Rumor has it that, in the 50s, an underground nuclear test smacked a manhole cover into space.
Is this possible?
I’m guessing any manhole covers close enough to the blast to achieve orbit would probably have been vaporized.
Okay, let’s think about this. According to Wiki, low earth orbital velocity is around 7,800 m/s. Kinetic energy equals 1/2 the mass times the square of the velocity, so a 40 kilogram manhole cover at 7,800 m/s has 1.22*10^9 Joules of kinetic energy. The specific heat of iron is 0.45 J/g-K. That’s enough energy to raise the temperature of 40 kg of iron 7,270 K. Iron boils at 3,134 K. I think we can put this one to bed.
Irrelevant, actually. You can’t blast anything from Earth into orbit, no matter how much oomph you give it. Either it comes right back down again, or (if you blast it fast enough) it escapes. To go into a closed orbit, you need to give the object another acceleration when it reaches the peak of its flight, to shift it from a trajectory which intersects the Earth to one that doesn’t.
Now, that said, if you don’t care about the thing staying in space, it’s not too hard to get it into space (depending on exactly how you define “space”. If, for instance, we call anything above 100 km “space”, then it’d only take 4*10[sup]7[/sup] J to get that 40 kg cover up there, or about 1/30 of your figure. Converting all of that to heat, we’re still below the melting point of iron, much less boiling.
I didn’t think they tested these things in the city 
Remembered this from an earleir thread.
http://boards.straightdope.com/sdmb/showthread.php?t=254753&highlight=manhole+cover
Actual article link:
http://www.strangehorizons.com/2002/20021021/manhole.shtml
Verdict- urban legend/tall story.
Otara
This sounds familiar.
I think it was the Pascal-B test in the Plumbbob test series.
Hang on though. Couldn’t you just blast it into geostationary orbit? It need only keep the angular momentum it had relative to the Earth’s centre - it doesn’t need any more. And isn’t that implicit in the statement that “either it comes back down again, or it escapes”… there’s a crossover point where it does neither?
Yeah but you’d have to be incredibly precise. You’d have to be NASA or something to figure it out.
And of course there are enough variations up there to bring something like that back down eventually.
Dunno - a ballistic trajectory should be a parabola (ignoring air resistance etc) - I’m not sure there can be such a thing as a ballistic trajectory that turns into a stable orbit. I don’t think you can even shoot it straight upwards to the point where it should be in a geostationary orbit, because angular momentum effects would make it go somewhere other than straight up.
It’s the same reason why you can’t throw a baseball from the space shuttle directly at the Earth and expect to hit it. Only in reverse.
Of course, the OP doesn’t say anything about orbit. It says “into space.”
Apart from that thing at the top. The thread title.
Nope. The problem with kicking something into orbit from a single impulse straight up is that you’re only giving it linear momentum, and ignoring any other contributions, it takes an involute path that won’t form a stable elliptical orbit. Now if you kick it off at a significant angle and juggle the contributions of atmospheric drag and gravitational coupling with absurd accuracy and hold your mouth just right you might be able to get it into an elliptical orbit, but not a circular one and certainly not a geostationary orbit, which would require a minimum of two burns (one to achieve the orbital energy state and one to circularize the orbit); from a practical standpoint (see below) this simply isn’t feasible. Although there are more nuances than just the Newtonian orbital mechanics, Chronos has it essentially right.
As for a crossover point where and object thrown straight up remains forever suspended, no; you’ll either have too little energy, in which it falls back, too much energy, in which it ‘escapes’ and essentialy moves at constant velocity (assuming no other gravitational or external force influences) or a metastable state where it continues to move away but at an ever decreasing rate on a shallow involute curve, but always bound to the Earth. In reality, once it leaves the Earth’s sphere of influence it’ll then be in a more-or-less Earth-like orbit of the Sun, and perturbations by the other planets will either kick it off or cause it to fall back around the Earth in a chaotic and unstable orbit like Cruithne.
The object in question by the o.p. is in fact the nuclear test bore cap (not a manhole cover–much larger and heavier) of the Pascal B test of the Operation Plumbbob nuclear weapon test series. While is may well have acheived escape velocity (this based on a single frame image of the cap), aerodynamic loads and ram pressure heating would have turned the object into metallic vapor long before it entered space.
Stranger
Blimey!
When the plane landed, the infant was sitting happily on the wing.
Guess what it had in it’s mouth?
When the smoke cleared, the manhole cover was in the next parking space, nestled in a case of Orbit® Gum. 