back to article Did speeding American manhole cover beat Sputnik into space? Top boffin speaks to El Reg

As any space enthusiast knows, beachball-sized Sputnik was the first manmade object to orbit the Earth after it was launched by the Soviets in October 1957. But it's possible the US managed to put an object into space a few months before that. In 1956, astrophysicist Dr Robert Brownlee was asked by his boss at the Los Alamos …

Re: First ORION launch?

And indeed the Plumbbob tests are mentioned in George Dyson's book 'Project Orion: The True Story of the Atomic Spaceship'.

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Anthony Zuppero has an interesting, but rambling, document of other nuclear (and space) related things:

http://www.neofuel.com/inhabit/inhabit.pdf

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DJV
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Joke

If manhole covers look a bit like dustbin lids...

...then I suspect it may have landed here.

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Joke

Re: If manhole covers look a bit like dustbin lids...

Ooops, someone dropped a Clanger

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Father Ted

If he were still around, it would surely land on his head.

Dr. Brownlee fails to mention whether the plug was adorned with "Shit Happens", but that would be a nice touch.

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Anonymous Coward

Karl pilkington knew it

This is probably the incident that Karl was referring to in the xfm show

http://www.pilkipedia.co.uk/wiki/index.php?title=24_August_2002

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Anonymous Coward

Answer to question in headline is (nearly always) "no"

See https://en.wikipedia.org/wiki/Impact_depth

The Earth's atmosphere is roughly equivalent, in kilograms per square metre, to about ten metres of water. You can't shoot a manhole cover through ten metres of water, either, I would guess, though I've not tried it.

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As the lid sped into space, it was heard to say ....

... HOLY FECK !

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Re: As the lid sped into space, it was heard to say ....

By the bowl of petunias?

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Re: As the lid sped into space, it was heard to say ....

Or maybe

I gotta get outta this place // if it's the last thing I ever do

With the volume turned up to, er, 11^11 ?

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Anonymous Coward

No manhole covers involved

FYI - A concrete and steel cap is not a manhole cover. A manhole cover is just made of cast iron or steel, no concrete. Chances are the concrete was vaporized but not the steel which may or may not have made it into space.

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(Written by Reg staff)

Re: No manhole covers involved

I stood on a concrete manhole cover once. It cracked; I stepped off. The next person to stand on it fell in.

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Coat

Re: No manhole covers involved @ Gaz

Err - would it be too rude to suggest you might need to go on a diet?

Thanks - its that nice slim one that doesn't quite fit.

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Headmaster

Re: No manhole covers involved

Surely a manhole cover is defined by function? Sounds like they drilled a shaft, lowered the device down and covered it. No mention of a man (or other person) entering the shaft, so it's a shaft cover or hole cover or lid, not a manhole cover.

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Thumb Up

" ... the hypersonic expanding column of vaporized concrete ..."

Icon: For the phraseology

But why does a certain luvvie come to mind ?

F*y me to the moon.

and let me play among the stars ...

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Lost or vaporised

Was the manhole / hatch inscribed with the numbers 4 8 15 16 23 42 ?

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Heads or Tails?

Call it, and find it on the moon.

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It was an inspiration

Skip forward a few years, and the "sport" of anvil shooting was born:

https://www.youtube.com/watch?v=IhQ4dE_RGnQ

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Mushroom

Plot Device

And thus, the plot/plot complication for The Martian Returns/Gravity 2 was birthed. Extra points if the plug/cover has "V GER" scribed somewhere on it.

Icon b/c it's oddly appropriate.

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Flame

Numbers, man, numbers!

I ran the numbers on this event a while back during a discussion about it in an email bounce...

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Working the numbers as I go along while poking Dickipedia with a long stick... specific heat of steel averages 620J/kg per deg C. The steel lid is about 600 cubic inches if the size you give is correct, that's about 10,000 ccs in volume. Typical steel density is 7.9 g/cc so the lid weighed 790kg. Melting point of steel is about 1500 deg C so it would take 620 x 1500 x 790 Joules or about 750 MJ for complete slagging of the plate. I am ignoring any radiation heating from the explosion (X-rays, neutrons, gamma flux etc.) as I assume the cap was a last-defence thing and not directly coupled to the Device which was Exploding (i.e. it was not line-of-sight to the device).

Assuming the 50km/sec figure at ground level is correct and that is a SWAG at best -- explosive-gas-driven devices such as artillery shells top out at about 2 km/sec and light-gas guns using hydrogen or similar low-mass gasses are not that much faster -- then its kinetic energy on "takeoff" was 1/2 M x V^2 = 1/2 x 790 x 50 x 50 x 10^6 = 1TJ or over a thousand times as much energy as required to melt it completely. The Pascal-B shot only yielded about 300 tonnes equivalent, or about 1.25TJ which would mean the explosion would have to have expended 80% of its energy in driving the plate to that speed.

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There are other factors which also indicate the manhole cover never reached anything like escape velocity -- the shaft to the Pascal-B device was 150 metres deep and about 1 metre square assuming the size of the cap so there's another 180kg of air to be accelerated up to at least 50km/s before it hits the underside of the cover. There's also friction with the walls of the shaft, energy losses in compressing and heating that much gas etc.

Pity.

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if true, very funny the 1st satellite was a manhole cover...in July 1957.....

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