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.
Klear@sh.itjust.works
on 03 Dec 10:49
nextcollapse
Unfortunately they got almost everything else wrong though. Mainly - the cover actually almost certainly just vaporiserd.
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.
very_well_lost@lemmy.world
on 02 Dec 18:37
nextcollapse
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.
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.
It would spread outward a bit, but the entire kinetic energy and momentum in the system would remain the same. But, the more it broke apart, the more surface area it would have. The more surface area, the more surface exposed to heating. The more heating, the more it would break apart. I’m guessing that it was a silicon, iron and oxygen plasma without individual grains by the time it hit the upper atmosphere.
The atmosphere is just about 10 kg/m^2 in sectional density; the manhole cover was very likely higher than that, wouldn’t that mean the cover’s mass should have come out at the other side, intact or not?
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.
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.
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.
I don’t know that that makes a huge difference to the physics involved, though it certainly may have.
But in that case we’re talking about human survivability, and a chunk of solid iron is going to survive a whole lot longer than humans or delicate instrumentation. It might look a little worse for the wear, but it’s much more likely to be recognizable after the whole experience than anything designed for people.
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.
But after initial heating, the air cushion begins heating itself up instead of the object, reducing the amount of heat the object receives.
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.
But it would also tail off as the bore cap heated, reducing stresses on it as it went higher.
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.
True, but on the other hand the a Apollo heat shield wasn’t designed to convect heat to other parts of itself. And again, it had a much harder job (keep the Apollo command module at human-survivable temperatures) than the bore cap (not reach the boiling point of iron).
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.
All the stuff I read only mentioned the iron, but keep in mind that it has to not only reach the melting point but also undergo phase change, which requires a lot more energy.
I don’t know where you’re getting the maximum of 22MJ of energy.
11 kJ per m² per second was the peak amount of energy that the Apollo heat shield encountered. Double that for the approximately two seconds it would’ve been in atmosphere, and it’s a pretty handy approximation since the bore cap was about a meter itself.
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. […] 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.
You’re right, the total amount would’ve been a way better approximation than the peak. Worth looking into.
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.
I don’t have any argument with that. I think the outer surface would definitely have begun to melt.
Would it all have melted / vaporized / plasmafied away? I don’t know, it’s a huge plug.
Yep. Even just considering the amount of time it would take for the heat to excite all the molecules in the massive chunk of iron, and then for them all to undergo phase change, I just don’t think it could’ve made it.
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.
That’s something I couldn’t find information on: is iron’s tensile strength high enough to prevent the thing shattering apart on contact with air? I’m inclined to think it is—chunks of meteorites bigger than a meter have made it through the atmosphere, for instance. The Hoba meteorite is estimated to only be slightly bigger than it
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.
I don’t know that that makes a huge difference to the physics involved, though it certainly may have.
Of course it will make a difference. The whole challenge is about managing the heat build-up, which is the energy per second (i.e. power). If you hit the thin upper atmosphere you’re encountering less material, so less friction / pressure, so less heating. It means you can keep the heat on the heat shield in a manageable range, rather than putting it at a temperature where it would melt or explode.
the air cushion begins heating itself up instead of the object, reducing the amount of heat the object receives.
No, both heat up. The air cushion transfers its heat to the object next to it. At the kinds of pressures we’re talking about, you might even be getting nitrogen plasma rather than just nitrogen gas.
But it would also tail off as the bore cap heated, reducing stresses on it as it went higher.
If it went high enough for that to matter. If it disintegrated in the lower atmosphere it wouldn’t matter that the air got thinner in the upper atmosphere.
chunks of meteorites bigger than a meter have made it through the atmosphere, for instance
Is a metre the original size, or the final size? Also, reverse meteors (something starting with its maximum speed in the lower atmosphere) are doing things the hard way. Rather than getting slowed down initially by the thin upper atmosphere and then only hitting the thick atmosphere once they’re slower, they start out in the thickest atmosphere. OTOH, a meteor is a random collection of rock and metal formed by gravity in space. A pure metal plug cast on Earth is probably going to be a lot less prone to breaking apart.
the bore cap starting at the bottom of the atmosphere means that it’s likely it experienced less fracture stress, since the air would’ve accelerated with it rather than being static.
That doesn’t make sense to me. Something in a thicker medium is going to experience more stress. Try pushing a cracker through the air vs. through water vs. through gelatin. Which medium will cause the cracker to crack first? Obviously it’s the thicker medium.
Most of this is going to be “eh, agree to disagree” because we just don’t have enough data. But I do want to call out a couple of things:
No, both heat up. The air cushion transfers its heat to the object next to it.
Over time, yes. But the bore cap doesn’t have very much of it. Heat transfer is not instantaneous; would it be long enough for the air to transfer its heat to the object, before the object reaches the Karman Line? Radiation is pretty quick (like, speed-of-light quick), but conduction is much slower; particularly when one of the bodies (the air) is an insulator. And with iron being an excellent conductor, any heat transferred will be spread throughout the body more quickly than it can be absorbed.
If it disintegrated in the lower atmosphere it wouldn’t matter that the air got thinner in the upper atmosphere.
True, but it’s not like there’s a line (er, well, I mean, not a physical demarcation…there is the Karman Line, but…ah, you know what I mean). Atmospheric density is a decreasing gradient from the ground to the Karman Line. So as it approaches its mechanical and physical limits, the amount of energy acting upon it decreases millisecond by millisecond. Is that enough to save it? Shrug. Not enough data. But it’s possible.
Is a metre the original size, or the final size? [of the meteorite chunk]
Actually it’s almost three meters, and as far as we can guess that was about its original size. Though in fairness, it was entering the atmosphere at a steeper angle and may even have come down entirely in “dark flight.” Still, there are other large meteorites which have impacted at a size greater than 1 meter across, though obviously we have no way to confirm exactly how big they were before they landed.
Rather than getting slowed down initially by the thin upper atmosphere and then only hitting the thick atmosphere once they’re slower, they start out in the thickest atmosphere. […] Something in a thicker medium is going to experience more stress. Try pushing a cracker through the air vs. through water vs. through gelatin. Which medium will cause the cracker to crack first? Obviously it’s the thicker medium.
True! But remember, the “reverse meteor” (great phrase, btw) is not hitting the stationary atmosphere at full speed like a regular meteor (or space capsule) does. The iron plug accelerated (incredibly quickly, but it did accelerate) while already in contact with the air above it. This means that the air accelerated at the same rate the iron did, reducing the fracture forces that would seek to crack it. Imagine the difference between swishing your hand in a swimming pool vs. slapping the surface of a swimming pool; it may require more force, but it won’t hurt as badly.
OTOH, a meteor is a random collection of rock and metal formed by gravity in space. A pure metal plug cast on Earth is probably going to be a lot less prone to breaking apart.
Oh, great point, and one I hadn’t thought about. Something that’s an aggregate of 80% iron and 20% “other stuff” isn’t going to have nearly as much tensile strength as a homogeneous plate of iron.
IrritableOcelot@beehaw.org
on 02 Dec 18:46
nextcollapse
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.
DaddleDew@lemmy.world
on 02 Dec 19:21
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In Stargate SG1 they do that to destroy and invading alien ship approaching Earth.
DaddleDew@lemmy.world
on 02 Dec 19:27
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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!”
deadbeef79000@lemmy.nz
on 02 Dec 20:18
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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.
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.
Good_morning@lemmynsfw.com
on 02 Dec 20:05
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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.
YarHarSuperstar@lemmy.world
on 02 Dec 20:19
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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. :)
chuckleslord@lemmy.world
on 02 Dec 21:30
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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.
ICastFist@programming.dev
on 02 Dec 21:56
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We should test this again, but with a fridge and someone inside it for the nuclear blast. I bet that would work out great
Hossenfeffer@feddit.uk
on 03 Dec 09:41
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Where are we going to get the archaeologist?
ICastFist@programming.dev
on 03 Dec 18:56
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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.
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.
dragonfucker@lemmy.nz
on 03 Dec 04:16
nextcollapse
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.
mindbleach@sh.itjust.works
on 03 Dec 17:18
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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
user1234@lemmynsfw.com
on 03 Dec 01:11
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The foundry that made that manhole cover has some great potential advertising claims.
Professorozone@lemmy.world
on 03 Dec 03:51
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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.
finitebanjo@lemmy.world
on 03 Dec 04:15
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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.
Exactly. It’s the minimum speed required to get into orbit assuming you get the direction correct. If you launch vertically, you’ll almost certainly come back down, no matter how far out into space you go. The only consideration is that if you go far enough out you might be influenced by the gravity of something else like the moon which could change your trajectory.
42.1 km/s is the speed required relative to the sun’s surface for objects launching from Earth’s surface. You need to look at the value labelled V_te, which is the speed relative to the minor body the object is launching from. In this case, it is 16.6 km/s.
RememberTheApollo_@lemmy.world
on 03 Dec 03:59
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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
on 03 Dec 04:16
nextcollapse
It didn’t stay solid upon initial blast impact. Probably didn’t even stay liquid.
I don’t count having no visual indication of the object as “tracking” it, if we’re talking semantics. One frame could equal an even faster speed than what it would minimally take to cross the entire width of the image at some trajectory vector. For other vectors, it could be (much) less (like not passing straight through the image from on side to the opposite side, e.g.).
It’s important to not hang too hard on this as the escape speed is dependent on air resistance, or rather lack thereof. Those escape speed numbers are defined along with the assumption of zero air resistance or other forces acting on the object.
No, not really. The object was placed directly above the payload beneath a 150M straight borehole. If there was some sort of angle to the hole them I’m sure the researchers would have accounted for it.
Idk what you think trajectory means but they know the angle the steel cap shot off at and they know the angle and distance from which the high speed camera viewed it. There is no room for ambiguity, they calculated the minimum speed. There are no outside forces that could have curved the shot, either. An 900kg object going any number of kilometers per second won’t be effected by windspeed for example.
You’re just making an ass of yourself, speaking nonsense.
Trajectory means what it means. Look it up and we’ll have the same understanding of it.
You’re saying the trajectory is known, and I’m saying that in that case what you’ve been saying should be correct. Maybe if you fuckin relax and don’t attack someone just because you don’t understand what they’re saying you’d not come off as such an asshole. Jesus Christ, Mr. Hothead.
An 900kg object going any number of kilometers per second won’t be effected by windspeed for example.
Uh. Excuse me? How much do you think an aeroplane might weigh? 😆 Probably more than 900 kg. And the wind speed is probably not the issue. It would be the drag. 👌
So anyway. Let’s relax in the next comment, shall we? Let’s have a nice discussion from now on, no attacking. That would be cool, and adult.
tbf the calculated speed is actually roughly the minnimum based on its starting position and the frame it appeared in. it could have actually been going even faster.
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.”
IrritableOcelot@beehaw.org
on 05 Dec 05:07
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Hypersonic heating is really weird. We only have data going to about mach 17 (the HTV-2 was the fastest solidly atmospheric vehicle I found) but as we go from subsonic, to supersonic, to hypersonic regimes air becomes pretty much incompressible, and forms a really solid shockwave in front of a fast-moving object. Air is a pretty good thermal insulator, so for very fast, blunt objects they actually heat much slower than you might expect.
Tl;Dr it absolutely vaporized, but it likely lasted longer than you might expect.
RizzRustbolt@lemmy.world
on 03 Dec 13:45
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How to solve the Three Body Problem.
captain_aggravated@sh.itjust.works
on 03 Dec 19:46
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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
on 04 Dec 01:32
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In my head I know you’re right but my heart wants this.
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.
captain_aggravated@sh.itjust.works
on 04 Dec 02:54
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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?
anothercatgirl@lemmy.blahaj.zone
on 04 Dec 07:04
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It’s not going fast enough to escape the Milky Way Galaxy.
The escape velocity for the solar system and from Earth’s surface should not be the same. This is why you should always double check anything ChatGPT says.
pineapplelover@lemm.ee
on 04 Dec 07:20
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Man. I haven’t seen an ifunny logo in so long. Are people still on it?
threaded - newest
There is one detail wrong in the first post; that is not the lids speed but rather it’s minimum speed.
Notice, children, how the common apostrophe from lid’s migrated all the way to its.
Isn’t nature amazing?
What makes it more amazing is I understood without even noticing the mistake.
Curious, that doesn’t seem amazing at all. But to each their own!
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.
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.
theregister.com/…/america_soviets_space_race/
Sadly, the cover likely did burn up in the atmosphere at those speeds, like a meteorite in reverse.
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.
<img alt="" src="https://slrpnk.net/pictrs/image/542f4596-a7f7-4421-a360-9ae84d2a09d2.gif">
So sad about what happened to planet Kerbin.
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.
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.
Vaporization would certainly slow the material. It’s transitioning kinetic energy into thermal.
Also, the vaporized iron would disperse outward rather than stay coherent.
It would spread outward a bit, but the entire kinetic energy and momentum in the system would remain the same. But, the more it broke apart, the more surface area it would have. The more surface area, the more surface exposed to heating. The more heating, the more it would break apart. I’m guessing that it was a silicon, iron and oxygen plasma without individual grains by the time it hit the upper atmosphere.
The atmosphere is just about 10 kg/m^2 in sectional density; the manhole cover was very likely higher than that, wouldn’t that mean the cover’s mass should have come out at the other side, intact or not?
It was being propelled by a nuclear blast. The speed was calculated from 1 frame of a high speed camera. It most definitely vaporized.
Yes, it absolutely would have vaporized before exiting the atmosphere.
Here’s a video on the subject: www.youtube.com/watch?v=mntddpL8eKE
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.
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.
I don’t know that that makes a huge difference to the physics involved, though it certainly may have.
But in that case we’re talking about human survivability, and a chunk of solid iron is going to survive a whole lot longer than humans or delicate instrumentation. It might look a little worse for the wear, but it’s much more likely to be recognizable after the whole experience than anything designed for people.
But after initial heating, the air cushion begins heating itself up instead of the object, reducing the amount of heat the object receives.
But it would also tail off as the bore cap heated, reducing stresses on it as it went higher.
True, but on the other hand the a Apollo heat shield wasn’t designed to convect heat to other parts of itself. And again, it had a much harder job (keep the Apollo command module at human-survivable temperatures) than the bore cap (not reach the boiling point of iron).
All the stuff I read only mentioned the iron, but keep in mind that it has to not only reach the melting point but also undergo phase change, which requires a lot more energy.
11 kJ per m² per second was the peak amount of energy that the Apollo heat shield encountered. Double that for the approximately two seconds it would’ve been in atmosphere, and it’s a pretty handy approximation since the bore cap was about a meter itself.
You’re right, the total amount would’ve been a way better approximation than the peak. Worth looking into.
I don’t have any argument with that. I think the outer surface would definitely have begun to melt.
Yep. Even just considering the amount of time it would take for the heat to excite all the molecules in the massive chunk of iron, and then for them all to undergo phase change, I just don’t think it could’ve made it.
That’s something I couldn’t find information on: is iron’s tensile strength high enough to prevent the thing shattering apart on contact with air? I’m inclined to think it is—chunks of meteorites bigger than a meter have made it through the atmosphere, for instance. The Hoba meteorite is estimated to only be slightly bigger than it
Of course it will make a difference. The whole challenge is about managing the heat build-up, which is the energy per second (i.e. power). If you hit the thin upper atmosphere you’re encountering less material, so less friction / pressure, so less heating. It means you can keep the heat on the heat shield in a manageable range, rather than putting it at a temperature where it would melt or explode.
No, both heat up. The air cushion transfers its heat to the object next to it. At the kinds of pressures we’re talking about, you might even be getting nitrogen plasma rather than just nitrogen gas.
If it went high enough for that to matter. If it disintegrated in the lower atmosphere it wouldn’t matter that the air got thinner in the upper atmosphere.
Is a metre the original size, or the final size? Also, reverse meteors (something starting with its maximum speed in the lower atmosphere) are doing things the hard way. Rather than getting slowed down initially by the thin upper atmosphere and then only hitting the thick atmosphere once they’re slower, they start out in the thickest atmosphere. OTOH, a meteor is a random collection of rock and metal formed by gravity in space. A pure metal plug cast on Earth is probably going to be a lot less prone to breaking apart.
That doesn’t make sense to me. Something in a thicker medium is going to experience more stress. Try pushing a cracker through the air vs. through water vs. through gelatin. Which medium will cause the cracker to crack first? Obviously it’s the thicker medium.
Most of this is going to be “eh, agree to disagree” because we just don’t have enough data. But I do want to call out a couple of things:
Over time, yes. But the bore cap doesn’t have very much of it. Heat transfer is not instantaneous; would it be long enough for the air to transfer its heat to the object, before the object reaches the Karman Line? Radiation is pretty quick (like, speed-of-light quick), but conduction is much slower; particularly when one of the bodies (the air) is an insulator. And with iron being an excellent conductor, any heat transferred will be spread throughout the body more quickly than it can be absorbed.
True, but it’s not like there’s a line (er, well, I mean, not a physical demarcation…there is the Karman Line, but…ah, you know what I mean). Atmospheric density is a decreasing gradient from the ground to the Karman Line. So as it approaches its mechanical and physical limits, the amount of energy acting upon it decreases millisecond by millisecond. Is that enough to save it? Shrug. Not enough data. But it’s possible.
Actually it’s almost three meters, and as far as we can guess that was about its original size. Though in fairness, it was entering the atmosphere at a steeper angle and may even have come down entirely in “dark flight.” Still, there are other large meteorites which have impacted at a size greater than 1 meter across, though obviously we have no way to confirm exactly how big they were before they landed.
True! But remember, the “reverse meteor” (great phrase, btw) is not hitting the stationary atmosphere at full speed like a regular meteor (or space capsule) does. The iron plug accelerated (incredibly quickly, but it did accelerate) while already in contact with the air above it. This means that the air accelerated at the same rate the iron did, reducing the fracture forces that would seek to crack it. Imagine the difference between swishing your hand in a swimming pool vs. slapping the surface of a swimming pool; it may require more force, but it won’t hurt as badly.
Oh, great point, and one I hadn’t thought about. Something that’s an aggregate of 80% iron and 20% “other stuff” isn’t going to have nearly as much tensile strength as a homogeneous plate of iron.
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.
So has it been replaced ?
In Stargate SG1 they do that to destroy and invading alien ship approaching Earth.
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!”
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
That quote is not from the first one though, it’s from the second one
Balls exposed 🙀🙀🙀🙀
Citadel lobby, yes.
Sorry! :(
I love the idea that our first message to aliens might be “FRESH WATER ONLY. NO WASTE.”
What are the chances it was blasted into the sun?
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.
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.
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.
Humanity: did I do that? Hehehe
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. :)
youtu.be/mntddpL8eKE
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.
We should test this again, but with a fridge and someone inside it for the nuclear blast. I bet that would work out great
Where are we going to get the archaeologist?
Say there’s a college grant inside, easy peasy
future president of the us perchance?
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.
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.
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.
You refer to yourself as “drag” in the third person, rather than just say “me”?
No, drag is using drag’s first person pronoun, drag.
Well that’s a drag.
Drag am using it?
Drag’s pronoun isn’t inflected like that.
– Douglas Adams, The Hitchhiker’s Guide To The Galaxy
The foundry that made that manhole cover has some great potential advertising claims.
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.
Also it would have atomized.
Gotta love Tumblr. Just massive amounts of disinformation and bullshit all the time.
yeah, and it is not “research” to check it. They literally teach it in primary school physics.
Not in our freedom schools!
I mean, what for? Knowing that number isn’t a life skill.
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?
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I didn’t see that reference but the image is all blurry now.
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.
Escape velocity means you could stay in orbit. It doesn’t guarantee anything if you launch at the wrong angle.
Exactly. It’s the minimum speed required to get into orbit assuming you get the direction correct. If you launch vertically, you’ll almost certainly come back down, no matter how far out into space you go. The only consideration is that if you go far enough out you might be influenced by the gravity of something else like the moon which could change your trajectory.
That is not the definition of escape velocity. Escape velocity is the minimum velocity to escape a body’s gravity well entirely. Orbital is much lower
That is not the definition of escape velocity. Escape velocity is the minimum velocity to escape a body’s gravity well entirely. Orbital is much lower
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.
Source: en.m.wikipedia.org/wiki/Escape_velocity
42.1 km/s is the speed required relative to the sun’s surface for objects launching from Earth’s surface. You need to look at the value labelled V_te, which is the speed relative to the minor body the object is launching from. In this case, it is 16.6 km/s.
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.
It didn’t stay solid upon initial blast impact. Probably didn’t even stay liquid.
Yeah it vanished because it vaporized.
I think they were able to track it for at least 2 frames, thus calculate it’s speed.
Nope, just one frame. Adds to the myth, when people don’t know the exact speed.
One frame before the blast and one frame after, but semantics.
I don’t count having no visual indication of the object as “tracking” it, if we’re talking semantics. One frame could equal an even faster speed than what it would minimally take to cross the entire width of the image at some trajectory vector. For other vectors, it could be (much) less (like not passing straight through the image from on side to the opposite side, e.g.).
It’s important to not hang too hard on this as the escape speed is dependent on air resistance, or rather lack thereof. Those escape speed numbers are defined along with the assumption of zero air resistance or other forces acting on the object.
You can use the frame from before to calculate the MINIMUM speed. It could have been going even faster.
Or slower, depending on trajectory across the image.
No, not really. The object was placed directly above the payload beneath a 150M straight borehole. If there was some sort of angle to the hole them I’m sure the researchers would have accounted for it.
Right. Then the angle is such that you could calculate it. But it still depends on the trajectory, so that’s not wrong, for whoever down voted…
Lmao you’re so confused
About what am I confused? How about you present an argument instead of just down voting? Please elaborate, thank you.
Idk what you think trajectory means but they know the angle the steel cap shot off at and they know the angle and distance from which the high speed camera viewed it. There is no room for ambiguity, they calculated the minimum speed. There are no outside forces that could have curved the shot, either. An 900kg object going any number of kilometers per second won’t be effected by windspeed for example.
You’re just making an ass of yourself, speaking nonsense.
Trajectory means what it means. Look it up and we’ll have the same understanding of it.
You’re saying the trajectory is known, and I’m saying that in that case what you’ve been saying should be correct. Maybe if you fuckin relax and don’t attack someone just because you don’t understand what they’re saying you’d not come off as such an asshole. Jesus Christ, Mr. Hothead.
Uh. Excuse me? How much do you think an aeroplane might weigh? 😆 Probably more than 900 kg. And the wind speed is probably not the issue. It would be the drag. 👌
So anyway. Let’s relax in the next comment, shall we? Let’s have a nice discussion from now on, no attacking. That would be cool, and adult.
What a clown
Very eloquent rebuttal. 👌 Big L. 😆
tbf the calculated speed is actually roughly the minnimum based on its starting position and the frame it appeared in. it could have actually been going even faster.
Pretty sure that’s not really true though.
It isn’t speed.
lol what
Take a coin and trow it as hard as you can. The curving is not that much.
If it’s like a frisbee, yeah, but it still curves. Now start it spinning like spinning a coin on edge. The curving will be much more dramatic.
Throw it into water or gelatin. At thousands of metres per second the air is going to seem much more dense.
I don’t have the arm strength to trow anything at the speed needed to make your analogy work.
Hit the gym, delete the lawyer, face the book.
Surprised no one has posted this but Kyle hill made a video on it
Most likely it just evaporated, or disintegrated or something, but I think its pretty unlikely it survived that absolutely bonkers acceleration.
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.
Hypersonic heating is really weird. We only have data going to about mach 17 (the HTV-2 was the fastest solidly atmospheric vehicle I found) but as we go from subsonic, to supersonic, to hypersonic regimes air becomes pretty much incompressible, and forms a really solid shockwave in front of a fast-moving object. Air is a pretty good thermal insulator, so for very fast, blunt objects they actually heat much slower than you might expect.
Tl;Dr it absolutely vaporized, but it likely lasted longer than you might expect.
How to solve the Three Body Problem.
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.
In my head I know you’re right but my heart wants this.
If we kill him he never will have said it and the manhole cover will be in space.
I like the energy.
You’ll have to kill Kyle Hill too.
That I’d do for free.
As much energy to put a manhole in space?
As much energy to put a man, whole, in space
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?
It’s not going fast enough to escape the Milky Way Galaxy.
.
The Parker Solar Probe moves 120 miles per second as it passes around the Sun. That’s nearly half a million miles per hour!
en.wikipedia.org/wiki/Parker_Solar_Probe
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
RIP jpgd to death
Slightly less recompressed version: imgur.com/2UHiL4r
Definitely easier to read thx
Fact check , some of those comparisons were wrong. chatgpt.com/…/674ffea4-35e8-800a-8e9a-555180b4c18…
Don’t use gpt to fact check.
The escape velocity for the solar system and from Earth’s surface should not be the same. This is why you should always double check anything ChatGPT says.
Man. I haven’t seen an ifunny logo in so long. Are people still on it?
Maybe it desintegrated and thus vanished from the consecutive frame?
Atomic blasts are kind of powerful versus an iron lid.