Skip to comments.Manhole Covers in Space
Posted on 06/27/2009 11:13:51 PM PDT by ErnstStavroBlofeld
A question on the letters page of the September 2002 issue of Fortean Times -- a British magazine which covers fringe science or "Fortean" subjects -- piqued my interest. Was it true that a manhole cover, accidentally blasted upwards at escape velocity during the American nuclear tests in the 1950s, was in fact the first manmade object in space, beating Sputnik 1 by a long way? Or was it just an urban myth?
The Internet is the natural home of the urban myth: the two could have been made for each other. The question therefore was: could it find room for the truth as well?
It's often thought necessary to give dire warnings about not trusting anything you see or read online. I would go further -- don't trust ANY source implicitly. The advice my history teacher gave me all those years ago seems to me to apply as well to the net as to anything else: When considering the validity of a source, ask yourself these questions: who created it, when (especially in relation to the events described), and why? With this in mind, and convinced that the story had to be nonsense, I nonetheless made some enquiries on the Internet, using Google as my base.
Here's what I found out.
"The first man-made object sent into space was a manhole cover which by now has travelled well past Pluto!" (SAAO). Sadly, the link promising the 'full story' is broken. Isn't it always the way?
(Excerpt) Read more at strangehorizons.com ...
I think that they vould be vaporized by a undeground nuke
The February/March 1992 issue of Air & Space magazine, published by the Smithsonian, contained an article about nuclear rocket propulsion and this incident.
No. It was Timothy Leary in some experiments prior to the mushroom thing.
parsy, who just knows Tim is up there somewhere
The February/March 1992 issue of Air & Space magazine, published by the Smithsonian, contained an article about nuclear rocket propulsion:
“Every kid who has put a firecracker under a tin can understands the principle of using high explosives to loft an object into space. What was novel to scientists at Los Alamos [the atomic laboratory in New Mexico] was the idea of using an atomic bomb as propellant. That strategy was the serendipitous result of an experiment that had gone somewhat awry.
“Project Thunderwell was the inspiration of astrophysicist Bob Brownlee, who in the summer of 1957 was faced with the problem of containing underground an explosion, expected to be equivalent to a few hundred tons of dynamite. Brownlee put the bomb at the bottom of a 500-foot vertical tunnel in the Nevada desert, sealing the opening with a four-inch thick steel plate weighing several hundred pounds. He knew the lid would be blown off; he didn’t know exactly how fast. High-speed cameras caught the giant manhole cover as it began its unscheduled flight into history. Based upon his calculations and the evidence from the cameras, Brownlee estimated that the steel plate was traveling at a velocity six times that needed to escape Earth’s gravity when it soared into the flawless blue Nevada sky. ‘We never found it. It was gone,’ Brownlee says, a touch of awe in his voice almost 35 years later.
“The following October the Soviet Union launched Sputnik, billed as the first man-made object in Earth orbit. Brownlee has never publicly challenged the Soviet’s claim. But he has his doubts.”
This article appears to be largely responsible for the presence of the “Sputnik manhole cover” legend on the Internet, where it has been often discussed. It does not identify the test, but from the information in the article it can be deduced that it had to be Pascal-B, which has since be confirmed to me by Dr. Brownlee
The article is more-or-less accurate, but gives a false impression of what was actually known about the plate’s journey (and is wrong in its use of the term Project Thunderwell). For an authentic account of this incident by Dr. Robert Brownlee himself, this web site is pleased to host:Learning to Contain Underground Nuclear Explosions.
As Dr. Brownlee explains, the figure of “a velocity six times that needed to escape Earth’s gravity” refers to the results of a simulation, that may not of been a good model of the actual test conditions (the actual yield for example, was unknown even if all other parameters were correct). No measurement of the actual plate velocity was made.
If the description of the plate is accurate - 4 feet wide, 4 inches thick and made of steel - then it would weigh about 900 kg (a lower weight is possible if the dimensions are inaccurate or if it was not of uniform thickness). A velocity of 6 times Earth’s escape velocity (67 km/sec, since escape velocity is 11.2 km/sec) would give the plate a kinetic energy 60% larger than the total energy released by the explosion. This is clearly impossible.
Brownlee explained to this author, by email, that the concrete plug placed in close proximity to the bomb was vaporized by the explosion. Thus the propulsion of the plate could be considered to be due to the energy imparted by this expanding vaporized material, rather like the propellant of a gun. From the descriptions available of the plug a mass of at least 3000 kg can be estimated, and if half the bomb’s energy were deposited in it then it would have an energy density of 50 times that of normal gun propellant. From the physics of high velocity guns, it can be estimated that velocities produced by the gas expanding up the long shaft could propel and object to velocities exceeding Earth’s escape velocity, perhaps as much as twice escape velocity
Sure, for a minute or two maybe. But without continual propulsion that thing is gonna slow down to well under escape velocity long before it reaches anything close to orbit. Then it’s just a dumb ballistic missile.
Or should that be, ballistic projectile?
And if it did, falling at terminal velocity either intact or as a rain of molten metal, wouldn't it have buried itself deep in the sands? It would be an interesting experiment to deliberately drop a manhole cover over the desert from the estimated height (less than 100 miles, the Space Shuttle goes much higher) and track what happens to it.
Well its based on the Project Orion.Nuclear pulse propulsion is a proposed method of spacecraft propulsion that uses nuclear explosions for thrust. It was first developed as Project Orion by DARPA, after a suggestion by Stanislaw Ulam in 1947.
Thanks for explaining.
I believe on of the scientists saw it on a frame of a high speed film and it was gone the next. If it came down somebody would have reported it.
Thank you very much for the suggestion. I will order it tonight.
Thinking of Harry Reid at this moment.
If you’re at “escape velocity” you have enough KE to leave the influence of the gravity well in question. Values less than that specified for the given well can result in either falling back down or an orbit...
At that velocity, wouldn’t it have burned up in the earth’s atmosphere like a meteor?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.