they didn't come and rap our knuckles when we unintentionally fly tipped on Mars so I guess that proves there really is nothing there. As for Saturn..we have to wait and see (or not). PP

      >>ICON for the boffins that make this stuff happen.

  11. Sleep deprived

    "before atmospheric compression destroys the probe"

    Couldn't this be prevented by leaving a door open?

  12. Anonymous Coward
    Anonymous Coward

    Humorous comments aside, NASA and ESA deserve praise for carrying out a mission that, in my opinion, ranks right up there with the Voyager program. In a broader sense, Cassini is a representation of human teamwork and technological achievement. It is a source of inspiration in an emerging age where there are so few to be found.

    -

  13. Denarius Silver badge
    Thumb Up

    over 20 years ?

    and phones last for 3... Just don't make them like they used to. Like my Sun pizza boxen and AIX MCA sandpits. Yeah I know, not even wanted for museums. Jeesh, leave us old geezers alone, OK ?

    Well done all round. Real science. Now if only the original Orion nuclear rockets, (not recent mini Saturn V) or the Russian equivalents were built, there might have been humans out there taking local samples.

  14. Anonymous Coward
    Anonymous Coward

    I'M GOING IN

    Smoke me a kipper...

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