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

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

Notice, children, how the common apostrophe from lid's migrated all the way to its.

Isn't nature amazing?

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

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

Also it would have atomized.

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'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.

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

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.

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

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

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."

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.

Slightly less recompressed version: https://imgur.com/2UHiL4r

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. :)