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!"
"What is Newton's first law of motion?"
"No credit for partial answers!"
There is one detail wrong in the first post; that is not the lids speed but rather it's minimum speed.
Unfortunately they got almost everything else wrong though. Mainly - the cover actually almost certainly just vaporiserd.
That's assuming it crossed the image straight from edge to edge, though.
The cover obtained all of its energy from the blast, it can only go slower than its initial speed unless acted upon by another force.
No no, because they only had one frame of it moving, they can only calculate and upper and lower bound on it's speed. The number given was the lower bound is what theyre saying.
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.
Gotta love Tumblr. Just massive amounts of disinformation and bullshit all the time.
Also it would have atomized.
94000mph is relative to the sun's surface. Relative to the Earth's surface, it is around 37000mph, which means they were still wrong.
Not according to Wikipedia. At Earth relative to Sun is 42.1 km/s = 94,175 mph. From the sun's surface is 617.5 km/s = 1.38 x 10e6 mph.
That's 11.2 km/s and 42.1 km/s.
Also, even if the manhole cover was going at above 12 km/s the trajectory has to be right for that to result in orbit. Most paths it would take would result in it going up and then coming back down again. Similarly, if somehow it did manage more than 50 km/s and wasn't destroyed in the atmosphere, it might have the velocity to escape the sun's gravity, but probably wouldn't be on the right path to do it. Most likely it would fall into the sun.
So, assuming the 125,000 mph (55 km/s) velocity is correct, the most likely outcome is that it was a reverse-meteor, something that burned up going up through the atmosphere, not down. And even if it did have enough speed to get out of the atmosphere, and there was enough of it left, it most likely fell right back down through the atmosphere somewhere else, either burning up on re-entry or hitting the ground (or the water) somewhere else.
Ignoring that it burned up and ignoring losses due to drag if it somehow didn't. Isn't the point of escape velocity that it explicitly won't come back down.iar least not on earth. Your trajectory won't matter as you have enough velocity to escape the gravity of earth and will orbit the sun. Further if you managed the solar system escape velocity you will end up orbiting the galactic core. Trajectory doesn't matter if you have escape velocity. Correct trajectory just minimizes the delta v needed to reach that escape velocity.
At least that's all my recollection.
Sadly, the cover likely did burn up in the atmosphere at those speeds, like a meteorite in reverse.
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):
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To heat the bore cap to iron's melting point: 0.46 kJ/kg * 907 kg * (1808K-298K) = 630,002 kJ
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To phase change the iron from solid to liquid: 69.1 KJ/kg * 907 kg = 62,674 kJ
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To heat the bore cap to iron's boiling point: 0.82 kJ/kg * 907 kg * (3023K-1808K) = 903,644 kJ
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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.
I don't think you can compare the Apollo heat shields to a bore cap being launched into space. For one thing, the Apollo shield started in the very thin upper atmosphere, and they came in at an angle that meant they bled off as much speed/energy as possible in that thin upper atmosphere before going into the thicker atmosphere. In fact, one of the engineers said that if they came in too steep they'd generate too much heat and probably not survive the re-entry.
The layer of air you're talking about at the front of the spacecraft was what heated up the heat shield. Instead of causing heating via friction, the heat was the result of compressing the air. The amount of compression you're talking about would be orders of magnitude higher for something starting at 40 km/s in the thick lower atmosphere.
Also, the Apollo heat shield did heat up to 5000F or 2800C but was designed to be ablative, so that the hot layers burned off and flew off to the sides leaving new material to be heated up and burned off. This concrete and metal plug wouldn't have been designed the same way. Concrete apparently melts at 1200C, and steel is approximately the same, so it's very likely some of it melted or vaporized, the question is how much.
I don't know where you're getting the maximum of 22MJ of energy. The whole point of Apollo not going directly into the atmosphere was to take as long as possible to slow down, going through the thinnest part of the atmosphere for as long as possible. The whole point would be to reduce their energy-per-second as low as possible by taking as many seconds as possible. One reasonable first approximation of the energy would be to integrate the entire energy per second / power for Apollo's re-entry over the entire 7 minutes (or however long it took until parachutes deployed) and then divide that energy by 2 for the 2 seconds the plug was in the atmosphere.
My guess is that that would have been temperatures well in excess of 1200C which would have made the outer surface start to melt, and most likely a temperature where it just turns to plasma. Would it all have melted / vaporized / plasmafied away? I don't know, it's a huge plug. Since it was launched vertically, anything remaining would probably have come right back down. But, that's assuming it stayed in one piece. I'm guessing it broke apart due to the stresses on it, and breaking apart would have meant more surface area, which would have meant more areas exposed to massive heating, which would have meant more breaking apart.
TL;DR: I doubt it made it out of the atmosphere.
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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.
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.
It was being propelled by a nuclear blast. The speed was calculated from 1 frame of a high speed camera. It most definitely vaporized.
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.
Yes, it absolutely would have vaporized before exiting the atmosphere.
Here's a video on the subject: https://www.youtube.com/watch?v=mntddpL8eKE
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.
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.
Or, you just decided on first contact, but, suddenly, ship goes boom after being struck in the propulsion system with a bullet like manhole cover.
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.
Take a coin and trow it as hard as you can. The curving is not that much.
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.
I'd like to think that it's possible that it was launched fast enough that it escaped the blast and Earth's atmosphere and made its way to a neighboring galaxy where it's now living lodged in some far off asteroid or some comet or planet.
Manhole cover first man made object in Andromeda.
This was in what? the 50's? So it would have had to travel ~2 million light years in 70 years, so it would have had to hit several hundred thousand times the speed of light?
Nope, it would just have bursted due to thermal schock and pressure. Escape velocity, what are you dreaming, is the lid made of tungsten?
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."
Tl;dw: Vaporized
I disagree. He did the math assuming all the energy would be dissipated but that's assuming it came to a stop which is the whole debate. Essentially a mathy begging the question.
The jet of hot gasses coming up around and with the cover could've provided a good bit of protection from friction for the first bit (where the atmosphere would have the greatest effect) and ablative effects and the short travel time though the atmosphere could've been enough for a likely slightly smaller and very hot cover to blast into space.
I love the idea that our first message to aliens might be "FRESH WATER ONLY. NO WASTE."
Surprised no one has posted this but Kyle hill made a video on it
We should test this again, but with a fridge and someone inside it for the nuclear blast. I bet that would work out great
future president of the us perchance?
Where are we going to get the archaeologist?
Say there's a college grant inside, easy peasy
RIP jpgd to death
Slightly less recompressed version: https://imgur.com/2UHiL4r
Definitely easier to read thx
ifunny.c😀
The foundry that made that manhole cover has some great potential advertising claims.
Ok, tin foil hats for this one, our universe isn't exactly infinite in the way people traditionally think like numbers. The edges of the universe bend and form a large shape, say a sphere for simplicity. That cover speeds through and circles back eventually, but do to it's speed and travelling along the edges of everything and relativity, when it returns it's not at the same point or even at the same speed. It arrives before it initially left, quite a bit before it left... So much so that it kills off the dinosaurs.
Sadly, the escape velocity of our galaxy is an order of magnitude higher than the manhole cover's velocity. And even at that speed it wouldn't hit with nearly enough energy to cause a mass extinction. Still a fun idea though. :)
Humanity: did I do that? Hehehe
Most likely it just evaporated, or disintegrated or something, but I think its pretty unlikely it survived that absolutely bonkers acceleration.
How to solve the Three Body Problem.
The Parker Solar Probe moves 120 miles per second as it passes around the Sun. That's nearly half a million miles per hour!
Parker Solar Probe: 191 km per second.
Nuclear Manhole Cover: 55 km per second
Voyager 1: 17 km per second
Voyager 2: 15 km per second
So has it been replaced ?
What are the chances it was blasted into the sun?
Saying this with only an understanding of orbital mechanics learned from Kerbal Space Program, I'd say the chances are damn near 0%. Hitting the sun is actually pretty difficult and requires a precise amount of Δv (change in velocity). This thing had such a huge Δv that it would have left the solar system.
If the event was near the equatorial near midday then there's a very very (very) slim chance it was pointed directly at the sun.
If it was pointed directly at the sun, it would miss. Not that this would make the odds any better, but aiming straight at the sun doesn't work either.
In Stargate SG1 they do that to destroy and invading alien ship approaching Earth.
Maybe it desintegrated and thus vanished from the consecutive frame?
Atomic blasts are kind of powerful versus an iron lid.
Man. I haven't seen an ifunny logo in so long. Are people still on it?
