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[-] DaddleDew@lemmy.world 132 points 2 weeks ago

This reminds me of that quote from Mass Effect:

"This, recruits, is a 20-kilo ferrous slug. Feel the weight! Every five seconds, the main gun of an Everest-class Dreadnought accelerates one to 1.3 percent of light speed. It impacts with the force of a 38-kiloton bomb. That is three times the yield of the city buster dropped on Hiroshima back on Earth. That means: Sir Isaac Newton is the deadliest son-of-a-bitch in space! (...) I dare to assume you ignorant jackasses know that space is empty! Once you fire this hunk of metal, it keeps going 'till it hits something! That can be a ship, or the planet behind that ship. It might go off into deep space and hit somebody else in ten thousand years. If you pull the trigger on this, you are ruining someone's day, somewhere and sometime!"

[-] TwoBeeSan@lemmy.world 37 points 2 weeks ago* (last edited 2 weeks ago)

That first mass effect can't be beat for setting the stage and immersing you in the world.

I can hear the VA in my head lmao

Edit: I like mass effect I don't have a good memory

[-] hikaru755@lemmy.world 22 points 2 weeks ago* (last edited 2 weeks ago)

That quote is not from the first one though, it's from the second one

[-] TwoBeeSan@lemmy.world 15 points 2 weeks ago

Balls exposed 🙀🙀🙀🙀

[-] zephorah@lemm.ee 5 points 2 weeks ago

Citadel lobby, yes.

[-] deadbeef79000@lemmy.nz 11 points 2 weeks ago

"What is Newton's first law of motion?"

[-] JakenVeina@lemm.ee 11 points 2 weeks ago

"No credit for partial answers!"

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[-] Zwiebel@feddit.org 102 points 2 weeks ago

There is one detail wrong in the first post; that is not the lids speed but rather it's minimum speed.

[-] Klear@sh.itjust.works 16 points 2 weeks ago

Unfortunately they got almost everything else wrong though. Mainly - the cover actually almost certainly just vaporiserd.

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[-] Professorozone@lemmy.world 64 points 2 weeks ago

Ummm, not sure where they got these numbers from but Earth's escape velocity is not 7000mph and escaping the sun's gravitational pull (leaving the solar system from Earth) is not 30,000mph. Respectively the numbers are approximately 25,000mph and 94,000mph. You're welcome.

[-] Bosht@lemmy.world 24 points 2 weeks ago

Gotta love Tumblr. Just massive amounts of disinformation and bullshit all the time.

[-] finitebanjo@lemmy.world 15 points 2 weeks ago

Also it would have atomized.

[-] SwordInStone@lemmy.world 9 points 2 weeks ago

yeah, and it is not "research" to check it. They literally teach it in primary school physics.

[-] Crashumbc@lemmy.world 15 points 2 weeks ago

Not in our freedom schools!

[-] MonkderVierte@lemmy.ml 5 points 2 weeks ago

I mean, what for? Knowing that number isn't a life skill.

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[-] atocci@lemmy.world 44 points 2 weeks ago

Sadly, the cover likely did burn up in the atmosphere at those speeds, like a meteorite in reverse.

[-] ilinamorato@lemmy.world 42 points 2 weeks ago

I'm not so sure.

Let's compare with the Apollo Command Module heat shield, a remarkably close analogue for the bore cap. They're a similar weight (3,000 lb for the heat shield, 2,000 lb for the bore cap) and have melting points within an order of magnitude of each other (5,000°F for the AVCOAT heat shield and about 2,800°F for the iron bore cap). They're even both of a similar shape and aerodynamic profile (disc-shaped and blunt). Both had to travel 62 miles (the distance from sea level to the Karman Line, where atmosphere becomes negligible).

The Apollo CM made that distance in about seven minutes; at 130,000mph, the Pascal B bore cap took at most 1.72 seconds to make the trip.

What was discovered during the development of the Apollo heat shield is that the blunt shape caused a layer of air to build up in front of the spacecraft, which reduced the amount of heating that convected into the heat shield directly. This reduced the amount of heat load that the heat shield needed to bear up under.

Further, it's also worth noting that the Apollo command modules weren't tumbling, which the bore cap likely would have been, allowing brief instants during its ascent for the metal to cool before being subjected again to the heat of the ascent.

But probably most critical at all is the remarkably brief amount of time that the bore cap spent in atmosphere. This person did the math on how much power it would take to vaporize a cubic meter of iron, and the answer is 25,895,319 kJ. Now, the bore cap isn't quite a cubic meter, but we can use all of his calculations and just swap in 907kg (2000lbs):

  • To heat the bore cap to iron's melting point: 0.46 kJ/kg * 907 kg * (1808K-298K) = 630,002 kJ

  • To phase change the iron from solid to liquid: 69.1 KJ/kg * 907 kg = 62,674 kJ

  • To heat the bore cap to iron's boiling point: 0.82 kJ/kg * 907 kg * (3023K-1808K) = 903,644 kJ

  • To phase change the iron from liquid to gas: 1520 kJ/kg * 907 kg = 1,378,649 kJ

So, in total, 2,974,969 kJ. The Apollo heat shield encountered a peak of 11,000 kJ/m^2/s. Since the Pascal B bore cap was about a meter in diameter and was traveling through the atmosphere for about two seconds, we can very neatly estimate that it absorbed a maximum of 22,000 kJ due to atmospheric compression--not even close to enough to get it to melting temperature.

Interestingly, early missiles actually did use solid metal heat shields; not iron, but titanium, beryllium, and copper. They were effective, but abandoned due to their weight.

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[-] very_well_lost@lemmy.world 19 points 2 weeks ago* (last edited 2 weeks ago)

I'm not so sure... At those speeds, it would've taken under 10 seconds to completely clear the atmosphere. Even with intense compressional heating, I don't think it would've been in contact with the atmosphere long enough to completely vaporize — although it probably didn't look much like a manhole cover anymore by the time it escaped.

[-] troyunrau@lemmy.ca 35 points 2 weeks ago

I don't think melting is the issue here. I think it literally disintegrates at those speeds. Like, this is Mass Effect mass driver level of impact with the atmosphere.

For reference, RICK ROBINSON'S FIRST LAW OF SPACE COMBAT: "An object impacting at 3 km/sec delivers kinetic energy equal to its mass in TNT."

Assuming the lid is travelling 55km/s, it's well beyond that point. The atmosphere it's travelling through is basically a solid at that speed. Even if it isn't heating due to the friction (and waiting for heat flow), it is heating due to the compressive force of being slammed into the atmosphere. It's very likely the whole thing vaporized.

But I could be wrong, and some alien SOB is going to have a bad day when the manhole cover slams into their ship in interstellar space.

[-] Rhaedas@fedia.io 10 points 2 weeks ago

Would vaporization slow the material though? Perhaps the end result wasn't a manhole escaping the solar system but a huge collection of microscopic metal fragments scattershot that direction. Which really makes the Mass Effect quote even more relevant to a huge amount of aliens somewhere.

[-] chaogomu@lemmy.world 12 points 2 weeks ago

Vaporization would certainly slow the material. It's transitioning kinetic energy into thermal.

Also, the vaporized iron would disperse outward rather than stay coherent.

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[-] mkwt@lemmy.world 14 points 2 weeks ago

And for reference, the earth escape velocity from the surface is 11.2 km/s or 25,000 mph, not 7,000 mph.

To escape the solar system from the earth surface, the minimum speed is 16.6 km/s, or 37,100 mph. But this assumes that you launch in the correct direction to take the most advantage of the Earth's 30 km/s. If you launch in the most disadvantageous direction, you can add another 60 km/s to escape.

[-] transientpunk@sh.itjust.works 12 points 2 weeks ago* (last edited 2 weeks ago)

Yes, it absolutely would have vaporized before exiting the atmosphere.

Here's a video on the subject: https://www.youtube.com/watch?v=mntddpL8eKE

[-] sp3tr4l@lemmy.zip 37 points 2 weeks ago

Responding to the last comment in the image:

You could literally just do reverse Starship Troopers, the movie at least.

You're a bunch of aliens and blam out of no where the nuclear launched manhole obliterates a holy site on your homeworld, your scientists track the trajectory back to Earth, conclude they must have launched it intentionally, and then launch an interstellar jihad against totally unaware Earthlings.

[-] dragonfucker@lemmy.nz 25 points 2 weeks ago

That reminds drag of Halo, though significantly more silly.

In Halo, the Covenant are on an interstellar crusade for holy artifacts left behind by the Forerunners. When they discovered the planet Harvest, inhabited by humans, they saw tons of artifacts on their scanners. So naturally, they landed on the planet and started blasting the humans to steal the artifacts. But the more humans they killed, the more artifacts disappeared from their monitors. The humans must be destroying the artifacts out of petty spite! What heresy!

The Prophet of Truth is curious about what kind of artifacts the humans have, so he goes to talk to an ancient Forerunner AI they have in storage, Mendicant Bias. Truth shows Bias the symbol that they keep seeing on human worlds. Bias says "You fool, you've got it upside down. Turn it around, see? It says Reclaimer. It means a person the Forerunners have chosen to inherit their empire. You've just been killing these humans? No wonder the reclaimers keep disappearing, you're the one who's doing it!"

So Truth realises that he's been ordering his troops to kill what should rightfully be considered demigods by his religion, and who he should be worshipping. And he realises that if he reveals this information to the people, he and the other Prophets will lose all their political power since there are Actual Fucking Gods walking around. So naturally, Truth declares a Holy Genocide against humanity so that nobody will ever figure out that he's guilty of Deicide and that their entire religious political structure is a lie.

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[-] mindbleach@sh.itjust.works 6 points 2 weeks ago

It is of course well known that careless talk costs lives, but the full scale of the problem is not always appreciated.

For instance, at the very moment that Arthur said ”I seem to be having tremendous difficulty with my lifestyle,” a freak wormhole opened up in the fabric of the space-time continuum and carried his words far far back in time across almost infinite reaches of space to a distant Galaxy where strange and warlike beings were poised on the brink of frightful interstellar battle.

The two opposing leaders were meeting for the last time.

A dreadful silence fell across the conference table as the commander of the Vl’hurgs, resplendent in his black jewelled battle shorts, gazed levelly at the G’Gugvuntt leader squatting opposite him in a cloud of green sweet-smelling steam, and, with a million sleek and horribly beweaponed star cruisers poised to unleash electric death at his single word of command, challenged the vile creature to take back what it had said about his mother.

The creature stirred in his sickly broiling vapour, and at that very moment the words I seem to be having tremendous difficulty with my lifestyle drifted across the conference table.

Unfortunately, in the Vl’hurg tongue this was the most dreadful insult imaginable, and there was nothing for it but to wage terrible war for centuries.

Eventually of course, after their Galaxy had been decimated over a few thousand years, it was realized that the whole thing had been a ghastly mistake, and so the two opposing battle fleets settled their few remaining differences in order to launch a joint attack on our own Galaxy – now positively identified as the source of the offending remark.

For thousands more years the mighty ships tore across the empty wastes of space and finally dived screaming on to the first planet they came across – which happened to be the Earth – where due to a terrible miscalculation of scale the entire battle fleet was accidentally swallowed by a small dog.

-- Douglas Adams, The Hitchhiker's Guide To The Galaxy

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[-] RememberTheApollo_@lemmy.world 26 points 2 weeks ago

Ive seen this claim a dozen times. It’s a disc shape. How this thing isn’t going to start flipping and curving its trajectory, or just plain old running out of energy due to air resistance, and not making it out of earth’s atmosphere is beyond me.

[-] finitebanjo@lemmy.world 13 points 2 weeks ago

It didn't stay solid upon initial blast impact. Probably didn't even stay liquid.

[-] Crashumbc@lemmy.world 8 points 2 weeks ago

Yeah it vanished because it vaporized.

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[-] gens@programming.dev 5 points 2 weeks ago

Take a coin and trow it as hard as you can. The curving is not that much.

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[-] captain_aggravated@sh.itjust.works 23 points 2 weeks ago

The calculation of its speed was made by high speed camera, as you've probably seen the Mythbusters do. In this case the manhole cover was seen in flight in precisely one frame of high speed camera footage, and for it to go "installed, in flight, gone" in three frames means it would have had to be moving at mach jesus.

It likely didn't make it to space intact; it would have had ultrasonic compression heating on one side and a nuclear explosion on the other. It's probably still here in the form of iron oxide dust scattered about the Northwestern hemisphere.

[-] Idontevenknowanymore@mander.xyz 10 points 2 weeks ago

In my head I know you're right but my heart wants this.

[-] Iheartcheese@lemmy.world 8 points 2 weeks ago

If we kill him he never will have said it and the manhole cover will be in space.

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[-] MonkderVierte@lemmy.ml 23 points 2 weeks ago* (last edited 2 weeks ago)

Nope, it would just have bursted due to thermal schock and pressure. Escape velocity, what are you dreaming, is the lid made of tungsten?

[-] logos@sh.itjust.works 9 points 2 weeks ago* (last edited 2 weeks ago)

This is the origin apparently.

RRB: "My calculations are irrelevant on this point. They are only valid in speaking of the shock reflection." Ogle: "How fast did it go?" RRB: "Those numbers are meaningless. I have only a vacuum above the cap. No air, no gravity, no real material strengths in the iron cap. Effectively the cap is just loose, traveling through meaningless space." Ogle: And how fast is it going?" This last question was more of a shout. Bill liked to have a direct answer to each one of his questions. RRB: "Six times the escape velocity from the earth."

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[-] MajorHavoc@programming.dev 17 points 2 weeks ago

I love the idea that our first message to aliens might be "FRESH WATER ONLY. NO WASTE."

[-] OrnateLuna 15 points 2 weeks ago

Surprised no one has posted this but Kyle hill made a video on it

[-] ICastFist@programming.dev 14 points 2 weeks ago

We should test this again, but with a fridge and someone inside it for the nuclear blast. I bet that would work out great

[-] SwordInStone@lemmy.world 5 points 2 weeks ago* (last edited 2 weeks ago)

future president of the us perchance?

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[-] IrritableOcelot@beehaw.org 8 points 2 weeks ago* (last edited 2 weeks ago)

One thing that no one ever talks about with this is the massive air resistance on it going Mach 164 through the atmosphere would incur (albeit for a very brief period)...I bet that would knock 25-50 kmph off it easily.

[-] Earflap@reddthat.com 7 points 2 weeks ago* (last edited 2 weeks ago)

Most likely it just evaporated, or disintegrated or something, but I think its pretty unlikely it survived that absolutely bonkers acceleration.

[-] RizzRustbolt@lemmy.world 7 points 2 weeks ago

How to solve the Three Body Problem.

[-] glibg@lemmy.ca 5 points 2 weeks ago

The Parker Solar Probe moves 120 miles per second as it passes around the Sun. That's nearly half a million miles per hour!

https://en.wikipedia.org/wiki/Parker_Solar_Probe

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this post was submitted on 02 Dec 2024
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