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 …
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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 ---> )
"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...
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.
> "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.
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.
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.
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?
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.
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"
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.
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?
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.
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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.
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