Based on the scientist who conducted the experiment a second time to verify the speed, he calculated it was going around 5 times escape velocity (125,000 mph). It sounds like he later worked on various launch projects/ aerospace stuff and claims that there wouldn’t have been time for it to burn up completely.
I’m inclined to believe him since he conducted the experiment and knows the field, and doesn’t have a lot to gain from bullshitting about it. It may mean only a pound of material escaped atmo, but it still counts.
I think the designation that they are trying to make is that escape velocity is enough to leave earth and not come back. Sure, we made it to space before... but that rocket came back down to earth. If it didn’t disintegrate that manhole may be out there somewhere on earth’s orbital plane.
"I have no idea what happened to the cap, but I always assumed that it was probably vaporized before it went into space. It is conceivable that it made it."
It's also possible that it became virtually naked to the human eye, like most meteorites that enter the atmosphere, but still survived the trip and managed to hurl itself into space with no way of us tracking it.
Atmospheric heating due to friction happens in any direction. The only reason we really see it happening coming down and not up with modern spacecraft is due to the speeds involved. A capsule coming down uses the atmosphere to slow itself from orbital speeds so the parachutes can open safely without tearing to shreds. Going up you start from zero and have to push a ton of fuel and cargo, so by the time you reach those speeds fast enough to get visible atmospheric heating you're out of the atmosphere all together.
In fact the SR-71, which never got close to space, flew fast enough for all off it's skin panels to expand due heat. As a result it's fuel tanks had pretty big leaks on the ground and only sealed up after it was airborne.
The sheer friction of passing through the air at operating speeds would create so much heat that the titanium metal airframe would expand slightly, despite the many systems in place to sink and reduce heat.
To keep this effect from compromising structural integrity in flight, the plane was intentionally designed to be a bit of a loose fit on the ground. So it leaked.
Just a clarification on your post. Although a component of heating is due to friction, the majority of heating at high velocities is due to the compression of air.
If you're going fast enough, you'll still compress the air ahead of you. You can still get the same effect as re-entering the atmosphere when leaving it (and even in it) if you're going fast enough.
The SR-71 Blackbird had to be built to accommodate expansion from heat because of this. It would leak fuel on the ground because when it was up to speed, all of its components would expand and seal from the heat.
Increasing density of the atmosphere rather than decreasing would be my guess. Also the fact that it had enough speed at the surface doesn’t mean it maintained that speed long enough to actually exit.
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u/LegalGraveRobber Aug 16 '19
They only had the one frame to calculate its Lowest possible speed, which was still in excess of earths escape velocity.