Tuesday, July 07, 2009
PIONEERING ACROSS THE UNIVERSE
There has been some argument over when the first launch into space was - anywhere from some of the V2 tests up to Sputnik - mostly depending on how low you count "space" as.
However there can be no doubt about the first launch that went up there & didn't come straight back down.
On August 27, 1957, astrophysicist Bob Brownlee and other Los Alamos scientists detonated an atom bomb at the bottom of a 500-foot, concrete-lined vertical tunnel drilled in the Nevada desert.
The goal of the test, codenamed Pascal-B, was to see what would happen if a plutonium bomb was accidentally detonated. The expected yield was equivalent to a few tons of TNT. A steel lid, 10 cm thick and weighing several hundred kilograms, was placed directly above the bomb; it was expected that it would be blown off, but nobody knew exactly how fast.
It turned out that the yield of the Pascal-B was closer to 300 tons of TNT; when the explosion vaporized the concrete walls of the shaft, the lid rose on a column of superheated gas and emerged at an unprecedented speed of 56 Km/sec, as confirmed by high-speed cameras and by some calculations made afterwards.
They never found it.
As the article points out escape velocity is 11.2 km/sec. he article suggests that it would have been vapourised on the way up by the atmosphere but I think this assume it went upblunt side up whereas if air pressure pushed it side on the vapourisation would be little more than with with a normal nickel-iron metero & ones of that size to reach Earth.
If so it got up there just over a month before Sputnik on 4th October 1957
Dr Brownlee reports
However there can be no doubt about the first launch that went up there & didn't come straight back down.
On August 27, 1957, astrophysicist Bob Brownlee and other Los Alamos scientists detonated an atom bomb at the bottom of a 500-foot, concrete-lined vertical tunnel drilled in the Nevada desert.
The goal of the test, codenamed Pascal-B, was to see what would happen if a plutonium bomb was accidentally detonated. The expected yield was equivalent to a few tons of TNT. A steel lid, 10 cm thick and weighing several hundred kilograms, was placed directly above the bomb; it was expected that it would be blown off, but nobody knew exactly how fast.
It turned out that the yield of the Pascal-B was closer to 300 tons of TNT; when the explosion vaporized the concrete walls of the shaft, the lid rose on a column of superheated gas and emerged at an unprecedented speed of 56 Km/sec, as confirmed by high-speed cameras and by some calculations made afterwards.
They never found it.
As the article points out escape velocity is 11.2 km/sec. he article suggests that it would have been vapourised on the way up by the atmosphere but I think this assume it went upblunt side up whereas if air pressure pushed it side on the vapourisation would be little more than with with a normal nickel-iron metero & ones of that size to reach Earth.
If so it got up there just over a month before Sputnik on 4th October 1957
Dr Brownlee reports
Ogle: And how fast is it going?"I very much regret that a Google search for the image in that one frame found nothing. I am sure it must still exist somewhere in US government records & would very much like to have been able to put it here. Perhaps sometime in future.
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."
Bill was quite delighted with the answer, for he had never before heard a velocity given in terms of the escape velocity from the earth! There was much laughter, and the legend was now born, for Bill loved to report to anybody who cared to listen about Brownlee's units of velocity. He says the cap would escape the earth. (But of course we did not believe that would ever happen.)
The next obvious decision was made. We'll put a high-speed movie camera looking at the cap, and see if we can measure the departure velocity.
In the event, the cap appeared above the hole in one frame only, so there was no direct velocity measurement. A lower limit could be calculated by considering the time between frames (and I don't remember what that was), but my summary of the situation was that when last seen, it was "going like a bat!!"
Labels: Science/technology, space
